IMPAIRED SEXUAL-RESPONSE AFTER LESIONS OF THE PARAVENTRICULAR NUCLEUSOF THE HYPOTHALAMUS IN MALE RATS

N-methyl-D-aspartic acid (NMDA) or radiofrequency (RF) lesions were ma de in the paraventricular nucleus of the hypothalamus (PVH) of male ra ts. The rats were tested for copulation, noncontact erection (NCE) evo ked by remote cues from estrous females, and (after RF lesions) reflex ive erection. NMDA, which destroyed parvocellular but spared magnocell ular neurons, caused no deficits in copulation but caused longer NCE l atencies and fewer NCEs. Rats with RF lesions had parvo-and magnocellu lar neuron damage; these males copulated to ejaculation, but they had lower intromission ratios and longer ejaculatory latencies. RF-lesione d rats also had longer NCE latencies, and a smaller proportion of male s displayed reflexive erection. Results indicate that the PVH particip ates in mediating erectile function in copula and ex copula, and that the parvo-and magnocellular PVH neurons may have different roles in me diating erection.