Endomorphin-1, effects on male sexual behavior.
We examined the effect of endomorphin-1 (EM-1), an endogenous opioid peptide that binds selectively to the mu receptor, on male copulatory behavior in sexually vigorous Wistar rats. In the first experiment, four doses of EM-1 (1, 10, 50, and 100 muM) injected intracerebroventricularly produced a marked increase in ejaculation latency and interintromission interval and reduced the number of ejaculations during the test. In experiment 2 the effects of EM-1 were completely blocked by pretreatment with naloxone (5 mg/kg) 30 min prior to intracerebroventricular injection of EM-1 (100 microM). Collectively these results indicate that the activation of micro receptors by EM-1 modifies parameters associated with ejaculation (increases ejaculation latency and reduces the number of ejaculations) confirming that opioids are released during sexual behavior.
Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad Universitaria, CP 04510, México. gamezlp@gmail.com
Leticia
L
Parra-Gámez
A Alejandro
AA
García-Hidalgo
A
A
Salazar-Juárez
B
B
Antón
Raúl G
RG
Paredes
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004542:Ejaculation / Q000187:drug effects; D005260:Female; D007276:Injections, Intraventricular; D008297:Male; D009270:Naloxone / Q000008:administration & dosage / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D017450:Receptors, Opioid, mu / Q000819:agonists* / Q000037:antagonists & inhibitors; D012726:Sexual Behavior, Animal / Q000187:drug effects*
D009292:Narcotic Antagonists; D009842:Oligopeptides; D017450:Receptors, Opioid, mu; C105293:endomorphin 1; D009270:Naloxone