Biopsych seminar 2020

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Gut-Brain Interactions: Buffington et al, Reber et al 2016

April 13 Papers (Buffington et. al, Reber et. al) I found this week’s papers to be quite novel in that they both proposed potential treatments for neurodevelopmental or psychiatric disorders that target bacterial or microbial abnormalities and how these give rise to certain behavioral and physical symptoms associated with the disorders. I thought this was a very unusual yet interesting approach, and as I have not previously studied the gut-brain axis, these papers offered me a fresh perspective on researching psychiatric and neurodevelopmental disorders. They were also unconventional in their focus of the physical symptoms that often accompany mental disorders, as this is not something that I have seen many other papers touch upon very much. Particularly, I was surprised by the Reber et al paper’s focus on the link between psychiatric disorders and inflammation in organs other than the brain, such as the colon, and the Buffington et al paper’s description of a relationship between ...

The papers for this week focused on the relationship between the gut and the brain, known as the gut-brain axis. This is a topic that interests me because I am currently taking Microbiology and we often discuss effects of a healthy and diverse human microbiome. It is commonly said that what you eat affects how you think and feel, but I was interested to explore some of the evidence behind this anecdote and the gut-brain connection. These papers as well as others demonstrate that the microbiome has influence over brain function and behavior, but it is clear that there is still a lot to be learned about this relationship. The first paper, Reber et al., studied how injecting mice with a heat-killed preparation Of M. vaccae, a non-pathogenic bacterium that lives in soil, protects against various negative stress-related outcomes. The researchers concluded that the immunization reduced the stress response, inflammation, and subordinate responses to a dominant ag...

Gut-Brain Interaction, Buffington & Reber

The Buffington and Reber papers both explored the effects of the gut microbiome on rodent behavior. Buffington et al studied how maternal high fat diets affected the social behavior of their offspring. Specifically, they identified one type of bacteria, L. reuteri, as a fundamental component of restoring normal social behaviors in mice with social deficits. Reber et al studied the bacteria, M. vaccae and how immunization with a heat-killed dose ameliorated stress responses in mice. After reading the Reber paper, I'm skeptical of the translatability of their results. We've discussed in class that it's difficult to model anxiety as we know it in rodents, and this paper, in my opinion, highlights this point. The authors use chronic subordinate colony housing (CSC) and single housed mice in their behavior experiments. These conditions are certainly stressful for mice, but it's looking at a very narrow section of what's considered stress with only one type of bacteria....

Buffington et al (2016) and Reber et al. (2016)

This week's articles were about the role of the gut-brain axis in neurodevelopment and stress. Reber and colleagues used a heat-killed version of the bacteria, M. vaccae, as a type of vaccine and found that administration to mouse models resulted in decreased response to chronic stress, prevented colitis related to stress, and reduced measures of anxiety. Reber et al. also used the inactivated M. vaccae in a mouse model of IBD and found that the bacteria prevented stress-induce flare-ups of colitis, but that this could be reversed by removing T cells. Buffington and colleagues instead examined the role of gut microbiota in maternal high-fat diets (MHFD) in the neurodevelopment and social behaviors of their offspring. Buffington et al. found that housing MHFD rats with the offspring of regular diet (MRD) rats prevented social deficits in their offspring. They also found that this co-housing arrangement prevented an imbalance in the gut bacteria Reber and colleagues' findings w...

Buffington and Reber

Buffington et al. explore a mechanism by which maternal obesity can induce neuronal and subsequent behavioral disorders. Using a model of high-fat diet (MHFD)-induced obesity, the authors showcase the strong connection between the brain and the gut, and its impact on behavior. The findings are provocative; by exposing these offspring to the microbiome of control offspring, there was evidence of a rescued observed behavioral phenotype. Furthermore, a phylogenetic profiling of the gut microbiome revealed a decrease in L. reuteri within MHFD offspring, and introduction of live L. reuteri into the drinking water shows successful rescue of the behavioral issues in the MHFD offspring. L. reuteri-induced expression of oxytocin within the paraventricular nuclei of the hypothalamus provides a potential mechanistic explanation for the behavioral changes. I thought this paper provided robust support for the hypothesized interaction between the gut biome and the developing CNS, with tremendous po...

Gut-Brain Interactions: Buffington et al. (2016) and Reber et al. (2016)

Buffington et al. (2016) and Reber et al. (2016) present quite fascinating approaches to studying the interactions or ‘axis’ between the rodent (and human) gut and brain. As the gut is a primary route for bringing things from the environment into our body, these two studies present very clear and convincing evidence for the relevance and translatable validity of their various hypotheses. One of the most interesting conclusions to me from Buffington et al. was that co-housing three high-fat diet offspring with just one regular-diet offspring was enough to rescue their social behavior deficits and microbiome profiles. This is remarkable, and I would like to hear more about possible mechanisms for this transfer to actually occur. Although the article mentions that mice do eat each other’s feces to transfer microbiota, could there be a certain “threshold” or level of bacteria needed to observe this phenotype switch? That is, how many more high-fat diet mice could have been house...