Laboratory of Molecular Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1083 Budapest, Szigony u, 43, Hungary.
Mol Neurodegener. 2011 May 4;6:28. doi: 10.1186/1750-1326-6-28.
Previous studies indicate a role of P2X7 receptors in processes that lead to neuronal death. The main objective of our study was to examine whether genetic deletion or pharmacological blockade of P2X7 receptors influenced dopaminergic cell death in various models of Parkinson's disease (PD).
mRNA encoding P2X7 and P2X4 receptors was up-regulated after treatment of PC12 cells with 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP). P2X7 antagonists protected against MPTP and rotenone induced toxicity in the LDH assay, but failed to protect after rotenone treatment in the MTT assay in PC12 cells and in primary midbrain culture. In vivo MPTP and in vitro rotenone pretreatments increased the mRNA expression of P2X7 receptors in the striatum and substantia nigra of wild-type mice. Basal mRNA expression of P2X4 receptors was higher in P2X7 knockout mice and was further up-regulated by MPTP treatment. Genetic deletion or pharmacological inhibition of P2X7 receptors did not change survival rate or depletion of striatal endogenous dopamine (DA) content after in vivo MPTP or in vitro rotenone treatment. However, depletion of norepinephrine was significant after MPTP treatment only in P2X7 knockout mice. The basal ATP content was higher in the substantia nigra of wild-type mice, but the ADP level was lower. Rotenone treatment elicited a similar reduction in ATP content in the substantia nigra of both genotypes, whereas reduction of ATP was more pronounced after rotenone treatment in striatal slices of P2X7 deficient mice. Although the endogenous amino acid content remained unchanged, the level of the endocannabinoid, 2-AG, was elevated by rotenone in the striatum of wild-type mice, an effect that was absent in mice deficient in P2X7 receptors.
We conclude that P2X7 receptor deficiency or inhibition does not support the survival of dopaminergic neurons in an in vivo or in vitro models of PD.
先前的研究表明 P2X7 受体在导致神经元死亡的过程中起作用。我们研究的主要目的是检查 P2X7 受体的基因缺失或药物阻断是否会影响各种帕金森病 (PD) 模型中的多巴胺能神经元死亡。
用 1-甲基-4-苯基-1,2,3,6-四氢吡啶 (MPTP) 处理 PC12 细胞后，P2X7 和 P2X4 受体的 mRNA 表达上调。P2X7 拮抗剂在 LDH 测定中可防止 MPTP 和鱼藤酮诱导的毒性，但在 PC12 细胞和原代中脑培养物中的 MTT 测定中，在鱼藤酮处理后未能保护。体内 MPTP 和体外鱼藤酮预处理增加了野生型小鼠纹状体和黑质中 P2X7 受体的 mRNA 表达。P2X7 敲除小鼠的 P2X4 受体基础 mRNA 表达较高，并且在用 MPTP 处理后进一步上调。P2X7 受体的基因缺失或药物抑制不会改变体内 MPTP 或体外鱼藤酮处理后存活或纹状体内源性多巴胺 (DA) 含量的耗竭。然而，仅在用 MPTP 处理后，P2X7 敲除小鼠的去甲肾上腺素耗竭显著。野生型小鼠黑质中的基础 ATP 含量较高，但 ADP 水平较低。鱼藤酮处理引起两种基因型黑质中 ATP 含量的相似减少，而在用鱼藤酮处理后，P2X7 缺陷小鼠纹状体切片中的 ATP 减少更为明显。尽管内源性氨基酸含量保持不变，但内源性大麻素 2-AG 的水平在野生型小鼠的纹状体中被鱼藤酮升高，而在缺乏 P2X7 受体的小鼠中则没有这种作用。
我们得出结论，P2X7 受体缺失或抑制不能支持体内或体外 PD 模型中多巴胺能神经元的存活。
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