目的：小鼠通过悬尾来模拟失重状态下体液头向重分布，然后观察视网膜电图(ERG)和视网膜微循环的变化。

方法：正常成年雄性C57BL/6J小鼠随机分到3个实验组和3个对照组，最终每组6只。具体分组如下：实验1组(尾悬15d)，实验2组(尾悬30d)，实验3组(悬吊30d后恢复体位30d)； 对照1组(正常饲养15d)，对照2组(正常饲养30d)，对照3组(正常饲养60d)。时间满足后马上检测暗适应闪光ERG，记录混合反应和振荡电位(OPs)，并进行荧光素眼底血管造影(FFA)。然后提取视网膜组织，用免疫组化法检测感光细胞视色素或视蛋白的表达，用TUNEL试剂盒检测视网膜组织细胞的凋亡情况。

结果：悬吊15d组，暗适应ERG的混合反应，b波较大而OPs振幅明显降低，后者第二个子波(O₂)幅值197±33μV，15d未悬吊组336±47μV(t=-5.938，P<0.001)。悬吊30d组，小鼠ERG恢复，O₂幅值264±39μV，与30d未悬吊组308±41μV无差异(t=-1.887，P>0.05)。悬吊15d组FFA，视网膜微血管较对照组更密集，呈迂曲扩张的表现，其他实验组基本正常。各实验组感光细胞视色素或视蛋白的表达未见明显异常，视网膜未见凋亡阳性细胞。

结论：模拟失重状态下体液头向重分布，短期内小鼠ERG和视网膜微循环可能受到影响，但未对视网膜产生明显的永久性损伤。

METHODS: Thirty-six adult male C57BL/6J mice(36 eyes)were randomly divided into three experimental groups and three control groups. Mice in the experimental groups were tail-suspended for 15d(Group one), tail-suspended for 30d(Group two), or tail-suspended followed by returning to normal position for 30d(Group three). Three control groups were similarly fixed with a harness but kept in the normal position for corresponding periods of 15, 30, and 60d. The mice were immediately examined using scotopic ERG(including oscillatory potentials \〖OPs\〗)and fundus fluorescein angiography(FFA)in vivo, and subsequently sacrificed to analyze the retinal histology(methods including immunohistochemistry and TUNEL staining)in vitro. Independent sample t-test was used for data comparison between the same time-point groups.

RESULTS: Following 15-days' tail-suspension, scotopic ERG showed a decline in OPs, but not in the b-wave; the second OP(O₂)showed an amplitude of 197±33μV, which was about 60% of the control level(t=-5.938, P<0.001). Following 30-days' tail-suspension, ERG recovered, with O₂ showing an average value of 264±39μV; when compared to the corresponding control group(308±41μV), no significant difference was observed(t=-1.887, P>0.05). Morphologically, only the 15-days' tail-suspended mice showed FFA with microvascular dilation and tortuosity. Rhodopsin and cone-opsin were almost normal and no apoptotic-positive signals were detected in the retinas of the three tail-suspended groups.

CONCLUSION: Simulating cephalad shifting of bodily fluids as under microgravity, using short-term tail-suspension can affect rodent ERG and retinal microcirculation; however, the change is reversible with no obvious permanent injury observed in the retinas.