Cerebral Proerectile Effect of Apomorphine and Vasoactive Agents in Anesthetized Rats

Yan, Bo Quan; Park, Hyun Jun; Park, Nam Cheol

Abstract

PURPOSE: To establish central control of a penile erection, the centrally elicited erectile effects of apomorphine hydrochloride and various vasoactive agents were investigated after intracerebroventricular administration.
MATERIALS AND METHODS
Anesthetized male Sprague-Dawley rats were used for the study. After intracerebroventricular administration of normal saline(NS), apomorphine hydrochloride(AH), prostaglandin E1(PGE1), sodium nitroprusside(SNP), phenylephrine hydrochloride(PE) and phentolamine(PT) under a stereotaxic setting, the intracavernosal pressure(ICP), systolic femoral artery pressure(FAP), heart rate(HR), time to first response, duration and number of erectile response and adverse reactions were evaluated for 60 minutes. To show if the centrally elicited erection by agents in native setting were effective, the above criteria were re-evaluated after a bilateral pelvic neurotomy and bilateral orchiectomy.
RESULTS
Cerebral proerectile effects were elicited by AH with no significant changes in the FAP and HR, but with PGE1, SNP, PE and PT significant changes in both the FAP and HR were observed. The ICP/FAP ratio was highest with SNP at 0.75+/-0.08. The mean time to first response was shortest with AH at 18.1+/-5.1min. The mean duration was longest with AH at 39.4+/-10.9min. The number of responses was highest with AH at 2.7+/-1.1. Adverse reactions, such as stretching, yawning and ejaculation, were simultaneously observed during increases in the ICP. In the case of a bilateral pelvic neurotomy or bilateral orchiectomy, these elicited erectile responses disappeared.
CONCLUSIONS
Vasoactive agents, such as SNP, PGE1 and PE, had a cerebral proerectile effect, but AH showed more an evidently potent proerectile effect in the aspects of ICP, time to first response and duration of erectile response. Testosterone and the pelvic nerve are suggested to be essential for a central proerectile response.