Local cerebral glucose utilization after chronic electroconvulsive shock: implications for the mode of action of electroconvulsive therapy.

The [(14)C]2-deoxyglucose autoradiographic technique measures local rates of glucose utilization simul taneously in all functional and anatomical subunits of the CNS and provides a measure of the functional consequences in the CNS of any manipulation. Glucose utilization was measured in 24 regions of the CNS in conscious rats one day after the end of a 7-day course of electroconvulsive shock (chronic ECS). Chronic ECS had minimal effects on local glucose utilization in most brain areas (including extrapyramidal, cortical, hippocampal and other limbic structures) with only the nucleus accumbens displaying a significant alteration (reduced by 25% from sham-treated animals). These data suggest that functional alterations in the nucleus accumbens may underly a unique therapeutic mechanism of electroconvulsive therapy (ECT), which is known to be effective in a wide variety of psychiatric syndromes characterized by mixed depressive and 'positive' psychotic symptoms. Our findings (supported by preliminary data from a study of sub-convulsive ECS) suggest that the functional sequelae of repeated electroconvulsions in selectively vulnerable limbic and hippocampal structures-more likely to underly ECT's unwanted cognitive side effect than its wanted therapeutic effect-may be attenuated by reducing the power of the stimulus required to induce seizures.