Abstract: ObjectiveTo investigate the effect of 48% chlorpyrifos on cholinesterase activity and signal transduction pathway in rats.MethodsThirty-two rats were randomly divided into low-dose(1/40 median lathal dose LD₅₀),moderate-dose(1/20 LD₅₀),high-dose(1/10 LD₅₀)groups,and saline control group.The rats were treated by oral gavage for 28 days.The activity of whole blood cholinesterase was detected with ferric chloride colorimetric method; the expression of the receptor of advanced glycation end-products(RAGE)and protein kinase C(PKC)in brain tissue were detected with the immunohistochemistry;the expression of Gq protein in brain tissue were detected with western blot.ResultsThe activity of whole blood cholinesterase decreased with the increase of exposure,with the value of 33.75 ±5.03,29.70±4.01,10.40±1.95,and 5.25±0.05 for control group,low-,moderate-,and high-dose groups.The expressions of RAGE,Gq protein,and PKC increased with the increase of exposure,with the RAGE expression of 0.32± 0.01,2.01±0.09,5.03±0.05,8.02±0.04,Gq protein expression of 0.84±0.01,0.90±0.01,1.10±0.02,1.59± 0.01,and PKC expression of 0.12±0.01,2.01±0.03,3.52±0.02,5.01±0.08 for control group,low-,moderate-,and high-dose group,respectively.ConclusionChlorpyrifos shows toxicity to rats by inhibiting the activity of cholinesterase.The high expression of RAGE,Gq protein and PKC might be involved nervous system pathological signal transduction in chlorpyrifos poisoning.