Ethanol and brain ribosomes

The effects of chronic ethanol intake by mice and rats have been determined on brain ribosomes. Under conditions of ethanol administration, when physical dependence on ethanol either does or does not develop in rats, significant inhibition of polypeptide synthesis was observed in comparison with animals not receiving ethanol. In both rats and mice drinking a 10% ethanol solution, in vitro protein synthesis was found to be diminished more in the free than membrane-bound polyribosomes (polysomes) when compared to similar fractions obtained from control animals. Addition of exogenous amino acids stimulated protein synthesis of free polysomes to a greater extent than that of bound polysomes obtained from both groups of micemin vivo incorporation of [5-3H]-orotic acid into RNA was more inhibited in polysomes than ribosomes of ethanol-drinking mice, suggesting that ethanol affects messenger RNA. In addition, chronic ethanol ingestion produced a decreased in vivo incorporation in ribosomal RNA of a mixed population of ribosomes and polysomes. Chronic ethanol ingestion by mice led also to a differential effect on the polysomal population of the brain. It decreased the amount and the incorporation of precursor label into RNA of free polysomes while exerting an opposite effect on bound polysomes. The significance of these findings relative to brain metabolism is discussed.