Opiate receptor subtype involvement in the stimulation of prolactin release by beta-endorphin in female rats.
The prolactin secretory response to beta-endorphin and the involvement of opiate receptor subtypes in this response was determined in both diestrous and postpartum, lactating female rats. The involvement of the mu-, delta- and/or kappa-site was determined by administering specific antagonists for each of these sites prior to beta-endorphin. beta-Funaltrexamine (beta-FNA, 1 or 5 micrograms) was administered to block mu-sites, ICI 154,129 (5, 10 or 25 micrograms) blocked delta-sites and nor-binaltorphimine (norBNI, 8 micrograms) blocked kappa-sites. The ability of beta-FNA and ICI 154,129 to block prolactin secretion following morphine administration was also determined. A dose response study for beta-endorphin indicated that beta-endorphin, at doses as low as 25 ng, was a potent stimulus for prolactin release producing an increase in prolactin that mimicked the suckling-induced prolactin increase. In addition, all three antagonists were capable of antagonizing the stimulatory effect of beta-endorphin in both diestrous and postpartum female rats. These results indicate that beta-endorphin is a potent stimulus for prolactin secretion and that these three opiate receptor subtypes interact to produce its stimulatory effect on prolactin release.
Kehoe
L
L
Zoology Department, Miami University, Oxford, Ohio 45056.
Parman
R
R
Janik
J
J
Callahan
P
P
D000818:Animals; D004031:Diestrus; D004305:Dose-Response Relationship, Drug; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D007774:Lactation; D008297:Male; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011957:Receptors, Opioid / Q000145:classification / Q000502:physiology*; D001615:beta-Endorphin / Q000494:pharmacology*
D009292:Narcotic Antagonists; D011957:Receptors, Opioid; C051844:norbinaltorphimine; D004743:Enkephalin, Leucine; D009271:Naltrexone; D001615:beta-Endorphin; C024524:beta-funaltrexamine; D011388:Prolactin; C036405:ICI 154129