title: Repeated electroconvulsive shock induces changes in high-affinity [3H]-ouabain binding to rat striatal membranes.
abstract: Repeated electroconvulsive shock is an effective treatment for affective disorders. Striatum, hippocampus and brainstem are involved in affective disorders. Sodium-potassium/ATPase is of paramount importance for the proper functioning of the brain and its involvement in the affective disorders has been claimed for a long time. Sodium-potassium/ATPase has an extracellular regulatory binding site to which cardiotonic glycosides, such as ouabain, bind to, thus regulating the activity of the enzyme. Endogenous "ouabain-like" substances exist in the brain and their actions on the sodium-potassium/ATPase resemble ouabain biological properties. The aim of this work was to determine if electroconvulsive shock (ECS) would induce changes in the high-affinity binding of ouabain to the sodium-potassium/ATPase from rat brain regions. Adult, male Wistar rats received one (ECSx1 group) or seven electroshocks (ECSx7 group) delivered daily through ear-clips electrodes. Control rats received the same manipulations; however, no current was delivered through the electrodes (SHAMx1 and SHAMx7 groups). All groups were sacrificed 24 h after the last ECS session. The B (max) and K (D) of high-affinity [(3)H]-ouabain binding were determined in crude membrane preparations from the striatum, hippocampus and brainstem. The results obtained showed a statistically significant increase in the affinity of [(3)H]-ouabain (lower K (D)) to striatal membranes in those rats receiving seven ECS. In the striatum there was no change in the K (D) after one ECS; as well as there was no change in the B (max) after a single or seven ECS. High-affinity [(3)H]-ouabain binding to hippocampus and brainstem did not reveal any significant differences either in K (D) or B (max) after one or seven ECS. The increased affinity of ouabain to the striatal sodium-potassium/ATPase induced by repeated ECS suggests an increased interaction in vivo of the endogenous "ouabain-like" substances with the enzyme and the involvement of the extracellular regulatory allosteric ouabain binding site in the striatal sodium-potassium/ATPase in the effects of electroconvulsive shock.
authors.affiliation: Departamento de Psicobiologia, Universidade Federal de São Paulo, Brazil.
authors.forename: Magda
authors.initials: M
authors.lastname: Bignotto
authors.forename: Marco Antonio Campana
authors.initials: MA
authors.lastname: Benedito
mesh_terms: D000818:Animals; D002316:Cardiotonic Agents / Q000737:chemistry / Q000493:pharmacokinetics; D003342:Corpus Striatum / Q000166:cytology / Q000378:metabolism; D004597:Electroshock; D008297:Male; D010042:Ouabain / Q000737:chemistry / Q000493:pharmacokinetics*; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D014316:Tritium / Q000378:metabolism
chemical_list: D002316:Cardiotonic Agents; D014316:Tritium; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase