Vasopressin facilitates play fighting in juvenile golden hamsters.

Vasopressin facilitates aggression in adult hamsters. Whether this neuropeptide has a similar role in play fighting remains unknown. The goal of the present study was to identify whether vasopressin controls play fighting in juvenile golden hamsters as well. Juvenile male golden hamsters were tested for play fighting after microinjections of a vasopressin V1A-receptor antagonist, Manning compound, either 0, 9, or 90 microM, into the anterior hypothalamus. The treatment selectively inhibited offensive aspects of play fighting in experimental animals. Attack frequencies were significantly decreased by both doses of Manning compound. In addition, the high dose of the receptor antagonist increased attack latencies, decreased bite frequencies, and decreased the averaged number of attacks per contact bout. Together, these results show that vasopressin controls offensive behaviors throughout development from play fighting in juveniles to aggression in adults.