Central oxytocin administration significantly boosts social interaction and shoaling behavior in guppies

Nonapeptides like vasotocin and oxytocin are evolutionarily conserved, regulating diverse social behaviors such as mating, aggression, and parental care across vertebrates. Despite their widespread influence, their precise role in foundational social behaviors like grouping with conspecifics (shoaling) remains underexplored. Understanding these mechanisms in model organisms like the guppy (Poecilia reticulata) can shed light on the ancestral functions of these peptides and their relevance to complex social cognition and social bonding across species.

Researchers investigated the effects of nonapeptides on shoaling behavior in wild-origin guppies. They performed two experiments using intracerebroventricular administration, first focusing on oxytocin and then on vasotocin. Guppies received central injections of either the nonapeptides or their putative receptor antagonists. Following administration, shoaling behavior and social interaction were monitored for 2.5 hours to assess changes in grouping tendencies and social engagement. The study aimed to identify which nonapeptide, if any, influenced this fundamental social behavior.

Central administration of oxytocin significantly increased social interaction and shoaling behavior in guppies. The effects were time-dependent, becoming evident after 90 minutes post-administration. In contrast, vasotocin did not produce significant changes in social interaction or shoaling preferences. Furthermore, the putative receptor antagonists for oxytocin and vasotocin did not elicit clear behavioral effects, suggesting a complex interaction or limitations in antagonist specificity. The study highlights the importance of temporal dynamics in nonapeptide actions. > After 90 minutes, central oxytocin significantly increased social interaction, with a similar effect on shoaling behavior in guppies.