(But it does come with this awesome sexy rat drawing from MysticGaia, used with permission of the artist)

Advokat C, Lane SM, Luo C. “College students with and without ADHD: comparison of self-report of medication usage, study habits, and academic achievement.” J Atten Disord. 2011 Nov;15(8):656-66. Epub 2010 Aug 2.

Sibley MH, Smith BH, Evans SW, Pelham WE, Gnagy EM. “Treatment Response to an Intensive Summer Treatment Program for Adolescents With ADHD.” J Atten Disord. 2012 Mar 16. [Epub ahead of print]

Fassbender C, Schweitzer JB, Cortes CR, Tagamets MA, Windsor TA, Reeves GM, Gullapalli R. “Working memory in attention deficit/hyperactivity disorder is characterized by a lack of specialization of brain function.” PLoS One. 2011;6(11):e27240. Epub 2011 Nov 10.

For statistics on ADHD diagnosis and treatment, see rates at the CDC.

(I can’t wait til Jonathan Coulton writes a song about the epigenome)

One of the most interesting things about the epigenome is that you can pass it along in the germline. To your kids. So in theory, if you had methylation in certain parts of your genome, your kids could as well. But we’re starting to realize that epigenetics is more malleable than that.

Take muscle tissue for instance. Gene expression in muscle tissue can change the efficiency of glucose metabolism by muscle. And glucose metabolism has a very large effect on many bodily processes, include weight gain and problems like cardiovascular disease and type II diabetes. Muscle itself is very plastic, and responds quickly to changes in the environment (which for a muscle, means increases and decreases in exercise or how many calories are getting in). We know that exercise can change gene expression in muscle, but can it also change the epigenome? While immediate changes in gene expression can be very short, changes to the epigenome indicate much longer-term changes. Could bouts of exercise influence the methylation of muscle, and thus have long-term effects?

Barres et al. “Acute Exercise Remodels Promoter Methylation in Human Skeletal Muscle” Cell Metabolism, 2012.

The cool thing is that the authors of this study were able to do large sections of this study in humans. Humans, at least, who did not object to getting muscle biopsies.

They took 14 sedentary humans and had them exercise to fatigue (a pretty difficult exercise bout). They biopsied the muscles before and after the exercise, and looked to see what the methylation in the muscle looked like.

What you can see here is that the acute bout of exercise decreased the methylation in the muscle tissue. When they looked a little closer, the authors found that the methylation was particularly decreased in the promotor regions of metabolically related genes. Many of these promotor regions, which directly control the expression of a gene, show changes in methylation during type II diabetes. After exercise the methylation in these promotor regions was decreased, which could result in more gene expression of those genes, and thus result in changes in metabolism.

Further studies showed that this change in methylation depended on exercise intensity. In a group of mice exposed to low or high intensity exercise, only the high intensity produced the gene methylation changes seen in humans.

So we know that exercise is changing DNA methylation (and that this can be changed in response to a single acute bout of exercise), but what is the mechanism? The authors hypothesized that it might have to do with changes in calcium influx into the muscle cells starting an activation of activities leading to changes in methylation. So they applied caffeine to cells in culture. While pharmacologists like me usually think of caffeine as an adenosine receptor antagonist, in muscle cells it can increase calcium influx into the cell. And they found that caffeine application had the same effect that acute exercise did, reducing methylation and changing gene expression. If the authors used another drug (dantrolene) to block the calcium influx, they could block the effects of caffeine (whether caffeine works this way during human consumption? I don’t know, the effects would probably be a good bit milder than those on cells in a dish, to say the least).

We know that increases in methylation in muscle cells are associated with things like insulin resistance, so it’s possible that decreases in methylation could explain some of the protective effects of exercise. And it’s very interesting to see that the authors got changes in methylation after a single exercise exposure. Of course, it would interesting to see if these changes persist with chronic exercise, and whether caffeine ingestion in humans in normal amounts produces similar changes, but I imagine maybe the humans in these studies weren’t up for the biopsies. But it’s an interesting study, helping us begin to see how changes in the epigenome, caused by changes in our own behaviors, might begin to impact our health in the long term. It makes me want to go for a workout.

Barrès, R., Yan, J., Egan, B., Treebak, J., Rasmussen, M., Fritz, T., Caidahl, K., Krook, A., O’Gorman, D., & Zierath, J. (2012). Acute Exercise Remodels Promoter Methylation in Human Skeletal Muscle Cell Metabolism, 15 (3), 405-411 DOI: 10.1016/j.cmet.2012.01.001

Today’s Friday Weird Science is up at Neurotic Physiology, where I’m talking about a recent study in Scandinavia. The authors walked up to some bears. Repeatedly. Without wearing body armor or anything! FOR SCIENCE. That, my friends is dedication. Head over and check it out!

Reader David sent me this paper the other day, and asked if I could blog about it. I said ok, maybe, and then I read…

…”Gene therapy”…

…oooooh…

Sounds very cool, doesn’t it? Sounds like the FUTURE! Where’s my JETPACK!!!?!?!

But of course “gene therapy” is kind of a buzzword. A lot of people throw it around, but it seems like a lot of people don’t know what it really MEANS, and what it can be used for.

But it turns out, it can be used for quite a lot! And it may not be quite so far in the future. After all, they’re marketing jetpacks.

Alexander et al. “Reversal of Depressed Behaviors in Mice by p11 Gene Therapy in the Nucleus Accumbens” Science Translational Medicine, 2010.

So let’s start with gene therapy and what it is, and then we’ll go into why they used it in this particular paper. Gene therapy is based on the idea of inserting a gene into someone’s genome, either in the whole body or in specific parts, to change the gene expression of that cell or group of cells, and to use this technology to treat disease. In this case, what we’re talking about is viral-mediated gene expression. This is where we use a virus (for our own nefarious purposes mwah-ha-ha-ha!!), take out the nasty bits of the viral DNA, and load the virus with the gene you want to express. You then inject the virus into your area of interest (normally this is really site specific), and the virus, using its own virusy ways, will insert your gene of interest into your area of interest. The gene will get incorporated into the genome, and get expressed by your cells!

Like So.

