Electroconvulsive shock stimulates polyphosphoinositide degradation and inositol trisphosphate accumulation in rat cerebrum: lithium pretreatment does not potentiate these changes

Abstract

Using an in vivo model, we explored the acute effects of electroconvulsive shock (ECS) and lithium on rat cerebral polyphosphoinositides and inositol phosphates. ECS was shown to increase the [3H]inositol trisphosphate ([3H]IP3) by 75%, decrease the endogenous mass of phosphatidylinositol 4,5-bisphosphate (PIP2) by 23%, and enhance [3H]myo-inositol labeling into the polyphosphoinositides. In contrast, lithium pretreatment 20-24 h prior to ECS appeared to attenuate the ECS-induced [3H]IP3 increase and the decrease in mass of PIP2; [3H]inositol monophosphate ([3H]IP1) levels demonstrated no differences between the lithium ECS and lithium-alone groups. These results indicate that ECS stimulates the inositol lipid cycle in brain possibly due to neurotransmitter release. Moreover, the effects of lithium suggest other possible sites of action of this cation on inositol lipid metabolism in addition to an inhibition of inositol-1-phosphatase.