The role of the gut microbiome on socio-sexual behaviours in mice

Salia, Stephanie (2021) The role of the gut microbiome on socio-sexual behaviours in mice. Masters thesis, Memorial University of Newfoundland.

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Abstract

The gut microbiome is host to trillions of microorganisms that influence the brain and behaviour via the gut-brain axis. Gonadal hormones drive sex differences in the gut microbiota composition that translates into sex-dependent effects on behaviour when depleted. To date, these studies have primarily examined the gut’s depletion on psychiatric disorders, including anxiety and depressive-like behaviours in rodents. The current study explored the role of gut microbiota on socio-sexual behaviours in male and female mice. Broad-spectrum antibiotic (ABX) in drinking water was used to deplete the microbiota in either early development (embryonic day 16 to postnatal day 21) or adulthood (day 60 to 81) while the control group received normal drinking water. Compared to control males, early and adult ABX decreased male territorial aggression, while adulthood ABX also decreased sexual odor preferences among males. Next, I examined whether these decreases in socio-sexual behaviour among males following ABX resulted from the depletion of the gut microbiota, rather than other non-specific effects of antibiotics, and/or whether these behavioural deficits could be due to decreases in androgens. To do so, cecal microbiota transplantation with same and opposite-sex control cecum contents or testosterone treatment was provided to adult antibiotic-treated males. Microbiota transplant with male cecum restored both olfactory preference and male aggression among adult ABX males. Female microbiota partially restored olfactory preference but not aggression among ABX males, while testosterone treatment was insufficient to rescue any of these behaviours. In adult ABX females, male microbiota transplant did not alter socio-sexual behaviours, but testosterone treatment increased male-typical sexual behaviours. Together, the results suggest a sex-dependent role for the gut microbiome in the display of sex-typical behaviours in mice that is independent of androgen.

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