Electroconvulsive treatment: Effects on phospholipase C activity and GTP binding activity in rat brain

Abstract

The effect of electroconvulsive treatment (ECT) on activities of phospholipase C hydrolyzing phosphatidylinositol (PI-PLC) and phosphatidylinositol 4,5-bisphosphate (PIP₂-PLC) and guanosine-5′-(3-O-thio)triphosphate (GTPγ S) binding activity were examined in membrane and cytosol fractions from four discrete areas (prefrontal cortex, hippocampus, striatum, and amygdala) of the rat brain. A single ECT resulted in an increase in cytosolic activities of PI-PLC in the prefrontal cortex and of PIP₂PLC in all 4 brain regions examined. There were no significant changes in either PI-PLC or PIP₂-PLC activity in membrane fractions after a single ECT. Repeated ECT caused regionally specific changes in PLC activities as follows: in the prefrontal cortex, both cytosolic PI-PLC and PIP₂-PLC and membranous PI-PLC activities were decreased; in the hippocampus, no changes in any PLC activities were seen; in the striatum, only membranous PI-PLC activities were increased; and, in the amygdala, cytosolic and membranous PI-PLC and cytosolic PIP₂-PLC activities were increased. The pattern of changes in GTPγ S binding activity following repeated ECT resembled those found in PLC activity as follows: in the prefrontal cortex, GTPγ S binding activities were significantly reduced in both membrane and cytosol; in the hippocampus, the activity was decreased in membrane; in the striatum, no changes in GTPγ S binding activity were seen in any fraction; and, in the amygdala, the activity was increased in cytosol. These findings suggest that ECT has complex effects on the G protein-phospholipase C system, possibly affecting neuronal signal transduction.