CHRONIC ADMINISTRATION OF CITALOPRAM INHIBITED EL MOUSE CONVULSIONS AND DECREASED MONOAMINE OXIDASE-A ACTIVITY

Serotonin (5-HT) is thought to play an important role in the seizures of Et mice because the seizure threshold of El mice correlates with th e 5-HT concentration in the central nervous system, In this study, the anticonvulsant effect of a 5-HT reuptake blocker, citalopram, was eva luated behaviorally and biochemically. El mouse convulsions were inhib ited by chronic administration of citalopram (80 mg/kg/day, p.o, for 2 weeks), but were not inhibited by acute administration of citalopram (80 mg/kg, i.p., 2h after single injection), Both chronic and acute ad ministration of citalopram decreased the concentration of 5-hydroxyind olacetic acid in the brain, whereas the concentration of 5-HT was not changed by treatment with citalopram, Tryptophan hydroxylase activity was not different between the citalopram and control groups, although the monoamine oxydase-A activity was lowered by chronic administration of citalopram. These findings suggest that both acute and chronic adm inistration of citalopram depresses the 5-HT turnover rate, however ch ronic administration is necessary to inhibit El mouse convulsions,