Lipopolysaccharide preconditioning induces protection against lipopolysac-charide -induced neurotoxicity in organotypic midbrain slice culture

脂多糖预处理改善脂多糖诱导的中脑脑片神经元损伤(英文)

Objective To identify the protective effect of lipopolysaccharide （LPS） preconditioning against LPS-induced inflammatory damage in dopaminergic neurons of midbrain slice culture and the possible mechanisms. Methods After cultured in vitro for 14 d, the rat organotypic midbrain slices were pretreated with different concentrations （0, 1, 3, 6 or 10 ng/mL） of LPS for 24 h followed by treatment with 100 ng/mL LPS for 72 h. The whole slice viability was detelmined by measurement of the activity of lactic acid dehydrogenase （LDH）. Tyrosine hydroxylase-immunoreactive （TH-IR） neurons and CD 1 1 b/c equivalent-immunoreactive （OX-42-IR） microglia in the slices were observed by immunohistochemical method, and tumor necrosis factor-α （TNF-α levels in the culture media were detected by enzymelinked immunosorbent assays （ELISA）. Results In the slices treated with 100 ng/mL LPS for 72 h, the number of TH-IR neurons reduced from 191± 12 in the control slices to 46±4, and the LDH activity elevated obviously （P 〈 0.01）, along with remarkably increased number of OX-42-IR cells and production of TNF-α （P 〈 0.01）. Preconditioning with 3 or 6 ng/mL LPS attenuated neuron loss （the number of TH-IR neurons increased to 126± 12 and 180± 13, respectively） and markedly reduced LDH levels （P 〈 0.05）, accompanied by significant decreases of OX-42-IR microglia activation and TNF-α production （P 〈 0.05）. Conclusion Low-dose LPS preconditioning could protect dopaminergic neurons against inflammatory damage in rat midbrain slice culture, and inhibition of microglial activation and reduction of the proinflammatory factor TNF-α production may contribute to this protective effect. Further understanding the underlying mechanism of LPS preconditioning may open a new window for treatment of Parkinson＇s disease.

目的探讨脂多糖(lipopolysaccharide,LPS) 预处理对脂多糖所致中脑脑片多巴胺能神经元炎性损伤的影响及其可能的机制。方法建立大鼠中脑脑片体外培养体系,于体外培养 14 d 后以不同剂量脂多糖(0、1、3、6及10 ng/mL)预处理24 h,然后用大剂量脂多糖(100 ng/mL)作用72 h,观察脂多糖预处理对脑片乳酸脱氢酶(lactic aciddehydrogenase,LDH)活性的影响。通过免疫组化检测酪氨酸羟化酶(Tyrosine hydroxylase,TH)和 OX-42 的阳性细胞数变化,应用酶联免疫吸附法测定培养液上清肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)水平。结果 100 ng/mL脂多糖作用72 h后引起脑片TH阳性细胞数从对照组的191±12减少到46±4,LDH活性明显升高(P < 0.01),小胶质细胞大量激活,TNF-α水平显著增高(P < 0.01)。脂多糖预处理能减少神经细胞的丢失(3 ng/mL和6 ng/mL的LPS 处理后TH阳性细胞数分别为126±12和180±13),降低脑片LDH活性(P < 0.05),并有效地抑制小胶质细胞的激活,明显减少TNF-α的生成(P < 0.05)。结论小剂量脂多糖预处理可改善脂多糖对大鼠中脑脑片多巴胺能神经元的损伤,其作用机制可能是通过抑制小胶质细胞的激活,减少TNF-α的释放,减轻炎症反应对神经元的损伤。这种保护作用可为帕金森氏病的治疗提供新思路。