Vasopressin mediates nonapeptide and glucocorticoid signaling and social dynamics in juvenile dominance hierarchies of a highly social cichlid fish
Abstract: Early-life social experience can strongly affect adult behavior, yet the behavioral mechanisms underlying developmental trajectories are poorly understood. We use the highly social cichlid, Burton’s Mouthbrooder (Astatotilapia burtoni) to investigate juvenile social status and behavior, as well as the underlying neuroendocrine mechanisms. We placed juveniles in pairs or triads and found that they readily establish social status hierarchies, with some group structural variation depending on group size, as well as the relative body size of the group members. Next, we used intracerebroventricular injections to test the hypothesis that arginine vasopressin (AVP) regulates juvenile social behavior and status, similar to adult A. burtoni. While we found no direct behavioral effects of experimentally increasing (via vasotocin) or decreasing (via antagonist Manning Compound) AVP signaling, social interactions directed at the treated individual were significantly altered. This group-level effect of central AVP manipulation was also reflected in a significant shift in whole brain expression of genes involved in nonapeptide signaling (AVP, oxytocin, and oxytocin receptor) and the neuroendocrine stress axis (corticotropin-releasing factor (CRF), glucocorticoid receptors (GR) 1a and 1b). Further, social status was associated with the expression of genes involved in glucocorticoid signaling (GR1a, GR1b, GR2, mineralocorticoid receptor), social interactions with the dominant fish, and nonapeptide signaling activity (AVP, AVP receptor V1aR2, OTR). Together, our results considerably expand our understanding of the context-specific emergence of social dominance hierarchies in juveniles and demonstrate a role for nonapeptide and stress axis signaling in the regulation of social status and social group dynamics. This Mendeley dataset contains: Experiment 1: Study of juvenile A. burtoni social behavior and group structure in pairs and triads, including matched pairs (size-matched fish), mismatched pairs (larger and smaller fish), matched triads (larger juvenile with smaller size-matched fish), and mismatched triads (larger, medium, and small fish). The Experiment 1 variable key describes each variable. Experiment 2: Pharmacological manipulation of juvenile A. burtoni in matched triads (larger juvenile with smaller size-matched fish) using intracerebroventricular (ICV) injection. One of the size-matched fish received ICV injection of vehicle (control). The other received either arginine vasotocin or antagonist Manning Compound. The Experiment 2 variable key describes each variable.