title: Effect of the interaction between pro-leu-gly-NH2 and catecholaminergic drugs on MSH release from rat pituitaries incubated in vitro.
abstract: The effect of the interaction between Pro-Leu-Gly-NH2 (PLG) and catecholamines on the release of MSH by rat pituitaries glands was studied in vitro. The catecholamines dopamine (DA) and norepinephrine (NE) inhibited the release of alpha-MSH from pituitary glands incubated in vitro. The DA effect appeared at low concentrations while NE was effective in concentrations 20 times greater than DA. These effects were blocked by an alpha-adrenergic blocker agent. On the other hand, epinephrine (E) at the concentrations tested did not modify MSH release. When 50 or 500 ng/ml of DA is added to the medium containing PLG concentrations it strengthened the inhibitory effect of PLG release, whereas the action of NE and PLG was additive; at the highest tested concentration E (5,000 ng/ml) blocked the inhibition of MSH induced by PLG. It is concluded that, whereas the inhibitory release of MSH by catecholamines is mediated by an alpha-adrenergic receptor, the inhibitory effect of PLG is not exerted through a catecholaminergic receptor since its action is not prevented by any of the catecholamine receptor blockers studied. Thus, it seems that specific PLG receptors are present at the pituitary level.
mesh_terms: D000818:Animals; D046508:Culture Techniques; D004298:Dopamine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology*; D009075:MSH Release-Inhibiting Hormone / Q000494:pharmacology*; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology*; D010643:Phenoxybenzamine / Q000494:pharmacology; D010868:Pimozide / Q000494:pharmacology; D010902:Pituitary Gland / Q000187:drug effects*; D011433:Propranolol / Q000494:pharmacology; D051381:Rats
chemical_list: D010643:Phenoxybenzamine; D010868:Pimozide; D009074:Melanocyte-Stimulating Hormones; D009075:MSH Release-Inhibiting Hormone; D011433:Propranolol; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine