Convulsant activity of Naja Naja venom and its phospholipase A component.

Abstract

Abstract Naja naja (hooded cobra) venom and its purified components were injected intraventricularly into rats. Purified cobrotoxin (50 μg) and cardiotoxin (125 μg) caused piloerection, lacrimation and death but no convulsive activity. Crude cobra venom (5 μg) and a partially purified phospholipase A (2·5 μg) isolated from Naja naja venom induced convulsions. Analysis of brain phospholipids after injection of 330 μg phospholipase A demonstrated an increase in lysophosphatides. Hydrolysis of phospholipids was greater at the onset of convulsions than 1 2 hr before onset. Lysolecithin (100 μg) and stearic acid (500 μg), hydrolysis products of phospholipase A action, did not induce convulsions after intraventricular injection. Phospholipase C in doses as low as 1 μg caused convulsions when injected intraventricularly. Examination of brain phospholipids at the onset of convulsant activity after injection of 250 μg of the enzyme showed a reduction in total lipid phosphorus and a corresponding increase in total aqueous phosphorus and diglyceride as a result of the enzyme's action. The possible involvement of phospholipase A in convulsant activity is discussed.