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 (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.

Electroconvulsive shock treatment differentially modulates cortical and subcortical endocannabinoid activity

“…There is a possibility that ECS‐induced changes in the G protein level may have influenced our data. For example, repeated ECS sessions have been shown to result in a reduction in basal GTPγS binding in the PFC exclusively, which could, in turn, reflect changes in either absolute content of G protein subunits or altered ability of these proteins to associate with a specific receptor (Nishida et al. 1990).…”

“…Given the lack of concurrent change in CB 1 receptor binding following repeated ECS sessions, this increased sensitivity of the CB 1 receptor likely occurs at a downstream location. Accordingly, a comparable ECS regimen has been found to result in increased basal [ 35 S]GTPγS binding in the amygdala, which is likely reflective of increased expression of specific G proteins (such as the G oα ) or enhancement of the ability of specific G proteins to interact with specific metabotropic receptors (Nishida et al. 1990), such as the CB 1 receptor.…”

Electroconvulsive Shock Reduces Inositol 1,4,5‐Trisphosphate 3‐Kinase mRNA Expression in Rat Dentate Gyrus

“…It has been reported that electroconvulsive shock (ECS) or convulsions increase phosphaddylinositol 4,5-bisphosphate (PIP Z) breakdown and inositol 1,4,5-trisphosphate (InsP3 ) accumulation and activate phosphoinositide-specific phospholipase C (PI-PLC) in the rat brain (Vadnal and Bazan, 1987 ;Nishida et al ., 1990 ;Bodjarian et al ., 1993) . These findings suggest that ECS may affect the metabolism of InsP3 , which is a hydrolyzation product of PIPZ by PI-PLC .…”