Effects of heat stress with organophosphorus pesticide intoxication on blood AChE activity and tissue anti-oxidation ability in mice

Objective To explore the combined effect of heat stress with organophosphorus O,O-dimethyl-O-2,2-dichlorovinylphosphate(DDVP) intoxication on blood acetyl cholinesterase(AChE) activity and tissue lipid peroxidation.Methods Fifty-four mice were randomly divided into control group,heat stress group and heat stress combined with DDVP poisoning group(the combined group).Mice were put into experiment chamber with(60±5)% relative humidity.The chamber temperature was 24℃ for control group,and 38 or 40℃ for heat stress group.One hour later,mice in combined group were intraperitoneally given 9 or 15 mg/kg DDVP.Saline of an equal volume was applied to control and heat stress groups.After 30 minutes,the mice were sacrificed and samples of the blood,heart,brain,and liver were collected.Blood AChE activity,tissue SOD activity,MDA content and ·OH inhibiting ability in tissue homogenates of the brain,heart and liver were determined respectively.Results Mice became agitated and restless with increased activity when exposed to 38 or 40℃ ambient temperature.Water intake and body mass were decreased.Compared with temperature-matched controls,the heat exposure combined with DDVP poisoning at 38 or 40℃ caused significant decline of blood AChE activity,tissue SOD activity and ·OH inhibiting ability,and increase of tissue MDA content in the brain,heart and liver(P0.05).Heat stress and organophosphorus pesticide intoxication showed synergistic interaction between the above parameters.Conclusion Under present experimental conditions,both ambient temperature and organophosphorus poisoning can significantly suppress the blood AChE activity while causing enhanced tissue lipid peroxidation.These data suggest that oxidative stress plays a role in the aggregative effect of organophosphorus intoxication under high ambient temperature.