Species-specific behavioural responses to peripheral arginine vasopressin in two African striped mice (genus...

Peripheral arginine vasopressin (AVP) administration modulates social behaviour in several mammalian species, although its effects are inconsistent and can be species- and context-specific. We investigated whether peripheral AVP modulates behavioural responses in females of two closely related African striped mouse species that differ in social organisation: group-living Rhabdomys pumilio and solitary-living R. dilectus dilectus. Using a three-chamber sociability and social novelty test, we investigated the behavioural responses of focal females, following saline, low-dose or high-dose subcutaneous AVP injections, to either familiar or novel stimulus females. We recorded the duration of time spent in the chambers of each stimulus female, the number of approaches, and the duration of affiliative and aggressive behaviours. Under high AVP, both species spent more time with, and made more approaches to, stimulus females, suggesting enhanced activity or investigatory behaviour. Specifically, under high AVP, R. d. dilectus showed increased affiliative behaviour toward familiar females, while R. pumilio generally showed greater aggression overall and more affiliative behaviour towards the novel female under high AVP. Our findings suggest that peripheral AVP can modulate certain aspects of social behaviour in Rhabdomys, although the underlying mechanisms (social, arousal-based or locomotor) remain untested. These results highlight the importance of considering species differences and peripheral neuropeptide effects when evaluating the associations between AVP expression and behaviour.