Correlation between whole blood cholinesterase activity and cerebral cortex cholinesterase activity in rats treated with parathion.

Organophosphate and carbamate insecticides are inhibitors of cholinesterases (ChE). The depression of blood ChE activity is frequently used as indicative of exposure to these chemicals. However, it is not known whether the inhibition of blood ChE activity reflects the inhibition of ChE in target tissues (e.g. brain and muscle). In this study we investigated the possibility of using whole blood ChE activity to predict frontal cerebral cortex ChE activity in rats treated with parathion. Twenty four hours after the intraperitoneal administration of several doses of parathion, the activity of ChE in whole blood and the activity of ChE in frontal cerebral cortex were determined in each animal. A high correlation between the two parameters was found (r = 0.96, p < 0.05) and the model of linear regression fitted to the data accounted for 93% of its variability. Thus, these results seem to indicate that 24 hours after the treatment with parathion the effects induced on whole blood ChE activity may be used to predict the effects caused on frontal cerebral cortex ChE activity.