Carmo Marta R S, Menezes Ana Paula F, Nunes Ana Carla L, Pliássova Anna, Rolo Anabela P, Palmeira Carlos M, Cunha Rodrigo A, Canas Paula M, Andrade Geanne M
Department of Physiology and Pharmacology, Federal University of Ceará, Brazil; CNC - Center for Neurosciences and Cell Biology, University of Coimbra, Portugal.
Department of Physiology and Pharmacology, Federal University of Ceará, Brazil.
Neuropharmacology. 2014 Jun;81:142-52. doi: 10.1016/j.neuropharm.2014.01.045. Epub 2014 Feb 6.
Parkinson's disease (PD) involves an initial loss of striatal dopaminergic terminals evolving into a degeneration of dopaminergic neurons in the substantia nigra (SN), which can be modeled by 6-hydroxydopamine (6-OHDA) administration. Since ATP is a danger signal acting through its P2X7 receptors (P2X7R), we now tested if a blood-brain barrier-permeable P2X7R antagonist, Brilliant Blue G (BBG), controlled the 6-OHDA-induced PD-like features in rats. BBG (45 mg/kg) attenuated the 6-OHDA-induced: 1) increase of contralateral rotations in the apomorphine test, an effect mimicked by another P2X7R antagonist A438079 applied intra-cerebroventricularly; 2) short-term memory impairment in the passive avoidance and cued version of the Morris Water maze; 3) reduction of dopamine content in the striatum and SN; 4) microgliosis and astrogliosis in the striatum. To grasp the mechanism of action of BBG, we used in vitro models exploring synaptotoxicity (striatal synaptosomes) and neurotoxicity (dopamine-differentiated neuroblastoma SH-SY5Y cells). P2X7R were present in striatal dopaminergic terminals, and BBG (100 nM) prevented the 6-OHDA-induced synaptosomal dysfunction. P2X7R were also co-localized with tyrosine hydroxylase in SH-SY5Y cells, where BBG (100 nM) attenuated the 6-OHDA-induced neurotoxicity. This suggests that P2X7R contribute to PD pathogenesis through a triple impact on synaptotoxicity, gliosis and neurotoxicity, highlighting the therapeutic potential of P2X7R antagonists in PD.
帕金森病（PD）最初涉及纹状体多巴胺能终末的丧失，进而发展为黑质（SN）中多巴胺能神经元的变性，这可以通过给予6-羟基多巴胺（6-OHDA）来模拟。由于三磷酸腺苷（ATP）是一种通过其P2X7受体（P2X7R）发挥作用的危险信号，我们现在测试了一种可透过血脑屏障的P2X7R拮抗剂亮蓝G（BBG）是否能控制6-OHDA诱导的大鼠帕金森病样特征。BBG（45毫克/千克）减轻了6-OHDA诱导的：1）阿扑吗啡试验中对侧旋转增加，脑室内注射另一种P2X7R拮抗剂A438079也有类似作用；2）被动回避和莫里斯水迷宫线索版中的短期记忆损伤；3）纹状体和黑质中多巴胺含量降低；4）纹状体中的小胶质细胞增生和星形胶质细胞增生。为了掌握BBG的作用机制，我们使用了体外模型来探究突触毒性（纹状体突触体）和神经毒性（多巴胺分化的神经母细胞瘤SH-SY5Y细胞）。P2X7R存在于纹状体多巴胺能终末，BBG（100纳摩尔）可防止6-OHDA诱导的突触体功能障碍。P2X7R也与SH-SY5Y细胞中的酪氨酸羟化酶共定位，在该细胞中BBG（100纳摩尔）减轻了6-OHDA诱导的神经毒性。这表明P2X7R通过对突触毒性、胶质细胞增生和神经毒性的三重影响参与帕金森病的发病机制，突出了P2X7R拮抗剂在帕金森病中的治疗潜力。