This is a really useful technique that is now being widely used in a lot of fields, including neuroscience. You can insert genes to increase expression of a specific protein, OR use genes that DECREASE expression of that protein. So it allows you to carefully and selectively look at a specific thing in a specific brain region (in neuroscience, anyway).

Now we’ve got gene therapy, what about p11?

p11 is a relatively new protein on the depression scene (I think the original paper was only as early as 2006), but the effects got everyone excited. p11 is a protein that controls the expression of two serotonin receptors. Serotonin is thought to be one of the major players in mood disorders like depression (while selective serotonin reuptake inhibitors may not work in many patients, this doesn’t mean that serotonin isn’t playing a role, it’s the role that it’s playing that’s up for debate), and so the consequences of p11 became suddenly interesting. And it turned out that mice with a knockout of the p11 gene displayed what we call a depressive phenotype, where they show more immobility (which used to be called behavioral despair, but now we don’t think that’s accurate) in tests such as the forced swim test and the tail suspension test, tests which are sensitive to the effects of antidepressants.

The thing is though, that these p11 knockout mice have p11 knocked out EVERYWHERE. That’s some big changes, and they are also changes that exist during the whole of the mouse’s life, and so could affect a lot of other things. In order to really narrow down what p11 is doing and where it is most important in depression, the authors of this paper wanted to take a normal mouse, and change p11, in very specific brain regions.

The two brain regions they picked were the nucleus accumbens (they abbreviate it NAcc, but I hate that, I prefer NAc, because to me NAcc means the NAc CORE, but whatever) and the anterior cingulate cortex. The nucleus accumbens is a brain area located here:

I blog about it a lot because it’s thought to be involved in the rewarding and reinforcing properties of drugs like cocaine. But many people have thought that it could ALSO be involved in some of the issues associated with depression, specifically things like anhedonia, which is a lack of the ability to feel pleasure, and thus very closely related to things like reward.

The anterior cingulate cortex on the other hand, is located here:

They are interested in the anterior cingulate cortex because a HUMAN study found that depressed humans had lower levels of p11 in the anterior cingulate cortex.

So what did they find? Let’s start with the NAc.

Pretty, huh?

To start with, they used a virus to insert a gene into the NAc which knocked DOWN p11 in normal mice, only in the NAc. All of the pretty glowy pictures there are of them proving that they can do that. What we are interested in is the three graphs at the bottom (the bar graphs), which all show immobility. These are immobility measures in the tail suspension test and the forced swim test. The first two (left and middle) show that mice with a knockdown of p11 only in the NAc show increases in immobility in these tests, which indicate a pro-depressive phenotype. The graph on the right shows treatment with imipramine, an antidepressant, and shows that the antidepressant still exerts some effects when p11 is knocked out. So it looks like, so far, that these mice are more “depressed”, but that the still respond to antidepressants.

So then the question is, can ADDING p11 rescue a “depressed” mouse? To do this, they used p11 knockout mice, that had had p11 knocked out all their lives, and this time used the viral vector to INCREASE p11 in the NAc. When they increased p11, they got a reversal of the “depressive” effects seen in p11 knockout mice. These mice showed more swimming in the forced swim test, more struggling in the tail suspension test, and even showed increased sucrose preference (which is through to be a measure of anhedonia). You can see all that here:

The diagonal bars show the animals that had p11 increased. The sets of bars on the right are the p11 knockouts, and you can see they show longer immobility, until the p11 is increased in the diagonal bars.

But of course, all this stuff was in mice. How does this relate to HUMANS?

They looked at human post-mortem tissue (that’s dead) from depressed and control patients, and they tested each NAc for p11.

Looks nice, yeah?! The depressed patients showed a DECREASE in p11 in the NAc (which is comparable in the mice to knocking down p11 in that area, as shown in the first set of figures).

They WERE going to look at the anterior cingulate, but it all got shoved to the supplemental data because there was no difference (and I had to hunt around for that little sentence. Stupid supplemental data!). But that’s ok.

So this all lines up, and it all looks pretty nice. Sci likes this paper, it’s neatly done, and they nicely knock something down specifically, increase it specifically, and look at behavior as a consequence. Good and thorough. But the question is: now what? p11 controls the expression of two serotonin receptors (the 5-HT1B and the 5-HT4). Which of these receptors is undergoing the changes from lack of p11 that is causing the depressive phenotype? Is it both? Are they expressed in the NAc? Or do changes in p11 changes serotonin receptor expression elsewhere? Other brain areas like the hippocampus have been implicated in depression, and also in the actions of antidepressants, does p11 play a role there as well?

And once we’ve got this worked out, what are we going to do about it? It’s too much to ask to give a viral vector in the brain of every depressed person. In fact, we can’t really do that yet at all, it’s a very risky technology still (especially in brain). Are there drugs that increase p11? What about the specific receptors, the 5-HT1B and 5-HT4? 5-HT1B and 5-HT4 receptor activating drugs have been shown to be effective in animal antidepressant tests, but have never been developed. Should we develop those? Or go after p11? And of course, although there are studies showing p11 is lower in depressed patients, there are also studies out there showing that p11 isn’t really changed in depression, after all.

Ah, science, always with the more questions! But you keep an eye on p11, this little protein looks like it might have some potential.

Alexander B, Warner-Schmidt J, Eriksson T, Tamminga C, Arango-Llievano M, Ghose S, Vernov M, Stavarche M, Musatov S, Flajolet M, Svenningsson P, Greengard P, & Kaplitt MG (2010). Reversal of Depressed Behaviors in Mice by p11 Gene Therapy in the Nucleus Accumbens. Science translational medicine, 2 (54) PMID: 20962330

But it this study, at least, it looks like diet-induced obesity might produce depressive-like effects in mice. But how the diet is doing that is not so well defined.

Sharma and Fulton. “Diet-induced obesity promotes depressive-like behaviour that is associated with neural adaptations in brain reward circuitry” International Journal of Obesity, 2012.

(Source)

Several studies in humans have found a correlation between obesity and the development of depression. But it’s important to keep in mind that correlation is not causation. Many people who become obese also have other things going on (socioeconomic status, family history, comorbid disorders) which can influence the development of depression. In order to determine if obesity itself is causing depression, you first have to deliberately cause obesity in a controlled population.

