Long-term monoamine changes in the striatum and nucleus accumbens after acute chlorpyrifos exposure

This study examined the time-course effects (2, 7, 14 and 30 days) of acute chlorpyrifos (CPF) intoxication (250 mg/kg, s.c.) on monoamine systems and acetylcholinesterase (AChE) activity in the striatum and nucleus accumbens of adult male rats. We show that CPF produced significant long-term inhibition of AChE activity in the striatum and nucleus accumbens. In the striatum, CPF intoxication resulted in changes in dopamine (DA) metabolism after 2 days and changes in serotonin (5-HT) turnover after 7 and 15 days. Significant decreases in monoamine content including norepinephrine (NE), DA, 5-HT and their metabolites were found in the nucleus accumbens 30 days after CPF intoxication. These results suggest that acute exposure to CPF induces long-term changes in the monoamine systems (NE, DA and 5-HT) in adult animals. The lack of correlation between regional AChE activity and neurochemical outcomes points to independent mechanisms.