Protective Effect For Dopaminergic Neurons Of Fragmin In MPTP-treated Mice And Its Mechanisms

Objective: The abnormal activation of microglia and abnormal expression of inflammatory factors are easily-ignored but important pathologic characters of Parkinson's disease (PD).Measures that try to control the activation of microglia and abnormal expression of inflammatory factors are improtant to attenuate the injury to Dopamingernic neurons. Fragmin, a kind of low-molecular-weight-heparin(LMWH), which is a widely used anticoagulatory drug clinically is recently found to have an anti-inflammatory effect and it's different from its anticoagulation structure.We established a MPTP-induced mouse model of Parkinson's Disease to investigate the protective effect for dopaminergic neurons of Fragmin in this model,and study its mechanisms by silver stain of microglia and immunohistochemistry. This may give experimental supports for the application of LMWH to the treatment of Parkinson's Disease.Mehhods:1. 25 C57BL mice were divided into 3 groups randomly with the result 10 in the MPTP group, 10 in the LMWH+MPTP group and 5 in the control group.2.LMWH+MPTP group were treated with LMWH for 8 days with 16 injections every 12 hours,together with subcutaneous injection of MPTP (30mg/kg) starting on the third day for 6 days; MPTP group were pretreated with normal saline before subcutaneous MPTP injection, and the control group received pretreatment with normal saline before subcutaneous saline injection. 3. The symptoms of each groups'mice were observed after the last injection of MPTP and behaviour tests including pole tests, traction tests and swim tests were performed after the last injection of MPTP. 4. The activation of microglia is investigated by Nao menke and Feigin sliver stain. 5.Immunohistochemistry is used to detect tyrosine hydroxylase positive cells and TNF-αpositive cells.6.The data are presented in the form of mean±std and ANOVA and SNK tests are performed to compare means.Results: 1.Behaviour tests of LMWH+MPTP group and control group present no obvious changes while the mice of MPTP group present obvious involuntary movement of the limbs. 2. The time of pole tests is longer in MPTP group and its traction and swim tests also score less compared to the other two groups. 3. The Nao menke and Feigin sliver stain shows that the number of actviaced microglia is significantly higher than those in the others. 4. TH immunohistcohemistry of the sections show a significant reduction of TH positive cells in the MPTP group compared to the others. 5. The number of TNF-αpositive cells in the substantia nigra (SN) increased significantly compared to the others.Conclusions: 1.We established a mouse model of Parkinson's disease. 2. Fragmin can improve the performance of MPTP treated mice. 3. Fragmin has a neuroprotective effect for preventing dopaminergic neuron from impairment by MPTP and it's related to inhibiting of the activation of microglia. 4. Fragmin has a neuroprotective effect for preventing dopaminergic neurons from impairment by MPTP and it's related to inhibiting of the expression of TNF-α.