Drug Induced Cerebral Proerectile Effect in Anesthethetized Rats

Park, Hyun Jun; Nam, Jong Kil; Park, Nam Cheol

Abstract

PURPOSE
To examine the centrally elicited erectile effects of alpha-MSH, oxytocin, prostagladin E1, and anabolic steroids after intracerebroventricular administration.
MATERIALS AND METHODS
We used anesthetized male Sprague-Dawley rats. After intracerebroventricular administration of normal saline (NS), alpha-melanocyte stimulating hormone (alpha-MSH), oxytocin acetate (OT), prostaglandin E1 (PGE1), methylprednisolone (MP), testosterone enanthate (TE) or 17beta-estradiol (E2) under stereotaxis, the intracavernosal pressure (ICP), systolic femoral artery pressure (FAP), heart rate (HR), time to first response, duration, and number of erectile responses and adverse reactions were evaluated for 60 minutes. To show whether erections were centrally elicited, the above criteria were re-evaluated after a bilateral pelvic neurotomy and bilateral orchiectomy.
RESULTS
A cerebral proerectile effect was elicited only by alpha-MSH and OT with no significant changes of FAP or HR. With PGE1, significant changes in FAP and HR were observed. The ICP/FAP ratio was highest (0.49 0.03) with alpha-MSH. The mean time latency was shortest with OT (20.6 5.6 min). The mean duration was longest in alpha-MSH (11.6 8.7 min). The number of responses was highest with OT (3.6 0.7). Adverse reactions, such as stretching, yawning and ejaculation, were simultaneously observed during increases in ICP. In the cases of a bilateral pelvic neurotomy or bilateral orchiectomy, these elicited erectile responses disappeared.
CONCLUSIONS
alpha-MSH had the most potent proerectile effect compared to OT and PGE1 as assessed by highest intracavernosal pressure as well as duration of erectile response. The results suggest that testosterone and the pelvic nerve were essential for the central proerectile response.