Amphetamine- and scopolamine-induced locomotor activity following treatment with chlorphenvinphos or chlorphyriphos in rats.

OBJECTIVES Effects of acute exposure to organophosphorous pesticides (OPs), chlorphenvinphos (CVP) or chlorphyriphos (CPF) on amphetamine (AMPH)- or scopolamine (SCOP)-induced open-field locomotion were compared in rats. MATERIALS AND METHODS CVP and CPF were administered intraperitoneally, both at doses resulting in about 50% inhibition of erythrocyte acetylcholinesterase (rbcAChE). The pesticide groups did not differ one from another in the magnitude of the acute behavioral effects. RESULTS Three weeks after the exposure, i.e. when AChE activity returned to normal level, the behavioral response to AMPH and SCOP was significantly reduced in CVP-, but not in CPF-pretreated rats. CONCLUSIONS These results confirm that a single exposure to organophosphorous pesticides may result in neurobehavioral effects detectable after restitution of AChE. They also show that CVP and CPF differ in respect of long lasting functional consequences of exposure, which suggests a difference in the mechanism of toxicity.