丹参多酚酸对PAP小鼠大脑海马组织内质网应激通路的影响

摘要

目的 探讨丹参多酚酸对PAP小鼠脑海马组织内质网应激(ERS)通路的影响.方法 选择PAP双转基因雄性小鼠20只,按随机数字表法分为PAP小鼠模型组和丹参多酚酸给药组,每组10只;另选择SPF级C57BL/6J雄性小鼠10只作为正常对照组.丹参多酚酸给药组经尾静脉注射丹参多酚酸0.9%生理盐水溶液(400 g/L),剂量21 mg·kg-1·d-1 ;PAP小鼠模型组和正常对照组给予等量生理盐水,3组均持续给药4周.在第4周末进行Morris水迷宫实验,观察各组小鼠逃避潜伏期、第三象限停留时间(RTQ)、入水朝向角度和跨越平台次数的变化;并检测各组小鼠大脑海马组织淀粉样前体蛋白(APP)阳性细胞、双链RNA样内质网激酶(PERK)-真核起始因子2α-增强子结合同源蛋白(PERK-eIF2α-CHOP)通路相关蛋白的表达水平.结果 PAP小鼠模型组第1～5天逃避潜伏期均较正常对照组明显延长,第5天时有下降趋势,但仍明显高于正常对照组(s :58.41±2.36比28.6±10.15);丹参多酚酸给药组各时间点逃避潜伏期均较PAP小鼠模型组明显缩短,第5天时达到最低水平(s :31.97±8.36比58.41±2.36).PAP小鼠模型组RTQ、跨越平台次数均较正常对照组明显降低〔RTQ(s):8.27±2.95比15.97±7.33,跨越平台次数(次/90 s):0.70±0.47比2.70±0.48〕,而入水朝向角度较正常对照组明显增大〔(47.94±4.68)°比(32.66±2.55)°,P＜0.05〕.丹参多酚酸给药组RTQ、跨越平台次数均较PAP小鼠模型组明显增加〔RTQ(s):13.57±1.86比8.27±2.95,跨越平台次数(次/90 s):1.60±0.97比0.70±0.47〕,而入水朝向角度较PAP小鼠模型组明显减小〔(35.46±6.79)°比(47.94±4.68)°,P＜0.05).PAP小鼠模型组APP阳性表达率和CHOP、p-eIF2α蛋白表达均较正常对照组明显增多〔APP阳性表达率:(60.44±6.19)%比(21.05±5.87)%,CHOP蛋白表达(灰度值):3.09±0.07比1.46±0.09,p-eIF2α蛋白表达(灰度值):0.98±0.09比0.47±0.06,均P＜0.01〕,PERK、p-PERK蛋白表达均较正常对照组减少〔PERK蛋白表达(灰度值):0.42±0.06比0.82±0.11,p-PERK蛋白表达(灰度值):0.98±0.09比0.64±0.10,均P＜0.01〕;丹参多酚酸给药组APP阳性表达率和CHOP、p-eIF2α蛋白表达水平均较PAP小鼠模型组明显著减少〔APP阳性表达率:(33.09±10.33)%比(60.44±6.19)%,CHOP蛋白表达(灰度值):1.57±0.12比3.09±0.07,p-eIF2α蛋白表达(灰度值):0.80±0.07比0.98±0.09,均P＜0.01〕,PERK、p-PERK蛋白表达较PAP小鼠模型组明显增加〔PERK蛋白表达(灰度值):0.89±0.12比0.42±0.06,p-PERK蛋白表达(灰度值):0.78±0.08比0.98±0.09,均P＜0.01〕.结论 丹参多酚酸可能通过PERK-eIF2α-CHOP通路减少PAP双转基因小鼠海马组织APP的蓄积,从而改善PAP双转基因小鼠的学习能力,延缓脑损伤的进程.%Objective To investigate the effect of Salvianolic acid on endoplasmic reticulum stress (ERS) pathway in brain hippocampus of PAP mice. Methods Twenty PAP dual transgenic male mice were selected, they were randomly divided into a PAP mice model group and a Salvianolic acid group, 10 mice in each group; another 10 SPF grade C57BL/6J male mice were selected as a normal control group. In the Salvianolic acid group, 0.9% normal saline solution of Salvianolic lyophilized injection (400 g/L) of dosage 21 mg·kg-1·d-1 was injected intravenously through a tail vein of mice; the PAP mice model and normal control groups were given the same amount of 0.9% normal saline, and the therapeutic course was consecutive 4 weeks in the three groups. At the end of the 4th week, the Morris water maze test was carried out to observe the changes of escape latency, the third quadrant residence time (RTQ), entry angle into water and cross-platform times of mice in each group; amyloid precursor protein (APP) positive cell expression in cerebral hippocampus of mice were detected by immunohistochemistry; Western Blot was used to detect the expression level of PER like endoplasmic reticulum kinase-eukaryon initiation factor 2α-C/EBP