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.
Parra-Gámez
Leticia
L
Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad Universitaria, CP 04510, México. gamezlp@gmail.com
García-Hidalgo
A Alejandro
AA
Salazar-Juárez
A
A
Antón
B
B
Paredes
Raúl G
RG
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