Effect of kynurenine and quinolinic acid on the action of convulsants in mice

Intraventricular injection of DL-kynurenine and L-kynurenine sulfate (40 microgram) into conscious mice potentiated convulsions and lethality produced by strychnine (1 mg/kg) and not by thiosemicarbazide nor pentylenetetrazol. Another metabolite of tryptophan with convulsive effect, quinolinic acid, was ineffective. Intraperitoneal injection of DL-kynurenine sulfate and quinolinic acid (25-100 mg/kg) was associated with prolongation of the latency of strychnine and thiosemicarbazide (only the former drug) seizures. Nicotinic, picolinic, and anthranilic acids (100 and 250 mg/kg) did not modify the action of convulsants. Data and suggestions about probable involvement of brain glycine and gamma-aminobutyric acid receptors in the convulsive action of kynurenines is discussed.