Subcellular distribution of glutamic acid decarboxylase in rat brain regions following electroconvulsive stimulation

Electroconvulsive stimulation of rats evoked significant increases of glutamic acid decarboxylase (GAD) activity in the synaptosomal fractions of neocortex (including white matter) and hippocampal formation. The elevation of synaptosomal-bound GAD activity was not significant in cingulate cortex, striatum, caudal brainstem and thalamus. The electroconvulsive shocks had no effect on the GAD activity of the cytoplasmic fractions of any brain regions investigated. The highest physiological level of synaptosomal GAD activity was found in thalamus, followed (in decreasing order) by striatum, hippocampus, cingulate cortex, caudal brainstem and neocortex.