From grouping and cooperation to menstruation: Spiny mice (Acomys cahirinus) are an emerging mammalian model for sociality and beyond

Affiliative relationships, such as parent-offspring bonds, male-female pair-bonds, and within-sex coalitions/alliances, are beneficial for group-living animals to increase fitness and reproductive success. Male-male affiliative relationship, such as coalitions/alliances, have been reported in social mammals and birds in situations where three or more individuals interact, suggesting that male-male affiliative relationships can be formed via interactive situations involving three (or more) individuals. However, no experimental studies have tested this hypothesis on social animals. Many studies on mammals and birds have revealed that an affiliative relationship is underpinned by the oxytocin (OT)/vasopressin (VP) system. However, the role of the OT/VP system has been studied only in parent-offspring bonds and pair-bonds and is lacking in male-male affiliative relationships. In this study, we found the 2-week cohabitation of three male crows in an aviary facilitated affiliative relationship formation between two of the three crows (Experiment 1). In Experiment 2, we examined the effects of peripheral administration of vasopressin 1a receptor (V1aR) antagonist peripheral administration on the social behaviour of affiliated males. We found that the V1aR antagonist caused the disappearance of affiliative behaviour and the resurgence of agonistic behaviour in affiliated males. Our findings provide the first evidence for V1aR involvement in male-male affiliative relationships in vertebrates.

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Vasopressin 1a receptor antagonist disrupts male-male affiliative relationships formed by triadic cohabitation in large-billed crows

Seguchi,

Izawa

2024

Preprint

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Same-sex affiliative relationships are common in humans and some social animals, forming one of the bases of group living. The neuropeptide vasopressin (VP) and its receptors mediate these relationships and behaviours in mammals and birds with gregarious and colonial social structures. In some species, affiliative relationships between dominant and subordinate individuals can be maintained while still retaining strict dominance hierarchies where three or more individuals interact. However, it is unclear whether triadic interaction promotes these relationships, and whether the VP system is also involved in such affiliations due to the lack of suitable animal models and experimental settings. This study addresses these questions with two experiments. In Experiment 1, two-week cohabitation among three male crows facilitated affiliative relationships in particular dyads within each triad. In Experiment 2, vasopressin 1a receptor (V1aR) antagonism disrupted affiliative behaviours and led to the resurgence of agonistic behaviours in affiliated males but not in unaffiliated ones by peripherally administering a V1aR antagonist. These findings suggest that the VP system might universally mediate same-sex affiliative relationships, despite differences in inherent aggression levels among individuals. The triadic cohabitation paradigm established here could advance our understanding of animal societies and be applied across various species, sexes, and social structures.

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From grouping and cooperation to menstruation: Spiny mice (Acomys cahirinus) are an emerging mammalian model for sociality and beyond

Cited by 4 publications

References 73 publications

Comparative review of the brain development in Acomys cahirinus

Comparative review of the brain development in Acomys cahirinus

Vasopressin 1a receptor antagonist disrupts male-male affiliative relationships formed by triadic cohabitation in large-billed crows

Vasopressin 1a receptor antagonist disrupts male-male affiliative relationships formed by triadic cohabitation in large-billed crows

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