Objective To observe the effects of Wendan decoction (WD) on depression-like behavior in a rat model of Parkinson's disease (PD) and explore the related mechanism.Methods Rodent model of PD was established by unilaterally lesioning medial forebrain bundle with 6-hydrodopamine.After intragastric administration with WD,the rats's behavior changes were detected by the open field test,sucrose preference test and forced swimming test;the contents of monoamine neurotransmitters in the rat brain were assessed by high-performance liquid chromatography with electrochemical detection.Results Compared with those of sham-operated rats,the horizontal and vertical activities of the PD model rats decreased significantly,and sucrose consumption decreased significantly,but immobility time during forced swimming was significantly prolonged.The contents of dopamine (DA),5-hydroxytryptamine (5-HT) and noradrenaline (NA) in the medial prefrontal cortex (mPFC) and DA in the striatum decreased significantly.After administration of WD for 2 weeks,the immobility time of the PD model rats was significantly decreased,sucrose consumption increased significantly;DA,5-HT and NA levels in the mPFC increased significantly.Conclusion WD improves the depression-like behavior in PD model rats,and the mechanisms may involve the regulation of monoamine neurotransmitters in mPFC.