Saland LC, Mennin SP, Selinfreund R, Rasmussen P. Interaction of beta-endorphin, naloxone and dopamine: effects on melanocyte-stimulating hormone secretion of amphibian pituitaries in vitro.
REGULATORY PEPTIDES 1982;
3:371-81. [PMID:
6287539 DOI:
10.1016/0167-0115(82)90060-x]
[Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Neurointermediate lobes from amphibians (Rana pipiens) were incubated in Medium 199 containing dopamine, beta-endorphin or dopamine plus beta-endorphin. Dopamine inhibited melanocyte-stimulating hormone (MSH) secretion as measured by bioassay in hypophysectomized frogs, an effect which was transiently reversed by beta-endorphin. The effects of endorphin were in turn partially suppressed by the opiate antagonist, naloxone hydrochloride. Cells treated with all three agents exhibited expanded rough endoplasmic reticulum and decreased secretory granule content, indicative of peptide release and new synthesis. Beta-Endorphin alone did not stimulate MSH secretion above control levels, and at one time period was seen to reduce MSH secretion. The findings indicate a complex interaction between beta-endorphin and dopamine directly upon MSH secretion at the level of the neurointermediate lobe.
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