Influence of gut microbes on sex differences

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Submitted by Marnia on
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This is kinda interesting, so I'm sharing it even though it has little direct relevance to things we discuss here. The explanation is by a scientist who has done research on trying to understand brain differences in homosexuals. (He's gay.)

It's well known that females are more susceptible than males to  several
auto-immune disorders, and this is true both in mice and humans. A newly
published study in Science (Markle JGM et al, Science 339, 1084-1088)
demonstrates that gut microbes are major players in generating this difference,  and
that they do so by changing testosterone (T) levels.

Here are the main findings:

1. In mice susceptible to an autoimmune disorder (type 1 diabetes), females
 develop the disorder at a much higher rate than males. This sex difference
is  mediated by the sex difference in T levels.

2. Raising these mice without gut microbes lowers T levels in males  but
raises T levels in females. In these microbe-free mice, the sex difference  in
susceptibility to diabetes is eliminated.

3. Transfering gut microbes from adult males (but not adult females) to
immature females raises T levels in those females and protects them against
diabetes. This effect of microbial transfer is prevented by treatment with
androgen blockers.

So the study suggests that the sex-specific gut microbiome amplifies the
innate sex difference in T levels through a positive-feedback loop, at least
in  these diabetes-prone mice. The authors discuss evidence suggesting that
the same  thing may be true in healthy humans. I speculate that this
feedback loop might  influence not only autoimmune diseases but also T-dependent
gendered  psychological traits. If so, this would open the door to possible
new  interpretations of many prior observations. For example,  the
well-established influence of same-sex and opposite-sex older siblings  on gendered
characteristics might come about because these older siblings are  sources of
sex-specific gut microbes, rather than through psychological  role-modeling.


this is just blowing me away. I am learning more about gut bacteria and wouldn't be surprised if a lot of our problems with health come from imbalances there. I am thinking there may be some way to fix these and fix a lot of health problems.