INJECTION OF OXYTOCIN INTO THE MEDIAL PREOPTIC-ANTERIOR HYPOTHALAMUS INCREASES ULTRASOUND PRODUCTION BY FEMALE HAMSTERS

Recent studies of hamsters have documented the facilitation of lordosi s and other sociosexual responses by injections of oxytocin (OXT) into the medial preoptic area-anterior hypothalamus (MPOA-AH). These data suggest the regulation of social interaction and bonds bq OXT. In turn , this suggests that OXT could act in the MPOA-AH to control other beh aviors involved in the initiation or maintenance of social contact, in cluding the ultrasonic vocalizations that female hamsters use to alert and attract potential mates. To test this possibility, we compared th e ultrasound rates of 11 naturally estrous hamsters before and after i njections of OXT (200 ng/200 nl of saline) or saline (200 nl) into the MPOA-AH. The data revealed a clear facilitation of ultrasound rate 30 min after OXT treatment. This result suggests the modulation of ultra sound rate by endogenous OXT acting within the MPOA-AH. It extends the range of social behaviors sensitive to control by OXT and supports th e possibility that OXT acts within the MPOA-AH to facilitate a variety of behaviors involved in the establishment or maintenance of the soci al interactions required for successful reproduction. At the same time , these data extend earlier observations linking ultrasound production to the MPOA-AH, anc: begin to describe the peptidergic mechanisms con trolling this form of reproductive behavior. (C) 1998 Elsevier Science Inc.