ENHANCED 5-HYDROXYTRYPTAMINE-MEDIATED BEHAVIORAL-RESPONSES IN RATS FOLLOWING REPEATED ELECTROCONVULSIVE SHOCK - RELEVANCE TO THE MECHANISM OF THE ANTIDEPRESSIVE EFFECT OF ELECTROCONVULSIVE-THERAPY

Treatment of rats with 1 electroconvulsive shock (ECS)/day for 10 days enhanced the hyperactivity syndrome produced by administration of tranylcypromine (10 mg/kg) and L-tryptophan (50 mg/kg) given 24 h after the final shock. Similar enhancement was seen whether the shock was alternating sinusoidal or direct current (fractionated), whether it was given through unilaterally or bilaterally placed electrodes and whether or not a neuromuscular blocking agent (fazadinium) was used. Shocks (5) spread over 10 days or 8 shocks in 1 day were ineffective. When ECS are given to rats similar to the way in which electroconvulsive therapy is given to patients with depression, enhancement of behavioral responses to increased 5-HT [5-hydroxytryptamine] function is produced.