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BACKGROUND: Recent researches have indicated that estrogen has extensive neuroprotective effects. So some studies designed ovariectomized animal models and administrated with estrogen, so as to verify its neuroprotective effects.OBJECTIVE: To observe the effect of 17 beta-estradiol on the content of norepinephrine (NE) and level of tumor necrosis factor (TNF) in submandibular glands of rats with sympathetic nerve injury, and analyze the dose-dependence and pathway of action.DESIGN: A randomized control animal study.SETTINGS: Department of Hand Surgery, the 252 Hospital of Chinese PLA; Department of Hand Surgery,Union Hospital affiliated to Tongji Medical College, Huazhong University of Science and Technology.MATERIALS: Fifty healthy female Wistar rats were randomly divided into 5 groups with 10 rats in each group: sham-operated group, ovariectomy+6-OHDA+saline group, ovariectomy+6-OHDA+17β-estradiol 50,200 and 500 μg/kg groups.METHODS: The experiments were carried out in Tongji Medical College, Huazhong University of Science and Technology between October 2005 and March 2006. Bilateral ovaries were only exposed but not resected for the rats in the sham-operated group, but bilateral ovaries were resected in all the other groups. In the ovariectomy+6-OHDA+17β-estradiol 50, 200 and 500 μg/kg groups, the rats were administrated with intraperitoneal injection of 6-OHDA (8 mg/kg), and then immediately given 17β-estradiol of corresponding dosages respectively, once a day for 10 days continuously. Rats in the sham-operated group and ovariectomy+6-OHDA+saline group were administrated with saline of the same volume. After administration, 5 rats in each group were killed to determine the NE contents in bilateral submandibular glands with high performance liquid chromatography-electrochemical detector (HPLC-ECD), and the other 5 rats were used to determine the TNF levels in submandibular glands with enzyme-linked immunosorbant assay.MATN OUTCOME MEASURES: The NE contents and TNF levels in submandibular glands of rats in each group were observed.RESULTS: All the 50 rats were involved in the analysis of results. ① The NE content was obviously lower in the ovariectomy+6-OHDA+saline group than in the sham-operated group [(1 035±196), (1 823±314) ng/g,P ＜ 0.05], there were no significant differences between the ovariectomy+6-OHDA+17β-estradiol 50 μg/kg group and ovariectomy+6-OHDA+saline group [(1 004±253), (1 035±196) ng/g, P ＞ 0.05], but obviously higher in the ovariectomy+6-OHDA+17β-estradiol 200 and 500 μg/kg groups than in the ovariectomy+6-0-ously higher in the ovariectomy+6-OHDA+saline group than in the sham-operated group [(3.498±0.792),(1.893±0.533) ng/g, P ＜ 0.05], there were no significant differences between the ovariectomy+6-OHDA+17β-estradiol 50 μg/kg group and ovariectomy+6-OHDA+saline group [(3.328 ±0.712),(3.498±0.792) ng/g, P ＞ 0.05], but obviously lower in the ovariectomy+6-OHDA+17β-estradiol 200 and 500 μg/kg groups than in the ovariectomy+6-OHDA+saline group [(2.639±0.438), (2.016±0.619),(3.498±0.792) ng/g, P ＜ 0.05].CONCLUSION: Estrogen has obvious protective effect dose-dependently on 6-OHDA induced chemical sympathetic nerve terminal injury in rats, and it may play its protective role by reducing TNF level and ameliorating inflammatory reaction.