甘草黄酮对MPTP帕金森病模型小鼠的神经保护效应及对小胶质细胞活化的影响

Neuroprotective Effect of Licorice Flavonoids on MPTP-induced Mouse Models with Parkinson’s Disease and Influence on Microglia Activation

摘要:

目的: 观察甘草黄酮对1-甲基-4-苯基-1,2,3,6-四氢吡啶(MPTP)帕金森病(PD)小鼠多巴胺(DA)能神经元数量和黑质小胶质细胞活化的影响。方法: 制作MPTP小鼠PD模型,随机分为6组:空白组、模型组、左旋多巴组(1次/d ig给予40 mg·kg^-1左旋多巴,1次/d,连续7次)和10,20,30 mg·kg^-1甘草黄酮处理组(ig给予不同浓度的甘草黄酮,1次/d 连续7次)。采用行为学观察、免疫组织化学和免疫蛋白印迹法,观察PD模型小鼠的行为学表现、 DA能神经元数量、黑质致密部OX-6阳性细胞(活化的小胶质细胞)数量和腹侧中脑酪氨酸羟化酶(TH)蛋白表达水平。结果: 模型组小鼠出现PD典型行为学表现,黑质致密部DA能神经元和腹侧中脑TH含量较对照组分别下降约62%和76%;同时黑质致密部OX-6阳性细胞数量大幅升高(P<0.01)。经过甘草黄酮处理后,小鼠行为表现、黑质致密部DA能神经元丢失和OX-6阳性细胞数量增加均较模型组改善,尤以30 mg·kg^-1甘草黄酮组最为明显。与对照组相比,30 mg·kg^-1甘草黄酮组小鼠黑质致密部DA能神经元和腹侧中脑TH含量仅下降约36%和42%;而与模型组相比,黑质致密部OX-6阳性细胞数量下降明显(P<0.01)。与左旋多巴组相比,30 mg·kg^-1甘草黄酮组TH阳性神经元数量也明显增多(P<0.01),同时OX-6阳性细胞数量也显著减少(P<0.01)。结论: 甘草黄酮对MPTP帕金森病小鼠DA能神经元具有神经保护效应;可能与其抑制黑质内小胶质细胞活化有关。

Abstract:

Objective: To study the neuroprotection of licorice flavonoids on dopamine (DA) neurons and the influence of microglia activation of the substantia nigra compact (SNc) in the mice with Parkinson's disease (PD). Method: The PD mouse models were established by 1,2,3,6-Tetrahydro-1-methyl-4-phenylpyridine;1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP) and the mice were randomly divided into 6 group:control group, model group, levodopa group(40 mg·kg^-1), 10,20,30 mg·kg^-1 licorice flavonoids group. The drugs were intragastrically perfused to the mice daily for 7 consecutive times.The number of OX-6 immunoreactive cells and DA neurons in the SNc, and the expression level of tyrosine hydroxylase (TH) in ventral midbrain were studied by immunohistochemical analysis and Western blot, and behavior changes were notied after levodopa or licorice flavonoids treatment. Result: Compared with control mice, the PD mice had the typical behaviors of PD, and the number of DA neurons in SNc and the level of TH in ventral midbrain decreased by about 62% and 76%. Meanwhile the number of the OX-6-positive cells in SNc increased markedly(P<0.01). After administered by licorice flavonoids, behavioral symptoms, reduction of DA neurons and increase of OX-6 positive cells in SNc were improved by licorice flavonoids. Especially in 30 mg·kg^-1 licorice flavonoids group, those mice with PD had slight behavioral symptoms, and the number of DA neurons in SNc and the expression level of TH in ventral midbrain declined by only about 36% and 42% in compared with the control. Compared with those PD mice without licorice flavonoids, the number of the OX-6 positive cells in the SNc of 30 mg·kg^-1 licorice flavonoids group was obviously down-regulated(P<0.01). Compared with those in the levodopa group, the increasing of the number of DA neurons and the decreasing of the number of OX-6 positive cells in 30 mg·kg^-1 licorice flavonoids group were significant(P<0.01). Conclusion: These results indicated the neuroprotection effect of licorice flavonoids on DA neurons of SNc in PD mice, and the inhibition of the microglia activation by licorice flavonoids might be responsible for it.