广西医学

目的基于RhoA/Cofilin通路探讨二苯乙烯苷（TSG）改善慢性铝中毒大鼠学习记忆功能的作用机制。方法将70只大鼠随机分为正常组、模型组、RhoA抑制剂组、阳性对照组、TSG低剂量组、TSG中剂量组、TSG高剂量组，各10只。正常组大鼠正常喂养，其余组大鼠每天给予AlCl3水溶液自由喂养，构建慢性铝中毒大鼠模型。3个月后，给予RhoA抑制剂组大鼠腹腔注射30 mg/kg盐酸法舒地尔溶液，给予阳性对照组大鼠灌胃0.15 mg/kg石杉碱甲溶液，给予TSG低剂量组、TSG中剂量组、TSG高剂量组大鼠分别灌胃33 mg/kg、100 mg/kg、300 mg/kg TSG溶液，1次/d，持续30 d。干预完成后，采用Morris水迷宫实验评估各组大鼠空间认知能力；通过透射电子显微镜观察各组大鼠海马CA1区突触超微结构并检测突触后致密区（PSD）厚度；采用Western blot实验检测各组大鼠海马组织RhoA、Cofilin、突触素（SYN）、突触后致密蛋白（PSD⁃95）蛋白表达水平。结果（1）Morris水迷宫实验训练第3天，模型组、TSG低剂量组大鼠的逃避潜伏期较正常组延长，RhoA抑制剂组、阳性对照组、TSG高剂量组大鼠的逃避潜伏期较模型组缩短，阳性对照组、TSG高剂量组大鼠的逃避潜伏期较TSG低剂量组缩短（P<0.05）；训练第4天，模型组、TSG低剂量组、TSG中剂量组大鼠的逃避潜伏期较正常组延长，RhoA抑制剂组、阳性对照组、TSG中剂量组、TSG高剂量组大鼠的逃避潜伏期较模型组缩短，阳性对照组、TSG高剂量组大鼠的逃避潜伏期较TSG低剂量组缩短（P<0.05）。（2）在透射电子显微镜下，模型组大鼠突触超微结构出现严重损伤；与模型组比较，RhoA抑制剂组、阳性对照组、TSG高剂量组大鼠的突触超微结构损伤有不同程度的好转。与正常组相比，其余6组大鼠海马组织的PSD厚度降低；与模型组相比，RhoA抑制剂组、阳性对照组、TSG高剂量组大鼠海马组织的PSD厚度升高；与RhoA抑制剂组相比，阳性对照组、TSG低剂量组、TSG中剂量组、TSG高剂量组大鼠海马组织的PSD厚度降低，其中TSG低剂量组、TSG中剂量组大鼠海马组织的PSD厚度低于阳性对照组、TSG高剂量组（P<0.05）。（3）与正常组相比，模型组大鼠海马组织的SYN、PSD⁃95蛋白表达水平降低；与TSG高剂量组相比，模型组、RhoA抑制剂组和TSG低剂量组大鼠海马组织的SYN、PSD⁃95蛋白表达水平降低（P<0.05）。7组大鼠海马组织的RhoA蛋白表达水平差异无统计学意义（P>0.05）。与正常组、模型组、TSG低剂量组比较，TSG中剂量组、TSG高剂量组大鼠海马组织的Cofilin蛋白表达水平升高（P<0.05）。结论高剂量TSG可以显著改善慢性铝中毒大鼠海马突触超微结构的形态变化，并可能通过影响RhoA/Cofilin信号通路中的相关蛋白表达从而影响SYN和PSD⁃95蛋白在大鼠海马组织中的表达，进而提高大鼠的学习记忆能力。

Objective To investigate the mechanism of 2,3,5,4'⁃tetrahydroxyl diphenylethylene⁃2⁃O⁃glucoside (TSG) in improving learning and memory function in chronic aluminum⁃intoxicated rats based on the RhoA/Cofilin pathway. Methods Seventy rats were randomly divided into normal group, model group, RhoA inhibitor group, positive control group, TSG low⁃dose group, TSG medium⁃dose group, or TSG high⁃dose group, with 10 rats in each group. Rats in the normal group were fed normally, while rats in the remaining groups were given AlCl₃ aqueous solution ad libitum daily to establish a chronic aluminum⁃intoxicated rat model. After three months, rats in the RhoA inhibitor group were intraperitoneally injected with 30 mg/kg fasudil hydrochloride solution, rats in the positive control group received intragastric administration of 0.15 mg/kg huperzine A solution, and rats in the TSG low⁃, medium⁃, and high⁃dose groups received intragastric administration of 33 mg/kg, 100 mg/kg, and 300 mg/kg TSG solution, respectively, once daily for 30 days. After the intervention completed, spatial cognitive ability of rats in each group was assessed using the Morris water maze test. Synaptic ultrastructure in the hippocampal CA1 region was observed using transmission electron microscopy, and postsynaptic density (PSD) thickness was measured. The protein expressions of RhoA, Cofilin, synapsin (SYN), and postsynaptic density protein 95 (PSD⁃95) in rat hippocampal tissue were detected by Western blot. Results (1) On day 3 of the Morris water maze test, the escape latency was longer in the model group and TSG low⁃dose group than in the normal group, whereas it was shorter in the RhoA inhibitor group, positive control group, and TSG high⁃dose group than in the model group, and it was shorter in the positive control group and TSG high⁃dose group than in the TSG low⁃dose group (P<0.05). On day 4 of training, the escape latency was longer in the model group, TSG low⁃dose group, and TSG medium⁃dose group than in the normal group, whereas it was shorter in the RhoA inhibitor group, positive control group, TSG medium⁃dose group, and TSG high⁃dose group than in the model group, and it was shorter in the positive control group and TSG high⁃dose group than in the TSG low⁃dose group (P<0.05). (2) Under transmission electron microscopy, severe damage to synaptic ultrastructure was observed in the model group. Compared with the model group, the synaptic ultrastructure damage in the RhoA inhibitor group, positive control group, and TSG high⁃dose group was ameliorated to varying degrees. Compared with the normal group, PSD thickness was decreased in the remaining six groups. Compared with the model group, PSD thickness was increased in the RhoA inhibitor group, positive control group, and TSG high⁃dose group. Compared with the RhoA inhibitor group, PSD thickness was decreased in the positive control group, TSG low⁃dose group, TSG medium⁃dose group, and TSG high⁃dose group, with PSD thickness in the TSG low⁃dose group and TSG medium⁃dose group being lower than that in the positive control group and TSG high⁃dose group in rat hippocampal tissue (P<0.05). (3) Compared with the normal group, the protein expressions of SYN and PSD⁃95 were decreased in rat hippocampal tissue of the model group. Compared with the TSG high⁃dose group, the protein expressions of SYN and PSD⁃95 in rat hippocampal tissue were decreased in the model group, RhoA inhibitor group, and TSG low⁃dose group (P<0.05). There was no statistically significant difference in RhoA protein expression between the seven groups (P>0.05). Compared with the normal group, model group, and TSG low⁃dose group, the protein expression of Cofilin in hippocampal tissue of rats was elevated in the TSG medium⁃dose group and TSG high⁃dose group (P<0.05). Conclusion High⁃dose TSG can significantly ameliorate the morphological changes of hippocampal synaptic ultrastructure in rats with chronic aluminum intoxication. It may improve the learning and memory ability of chronic aluminum⁃intoxicated rats by influencing the expression of SYN and PSD⁃95 proteins in the hippocampal tissue through the regulation of related protein expressions in the RhoA/Cofilin signaling pathway.