Beta-endorphin-stimulated prolactin release in lactating rats following alcohol administration.
To delineate the mechanism of alcohol inhibition of the suckling-induced prolactin increase, we examined beta-endorphin-stimulated prolactin release in lactating rats separated from their litters. On day 2 of lactation litters were adjusted to eight pups. On day 7, dams were implanted with an atrial catheter; experiments were conducted on lactation day 10. Litters were separated from their dams at 0800. After five hours, a PE50 extension tube filled with heparinized saline was attached to the catheter. At 1400 a preinfusion blood sample was removed and was followed by infusion of saline (control) or alcohol in saline (1.0 and 2.0 g/kg/body weight). Following the removal of a postinfusion blood sample, beta-endorphin (600 micrograms/kg/body weight) was administered. Additional blood samples were withdrawn 10, 30, 60, and 120 min after beta-endorphin. Alcohol infusion did not alter basal prolactin. beta-Endorphin administration resulted in pronounced prolactin increases in all groups. Alcohol failed to inhibit beta-endorphin-induced plasma prolactin increase. From the present study with beta-endorphin and our previous studies with sulpiride and thyrotropin-releasing hormone (TRH) it is concluded that the anterior pituitary is not the site where alcohol acts to inhibit suckling-induced prolactin release in rats.
Subramanian
M G
MG
Department of Obstetrics and Gynecology, Wayne State University, C.S. Mott Center for Human Growth and Development, Detroit, MI 48201.
D000818:Animals; D000431:Ethanol / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D005260:Female; D007700:Kinetics; D007774:Lactation / Q000502:physiology*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D001615:beta-Endorphin / Q000494:pharmacology*
D000431:Ethanol; D001615:beta-Endorphin; D011388:Prolactin