Wang Pu-qing, Sun Sheng-gang, Qiao Xian
Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
Zhonghua Yi Xue Za Zhi. 2009 May 19;89(19):1346-50.
To explore the protective effect of doxycycline (DC) upon dopaminergic neuron in lipopolysaccharide (LPS)-induce rat model of Parkinson's disease (PD).
Sixty SD rats were randomly divided into three groups: control, LPS and doxycycline treatment. LPS was stereotatically injected into unilateral substantia nigra (SNc) of rats to establish the PD models. The damage to the substantia nigra DA neurons was observed by using tyrosine-hydroxylase (TH) immunohistochemical staining. Specific antibody OX6 (MHCII marker) was used to detect the changes in morphology and the numbers of microglia. The contents of dopamine and DOPAC in striatum were measured by high performance liquid chromatography (HPLC). Western blot were used to detect the expression of MHCII (Major histocompatibility complex class II) protein.
After doxycycline treatment, the number of TH-positive cells remaining in the SNc increased from 38% +/- 5% to 79% +/- 4% (P < 0.01). The contents of dopamine and DOPAC in striatum increased from 4.89 +/- 0.27 and 0.70 +/- 0.07 to 7.00 +/- 0.34 and 1.10 +/- 0.10 respectively (P < 0.01); there was a significant decrease in rotational asymmetry in the doxycycline treatment group [(80 +/- 12) turns/30 min] when compared to the LPS group [(208 +/- 14) turns/30 min] (P < 0.01). However, the number of MHCII-positive microglia decreased significantly (LPS group: 835 +/- 82 vs doxycycline treatment group: 354 +/- 59, P < 0.01) after doxycycline treatment. Western blot were used to detect the expression of MHCII protein. The results showed that the expression of MHCII protein on microglia of LPS group increased significantly compared to the control group, but the expression of MHCII protein were inhibited significantly after doxycycline treatment in the doxycycline treatment group, as compared to the LPS group.
Doxycycline might inhibit dopaminergic neuron degeneration by down-regulating the MHCII expression on microglia.
探讨多西环素（DC）对脂多糖（LPS）诱导的帕金森病（PD）大鼠模型中多巴胺能神经元的保护作用。
将60只SD大鼠随机分为三组：对照组、LPS组和多西环素治疗组。通过立体定位将LPS注射到大鼠单侧黑质致密部（SNc）以建立PD模型。采用酪氨酸羟化酶（TH）免疫组化染色观察黑质多巴胺能神经元的损伤情况。使用特异性抗体OX6（MHCII标记物）检测小胶质细胞的形态和数量变化。采用高效液相色谱（HPLC）测定纹状体中多巴胺和3,4-二羟基苯乙酸（DOPAC）的含量。用蛋白质免疫印迹法检测MHCII（主要组织相容性复合体II类）蛋白的表达。
多西环素治疗后，SNc中剩余的TH阳性细胞数量从38%±5%增加到79%±4%（P<0.01）。纹状体中多巴胺和DOPAC的含量分别从4.89±0.27和0.70±0.07增加到7.00±0.34和1.10±0.10（P<0.01）；与LPS组[（208±14）转/30分钟]相比，多西环素治疗组的旋转不对称性显著降低[（80±12）转/30分钟]（P<0.01）。然而，多西环素治疗后，MHCII阳性小胶质细胞数量显著减少（LPS组：835±82 vs多西环素治疗组：354±59，P<0.01）。用蛋白质免疫印迹法检测MHCII蛋白的表达。结果显示，与对照组相比，LPS组小胶质细胞上MHCII蛋白的表达显著增加，但与LPS组相比，多西环素治疗组多西环素治疗后MHCII蛋白的表达受到显著抑制。
多西环素可能通过下调小胶质细胞上的MHCII表达来抑制多巴胺能神经元变性。
