OUP user menu

EFFECTS OF VOLUNTARY ETHANOL INGESTION ON THE POMC GENE EXPRESSION IN THE RAT PITUITARY AND ON THE PLASMA β-ENDORPHIN CONTENT

ANETT WINKLER, IRMGARD ROSKE, JENS FURKERT, JÖRNS FICKEL, MATTHIAS F. MELZIG
DOI: http://dx.doi.org/ 231-238 First published online: 1 March 1995

Abstract

Studies investigating the influence of chronic ethanol treatment on the β-endorphin content and the proopiomelanocortin (POMC) gene expression in the rat pituitary revealed contradictory results. Because of this we decided to start a more complex study to investigate the effects of isolation stress, chronic ethanol treatment and voluntary ethanol consumption on the POMC mRNA level in the rat pituitary. The immediately prepared total RNA from rat pituitaries was used in hybridization experiments (Northern- and Dot-blots). The results suggest a correlation between the POMC gene expression and the different fashions of ‘living conditions’ tested. So the POMC gene expression in long-term alcohol-treated animals was decreased supporting the theory of β-endorphin deficiency in alcoholism. More interestingly, data obtained from the group of voluntary ethanol consumption suggest an inverse correlation between total ethanol ingestion and POMC gene expression. This indicates the importance of the method of ethanol administration. Consistent with a decreased POMC gene expression in the pituitary during chronic ethanol treatment are previous studies showing a decrease in the plasma β-endorphin content in such situations. Surprisingly, in the present study the plasma β-endorphin levels measured by radioimmunoassay were only slightly decreased in chronically ethanol-treated rats. This may be due to dysregulatory effects of ethanol on post-translational processing, degradation and/or release of β-endorphin.