Effects of exposure to an organophosphate pesticide on behavior and acetylcholinesterase activity in the common shrew, Sorex araneus

Abstract

AbstractThe behavioral and physiological effects of exposure to dimethoate, an organophosphate (OP) pesticide, were examined in common shrews, Sorex araneus, under laboratory conditions. Shrews were given either saline or an acute sublethal dose (50 mg/kg intraperitoneal) of dimethoate, and a time course of behavior was recorded in five 10‐min open field tests spaced over a 12‐h period. Parallel measurements of brain acetylcholinesterase (AChE) activity were carried out to monitor the onset of brain AChE inhibition and its subsequent recovery. Dimethoate produced a significant depression of locomotor activity for approx. 6 h. Rearing, exploring, and sniffing activities were also significantly inhibited. The observed behavioral effects coincided with the maximal inhibition of AChE and disappeared before the brain AChE level had recovered. Statistically significant correlations were observed between the reduced frequencies of exploring, rearing, and crossings (a measure of locomotor activity) and the severity of inhibition of brain AChE activity, suggesting that brain AChE activity, the biomaker of exposure, could be used as a predictor of the severity of OP‐induced effects on behavior.