Kynurenines and audiogenic excitement in mice

Adult male and female albino mice (SHR strain) responded to sound by locomotor excitement (73-81%), running fits (33-47%), clonic convulsions (15-25%), tonic extension (10-22%) and lethality (7-17%). Intraperitoneal injection of metabolites of tryptophan on the kynurenine pathway (Kynurenines): DL- and L-kynurenine sulfate, 3-hydroxyanthranilic, anthranilic, quinolinic, picolinic, nicotinic and xanthurenic acids (in doses of 200 and 400 mg/kg) decreased audiogenic excitement. Intraventricular injection of kynurenines (1-50 mcg), even in stimulating and convulsive doses, had no effect. Intraventricular injection did not induce an audiogenic response in C57 BL/6 and CC57BR mice which are not normally susceptible to sound. Pentylenetetrazol and strychnine injected intraventricularly in up to lethal dosages did not modify audiogenic excitement. Decrease of audiogenic excitement by kynurenines is suggested to be partially related to lowering of body temperature.