And this is where mice come in. Using a specialty high fat and high sugar diet, Sharma and Fulton fed up a set of mice for 12 weeks, until they were significantly fatter than control mice. They then looked at behavioral tests for anxiety and depression.

(Click to embiggen)

What you can see above are different behavioral tests. The top two panels represent the elevated plus maze, a plus shaped design with two open arms and two closed arms. Mice prefer to stay in the closed arms of the maze, because they prefer darkness and small spaces. The more anxious a mouse is, the more time he will spend in the closed arms. In this case, the mice fed on a high-fat diet spent more time in the closed arms of the maze.

In the second set of bars, the open field, the findings were similar. The mouse is placed in a large open field. He will usually stay out of the center, preferring the more protected edges and corners. The more anxious a mouse is, the more he will stay to the edges of the field. Again, the high-fat diet mice stayed on the edges more than normal mice suggesting that high-fat diets make mice more anxious.

However, anxiety tests are not depression. For their main depression measure (the bottom set of bars), the authors used the forced swim test, where a mouse is placed in a bucket of water and swims for a few minutes. After a while it will realize it can’t get out and begin to float, a sign of “behavioral despair”. Mice given antidepressants will swim more and float less, and mice showing depressive-like behavior will float more. In this case, the high fat diet mice floated more than control mice, which the authors suggest is depressive like behavior.

High-fat diet mice showed other alterations as well. Depressive-like behavior has been correlated in the past with changes in stress-responses, so the authors looked at the stress hormone corticosterone (which is cortisol in humans). High-fat diet mice showed slightly higher corticosterone, but much higher levels after stress, suggesting that they may be more sensitive to stress than normal mice.

The authors also looked at alterations in reward pathways like the nucleus accumbens and striatum, and found significant changes. Though changes in these areas are not usually correlated with depressive-like behavior, they have been shown in other high fat studies and are thought to relate to differences in how animals eating high fat diets process rewards.

From these data the authors conclude that their high-fat diet obesity produced depressive-like behavior. And while I think the preliminary data has potential, I also think there could be improvements.

First off, they did not look at other tests of depressive-like behavior in mice, such as sucrose drinking or novelty-induced hypophagia. The forced swim test could be confounded by the fact that fat mice might have a harder time swimming.

Secondly, I would have liked to see more work done in areas which are known to be correlated with depressive-like behavior. For example, chronic stress is associated with depressive-like behavior and decreases in neurogenesis, something which can be improved with antidepressants. Does a high-fat diet produce decreases in neurogenesis? Changes in reward-related areas are fine, but that’s only one aspect, and not really what people focus on for depressive-like behavior.

Third, I think I would like to see this study performed…before the mice are fat. They gave the diet for 12 weeks and got fat mice, and that’s fine, but this diet also begins to produce things like insulin resistance typical of type 2 diabetes. And previous studies have shown that type 2 diabetes is also associated with depressive-like behavior, which could influence their results. I wonder what would happen after 6 weeks of high fat diet, when they’ve had plenty of exposure but aren’t yet obese?

Finally, like any good scientist, I wonder: what is the mechanism? HOW exactly does a high fat diet or obesity lead to depressive behavior? Is it the corticosterone and stress levels? If so, how is a high fat diet influencing the HPA axis? If not, what else is changing? Dopaminergic systems and reward are nice but are certainly not the whole story. Future studies will have to tell. But it does make me wonder what a high fat and high sugar diet might be doing, and what exactly is going on.

Sharma, S., & Fulton, S. (2012). Diet-induced obesity promotes depressive-like behaviour that is associated with neural adaptations in brain reward circuitry International Journal of Obesity DOI: 10.1038/ijo.2012.48

There’s very little that’s more serious than a heart attack. Otherwise known as a myocardial infarction (MI), a heart attack is a loss of blood flow to the heart. When there isn’t enough blood flow to the heart, the heart muscles do not receive enough oxygen, and heart cells begin to die and lose their ability to pump in rhythm.

In the past, the vast majority of people who suffered from a heart attack would die. But now advances in modern medicine have enabled many people to continue for years following MI. So we are not only concerned with survival of heart attack, we are also concerned with recovery, what can help recovery and make it faster, or reduce the severity of the heart attack in the first place.

And as Haar et al, from the University of Cincinnati College of Medicine have found, sometimes what’s bad for you might not be so bad for your heart, at least, in small doses. Haar has been looking at the effects of a high-fat diet on MI outcomes in mice. She previously found that short-term high-fat diets in mice (between 24 hours and two weeks of exposure, but not longer, otherwise you get some very fat mice), produced protection during a heart attack. When she induced an experimental heart attack in mice, mice that had been treated with a high fat diet for a short period of time showed reduced damage when compared to control mice. Haar also showed that 24 hours worth of high-fat diet produces protection for about 24 hours afterward, but not 48 hours (a double cheeseburger every other day, then?).

All this is well and good, but the important question is asking how does this protection work? Haar and her colleagues hypothesize that a high-fat diet can shift the damage balance in the heart from apoptosis (cell death) to autophagy (a shifting of cellular energy resources), and they hypothesize that an important molecule involved is NF-kappaB.

NF-kappaB (nuclear factor kappa-light-chain-enhancer of activated B cells), is a protein complex which affects the transcription of DNA, and could have widespread effects on how cells function under stress. To examine the role of NF-kappaB in the high-fat protection from MI, Haar took a group of dominant-negative mice, animals which specifically fail to activate NF-kappaB in the heart. She fed some of them on a high-fat diet, gave them all a heart attack, and looked to see if the protective effects of the high-fat diet were still present. In the NF-kappaB dominant negative mice, the injury size following MI was larger, and the high-fat diet failed to protect the mice from the effects.

