ENHANCEMENT OF ACTIVITY OF AN EPILEPTOGENIC FOCUS IN THE FROG HIPPOCAMPUS BY KYNURENINS AND ITS DEPRESSION BY SEROTONIN

Experiments on frogs with an epileptogenic focus produced by injection of 1000 units penicillin (0.4 μl) into the primordial hippocampus showed that preliminary injection of two kynurenins - quinolinic acid (QA, 0.1 μg) and kynurenin itself (K, 1 μg) - into the region of the focus or their injection into an already functioning epileptogenic focus led to an increase in the frequency of interictal epileptiform discharges and of electrographic correlates of fits on the EEG. Anthranilic acid (AA, 5 μg) had no effect on activity of the focus whereas serotonin (S, 1 μg) and 5-methoxytryptamine (1 μg) substantially depressed it. The provoking action of the kynurenins on epileptically predisposed brain neurons, it is suggested, may play an important role in the pathogenesis of epilepsy. © 1979 Plenum Publishing Corporation.