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

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 (GTP gamma 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 GTP gamma S binding activity following repeated ECT resembled those found in PLC activity as follows: in the prefrontal cortex, GTP gamma 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 GTP gamma 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.