Chronic ethanol increases proopiomelanocortin gene expression in the rat hypothalamus

Abstract

The effect of chronic ethanol exposure on proopiomelanocortin (POMC) mRNA accumulation, beta-endorphin (beta-EP) levels as well as incorporation of [3H]-phenylalanine into beta-EP-related peptides was investigated in the rat hypothalamus. Animals were treated with an ethanol-containing liquid diet for 15 days. Both sucrose pair-fed and ad libitum-fed control groups were included. The levels of immunoreactive beta-EP, as well as the relative proportions of nonacetyl and acetyl forms of beta-EP in the hypothalami of the ethanol-treated rats were not significantly different from those in the sucrose and lab chow fed control rats. Northern blot analysis of total hypothalamic RNA indicated that ethanol-treated rats had higher POMC mRNA levels than sucrose pair-fed and control rats. Quantitation of the in vitro incorporation of [3H]-phenylalanine into POMC, beta-lipotropin and beta-EP by the hypothalamus, using immunoprecipitation and polyacrylamide disc-gel electrophoresis with sodium dodecyl sulfate, revealed that the increased hypothalamic POMC mRNA content was associated with increased incorporation of [3H]-phenylalanine into POMC by the hypothalami of the ethanol-treated rats. It is concluded that chronic ethanol can alter the expression of the POMC gene in the hypothalamus.