Effects of Electroconvulsive Shock and Cycloheximide on the Incorporation of Amino Acids Into Proteins of Mouse Brain Subcellular Fractions1

Abstract —The incorporation of [4,5‐3H]lysine and [1‐14C]leucine into the proteins of subcellular fractions of mouse brain was examined following a single electroconvulsive shock (ECS) or following cycloheximide injections. When the [3H]lysine was injected intraperitoneally immediately after the ECS the incorporation into total brain proteins was decreased by more than 50% as compared to sham controls. The proportion of lysine incorporated into the microsomal fraction was increased, but no changes were observed in the other subcellular fractions including the synaptosomal fraction. With extended pulses administered at various times after the ECS there was no change in total incorporation nor were selective effects seen in any subcellular fractions. With intracranial injections of both [3H]lysine and [14C]leucine the decreased incorporation caused by ECS was not observed, neither were there selective changes in any subcellular fraction. This lack of inhibition occurred because the intracranial injection itself severely inhibited [3H]lysine incorporation. Cycloheximide (30 mg/kg) which depressed [3H]lysine incorporation into brain proteins by 84% caused a selective depression of the incorporation into the cell‐sap fraction and selective elevations into the microsomal and synaptosomal fractions. Similar changes were seen with a higher (amnestic) dose of cycloheximide (150 mg/kg) which inhibited incorporation by 94%. These data are interpreted in terms of the diverse mechanisms by which ECS and cycloheximide inhibit protein synthesis.