Objective: The purpose of this study was to investigate the effects of desensitized nicotinic receptors(n ACh Rs) on striatal dopaminergic system in the hemiparkinsonian rats treated with 6-hydroxydopamine(6-OHDA). Methods: We examined the effects of desensitized n ACh Rs on the levels of dopamine(DA) and its metabolites, m RNA expression of dopamine receptor D1,D2 and monoamine oxidase B(MAO-B) in the striatum of 6-OHDA-lesioned rats using high-performance liquid chromatography and reverse transcription-polymerase chain reaction. Results: The results showed that n ACh Rs desensitization following repeated nicotine stimulation could reverse significantly the decrease of striatal DA and its metabolites levels and the increase in DA turnover in lesioned side striatum of hemiparkinsonian rats. Dopamine D1 receptor m RNA expression increased significantly, whereas dopamine D2 receptor m RNA expression remained unchanged in lesioned side striatum of nicotine-treated rats compared to 6-OHDA-lesioned rats when n ACh Rs were desensitized. Meanwhile, nicotine-treated rats displayed a significant decrease in MAO-B m RNA expression in lesioned side striatum compared to 6-OHDA-lesioned rats after n ACh Rs desensitization. Conclusion: These results suggest that n ACh Rs desensitization could promote DA level, upregulate dopamine D1 receptor expression and downregulate MAO-B expression in striatum of hemiparkinsonian rats.
