INVESTIGATIONS INTO MECHANISMS RESPONSIBLE FOR SEIZURES INDUCED BY CHLORINATED HYDROCARBON INSECTICIDES: THE ROLE OF BRAIN AMMONIA AND GLUTAMINE IN CONVULSIONS IN THE RAT AND COCKEREL1

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Abstract
Abstract— Seizures were produced in adult female rats and in cockerels (Gallus domesticusL.) after the intracarotid administration of four structurally‐unrelated chlorinated hydrocarbon insecticides. The temporal relationship of the course of the convulsions to levels in whole brain of ammonia and glutamine was examined. High levels of brain ammonia occurred in rats and cockerels poisoned acutely with lindane, dieldrin, heptachlor and DDT. The intensity of convulsions and other neurological signs coincided with and were directly correlated with the increases in brain ammonia, whereas interictal periods were associated with decreased levels of ammonia. In both species the order of drug toxicity was lindane > dieldrin > heptachlor > DDT.Significantly elevated levels of brain glutamine were induced in the cockerels after administration of all four insecticides. In contrast, increased levels of glutamine in rats were found only in those intoxicated with lindane and dieldrin. Although the ammonia‐binding mechanism (conversion of free ammonia into glutamine) was saturated throughout the experiments in both the rats and cockerels, the latter were more resistant to ammonia toxicity by virtue of being able to convert free ammonia into glutamine more efficiently than rats. These data, together with data reported by others, lead to the conclusion that the four structurally‐unrelated chlorinated hydrocarbon insecticides probably induced convulsions in both species by a common mechanism, involving interference with the production and/or utilization of ammonia.