But NF-kappaB affects a lot of genes, what specifically was going on? It appears that the heart cells are not dying at the same rates in mice on a high-fat diet, Haar saw fewer markers of apoptosis in the high-fat group. To see if the cells were instead undergoing autophagy, she looked at the marker Beclin-1. Beclin-1 is a marker for autophagy, a way to show that cells are reallocating their resources to preserve function, rather than dying in response to the severe stress of the MI. And it turns out that a high-fat diet increases the expression of Beclin-1 in the damage zone of mice having a heart attack. Not only that, this increase is blunted in the dominant negative NF-kappaB mice following heart attack, showing that NF-kappaB may be controlling the increase of Beclin-1. This means that high-fat diets are shifting the balance of the heart from apoptosis to autophagy, allowing the heart to suffer less damage during heart attack.

Of course, it’s not a good idea to go eat a double-cheeseburger in perfect comfort. After all, people who habitually eat high fat diets are at a much greater risk for heart attack in the first place. But it’s an interesting look into how the heart can protect itself, and may mean new potentials for treatment in those who suffer heart attack. And maybe you don’t have to feel quite so guilty about the high-fat food, if you only have it once in a while.

When most scientists think of how we might study drug response, we usually think of rats or monkeys or mice, pressing levers to deliver drug, or showing different behaviors in response to treatments. Sometimes we will see studies on flies (http://arstechnica.com/science/news/2012/03/a-lack-of-sex-drives-flies-to-drink.ars). But what about fish? Specifically, zebrafish?

Zebrafish are a pretty attractive model for scientific research. They have a completely sequenced genome, a series of easily observed and modified behaviors, and they are cheap(er) than rodent or primate models. And it’s easy enough to test the effects of different drugs: just pour some into the tank and watch what happens, a much less stressful form of administration than having to inject a mammal.

There are already studies out there in zebrafish using cocaine (http://www.ncbi.nlm.nih.gov/pubmed/18499199) and morphine (http://www.ncbi.nlm.nih.gov/pubmed/22205946). Allan Kalueff’s lab at Tulane University is interested in hallucinogens, drugs like that mescaline and psilocybin. In particular they looked at mescaline, a drug derived from the peyote cactus, psilocybin, a drug derived from mushrooms, and phencyclidine (PCP), a drug that was once developed as an anesthetic, but has powerful hallucinogenic properties. Mescaline and psilocybin act at receptors for the neurotransmitter serotonin (http://scientopia.org/blogs/scicurious/2010/08/25/back-to-basics-3-depression-post-4-the-serotonin-system/), and PCP has its mechanism of action via the glutamate system (http://en.wikipedia.org/wiki/Phencyclidine). All three of them are powerful hallucinogenic drugs. And while you can’t tell if a zebrafish is seeing things, their easily classified behaviors can be used to examine similarities and differences between drugs, and help to understand their mechanisms of action.

So Collins, a student in Kalueff’s laboratory, has given zebrafish various doses of hallucinogens, and looked at how the fish behave. He started with the novel tank test, where you put a single fish in a novel tank with drug or saline. When the fish are exposed to a novel tank, they immediately swim to the bottom, and start to swim to the post as they get more comfortable, a measure of anxiety-like behavior. But with PCP or mescaline, the fish swam to the top of the tank more quickly than control fish, suggesting that they had decreased anxiety. Fish on PCP also showed more erratic swimming behavior. Collins also looked at social behavior in the shoaling test. Zebrafish are social, and like to shoal together, but will show differences in social behavior in response to different drugs. When Collins gave the fish mescaline, the fish appeared to be more social, showing decreases in inter-fish distance. Psilocybin and PCP also produced increases in the stress hormone cortisol.

By looking at the effects of hallucinogenic drugs in fish behaviors , Kalueff’s lab hopes to use the zebrafish as a model to understand the mechanisms behind drug-induced behaviors, and help us to understand how these very complicated drugs have their effects. Not only that, hallucinogenic drugs are often used to model psychiatric disorders like schizophrenia. So some day, zebrafish on PCP might provide the key to some complicated disorders.

When we think about cancer, what we usually think about is a cure. Science has made great strides in treatments for cancer, such as chemotherapy, radiation, and surgery. Some cancers, such as breast cancer and childhood leukemia, have 90% survival rates, and survival is always a cause for celebration.

But with the success cancer treatments, questions arise after the celebration. What are the long-term effects of chemotherapy? How will someone’s quality of life be impacted after the cancer? These are important questions to ask. Chemotherapy has many side effects immediately after delivery; everyone knows about the nausea, vomiting, and headaches. But there are also consequences of chemotherapy in the long term, including cognitive dysfunction. Patients who have been treated with chemotherapy for leukemia as children suffer from increased medical complications, poor academic outcomes, and impairments in executive brain function such as working memory and attention. Adult women who have been treated with chemotherapy for breast cancer show problems with memory performance, which correlates with brain changes included decreased volume in areas like superior frontal gyrus and parahippocampal gyrus, important areas for learning and memory.

How do we go about trying to help people with this cognitive dysfunction? The usual “cognitive enhancers” like Ritalin may work, though they might have a larger side effect profile in some people who have undergone chemo, and Modafanil also shows promise. Erithropoetin works during chemotherapy, but what about later? But the real issue is not treatment, it’s know why people who undergo chemotherapy have long-term cognitive dysfunction. How does it occur? What does it mean?

If we are going to help the cognitive dysfunction that occurs after chemotherapy, we need to find ways to study it. There are many potential confounds. First, there are the confounds associated with cancer itself: fatigue, the effects of surgery, elevated cytokines and other inflammatory markers. Chemotherapy drugs are often given in batches, and the combinations are often changed. There are many things that could confound how much cognitive impairment cancer patients experience. In order to try and get around the many confounds associated with studying the cognitive effects of chemotherapy in humans, Ellen Walker and her group at Temple University are looking at the effects of chemotherapy drugs in mice, looking in particular at adults, and at juvenile mice treated with chemotherapy.

First, the group looked at adult female mice doing an operant task, putting their noses into a nosepoke hole to receive food. The animals learn the task on the first day, and are back into the test the second day, to see how well they recall what they learned.

Walker and her group found that chemotherapy drugs like paclitaxel, carboplatin, and 5-Fluorouracil disrupted the performance of the mice, and the effects were not dose dependent. In a dose-dependent response, the learning deficits would get worse as the dose increased, but in this case, the effects of learning were actually worse at lower doses of carboplatin, meaning that we can’t just lower the dose to try and prevent the effects of cognitive impairment.

