ALTERATIONS IN GABA METABOLISM AND MET‐ENKEPHALIN CONTENT IN RAT BRAIN FOLLOWING REPEATED ELECTROCONVULSIVE SHOCKS

Abstract The effects of electroconvulsive shock (ECS; 120 V for 1 s through ear‐clip electrodes) or sub‐convulsive shocks (70 V for 1 s) on rat brain GABA and met‐enkephalin concentration and GABA turnover has been examined 24 h after a single treatment (×1) or once daily for 10 days (×10). ECS × 10 increased GABA concentrations in the N. caudatus and N. accumbens and decreased the synthesis rate of GABA by 40% and 50% respectively in these regions. Sub‐convulsive shocks (× 10 × 10) or ECS × 1 had no effect. No consistent changes were seen in the substantia nigra. Met‐enkephalin concentrations increased by 50% in the N. caudatus after ECS × 10 but were unchanged in the cortex and pons/medulla. No other shock regimen had any effect on the concentration of this peptide. The results are discussed in relation to the enhanced monoamine‐induced responses seen only after ECS × 10.