铁选择性损伤多巴胺能神经元的神经免疫炎症机制
Investigation on the neuroinflammatory mechanism of iron-induced selective dopaminergic neurodegeneration
目的 在模拟人中脑黑质的多种原代细胞培养体系中,研究铁对多巴胺能神经元的损伤及其神经免疫炎症机制.方法 采用5、25和100μmol/L的Fecl2(Fe2+):(1)处理中脑原代神经元-小胶质细胞-星形胶质细胞混合培养体系,7 d后计数酪氨酸羟化酶(TH)(+)多巴胺能神经元及抗神经特异性核蛋白抗体(Neu-N)(+)的全部神经元的数量,观察神经元形态,研究Fe2+对多巴胺能神经元的选择性损伤;(2)同时处理中脑原代神经元-小胶质细胞-星形胶质细胞混合培养体系和神经元-星形胶质细胞培养体系,7 d后计数TH(+)多巴胺能神经元的数量,研究小胶质细胞在Fe2+选择性损伤多巴胺能神经元中的作用;(3)处理原代小胶质细胞培养体系,测量细胞外超氧化物(O2·-)及细胞内活性氧类物质(iROS),研究Fe2+激活小胶质细胞导致的功能变化;(4)处理中脑原代神经元-小胶质细胞-星形胶质细胞混合培养体系,7 d后计数抗补体受体-3(OX-42)(+)小胶质细胞的数量,观察细胞形态,研究Fe2+激活小胶质细胞导致的形态学变化.结果 (1)5、25和100μmol/L Fe2+处理组TH(+)多巴胺能神经元的数量分别为对照组的89%、70%和55%,其中25、100 μmol/L Fe2+处理组与对照组比较差异具有统计学意义(F=12.047,P<0.01);多巴胺能神经元胞体皱缩,胞质淡染,神经突起数目减少;(2)5、25和100 μmol/L Fe2+处理组Neu-N(+)全部神经元的数量分别为对照组的100%、104%和101%,与对照组比较差异均无统计学意义;5、25和100μmol/L Fe2+处理组Neu-N(+)全部神经元的数量与TH(+)多巴胺能神经元数量的差值分别为11%、34%和46%,其中25和100 μmol/L Fe2+处理组两种神经元数量的差异具有统计学意义(分别为t=8.098,P<0.05;t=11.218,P<0.05);(3)在中脑原代神经元-小胶质细胞-星形胶质细胞混合培养体系和神经元-星形胶质细胞培养体系中,25μmoL/L Fe2+处理组TH(+)多巴胺能神经元的数量分别为对照组的70%和98%,差值为28%,差异具有统计学意义(t=8.061,P<0.05);100 μmoL/LFe2+处理组TH(+)多巴胺能神经元的数量分别为对照组的55%和75%,差值为20%,差异具有统计学意义(t=9.025,P<0.05);(4)5、25和100μmoL/L Fe2+处理组产生的细胞外O2·-分别为对照组的100%、127%和163%,其中100 μmol/L Fe2+处理组与对照组比较差异具有统计学意义(t=9.015,P<0.005);5、25和100μmol/L Fe2+处理组产生的iROS分别为对照组的147%、172%和231%,其中25和100μmol/L Fe2+处理组与对照组比较差异具有统计学意义(F=3.091,P<0.05);(5)5、25和100 μmol/L Fe2+处理组OX-42(+)小胶质细胞数量分别为对照组的183%、190%和240%,其中25和100μmol/L Fe2+处理组与对照组比较差异具有统计学意义(F=6.101,P<0.01);小胶质细胞激活后胞体变大,形状不规则.结论 Fe2+激活小胶质细胞,使其形态发生显著变化,并产生大量神经毒性因子,选择性损伤多巴胺能神经元;为抑制铁过度激活小胶质细胞成为治疗PD的新策略提供依据.
更多Objective To investigate the role and neuroinflammatory mechanism of iron on dopamine ( DA) neurons in multiple primary midbrain cultures that mimic human substantia nigra pars compacta.Methods Ferrous chloride ( Fe2+ ) with the desired concentrations of 5,25 and 100 μmol/L was used to ( 1 ) treat primary midbrain neuron-microglia-astroglia cultures for 7 days and the numbers of DA neurons and total neurons were counted after tyrosine hydroxylase (TH) and neuron-specific neuclear protein neurons in 5,25 and 100 μmol/L Fe2 + -treated groups were 89%,70% and 55% of control group,and 25,100 μmol/L Fe2+ significantly decreased DA neuronal numbers compared with control group ( F = 12.047,P <0.01);DA neuronal bodies were shrunk and smaller,cytoplasmic stainings were reduced,neuronal dendrites were decreased;(2) The numbers of Neu-N ( + ) total neurons in 5,25 and 100 μmol/L Fe2+-treated groups were 100%,104% and 101% of control group and Fe2+ did not decrease DA neuronal numbers compared with control group (t =4.458,P > 0.05 );5,25 and 100 μmol/L Fe2+-induced difference between total neurons and DA neurons were 11%,34% and 46%,and 25 and 100 (Amol/L Fe2+ produced significant difference(t =8.098,P <0.05;t = 11.218,P<0.05);(3) In primary midbrain neuron-microglia-astroglia and neuron-astroglia cultures,the numbers of DA neurons in 25 μmol/L Fe+-treated group were 70% and 98% of control group,respectively.The difference between two groups was 28%,which was statistically significant (t =8.061,P<0.05);The numbers of DA neurons in 100 μmol/L groups were 183%,190 % and 240% of control group,and 25 and 100 μmol/L Fe2 + significantly increased microglial numbers compared with control group ( F = 6.101,P < 0.01 );dramatic changes of microglial morphology were indicated by the enlarged cell bodies and irregular shape.Conclusions Fe2 + provokes selective DA neuronal damage and microglia are the mediators of the neurotoxic effect,which may be due to microglial over-activation featured by the significant production of neurotoxic factors and morphological changes of microglia.This investigation cast a new light for PD therapy by inhibiting Fe2+ -induced neuroinflammation characterized by the microglial over-activation.
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