Walker et al also wanted to look at the effects of chemotherapy in a childhood model. So they looked a young mice treated with the chemotherapy drugs mexthotrexate or cytarabine individually and in combination during development, carefully mimicking the doses used in humans. Then they tested the mice in a cognitive test called ‘novel object recognition’ when they were adults. Novel object is fairly simple, you give a mouse a single object on the first day, which it explores and gets to know. On the second day, you give it the first object, and a second, unknown object. This makes the mouse discriminate between an object it has seen before and one it hasn’t. Mice treated with methotrexate or cytarabine showed deficits in novel object discrimination, suggesting that being treated with chemotherapy drugs during development resulted in cognitive deficits, similar to those seen in humans.

And the changes went further than cognitive deficits. The mice treated with chemotherapy during development also showed more sensitivity to the rewarding properties of amphetamine (spending more time in drug paired environments).

By developing models of chemotherapy treatment in mice, Walker et al hope to understand the mechanisms that might underlie the cognitive dysfunctions seen in humans. Then, they hope to find ways to help, and help cancer survivors experience their new lease on life without some of the problems that might go with it.

We are always looking for new cancer treatments. Each type of cancer is different, from breast cancer to lung cancer or pancreatic, and there are also different subtypes of cancers within each type of cancer. Your breast cancer can be estrogen receptor positive or negative, and this can drastically effect what kind of treatments may work best. And new treatments can come from the oddest places.

In this case, the odd new treatment is a chemical called Dif-1, a chemical usually found in the slime mold Dictyostelium discoideum. (http://en.wikipedia.org/wiki/Slime_mold).

In the slime mold, Dif-1 is a morphogen, a chemical that controls the path of cellular development. In Dichty, Dif-1 causes reproductive stalk formation. But it may do more than that. Other laboratories have reported that Dif-1 might have anticancer properties, stopping cancer cells from proliferating (Mori, 2005: http://www.ncbi.nlm.nih.gov/pubmed/16153639, Gokan, 2005: http://www.ncbi.nlm.nih.gov/pubmed?term=dif-1%20gokan%202005). In this study, Bratton et al from Tulane University wanted to investigate how, exactly, Dif-1 might be acting to inhibit cancer cell proliferation. They hypothesized that the estrogen receptor might be involved.

To look at this, Bratton et al examined the activity of Dif-1 in a line of breast cancer cells (MCF-7) that express the estrogen receptors alpha and beta. In general, cells with estrogen receptors will proliferate in response to estrogen. So you can plate cells, add estrogen, and watch the cells grow. But when Bratton added Dif-1 to these cells, they found that the effects of estrogen were blocked, the cells could not proliferate. It looks like Dif-1 inhibits breast cancer cell proliferation, perhaps via an estrogen receptor based mechanism.

But how was this working? Bratton et al used a luciferase assay, which allows you to link a luminescent protein to a piece of DNA to which the ER binds.. When there is more active ER protein, you get more glow. In the presence of estrogen, the ER alpha receptor was activated, resulting in a bright glow, but not in the presence of Dif-1.

And the inhibition of estrogen receptors went further, estrogen receptor mRNA expression was down and downstream proteins like the progesterone receptor also showed decreased expression in the presence of Dif-1. But it doesn’t seem like Dif-1 is having its effects by directly inhibiting the estrogen receptor. If that were the case, estrogen receptor mRNA levels would not be affected. So where is Dif-1 acting? Bratton et al discovered that Dif-1 is acting at the promotor region of the estrogen receptor gene, which can control whether or not the gene is transcribed to mRNA. By interacting with the promotor (either directly or by activating a promoter binding protein), Dif-1 can repress gene transcription activity. When estrogen receptor mRNA is repressed, you get reduced amounts of estrogen receptor protein. And with less estrogen receptor, breast cancer cells cannot grow as well in response to estrogen. This could be how Dif-1 is working to prevent the growth of breast cancer cells, and it could be another way to treat certain types of breast cancer which depend on estrogen receptor alpha expression. Not too bad for a chemical from a slime mold!

Drug addiction is a vicious cycle, but the original high is not the problem. What is the problem are the changes in our brains and behavior that drive us to seek the next high, and the next. The relationship between drug-taking and the resulting high is what behavioral pharmacologists refer to as “reinforcement”. And if we are able to alter the reinforcing value of a drug, how much we desire to get that next hit, we might be able to help addicts overcome their addictions.

There are various methods that pharmacologists have tried over the years to decrease the reinforcing value of drugs in experimental situations. You can accompany a drug with an antagonist that blocks the drug effects, like combining heroin with naltrexone so that an addict attempting to take the drug cannot get high. This blocks the high, but people can always try to take more drug to overcome the antagonist effects. Another method is using long-acting, low dose drugs as replacements, such as methadone, to block the withdrawal of from drugs such as heroin or morphine. But again, people can always take more drug on top of it. Finally, there is the idea of using drug punishment. In this paradigm, you use a drug that induces nasty effects, like nausea or pain, in conjunction with the abused drug, to make people stop taking the drug. We call this paradigm a “drug punisher”.

This is the idea that Kevin Freeman, Brian McMaster, and William Woolverton of the University of Mississippi Medical Center, in their presentation at the Experimental Biology 2012 Behavioral Pharmacology meeting, have decided to work with in cocaine using rhesus monkeys. They trained the monkeys to self-administer cocaine by pressing a lever, which delivered a shot of cocaine into the monkey’s veins. This method, known as drug self-administration, can be used to study the maximum rewarding value that animals place on a drug, and how other drugs or environmental changes might be used to stop the animal from taking the drug. In this case, the authors wanted to study in particular the reinforcing value of cocaine, and how a drug punisher might change it. They put the monkeys on a special schedule of drug self-administration called a progressive ratio (PR). The monkey begins slowly, say having to press the lever only 5 times before it receives some cocaine. But after a short time of this, the requirements increase. Now the animal has to press 10 times. Then 50, then 100. At some point, it’s just too much work, and the monkey will give up, and stop pressing. Freeman et al. used this paradigm to determine how much ‘value’ an animal placed on the cocaine injection. They then set about trying to decrease that value using histamine.

