Influence of gonadal hormones and sexual behavior on ultrasonic vocalization in rats: I. Treatment of females.

Abstract

Ultrasonic vocalizations were measured when male rats were placed with ovariectomized females that had experienced various hormonal and behavioral treatments. In Experiment 1, 18 males were tested with females in each of the following conditions: nonestrous (OVX), estrogen treated (E), estrogen and progesterone treated (EP), and estrogen and progesterone treated and given two intromissions from a stud male prior to testing (EPI). Control conditions included clean cage (CL) and cage soiled by an estrous female (SOI). The treatments differed in effect on rate and maintenance of vocalization: EP greater than E greater than EPI = OVX greater than SOI greater than CL. In tests in which males produced a high rate of vocalization, some males with short intromission latencies shifted from the normal 50-kHz pulse to a 22-kHz pulse. In Experiment 2, the effect of the female's vocalization and movement on the rate of and latency to vocalization was measured. Twenty-one males were presented with each of the following stimulus conditions: estrous female with red light (EP), estrous female without red light (EP dark), estrous anesthetized female (EP anes), and nonestrous anesthetized female (OVX anes). Effects on vocalization of various treatments were as follows: EP = EP dark greater than EP anes greater than OVX anes. These data suggest that the 50-kHz vocalizations constitute a graded response influenced by the female's hormonal and sexual condition.