Objective To observe the effects of selegiline on tyrosine hydroxylase (TH) and neuronal nitric oxide synthase (nNOS) in the gastric antrum of rats with Parkinson disease(PD), so as to investigate the therapeutic effect and mechanism of selegiline for treatment of gastric disfunction in PD. Methods A total of 72 SD rats were randomly divided into normal control group, PD model group, and selegiline treatment group. PD rat models were established by subcutaneous rotenone injection. After the success of model preparation, PD group was given normal saline, and the therapy group was given selegiline (0.5 mg/kg) by intragastric administration. At 4 d and 8 d after therapy, residual rate of solid food was detected in the stomachs of animals, and the expressions of TH and nNOS were detected by immunohistochemistry method and Western blotting analysis. Results Compared with the control group, the model group had significantly higher residual rate of solid food, significantly lower TH expression, and significantly increased nNOS expression in the gastric antrum (all P<0.01). Compared with the model group, the treatment group had significantly decreased residual rate of solid food, significantly increased TH expression and significantly lower nNOS expression in the gastric antrum at all time points(P<0.05,or P<0.01). At 8 days after selegiline treatment, the residual rate of solid food was significantly lower, TH expression was significantly increased, and nNOS expression was significantly decreased (all P<0.05) compared with those at 4 days after treatment. Conclusion Selegiline can improve the gastric dysfunction in PD rats, which might be related to relieve of gastric dopaminergic neuronal injury and inhibition of nNOS expression.