Why histamine? You might be familiar with histamine as something involved in allergic responses, but it also is a punisher. It suppresses a lot of behaviors, including food self-administration. And in this case, adding histamine to cocaine self-administration made the monkeys ‘value’ the drug less. It also decreased the potency of cocaine as a reinforcer, the monkey ‘valued’ the drug less at low doses and lever-pressed for it less, showing that histamine as a drug punisher could decreasing the reinforcing value of the cocaine. And the effects of histamine on cocaine self-administration were dose-dependent, with low doses of the drug producing very little effect on how hard the monkeys worked for cocaine, while higher doses decreased cocaine’s reinforcing effects.

What can we do with this knowledge? After all, some punishment drugs have been tried before. Disulfuram, otherwise known as antabuse, is a punisher that creates severe nausea when even a small amount of alcohol is consumed. Unfortunately, it doesn’t work particularly well in alcoholics, who simply avoid taking the drug. But this is not what Freeman wants to do with the results of this research. Instead, he envisions eventually using drug punishers in combination with drugs before they are abused. If you combine an opioid painkiller with a low dose of drug punisher, for example, you could have the painkilling effects of the drug with no effects of punishment. But if you go on to try and get high off the drug by taking a lot of it, the dose of the punisher could become high enough to make you regret your choice. This may be able to stop recreational use of prescription drugs, and the accompanying reinforcement, before the habit develops.

But when I thought about it a bit more, I realized that in fact, my blogging has done a great deal to influence the way I think about science, and has helped me a great deal in my career. It’s just been doing its work behind the scenes.

First, blogging has been a great way for me to read widely. I first started my blog as an effort to convey science to the public, and of course, to keep up on my reading of the literature. But it also allowed me to read outside of my field, and exposed me to very different ideas than I encounter in my daily life as a scientist. When you are in one laboratory, seeing the science from one angle, for years at a time, it becomes harder to see that other scientists in slightly different fields have a very different view than you do. Reading outside of my field exposes me to different ideas, and makes me think in a very different way. I now try to synthesize my own work with the big picture of the field rather that getting twisted up in the details. In addition, writing about other people’s science, dissecting it carefully and looking for issues, as I would do during a Journal Club in my department, is not only good practice for reading papers with a skeptical eye, it also helps me plan my own papers and projects, trying to see the weaknesses and where they can be improved. While I get some practice with paper reviewing like this in my day to day life, my science blogging has given me far more experience.

Secondly, blogging has been good for my networking. Not because I can make a lot of connections with my pseudonym (though there have been a few). Rather, it’s because blogging, and the success I have had with it, have given me the confidence to approach people when I need to. It has helped me to believe I really can do things when I put my mind to them, that I am smart, and that my ideas are worth listening to. This can mean a lot when imposter syndrome strikes.

And finally, and possibly most importantly, my involvement with social media has helped my career in the blogs and tweets that I READ. Reading blogs by academics who are in more advanced stages of their career has taught me a lot about what I really need to do to get where they are. It’s taught me about the ins and outs of funding. It’s alerted me to issues in publishing that many (I would say most) people in my situation have no idea of. It’s given me new insights into writing papers, designing grants, and shown me the many, many avenues for PhD’s that are available outside of academia. Most of the benefit I have found has been in the reading, rather than the writing.

So even if you can’t write under your own name, social media can still help you in your career. Blogging and reading science is always a good learning experience that can influence your own work, and anything that can boost your confidence is always good fuel for networking! And even if you just lurk on social media, you can learn a lot, just from reading the work of other people who have been there.

But what about other people who use social media and science? What has it helped them with? To find out, you’ll have to join us at the Tweetup! Hope to see you there!

Last week, the New York Times’ “Well” section ran a piece titled, “How Exercise Can Prime the Brain for Addiction.” Scary, right? One minute you’re cruising along on the treadmill, and next thing you know, you’re ADDICTED TO COCAINE. Hovering over the web page tab header, however, reveals what may have been the original title—the more qualified, but less provocative “How Exercise May Make Addictions Better, or Worse.”

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Ironically, it’s the cutting-room-floor version of the title that more accurately (but only marginally so) reflects the findings of Mustroph et al (2012), an Illinois-based research group who studied the influence of exercise on the learning processes associated with drug use. In a nutshell, the researchers showed that the timing of exercise and drug exposure mattered: animals that exercised after getting a few injections of cocaine had an easier time “letting go” of their drug-associated cues than animals that exercised before cocaine exposure did. What Mustroph et al were not studying, though, was addiction—and this is only the beginning of where NYT writer Gretchen Reynolds does a disappointingly poor job of science reporting.

This paper is about learning. With every experience we have, we learn something about the circumstances in which that experience occurred, and experience with drugs is no different. If you always do drugs in a certain room of your house, or at one particular club, you’re going to start associating those places with the drug, and, in all likelihood, with the way the drug makes you feel. You might even enjoy hanging out in those places when you’re not using the drug, because of the positive associations you’ve formed.

This is the idea behind Conditioned Place Preference (CPP), a common test of context-drug associations in animals. An animal that experiences cocaine in one environment will choose to spend time in that environment later on, even if its system is drug free at the time. But as Reynolds describes it, “If a rodent returns to and stubbornly plants itself in a particular place where it has received a drug or other pleasurable experience, then the researchers conclude that the animal has become habituated.” She goes on, “All of the mice had, essentially, become addicts.”

A couple of things are wrong here. 1) Why are we calling the mice “stubborn?” This anthropomorphizing is not actually reflective of cocaine-treated animals’ behavior in CPP, and is totally unnecessary for the purposes of the article. 2) “Habituated?” I do not think it means what you think it means. In behavioral neuroscience, “habituation” usually refers to the way in which an animal can get used to a certain environment—much like how you sleep better after a couple of nights in a new home. Here Reynolds appears to be confusing the process of acclimating the mice to the testing environment before the experiment begins with that of the actual testing. 3) What a preference for the location previously associated with cocaine demonstrates is exactly that—the mouse understands the association. That mouse is, in no possible definition of the word, an “addict.”

