EFFECTS OF KYNURENINE METABOLITES ON THE ELECTROCORTICOGRAPHIC ACTIVITY IN THE RAT

We examined the effects of kynurenine metabolites administered into th e right cerebroventricle (1 mu mol) on the electrocorticogram (ECoG) o f rats to establish the role of kynurenines on brain function. Kynuren ine, anthranilic acid, quinaldic acid, xanthurenic acid or 8-hydroxyqu inaldic acid showed no effect on ECoG throughout the recording period of 4 hours. 3-Hydroxykynurenine had a transient suppressive effect on the ECoG, while kynurenic acid caused a slight suppression of ECoG act ivity. 3-Hydroxyanthranilic acid (3-OH-An), a metabolite of 3-hydroxyk ynurenine, induced spike discharges with a long latency (60-230min). 3 -OH-An is thought to be metabolized to o-aminophenol, 3-methoxyanthran ilic acid, quinolinic acid, 2-ketoadipic acid and picolinic acid. Amon g 3-OH-An metabolites, only o-aminophenol induced spike discharges sev eral minutes after administration, lasting for 60min. On the other han d, quinolinic acid suppressed ECoG, though 3-methoxyanthranilic acid, 2-ketoadipic acid and picolinic acid had no effects on ECoG. These ele ctrocorticographic findings suggest that 3-OH-An may induce spike disc harges after it is metabolized in the brain to o-aminophenol.