Abstract: Objective To study the effect of nicotine on the dopaminergic system by analyzing the altered expression of dopamine transporter(DAT) and tyrosine hydroxylase(TH) in the brain of nicotine-treated rats. Methods Healthy male Wistar rats were selected and then injected for 7 days with 0.4 mg/kg nicotine every day. Immunohistochemistry and Western blotting were used to detect the altered expression of DAT and TH in the dopaminergic system in different brain regions of the nicotine treated rats. Results Compared with the control: 1. Immunohistochemistry showed the mean gray value of DAT in nucleus accumbens (NACC) and ventral tegmental area(VTA) decreased 12.43 % and 12.85 % respectively, the mean gray value of TH in NACC and VTA decreased 11.87 % and 10.09 %. 2. Western blotting showed the ratio of relative absorbance of DAT/β-actinin in CPu-NACC and SN.VTA of the the nicotine-treated rats increased 75.68 % and 117.14 % respectively; the ratio of relative absorbance of TH/β-actinin in caudate putamen(CPu)-NACC and substantia nigra(SN)-VTA increased 66.32 % and 60.31 % respectively. Conclusion Nicotine treatment increases the expression of DAT and TH in rat brain, which may have some relations with the mechanism of nicotine dependence.

Key words: Nicotine, Dopamine transporter, Tyrosine hydroxylase, Immunohistochemistry, Western blotting, Rat