So then, what does it mean to be addicted to a drug? The DSM-IV criteria are easy enough to consult, and I can’t anywhere in there find the part where having four injections of cocaine makes you an addict. And yet, Reynolds refers to “cocaine-addicted mice” or the animals’ “addiction” over and over again throughout the article, when she just as easily could have said “cocaine-treated mice” or something similarly more accurate.

There are other inaccuracies, too; most egregious in my mind is a reference to the process of extinction as “forgetting.” In extinction, repeated exposure to the cues or contexts in the absence of the drug teaches the animal that it can’t expect drug in that environment anymore, and the animal will stop showing place preference. But as any recovering drug abuser will tell you (and as can be demonstrated in animals as well), the memories for a drug and its related cues are never forgotten—this is what makes relapses, or “falling off the wagon” so common. Instead, the animal learns that the predictive value of the environment has changed, and its behavior changes accordingly. This is a critical point of the study itself—the primary difference between experimental groups is in the way they to extinguish—and yet the significance of this finding gets lost in translation.

Now, why am I getting my panties in a twist over a couple of misappropriated scientific terms? Because people are smarter than this! Without interviewing both Ms. Reynolds and the study’s primary authors, it’s hard to know whether Reynolds did a bad job interpreting the science, or if the authors or public relations office “dumbed it down” for the journalist in a way that misrepresented their actual work (or a muddy combination of the two). But neither scientists nor science writers should shy away from telling the public what science is really about—and what the true implications of a given study may be, however less exciting they seem.

Do researchers want the public to find their work interesting? Yes! Do writers want people to read their articles? Naturally! But the people who read this article may have come away with the impression that exercising could make them more likely to become a cocaine addict, which is not at all the case. When scientific findings are overstated, oversimplified, or misinterpreted, neither the public nor scientists benefit.

Again, this paper was not about addiction, but learning—a distinction I’m willing to bet the average newspaper reader is able to make. So why was that so hard for the NYT to convey?

Mustroph, M., Stobaugh, D., Miller, D., DeYoung, E., & Rhodes, J. (2011). Wheel running can accelerate or delay extinction of conditioned place preference for cocaine in male C57BL/6J mice, depending on timing of wheel access European Journal of Neuroscience, 34 (7), 1161-1169 DOI: 10.1111/j.1460-9568.2011.07828.x

But perhaps I have emailed you, and asked to blog your poster, and perhaps you are considering emailing me about your latest and greatest work…and you pause. What IS this conference blogging, exactly? What is it for?

Well, look no further. Because this post (a re-post from my previous blogging of the Society for Neuroscience Meeting) is all about explaining what I’m planning for the conference, how I’m going to go about it, and what you can look forward to as a scientist when I blog your poster or talk. And because the more you know, the better prepared we will all be!

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I covered much of this information in a guest post over at the Science of Blogging, where I talked about tips for blogging a conference. But that post is from a blogger’s point of view, whereas this one will be from the perspective of you, the scientist.

So this is how it goes:

1. Over the next few days, I will either contact you, or you can contact me (scicurious at gmail) with your poster/presentation details. I will set up a time to come by your poster, and possibly also to meet with you for 30 minutes before or after your presentation.

2. If we meet up, I would like to hear from you about your work in detail. I will be reading the abstract that you submitted ahead of time, but If you could bring a copy of your poster or presentation (or send it ahead of time!) that would be wonderful! I will NOT use any of the graphs, tables, or images that you send in any post I may write up. What I will do is use your poster to give my my writing context and help me to remember and understand what we’ve talked about and the significance of your findings.

2a. If you are a student presenter (or heck, a postdoc!), you may want to bring your advisor along while we talk, if you are worried. Additionally, if your advisor requires credentials, let me know and I will provide them.

3. Once I’m done grilling you (gently!) about your work, I’ll head back, and start writing! I will try to get the post done before the next day.

4. And when the post is done…I will send it to you for any corrections that you may have. I have to use a fast turnaround time, so you may only have 12 hours to see and edit the work. If you have any edits, this is when you need to let me know!

5. Then the post goes live! I will send you a link to your work and you can share it with your world, put it on your lab website, whatever you want. If you didn’t get a chance to make edits before, you still can now, and if you have concerns, I will address them whenever I can.

And now you might be wondering, what is this for?? Well, aside from letting me take a good look at the latest and greatest science, I want to share it with the world. I want people to see what we scientists are doing and how we are doing it, and what it all means. The more people in general understand what we do, the more support we can get, and the more people can learn how their bodies work and what happens when things go wrong. And isn’t that a good thing?

So if you’re interested, send me your info! I am blogging all things Pharmacology this year, but other good science will always turn my head. I’d love to see what everyone has to offer!

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Social environment can have effects on your health. People (and animals) in bad social conditions are more susceptible to illness, and bad social situations can lead long term to issues like fertility or even survival. We’ve known about the correlation between social stress and health for a while, but most of what has been studied in humans about social environment and health has been correlational. You can’t really determine whether the social environment alone creates the problems. But if you have an animal model, it’s a lot easier to manipulate social environment, and to then look directly at the effects of social environment on various health measures. Using an animal model allows you not only to separate out social environment from other variables, it also allows you to look at mechanism, and try to see what changes in what areas produce the global susceptibility to illness and other problems associated with social stress.

In order to study the effects of social status directly, the authors Tung et al used a large colony of female rhesus monkeys. The monkeys are housed in small social groups of about 5. This becomes very important because monkeys will quickly organize themselves into strict social hierarchies, with one being most dominant, one being most subordinate, and the final three ranged in the middle. And there’s a simple way to control the hierarchy. Put one new monkey into an established group of four, and that one will usually end up at the low end of the totem pole. This means that you can control the social environment of the monkeys without issues of naturally dominant personalities (you might have been top in the old cage, but not anymore). And it means that you can use these social groups to look at the physical effects of social environment.

In this case, the authors were interested in the immune system, particularly peripheral blood mononuclear cells, which include things like white blood cells. They found a whole host of genes in these cells which varied in their transcription level as a function of social dominance.

