DISSOCIATION OF ANDROGEN-DEPENDENT SOCIOSEXUAL BEHAVIORS IN RESPONSE TO CASTRATION IN LONG-EVANS RATS

Dissociation of androgen-dependent sociosexual behaviors in response t o castration in Long-Evans rats. PHYSIOL BEHAV 55(3) 533-536, 1994.-Co pulatory behavior and associated social behaviors such as ultrasonic v ocalizations and scent marking are reduced in frequency following cast ration and are restored by exogenous administration of androgens. In t he present study, we report the behavior of a subgroup of male Long-Ev ans rats in which there was a dissociation between the responses of an drogen-dependent behaviors to castration. Five weeks after castration, 52% of the males tested (13 of 25) had higher 50 KHz vocalization fre quencies than during precastration tests. This group continued to emit vocalizations after castration and actually increased their number of vocalizations over postcastration tests (pretest: 34.5+/-4.8 to week 15: 62.8+/-10.9/10 min test). The remaining males (n=12) exhibited a d ecline in vocalizations (pretest: 29.7+/-5.1 to week 15: 6.5+/-2.7) th at we typically observe in our laboratory. Both groups showed the expe cted decline in scent-marking frequency over the postcastration tests and were impaired in performance of copulatory behavior. Seminal vesic le and adrenal gland weights did not differ between the two groups. Th e 25 males were of the same genetic strain as previous animals in our laboratory except that they were born and raised in a different locati on prior to shipment to our laboratory. Androgens, therefore, may be o nly one of the possible influences mediating ultrasonic vocalizations.