Abstract

Substantial evidence suggests that behavioral and reinforcing effects of cocaine can be mediated by the mesolimbic dopaminergic system. Many studies have shown that Coptidis Rbizoma has a suppressive effect on the central nervous system (CNS) can affect the neurotransmitter systems in the CNS. In order to investigate whether Coptidis Rbizoma has an influence on cocaine-induced reinforcement and behavioral sensitization, we examined the effect of Coptidis Rbizoma on repeated cocaine-induced locomotor activity and c-Fos expression in the nucleus accumbens and the striatum utilizing Fos-like immunohistochemistry method. Male SD rats received Coptidis Rbizoma (200mg/kg, p.o.) 30 min before injections of cocaine (15mg/kg, i.p.) for 10 days. Rats were followed withdrawal for 3 days and one challenge for 1 day. Systemic challenge with cocaine produced a much larger increase in locomotor activity and expression of c-Fos in the nucleus accumbens and the striatum. Pretreatment with Coptidis Rbizoma decreased in cocaine-induced locomotor activity and c-Fos expression. These results demonstrated that reduction in locomotor activity by Coptidis Rbizoma may be mediated by reduction of dopamine release and of postsynaptic neuronal activity in the nucleus accumbens. Our results suggest that Coptidis Rbizoma may have therapeutic effect on cocaine addiction.