Stimulation in vivo of the secretion of prolactin and growth hormone by beta-endorphin.
Morphine sulfate (MS) and the opioid peptide beta-endorphin beta-LPH-(61-91) stimulate prolactin and growth hormone release in steroid-primed and non-treated male rats when injected intravenously or intracisternally. On a molar basis beta-endorphin is at least 20 times more potent than MS, whereas Met5-enkephalin (beta-LPH-(61-65)) and alpha-endorphin (beta-LPH-(61-76)) are devoid of activity at the dose injected (300 mug). The in vivo stimulatory effects of beta-endorphin on prolactin secretion are reversed by the opiate antagonist naloxone. The absence of in vitro effect of MS and beta-endorphin on prolactin and growth hormone secretion by cultured rat pituitary cells suggest that they have a central nervous system site of action.
D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D013006:Growth Hormone / Q000378:metabolism*; D008024:Ligands; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000494:pharmacology*; D010455:Peptides / Q000494:pharmacology*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011957:Receptors, Opioid
D008024:Ligands; D009419:Nerve Tissue Proteins; D010455:Peptides; D011957:Receptors, Opioid; D009270:Naloxone; D009020:Morphine; D011388:Prolactin; D013006:Growth Hormone