TRPM2基因敲除通过调控GSK3β改善脂多糖诱导小鼠抑郁样行为

Amelioration of lipopolysaccharide induced depressive⁃like behavior by TRPM2 gene knockout via mediat⁃ing GSK3βexpression

目的研究TRPM2基因敲除(TRPM2^(-/-))对脂多糖(LPS)诱导的小鼠抑郁样行为的影响及机制。方法选取雄性TRPM2^(-/-)小鼠60只,分为TRPM2^(-/-)组和TRPM2^(-/-)+LPS组各30只;另取同基因型背景的野生型(WT)小鼠60只,分为WT组和WT+LPS组各30只。ELISA法检测海马和/或前额叶皮层5⁃羟色胺(5⁃hydroxytryptamine,5⁃HT)、TNF⁃α和IL⁃1β的含量;免疫荧光染色观察海马神经元和胶质细胞标志物表达变化;Western blot检测小鼠p⁃GSK3β和t⁃GSK3β蛋白表达;悬尾实验和强迫游泳实验检测小鼠的抑郁样行为。结果与WT+LPS组小鼠比较,TRPM2^(-/-)+LPS组小鼠海马5⁃HT的含量减少(P<0.05);海马GFAP和Iba⁃1阳性细胞数减少(均P<0.01);TNF⁃α和IL⁃1β的表达下调(均P<0.01);p⁃GSK3β的蛋白表达增加(P<0.01),而t⁃GSK3β的表达无明显差异。并且,TRPM2^(-/-)+LPS组小鼠悬尾实验中不动时间较WT+LPS组小鼠明显缩短(P<0.01),强迫游泳不动时间亦明显缩短(P<0.05)。结论TRPM2基因敲除显著改善LPS所致的小鼠抑郁样行为,可能与上调海马p⁃GSK3β的蛋白表达有关。

Objective To study the effect of TRPM2 gene knockout(TRPM2^(-/-))on lipopolysaccharide(LPS)induced depressive⁃like behavior and related mechanisms.Methods Male TRPM2^(-/-)mice were divided into TRPM2^(-/-)group(n=30)and TRPM2^(-/-)+LPS group(n=30);male wild type(WT)homogenotypic mice were divided into WT group(n=30)and WT+LPS group(n=30).Then the levels of 5⁃hydroxytryptamine(5⁃HT),TNF⁃αand IL⁃1βin hippocampus and/or prefrontal cortex were measured by ELISA assay.Expressions of neuronal and glial cell markers were observed by immunofluorescent staining.The protein levels of p⁃GSK3βand t⁃GSK3βwere detected by Western Blot and the depressive⁃like behavior was measured by tail suspension test and forced swim test.Results Compared with that of WT+LPS group,the concentration of 5⁃HT in the hippocampus of TRPM2^(-/-)+LPS group was decreased(P<0.05);the number of cells expressing GFAP and Iba⁃1 in the hippocam⁃pus of TRPM2^(-/-)+LPS group was decreased(P<0.01);the expressions of TNF⁃α and IL⁃1β in the hippocampus of TRPM2^(-/-)+LPS group were also decreased(P<0.01)but the protein level of p⁃GSK3βwas increased(P<0.01).No differences of t⁃GSK3βprotein level was found in the hippocampus of TRPM2^(-/-)+LPS group when compared with the WT+LPS group.Moreover,the mobility time in tail suspension test and forced swim test of the TRPM2^(-/-)+LPS group were significantly shortened(P<0.05)when compared with the WT+LPS group.Conclusion TRPM2 knockout can improve LPS induced depressive⁃like behavior in mice,and it may be correlated with the increased level of p⁃GSK3βin hippocampus.