Serotonin-dopamine antagonism ameliorates impairments of spontaneous alternation and locomotor hyperactivity induced by repeated electroconvulsive seizures in rats.

We have shown that seven consecutive administrations of electroconvulsive shock (ECS) produce impairment of spontaneous alternation behavior in a Y-maze test and a locomotor hyperactivity in an open-field test even 24h after the last administration in rats. To clarify the mechanisms of the behavioral impairments, we investigated the effect of drugs acting on dopaminergic and serotonergic nervous systems. The dopamine-2 (D(2)) receptor antagonists haloperidol and sulpiride abolished locomotor hyperactivity, but did not show effects on the impairment of spontaneous alternation behavior. The serotonin-2 (5-HT(2)) receptor antagonist ketanserin suppressed the impairment of spontaneous alternation behavior without affecting locomotor hyperactivity. The 5-HT(2) and D(2) receptor antagonist risperidone significantly ameliorated both behavioral impairments. These results suggest that 5-HT(2) receptors and D(2) receptors are associated with repeated ECS-induced impairment of spontaneous alternation behavior and locomotor hyperactivity, respectively.