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Gut-Brain Interaction, Buffington & Reber

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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. I'm also a bit confused about the authors relating their study to the "old friend" paradigm. They are only studying one bacteria, so how can they generalize that "exposure to environmental microorganisms" help mediate ways in which mice cope with stress?

The Buffington paper was much more straightforward to me, and I see a lot of potential to apply their data to humans, among other mammals who birth live offspring. Particularly, I'm impressed that the authors were able to identify oxytocin as the main peptide that L. reuteri affects, causing the rescue of social behaviors. I'm interested to know if there are dose-dependent effects of ingesting L. reuteri, especially under stressful conditions. That is, does ingesting a higher concentration of L. reuteri cause more profound effects on social interaction?

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