Abstract

Objetives: Substantial evidence suggests that reinforcing effects of nicotine can be mediated by the mesolimbic dopaminergic system. It has been shown that repeated injections of nicotine produce increase in locomotor activity and expression of the immediate-early gene, c-fos in the dopaminergic target areas. Herbal medicine as a therapeutic intervention has been widely used for the treatment of mental dysfunction. Many studies have shown that Radix Scutellariae (RS) can affect the biochemical balance in the central nervous system. In order to investigate whether RS have an influence on their nicotine-induced behavioral sensitization, we examined the effect of RS on nicotine-induced locomotor activity and c-Fos expression in the striatum and nucleus accumbens utilizing the Fos-like immunohistochemistry (FLI). Methods: Male SD rats received RS (200㎎/㎏, i.p.) 30 min before repeated daily injections of nicotine (0.4 ㎎/㎏, s.c.) for 7 days. Rats were followed withdrawal for 3 days and one challenge for 1 day. Results: System challenge with nicotine produced a much larger increase in locomotor activity and accumbal FLI. Pretreatment with RS significanly inhibited nicotine-induced locomotor activity and FLI in the striuatum and nucleus accumbens. Conclusions: These results demonstrated that reduction in locomotor activity by RS may be reflected by reduction of dopamine release and postsynaptic neuronal activity in the striatum and nucleus accumbens. Our results suggest that RS may have therapeutic effect on nicotine addiction. Supported in part by a fund of Korea Institute of Oriental Medicine and the Oriental Medicine R&D Project of Health and Welfare (0405-OM00-085-001), Korea.