Experience-based vocalization of male mice to female chemosignals.

Previous experimentation led to a suggestion that pituitary-mediated metabolites present in female urine are important determinants of stimulus potency in eliciting 70 kHz ultrasonic vocalizations from adult male mice (Mus musculus). In the present experiment this hypothesis was reexamined, taking into account the prior experience of the male test subjects. Male mice were given social experience with either hypophysectomized females or intact, normal females and were then monitored for ultrasonic vocalizations to chemosensory stimuli from both. Results indicated that males (1) will emit ultrasonic vocalizations to urine from hypophysectomized females and (2) tend to preferentially emit ultrasound to stimuli from the type of female previously encountered during the social experience regimen. It is proposed that the previously reported lack of ultrasound emission by males to chemosignals from hypophysectomized females can be accounted for via straightforward associative learning mechanisms.