Abstract: Abstract: Objective To observe the effects of Eldepryl on expressions of tyrosine hydroxylase (TH) and glial cell line-derived neurotrophic factor (GDNF) in substantia nigra and striatum in Parkinson’ s disease (PD) and to explore the protective mechanism of Eldepryl on dopaminergic neuron . Methods Healthy male Sprague-Dawley (SD) rats (n=72) were randomly divided into control group, model group and Eldepryl group (n=24 in each group). Each group was divided random⁃ ly into 2 subgroups as 4 day treatment group and 8 day treatment group (n=12 in each subgrop). Pakinson’ s disease model was established by injecting rotenone subcutaneously back the neck, rats in the control group were injected with an equal vol⁃ ume of sunflower oil subcutaneously at the same location. Rats in the Eldepryl group were then given Eldepryl 0.5 mg·kg-1 in⁃ tragastrically every day for 4 or 8 consecutive days and rats in model group and control group were given an equal volume of saline instead. The expression of TH and GDNF in substantia nigra and striatum were detected by immunohistochemistry and Western blotting. Results Immunohistochemistry and Western blotting showed that strong expression of TH positive cells with little expression of GDNF positive cells were seen in substantia nigra and striatum in rats of control group, and there was no significant difference between subgroup of 8 day treatment and 4 day treatment within control group. The expression of TH cells and GDNF were both significantly reduced in model group compared with those in control group (both P < 0.05), and there was no significant difference between subgroup of 8 day treatment and 4 day treatment within each group. The ex⁃ pression of TH positive cells were significantly reduced in Eldepryl group compared with those in control group, and were sig⁃ nificantly increased compared with those in model group. The expression of GDNF positive cells were significantly increased in Eldepryl group compared with those in control group and model group (all P<0.05). And there were significantly more ex⁃ pression of TH positive cells and GDNF positive cells at subgroup of 8 day treatment compared with those at subgroup of 4 day treatment within Eldepryl group with (all P < 0.05). Conclusion These data suggest that Eldepryl can protect the dam⁃ age of dopaminergic neurons in substantia nigra and striatum of PD rats. And its therapeutic mechanism may be associated with increased expression of GDNF.

Key words: Parkinson&rsquo, s disease, tyrosine 3-monooxygenase, glial cell line-derived neurotrophic factor, dopamine, monoamine oxidase inhibitors, tyrosine hydroxylase, Eldepryl