Ethanol-induced changes in properties of rat brian ribosomes.

Altered in vivo and in vitro brain protein metabolism have been demonstrated in rodents following long-term ethanol ingestion. In the present study, ethanol effects were examined on properties of brain ribosomes of male Sprague-Dawley rats ingesting a specially formulated Lieber-DeCarli liquid diet. The development of physical dependence was demonstrated by the presence of withdrawal reactions within 24 hr of ethanol abstinence. Data showed significant inhibition of in vitro protein synthesis by ribosomes from the "ethanol" and "1-day-withdrawn" groups. Partial reversal of inhibition occurred by using a control brain pH 5 enzymes source instead of the matched source. The observed [14C]leucine-incorporating activity was temperature dependent, with the optimum temperature being 37 degrees C. The determination of the state of ribosomal aggregation showed an increased monosomes--disomes ratio in the "ethanol" group. The ratio was even more increased in the "1-day-withdrawn" group. Data suggest that reduced ribosomal binding to stable mRNA may be a contributing factor in the ethanol-induced effects on protein synthesis.