Hormonal control of precopulatory sebaceous scent marking and ultrasonic mating vocalizations in male rats

The effects of testosterone (T) and its major metabolites, estradiol (E2) and dihydrotestosterone (DHT), on the restoration of sebaceous scent marking and 50-kHz ultrasonic vocalizations in male rats were measured in two studies (Experiments 1 and 2) employing different hormone levels. Silastic capsule administration of high and low doses of T (10 and 20 mm) or E2 (5%; 5 and 10 mm) completely restored marking to precastration levels. Both doses of DHT (30 and 40 mm) or no hormone replacement were without effect when tested in presence of estrous odor cues. In our testing paradigm, males appeared to mark glass objects with a sebaceous secretion rather than urine. Only the high dose of T (20 mm) restored vocalizations to intact levels, while animals receiving the high or low dose of E2 or DHT showed no restoration of behavior. In Experiment 3, habituation to estrous odor cues over weekly tests was not observed for marking or vocalizations. These results are discussed with respect to similarities and differences in the hormonal control of signaling behaviors by androgen metabolites in male rodents.