Electroconvulsive shock and postsynaptic catecholamine effects: increased psychomotor stimulant action of apomorphine and clonidine in reserpine pretreated mice by repeated ECS

Male mice were administered electric convulsive shocks (ECS) once daily for one (ECS X I), three (ECS X III) or seven days (ECS X VII). One (day 1), three (day 3) or six days (day 6) later they received reserpine 10 mg/kg, followed 2 hours later by clonidine, 1.5 mg/kg, and/or apomorphine, 1.5 mg/kg. Control animals received the same drug treatments but no ECS. The motor activity was recorded for 1 hour, starting immediately after the last drug injection. The behavioral depression induced by reserpine was equally pronounced in ECS-pretreated animals as in the control animals. The psychomotor stimulant effects of clonidine and/or apomorphine, given after reserpine was, however, enhanced by pretreatment with ECS X VII, DAY 1. Pretreatment wit- ECS X VII increased the motor activity also in animals given reserpine, apomorphine and clonidine at day 3 or day 6. ECS X III was also effective in this respect at day 1, whereas ECS X I, day 1, was ineffective. Mice given ECS X VII but no drug treatment showed at day 1 an increased motor activity during the initial 10 min and a decreased activity during the last 10 of the 1 hour recording period. At day 3 and day 6 after ECS X VII the motor activity was increased in comparison to that in untreated control animals during the whole 1 hour period. Animals given repeated ECS furthermore showed increased irritability and reduced body weight. The results indicate that repeated ECS increase the sensitivity of postsynaptic catecholamine receptors in the brain or alter neuronal structures which are connected to these receptors.