REPEATED ETHANOL ADMINISTRATION DECREASES PRODYNORPHIN BIOSYNTHESIS IN THE RAT HIPPOCAMPUS

The effect of single and repeated (19 days) intragastric ethanol administration on prodynorphin mRNA and alpha-neoendorphin levels in the hippocampus of the rat was studied using the situ hybridization and RIA methods, respectively. Single ethanol administration had no effect on either of these two parameters. Repeated ethanol administration decreased both immunoreactive (ir-) alpha-neoendorphin (by ca, 37%) and prodymorphin mRNA (by ca. 57%) levels. Two days after the last dose of ethanol no changes in the ir-alpha-neoendorphin tissue content were found, whereas the level of prodynorphin mRNA remained decreased (by ca. 44%). These results suggest that repeated ethanol evokes a long-lasting decrease in the biosynthesis of hippocampal prodynorphin, this effect that may play some role in the ethanol-induced deficiency of neuronal functions.