Monoaminergic regulation of proopiomelanocortin messenger RNA concentrations in primary cell cultures of rat hypothalamus.
The effect of monoaminergic neurotransmitters on a 1.1-kb proopiomelanocortin messenger RNA (POMC mRNA) detected in rat hypothalamic cells maintained in culture has been evaluated. Serotonin caused a 15% increase in POMC mRNA levels, an effect which was blocked by the 5-HT2 receptor antagonist ketanserin. Dopamine markedly decreased POMC mRNA levels in a dose related manner. Haloperidol and the selective D2 antagonist (+)-butaclamol prevented the inhibitory effects of both dopamine and the selective D2 agonist, 2-bromo-alpha-ergocryptine. The selective dopamine D1 receptor agonist, SKF 38393, as well as norepinephrine and acetylcholine did not affect POMC mRNA levels. It is concluded that serotonin exerts a positive control and dopamine a negative control on POMC mRNA concentrations in primary cultures of rat hypothalamic neurons. The negative effect of dopamine appears to be exerted via D2 receptor-mediated mechanism.