目的:研究P2X4受体(P2X4R)在脂多糖(LPS)诱导的抑郁状态下调节海马突触损伤中的作用。
方法:采用LPS注射建立大鼠抑郁模型。5-(3-溴苯基)-1,3-二氢-2H-苯并呋喃[3,2-e]-1,4-二氮杂-2-酮(5-BDBD)抑制了P2X4R的表达。通过行为测试确定抑郁症状。通过qRT-PCR测量P2X4R和细胞因子mRNA水平,而突触蛋白水平通过蛋白质印迹法测量。通过透射电子显微镜评估突触超微结构,以及脑源性神经营养因子(BDNF)与小胶质细胞的共定位,星形胶质细胞,并通过双重免疫荧光染色确定神经元。
结果:注射5-BDBD可减轻LPS诱导的抑郁症状。LPS注射显著增加海马P2X4R和促炎细胞因子的mRNA水平,尤其是在CA1区。突触蛋白的水平(BDNF,海马CA1区的PSD95和突触素I)明显低于海马其他两个区,海马CA1区突触超微结构明显改变。不出所料,海马IBA-1与BDNF共定位的Pearson相关R和重叠系数R降低,5-BDBD注入逆转了这些趋势。注射5-BDBD可增加海马BDNFmRNA的表达。
结论:P2X4R在LPS诱导的抑郁大鼠中可能通过影响小胶质细胞BDNF的表达而导致海马CA1区突触损伤。
OBJECTIVE: To study the role of the P2X4 receptor (P2X4R) in regulating hippocampal synaptic impairment in lipopolysaccharide (LPS)-induced depression.
METHODS: A rat model of depression was established by LPS injection. P2X4R expression was inhibited by 5-(3-bromophenyl)-1, 3-dihydro-2H-benzofuro[3,2-e]-1,4-diazepin-2-one (5-BDBD). Depressive symptoms were identified through behavioral tests. P2X4R and cytokine mRNA levels were measured by qRT-PCR, while synaptic protein levels were measured by Western blotting. Synaptic ultrastructure was assessed by transmission electron microscopy, and the colocalization of brain-derived neurotrophic factor (BDNF) with microglia, astrocytes, and neurons was determined by double immunofluorescence staining.
RESULTS: Injection of 5-BDBD alleviated LPS-induced depressive symptoms. LPS injection significantly increased the mRNA levels of P2X4R and proinflammatory cytokines in the hippocampus, especially in the CA1 region. The levels of synaptic proteins (BDNF, PSD95, and synapsin I) in the CA1 region were significantly lower than those in the other two regions of the hippocampus, and the synaptic ultrastructure in the hippocampal CA1 region was significantly altered. As expected, the Pearson\'s correlation R and the overlap coefficient R for the hippocampal colocalization of IBA-1 with BDNF were decreased, and 5-BDBD injection reversed these trends. Injection of 5-BDBD increased hippocampal BDNF mRNA expression.
CONCLUSIONS: P2X4R may induce synaptic impairment in the hippocampal CA1 region by influencing microglial BDNF expression in the context of LPS-induced depression in rats.