Potentiation of 5-HT3 receptor functions in the hippocampal CA1 region of rats following repeated electroconvulsive shock treatments

Modulation of serotonin (5-HT)(3)-receptor function by repeated electroconv ulsive shock (ECS) treatment was investigated to elucidate the mechanism un derlying the effectiveness of electroconvulsive therapy (ECT) which is clin ically used for drug-resistant depression. ECS (100 V, 1 s) was applied onc e a day for 14 days via an electrode placed on the ears of rats (ECS group) . For controls, rats were handled similar to the ECS-treated group except f or the stimulation. Hippocampal slices (thickness, 450 mum) were prepared 2 4 h after the final ECS treatment when rats were 5-6 weeks old. Intracellul ar recordings were made from the neurons in the CA1 pyramidal cell layer. A ctivation of 5-HT3 receptors increased spontaneous postsynaptic potentials (sPSP). Increased sPSP was mainly mediated by GABA. The 5-HT3 receptor medi ated increase in sPSP was potentiated in the ECS group compared with the co ntrol group. These findings suggest that the 5-HT3 receptor function is pot entiated by repeated ECS. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.