Serotonin regulation of aggressive behavior in male golden hamsters (Mesocricetus auratus)

These studies examined the neurochemistry and neuroanatomy of the serotonin (5-HT) system innervating the anterior hypothalamus (AH) and the interacti on of 5-HT receptor agonists with arginine vasopressin (AVP) in the regulat ion of offensive aggression in golden hamsters. Because specific 5-HT1A, 5- HT1B, and AVP V-1A binding sites were observed within the AH by in vitro au toradiography, the hamsters were tested for offensive aggression after micr oinjections of AVP in combination with either the 5-HT1A agonist 8-hydroxy- 2-(di-n-propylamino) tetraline (DPAT) or the 5-HT1B agonist CGS-12066A (CGS ) directly within the AH. Though treatment with DPAT resulted in a dose-dep endent inhibition of AVP-facilitated offensive aggression, CGS was ineffect ive. In addition, a retrograde tracer was injected within the AH to localiz e the distribution of 5-HT neurons projecting to the area. Retrogradely lab eled 5-HT neurons were found within the dorsal, median, and caudal linear r aphe nuclei and are suspected to inhibit AVP-facilitated offensive aggressi on by an activation of 5-HT1A receptors in the AH.