The effect of beta-endorphin on rat oocyte maturation in vitro.
Cumulus enclosed or denuded oocytes obtained from ovaries of 25- to 27-day Sprague-Dawley rats underwent spontaneous germinal vesicle breakdown (GVBD) when cultured for 6 h in Krebs-Ringer's buffered solution (KRBS). This spontaneous division was found to be inhibited by adding beta-endorphin to the culture system and the inhibition was dose dependent, ranging from 200 to 800 pg/ml KRBS. Naloxone, a potent opioid antagonist without any agonistic action, did not stimulate spontaneous GVBD when added to the KRBS at doses ranging from 80 to 120 pg/ml. However, by adding 80 pg/ml naloxone to the culture system containing 600 pg/ml beta-endorphin, the inhibitory effect of beta-endorphin on spontaneous GVBD could be reversed completely.
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Department of Anatomy, Faculty of Medicine, Hong Kong University.
D000818:Animals; D005260:Female; D066298:In Vitro Techniques; D008540:Meiosis / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology; D009865:Oocytes / Q000166:cytology / Q000187:drug effects*; D009866:Oogenesis / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D001615:beta-Endorphin / Q000494:pharmacology*
D009270:Naloxone; D001615:beta-Endorphin