Of these genes, the largest group were associated with immune system function. And the gene regulation varied as a function of social dominance, so much so that the authors could predict the rank of the monkeys in 80% of cases by their gene expression profile. And in cases where the social rank of a monkey changed during the experiment, the gene expression also changed, and again was predictive of the monkey’s social rank.

These changes in gene expression also went along with differences in the types of immune cells found in the monkeys’ bloodstreams (and which accounted for some of the differences in gene expression in the samples). Lower ranked monkeys showed lower levels of a type of immune cells called the CD8+ T cell, otherwise known as the killer T cells you might remember from your high school biology class. These are an important part of the immune response that can kill cells that have been infected with viruses, which gives a nice link between the social rank of the monkeys and the differences in illness susceptibility seen in previous studies in monkey and humans.

But changes in gene expression patterns are more the result of the social environment. They are not really the underlying mechanism. What is it that is changing in these cells which in turn changes the gene expression pattern? In this case, the appears to be gene methylation. Gene methylation (a type of epigenetic modifiction which is getting a lot of press these days) is when a methyl group is attached to a cytosine (part of the A, C, T, G of DNA) of a DNA strand. In most cases, this results in a decrease in the gene expression for that gene. Methylation is a changable process, and genes can be methylated or un-methylated in response to changes in the environment or physiology. In this case, they found different patterns of DNA methylation in high and low ranking monkeys, suggesting that changes in DNA methylation are responsible for the changes in gene expression, and thus immune function, that are found in high and low ranking animals.

These changes associated with gene expression and methylation mean that it’s the social dominance that changes the gene expression, rather than immune system gene expression playing a role in social dominance. Being at the bottom of the social totem pole really IS bad for your immune system. It will be interesting to see what role the stress of being the social subordinate (and it is a very stressful position, as seen in previous studies) plays in these changes in methylation and gene expression. And it also suggests that relieving social stress could really be good for your health, or at least, be good for your immune-related gene expression.

Tung, J., Barreiro, L., Johnson, Z., Hansen, K., Michopoulos, V., Toufexis, D., Michelini, K., Wilson, M., & Gilad, Y. (2012). Social environment is associated with gene regulatory variation in the rhesus macaque immune system Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1202734109

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Or at least, that’s what you’d think from all the headlines. “Want to cheer up? Stop eating junk food“, “Too much junk food can lead to depression“, “Sweets and fast food linked to depression“. And while this study did find that those who consume more fast food are more likely to be diagnosed with depression…correlation is not causation. Not only that, reading this study shows that there are many other possible correlations that need to be ruled out before we can say that it’s the fast food that’s really getting you down.

Sanchez-Villegas et al. “Fast-food and commercial baked goods consumption and the risk of depression” Public Health Nutrition, 2012.

The role of diet in the development of psychological disorders is starting to receive some attention. After all, it plays a role in so much else, and wouldn’t it be nice if we could just remove one thing from our diets and assured that everything would be ok?

The authors of this study hypothesized that fast food may be more than just bad for your body, it could also be bad for your mental health. They looked at a cohort of 8,964 participants, none of whom had a diagnosis of depression. They took the amount of fast food and commercial baked goods they ate at baseline, as well as other factors like the amount of healthy food, BMI, potential correlates of healthy lifestyle (leisure time vs active), employment status, hours worked, etc, etc. They then followed up with them for up to 6 years.

The authors found, after controlling for baseline BMI, leisure time, employment status, and potential healthy lifestyle factors and healthy food consumption, that people who ate more fast food were more likely to receive a diagnosis of depression in the 6 years followup than those who ate little to no fast food. With fast food there are a dose-response curve, with more fast food eaten correlated with higher rates of diagnosis. With commercial baked goods, they also found an association between consumption and depression diagnosis, though there was no dose effect. It appears as though the data are in: eating bad food means you’re at higher risk for depression.

Or is it? While I think the correlation is completely real, I also wonder what other things might be present that influence this correlation. For example, all they corrected for was employment status (employed vs not), not socioeconomic status, which is correlated heavily with both fast food consumption and mental illness diagnoses. They excluded diagnoses of comorbid disorders, but, and this is key, only at baseline. They only took the data on their BMI, comorbid disorders, etc, at the original point. And they then followed them out for two to six YEARS, without taking further data. Considering that comorbid disease is strongly correlated with depression, this would be good factor to control for, as people might develop comorbid disease and then depression. Not only that, they assessed intake of fast food and calories, again, only at baseline. Some of these diagnoses of depression were SIX YEARS following the start of the study, and who knows how much their diets may have changed.

In addition, the people more likely to be diagnosed with depression were also more likely to be smokers…and more likely to work 45/hours per week or more. This indicates a certain amount of stress in their lifestyles that might influence both the fast food consumption and the depression. High stress levels have been previously shown to increase the risk for depression, and they also correlate increased fast food consumption. They didn’t control for these factors and I wonder how much a high stress lifestyle influenced the results.

Finally, they didn’t actually call it fast food. The study was all self-report, and what they asked about was whether people ate sausages, burgers, and pizza. For baked goods they asked about muffins, doughnuts, croissants, and other commercial baked goods. The question is…how much of this was fast food? Did these people make some of these at home? Not only that, the authors hypothesize that it’s the trans fats and carbohydrates in these foods that correlate with the depressive symptoms, but there are many other sources of trans fats and carbohydrates, and there are plenty of carbohydrates in a healthy diet as well. There are also many other types of fast food (though apparently these are the ones consumed most often in Spain, where the study took place).

Don’t get me wrong, I believe this correlation. But correlation is not causation. I think it’s going to be a lot harder to prove that fast food causes depression, than to prove that things like higher BMI, higher stress levels, lower socioeconomic status, and other factors are correlated with fast food consumption AND with depression. But even though correlation is not causation, and fast food may not cause depression, there are probably enough reasons to put down that burger if you can.

Sánchez-Villegas, A., Toledo, E., de Irala, J., Ruiz-Canela, M., Pla-Vidal, J., & Martínez-González, M. (2011). Fast-food and commercial baked goods consumption and the risk of depression Public Health Nutrition, 15 (03), 424-432 DOI: 10.1017/S1368980011001856