光敏STIM1驱动视网膜损伤致应激性抑郁的相关机制研究

Mechanism of photosensitive STIM1 calcium channel driven retinal injury stress depression

目的探讨光敏STIM1钙通道激活驱动视网膜细胞死亡致应激性抑郁症发生的情况及颅内视觉相关脑区炎性变化情况。方法采用球内光敏修饰STIM1病毒感染构建光驱动视网膜损伤小鼠模型。运用HE染色、抑郁行为学评定视网膜病变程度和抑郁发生率;采用RT-PCR、Western blot和免疫荧光染色等技术检测抑郁鼠脑内小胶质细胞、炎性相关因子(IL-6、MIP-1α)及神经细胞损伤标志物S100B、凋亡蛋白Caspase-3、髓鞘碱性蛋白MBP的变化。结果①连续7 d、3 h/d的光照模式下可见小鼠视网膜各层细胞数量均显著减少(P<0.05)。②光敏+组在旷场实验中进入中心区次数、中心区活动路程及运动总路程均显著降低(P<0.05),蔗糖偏好实验中糖水偏好指数显著降低(P<0.01),强迫游泳实验、悬尾实验的不动时间显著增加(P<0.001)。旷场实验、蔗糖偏好实验、强迫游泳实验、悬尾实验4项行为学实验均为抑郁阳性的比例为23.26%。③光敏+组抑郁鼠视皮层、背外侧膝状核IBa-1+细胞密度增多(P<0.05);视皮层中IL-6、MIP-1αmRNA表达显著上调(P<0.001),S100B蛋白、Caspase-3蛋白含量显著升高(P<0.05);在白质区MBP蛋白表达显著降低(P<0.05),胼胝体(cc)区、扣带回(cg)区MBP荧光信号强度明显减弱(P<0.0001)。结论成功构建光驱动视网膜损伤致应激性抑郁发生小鼠模型,证实抑郁发生可能与视觉相关脑区炎性环境改变、凋亡发生及白质区脱髓鞘性损伤密切相关。

Objective To investigate the occurrence of stress depression caused by retinal cells death driven by activation of photosensitive STIM1 calcium channel and the changes in brain inflammation related to the visually-associated brain regions.Methods A mouse model of retinal injury driven by light was constructed by injecting STIM1 virus into the vitreous body of mouse eyeball.HE staining and depression-related behavior test were performed to assess the severity of retinopathy and incidence of depression.Reverse transcription-PCR(RT-PCR),Western blotting and immunofluorescence assay were used to analyze the changes of microglial cells,inflammatory factors(IL-6 and MIP-1α),nerve cell damage marker(S100B),apoptotic protein(Caspase-3)and myelin basic protein(MBP)in the depressive mice.Results①The cell density in each layer of the mouse retina were decreased significantly under the light mode of 3 h/d for 7 consecutive days(P<0.05).②In the open field test,the times of entering the central area,moving distance in the central area and total distance of movement were obviously decreased(P<0.05),the index of sucrose preference of the sucrose preference test was significantly decreased(P<0.01),and the immobile time in the forced swimming test and the tail suspension test was notably increased(P<0.001)in the mice from the photosensitive group.The positive rate of depression in all the 4 tests(open field test,sucrose preference test,forced swimming test and tail suspension test)was 23.26%.③The density of IBa-1+cells in the visual cortex and dorsolateral geniculate nucleus was elevated in the depressive mice of the photosensitive group(P<0.05).The expression of IL-6 and MIP-1αat mRNA level was obviously elevated(P<0.0001),as well as the expression of S100B and Caspase-3 at protein level was significantly enhanced(P<0.001),while the MBP protein in the white matter was clearly weakened(P<0.05).The intensity of MBP fluorescence signal was evidently reduced in the corpus callosum(cc)area and cingulate gyrus(cg)area in white matter(P<0.0001).Conclusion A stress depression-like mouse model caused by light-driven retinal injury is successfully constructed.Pathogenesis of depression is closely associated with inflammatory environment and neuronal apoptosis in the vision-related brain regions and demyelinating injury in white matter.