Experimental alcoholism in rats. Effect of acute ethanol intoxication on the in vitro incorporation of ( 3 H)leucine into neuronal and glial proteins.

Abstract

Abstract— Ethanol administered in vivo or in vitro during incubation of brain slices was studied with respect to its effect on brain protein synthesis.In the in vivo series the rats were given a single intraperitoneal injection of ethanol 3 h before death. Slices of cerebral cortex and liver were incubated in isotonic saline media containing [3H]leucine. Amounts of free and protein‐bound radioactivity were determined. Subcellular fractions and fractions enriched in neuronal perikarya and in glial cells were prepared from cortical slices subsequent to incubation, and the specific radioactivity determined for each cell type.The incorporation of [3H]leucine into brain proteins was inhibited while incorporation into liver proteins was stimulated in ethanol‐treated rats. The levels of TCA‐soluble radio‐activity, however, did not differ between the ethanol group and the controls. In the fractionated material from cerebral cortex, the specific radioactivity in the neuronal fraction was unaffected by ethanol, while the radioactivity in the glial fraction was significantly depressed. In vitro administration of ethanol induced a non‐linear response in both brain and liver, with depression of leucine incorporation into proteins of cerebral cortex at all concentrations used. When brain slices were exposed to ethanol in vitro, in concentrations corresponding to the in vivo experiments, a similar reduction of the leucine incorporation into the glial fraction was obtained. Incorporation of leucine into subcellular fractions from whole brain cortex was also investigated. The specific sensitivity of the glial fraction to ethanol is discussed in relation to the involvement of the different cell types with transport processes in the brain.