Numerous studies have demonstrated that activation of serotonin 5-HT(1A) or 5-HT(1B) receptor decreases aggression in male mammals. To determine whether female mammals also show decreased aggression in response to 5-HT(1A) or 5-HT(1B) activation, we assessed the effects of the serotonin receptor agonists 8-OH-DPAT (5-HT(1A)) and CGS-12066A (5-HT(1B)) On aggression in female Syrian hamsters. Female Syrian hamsters were tested for interfemale aggression 2 days before and 15 min after receiving intracerebroventricular infusions of 8-OH-DPAT (5, 10, 20 μg) or CGS-12066A (5, 10, 20 μg). Neither drug affected aggression as measured by the latency and frequency of attacks or uprights, although the highest dose of 8-OH-DPAT increased general activity. For male hamsters, intraventricular infusions of 10 μg of 8-OH-DPAT essentially eliminated aggression, whereas 5 μg of 8-OH-DPAT or 20 μg of CGS-12066A were without effect. Systemic treatment with 8-OH-DPAT (1 mg/kg body weight) did reduce aggression in females, although there was an attendant increase in symptoms of nonspecific serotonergic activity. There were no behavioral effects of systemic CGS-12066A (4 mg/kg body weight) on female hamsters. These results indicate that there may be sex differences in the neurochemical regulation of aggression and point to a need for more studies directed at this issue.
Bibliographical noteFunding Information:
This research was supported by grants from the National Science Foundation (IBN-9412543) and the Purdue Research Foundation. We thank Kyle Bunting and Gavin Cotter for assistance with the behavioral testing. We also express our appreciation to the anonymous reviewers of this manuscript for their helpful suggestions.
- Serotonin agonists
- Sex differences