homogenous protein (PERK-eIF2α-CHOP) pathway related proteins in hippocampus of mice. Results The escape latency of the PAP mice model group on the 1st to 5th day were significantly longer than those of the normal control group, although a downward trend was observed on the 5th day, it was still significantly longer than that of the model group (seconds: 58.41±2.36 vs. 28.60±10.15); compared with the PAP mice model group, the escape latency of Salvianolic acid group was shorter at each time point, and reached the shortest level on the 5th day (seconds: 31.97±8.36 vs. 58.41±2.36). In the PAP mice model group, the RTQ and the number of crossing platforms were significantly lower than those in the normal control group [RTQ (seconds): 8.27±2.95 vs. 15.97±7.33, numbers of crossing platforms (frequency/90 s): 0.70±0.95 vs. 2.70±0.48]; the entry angle was obviously greater than that of the normal control group [(47.94±4.68)°vs. (32.66±2.55)°, P < 0.05]. Compared with PAP mice model group, in Salvianolic acid group, the RTQ and number of crossing platform were significantly higher [RTQ (seconds): 13.57±1.86 vs. 8.27±2.95, number of crossing platforms (frequency/90 s):1.60±0.97 vs. 0.70±0.47], the entry angle was markedly smaller [(35.46±6.79)°vs. (47.94±4.68)°,P < 0.05]. The positive expression rate of APP and the protein expressions of CHOP, p-eIF2α in PAP mice model group were significantly higher than those in the normal control group [the positive rate of APP: (60.44±6.19)% vs. (21.05±5.87)%, CHOP protein expression (gray value): 3.09±0.07 vs. 1.46±0.09, p-eIF2αprotein expression (gray value): 0.98±0.09 vs. 0.47±0.06, all P < 0.01], the expression of PERK and p-PERK were lower than those in normal control group [PERK (gray value): 0.42±0.06 vs. 0.82±0.11, p-PERK protein expression (gray value): 0.98±0.09 vs. 0.64±0.10, both P < 0.01]; the positive expression rate of APP and protein expressions of CHOP, p-eIF2α in Salvianolic acid group were significantly lower than those in PAP mice model group [positive expression rate of APP: (33.09±10.33)% vs. (60.44±6.19)%, CHOP protein expression (gray value): 1.57±0.12 vs. 3.09±0.07, p-eIF2α protein expression (gray value): 0.80±0.07 vs. 0.98±0.09, all P < 0.01], while PERK and p-PERK expression were significantly higher than those in the model group [PERK (gray value): 0.89±0.12 vs. 0.42±0.06, p-PERK (gray value): 0.78±0.08 vs. 0.98±0.09, both P < 0.01]. Conclusion Salvianolic acid might work through the PERK-eIF2α-CHOP pathway to reduce the retention of APP in the hippocampus tissue of PAP dual-transgenic mice, thereby the learning ability of the mice is improved, and the progression of brain injury delayed.