Meeting Abstract
P1.117 Jan. 4 Evidence for a role of adrenocortical steroids in the mediation of seasonal aggression in Siberian hamsters (Phodopus sungorus) SCOTTI, M.L.*; DEMAS, G.E.; Indiana University, Center for the Integrative Study of Animal Behavior, Bloomington; Indiana University, Center for the Integrative Study of Animal Behavior, Bloomington mscotti@indiana.edu
Testosterone mediates aggressive behaviors in a wide variety of species. In some species, however, aggression levels remain high during the non-breeding season (i.e., winter), when testosterone levels are basal. In Siberian hamsters (Phodopus sungorus ), we have demonstrated photoperiodic changes in aggression with hamsters housed in short, �winter-like� days displaying significantly more territorial aggression than long-day animals, despite basal levels of testosterone. The mechanism by which photoperiod regulates aggression, however, remains unknown. Adrenocortical hormones (e.g., cortisol, dehydroepiandrosterone (DHEA)) have been implicated in mediating seasonal aggression, and bilateral adrenalectomy (ADx) can block increased aggression in hamsters treated with short-day-like melatonin, suggesting an important role for these steroids in the expression of aggressive behavior. Furthermore, circulating concentrations of these hormones have been correlated with aggressive behavior in some species. The goal of the present study was to examine the role of DHEA and cortisol in the mediation of photoperiodic changes in territorial aggression in male Siberian hamsters. Males were housed in long (LD 16:8) or short days (LD 8:16) and were treated with exogenous DHEA, cortisol, or no hormone. The hamsters were then tested using a resident-intruder model of aggression. Aggressive behavior was recorded and scored. DHEA did not affect aggressive behavior; however, there was a significant correlation between aggression and serum cortisol levels. Collectively, the results of this study will shed further light on the potential role of adrenocortical steroids in mediating seasonal and other forms of aggression.
