Role of protein kinase C in control of ethanol-modulated beta-endorphin release from hypothalamic neurons in primary cultures.
We have previously shown that short-term exposure to ethanol stimulates immunoreactive beta-endorphin (IR-beta-EP) release from hypothalamic neurons and that chronic ethanol exposure decreases the IR-beta-EP release from these neurons. The role of protein kinase C (PKC) in the ethanol-regulated beta-EP release from hypothalamic neurons has not been established. In this study, by using the primary cultures of hypothalamic neurons, we tested the effects of PKC stimulator phorbol ester 4 beta-phorbol 12-myristate-13-acetate (PMA) and PKC inhibitor chelerythrine chloride on ethanol-induced IR-beta-EP release. Additionally, the effects of ethanol with or without PMA on expression and translocation of various PKC isoenzymes from cytosolic to membrane fraction were determined. PMA treatment increased IR-beta-EP release in a time- and dose-dependent manner. Acute ethanol treatment (3 h) increased, while chronic ethanol treatment (24 h) reduced, the magnitude of PMA-induced IR-beta-EP release. The stimulatory effect of acute ethanol on IR-beta-EP release was reduced by chelerythrine chloride. Determination of the effects of ethanol with or without PMA on seven different PKC isoenzymes (PKC-alpha, -beta I, -beta II, -gamma, -delta, -epsilon, and -zeta) revealed that the expression and translocation of only two PKC isoenzymes, PKC-delta and PKC-epsilon, were stimulated by acute treatment with ethanol. Acute ethanol also increased PMA-stimulated expression of these two isoenzymes. Chronic ethanol treatment reduced both basal and PMA-induced increase of PKC-delta and PKC-epsilon expression and translocation. These data provide evidence for the first time that ethanol-regulated IR-beta-EP secretion is controlled by the PKC system, possibly involving PKC-delta and PKC-epsilon isoenzymes.
De
Alok
A
Department of Animal Sciences, Rutgers, The State University of New Jersey, Cook College, New Brunswick, New Jersey 08901-8525, USA.
Boyadjieva
Nadka
N
Sarkar
Dipak K
DK
D000470:Alkaloids; D000818:Animals; D053119:Benzophenanthridines; D015153:Blotting, Western; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D002478:Cells, Cultured; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D007031:Hypothalamus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010617:Phenanthridines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D051381:Rats; D001615:beta-Endorphin / Q000378:metabolism*
D000470:Alkaloids; D053119:Benzophenanthridines; D002492:Central Nervous System Depressants; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D010617:Phenanthridines; D000431:Ethanol; D001615:beta-Endorphin; C016299:chelerythrine; D011493:Protein Kinase C