title: In vitro effects of a synethetic enkephalin analogue (D-Met2,Pro5)-enkephalinamide on the hypothalamus-pituitary--testis function in rats.
abstract: The effects of (D-Met2,Pro5)-enkephalinamide, a synthetic analogue of the natural opioid pentapeptides, were investigated on the hypothalamus-pituitary-testis axis using in vitro tissue and isolated cell incubation systems. (D-Met2,Pro5)-enkephalinamide in a concentration range 10(-7)--10(-5) M did not alter the testosterone production and the troph-hormone sensitivity of the isolated Leydig cells, or the gonadotroph hormone release and the luteinizing-hormone--releasing hormone (LH-RH) sensitivity of the isolated anterior pituitary cells. However 10(-5)--10(-5) M synthetic enkephalin analogue induced a dose-dependent inhibition of LH-RH content and release of the mediobasal hypothalamus, which was prevented by equimolar concentrations of naloxone.
mesh_terms: D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004723:Endorphins / Q000494:pharmacology*; D004745:Enkephalins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism; D007031:Hypothalamus / Q000187:drug effects*; D007033:Hypothalamus, Middle / Q000187:drug effects*; D066298:In Vitro Techniques; D007985:Leydig Cells / Q000187:drug effects*; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D006063:Chorionic Gonadotropin; D004723:Endorphins; D004745:Enkephalins; D007987:Gonadotropin-Releasing Hormone; D009270:Naloxone