Effects of androgen on marking and aggressive behavior of neonatally and prepubertally bulbectomized and castrated male gerbils.

Abstract

The role of olfactory and androgenic influences on the development of scent-marking and aggressive behavior of male gerbils was assessed. Animals were bilaterally bulbectomized, unilaterally bulbectomized, castrated, given a combination of bulbectomy and castration, or given a sham operation at 2 days of age. Marking and fighting were recorded prior to and after androgen treatment in adulthood. Postoperative tests revealed that neonatal olfactory bulb removal, alone or in combination with castration, virtually eliminated scent-marking and fighting. Treatment with testosterone prioionate (TP) in adulthood was ineffective in facilitating marking after neonatal castration, bulbectomy or their combination. Animals given TP did exhibit increased aggressiveness. The most striking increases were found in bulbectomized and bulbectomized-castrated animals. Bulbectomy, castration or their combination at 35 days of age also reduced both marking and fighting. Androgen treatment in adulthood did fully restore marking in all groups to control levels with the exception of bulbectomized-castrated animals. Fighting was increased to extremely high levels following TP treatment in bulbectomized and bulbectomized-castrated animals.