RESUMEN
Recent evidence has demonstrated a sex-specific role of the gut microbiome on social behavior such as anxiety, possibly driven by a reciprocal relationship between the gut microbiome and gonadal hormones. For instance, gonadal hormones drive sex differences in gut microbiota composition, and certain gut bacteria can produce androgens from glucocorticoids. We thus asked whether the gut microbiome can influence androgen-dependent socio-sexual behaviors. We first treated C57BL/6 mice with broad-spectrum antibiotics (ABX) in drinking water to deplete the gut microbiota either transiently during early development (embryonic day 16-postnatal day [PND] 21) or in adulthood (PND 60-85). We hypothesized that if ABX interferes with androgens, then early ABX would interfere with critical periods for sexual differentiation of brain and thus lead to long-term decreases in males' socio-sexual behavior, while adult ABX would interfere with androgens' activational effects on behavior. We found that in males but not females, early and adult ABX treatment decreased territorial aggression, and adult ABX also decreased sexual odor preference. We then assessed whether testosterone and/or cecal microbiota transplantation (CMT) via oral gavage could prevent ABX-induced socio-sexual behavioral deficits in adult ABX-treated males. Mice were treated with same- or other-sex control cecum contents or with testosterone for two weeks. While testosterone was not effective in rescuing any behavior, we found that male CMT restored both olfactory preference and aggression in adult ABX male mice, while female CMT restored olfactory preference but not aggression. These results suggest sex-specific effects of the gut microbiome on socio-sexual behaviors, independent of androgens.
RESUMEN
Four studies (n = 1199) tested support for the idea that implicit theories about the fixedness versus malleability of gender roles (entity vs. incremental theories) predict differences in the degree of gender system justification, that is, support for the status quo in relations between women and men in society. Relative to an incremental theory, the holding of an entity theory correlated with more system-justifying attitudes and self-perceptions (Study 1) for men and women alike. We also found that strength of identification with one's gender in-group was a stronger predictor of system justification for men than it was for women, suggesting men's defense of the status quo may be motivated by their membership in a high status group in the social hierarchy. In 3 experiments, we then tested whether exposure to a fixed gender role theory would lead men to identify more with masculine characteristics and their male gender group, thus increasing their defense of the gender system as fair and just. We did not expect a fixed gender role theory to trigger these identity-motivated responses in women. Overall, we found that, by increasing the degree of psychological investment in their masculine identity, adopting a fixed gender role theory increased men's rationalization of the gender status quo compared with when gender roles were perceived to be changeable. This suggests that, when men are motivated to align with their masculine identity, they are more likely to endorse the persistence of gender inequality as a way of affirming their status as "real men." (PsycINFO Database Record