Sex‐Specific Involvement of Gut Microbiota in Behavioral and Endocrine Responses to Chronic Predator Odor in Brandt's Voles

Predator cues have profound impacts on the behavior and physiology of prey animals. However, the mechanisms underlying stress responses induced by chronic exposure to predator cues in mammals, particularly the role of the gut microbiota, remain insufficiently understood. This study investigated how gut microbiota contributes to behavioral and physiological responses in Brandt's voles (Lasiopodomys brandtii) under chronic predator odor exposure. Adult voles were repeatedly exposed to cat feces odor (CO) for 18 days (1 h/day), followed by behavioral tests to assess anti-predator and anxiety-like behaviors, hormonal measurements to evaluate basal hypothalamic-pituitary-adrenal (HPA) axis activity, and 16S rRNA sequencing to analyze gut microbiota composition. The results showed that repeated CO exposure increased anxiety-like behaviors and basal HPA axis activity in both sexes. However, anti-predator behaviors exhibited sex-specific responses: Males were habituated to repeated CO exposure by reducing freezing and alerting behaviors, whereas females consistently displayed concealing strategies, reflecting different adaptive strategies to prolonged predator threats. While CO exposure did not alter the α-diversity of gut microbiota, it significantly affected the β-diversity in females, including a reduction in the relative abundance of Treponema and Quinella. Cecal microbiota transplantation from female CO-exposed voles to naive recipients increased anxiety-like behaviors and basal HPA levels but did not alter anti-predator behaviors in the recipients. In contrast, male recipients showed no significant behavioral or physiological changes. These findings suggest that gut microbiota is involved in regulating anxiety-like behavior and HPA axis activity in female voles but has a limited regulating role in male voles.