Abstract: ObjectiveTo study the neurotoxicity effects of avermectine on the nerve metabolic enzyme in rat cerebellum.MethodsSeventy two Wistar rats were divided into 3 groups randomly and treated with avermcctine by gavage at doses of 2.5,5.0 mg/kg for three times.The rats were executed at 7d,14d and 21d and their body weight, cerebellum weight, organ body ratio,activity of the glutamine gynthetase(GS),lactic dehydrog enase(LDH),creatine kinase(CK)and the activity of calcineurin(CaN)in the cerebellum were detected.ResultsA vermectine had no influence on body weight and cerebellum body ratio.The activities of LDH,GS,CK and CaN in 5.0mg/kg group were 15.508±0.084,299.849±33.563 U/g·rot, 7.635±0.377 U/ml, 0.699±0.043 Umolpi/mg·prot/hour,respectively at the end of treatment.Compared with the control group,the activities of GS and CK were increased and the activity of CaN was decreased.ConclusionA vermectine may cause ataxia by disturbing the activity of nerve metabolism enzyme in rats.