Effects of dopamine D1 and D2 receptor agonists and antagonists on basal and ethanol-modulated beta-endorphin secretion from hypothalamic neurons in primary cultures.
In the present study, we determined the effects of dopamine receptor agonists and antagonists on basal and ethanol-modulated beta-endorphin (beta-EP) secretion from hypothalamic neurons in primary cultures. Treatment with various concentrations of dopamine D1 agonist SKF 38393 and D1 antagonist SCH 23390 did not affect basal IR-beta-EP release. However, dopamine D2 receptor agonist LY 141865 reduced basal immunoreactive (IR)-beta-EP release in a concentration dependent manner. D2 receptor antagonist, sulpiride, on the other hand, stimulated basal IR-beta-EP release and blocked LY 141865-induced inhibition of IR-beta-EP release in a concentration dependent manner. When the actions of these DA receptor agents on ethanol-modulated IR-beta-EP release were studied, both D1 and D2 receptor agents failed to affect ethanol-modulated IR-beta-EP release. These data suggest that the endogenous secretion of beta-EP from hypothalamic neurons is under the influence of an inhibitory dopaminergic system involving the D2 receptor. Furthermore, ethanol's effects on beta-EP secretion are not mediated by dopamine.
Boyadjieva
N I
NI
Department of Veterinary and Comparative Anatomy. Pharmacology and Physiology, Washington State University, Pullman 99164-6520, USA.
Sarkar
D K
DK
D000818:Animals; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D004298:Dopamine / Q000502:physiology; D065127:Dopamine D2 Receptor Antagonists; D000431:Ethanol / Q000494:pharmacology; D005260:Female; D005333:Fetus / Q000166:cytology; D007033:Hypothalamus, Middle / Q000166:cytology; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000819:agonists* / Q000037:antagonists & inhibitors*; D017448:Receptors, Dopamine D2 / Q000819:agonists*; D001615:beta-Endorphin / Q000187:drug effects / Q000378:metabolism*
D065127:Dopamine D2 Receptor Antagonists; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D000431:Ethanol; D001615:beta-Endorphin; D004298:Dopamine