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目的:探讨内质网应激在APPswe/PS1dE9转基因成年小鼠发生心肌肥厚中的作用。方法:选择APPswe/PS1dE9转基因成年小鼠及野生型(WT)成年小鼠各10只,分别为转基因实验组及对照组、野生型实验组及对照组,每组各5只,实验组背部皮下注射低剂量异丙肾上腺素(ISO)(2 mg/kg),每日1次,连续4周;对照组注射同等体积的生理盐水,4周后麻醉各组小鼠,描记体表心电图,计算心率,测量体重后处死,取出心脏,测量心脏质量及左室质量,计算左心室重量指数(LVW/BW)及全心重量比(HW/BW)。用于HE染色法测定心肌细胞病理形态学变化,应用Western Blot方法及免疫组织化学方法检测内质网应激相关蛋白即GRP78、JNK、P-JNK及CaMKⅡ的表达。结果:APPswe/PS1dE9转基因小鼠在低剂量的ISO诱导后较WT小鼠心脏明显肥大,APPswe/PS1dE9转基因实验组较转基因对照组及WT小鼠实验组及对照组HW/BW及LVW/BW显著增加(P<0.05);HE染色可见APPswe/PS1dE9转基因实验组较转基因对照组及WT实验组、对照组心肌细胞直径明显变大,细胞密度变小,毛细血管密度减少,细胞间质增多,细胞间距变大。Western blot结果显示APPswe/PS1dE9转基因实验组GRP78、p-JNK及CaMKⅡ的表达较转基因对照组及WT两组明显增加(P<0.05,P<0.01),而转基因对照组与WT两组无明显差异。免疫组化结果显示APPswe/PS1dE9转基因实验组GRP78及CaMKⅡ蛋白在心肌细胞胞浆中表达阳性率80%,明显高于野生型实验组(40%)(P<0.05),两组对照组表达均为阴性;转基因实验组p-JNK表达为90%,JNK表达为30%,其它三组均为阴性。结论:APPswe/PS1dE9转基因成年小鼠在较低剂量的ISO诱导后较WT实验组更容易出现心肌肥厚,内质网应激参与了APPswe/PS1dE9转基因成年小鼠心肌肥厚的发生。
Objective: To investigate the role of endoplasmic reticulum stress in cardiac hypertrophy in adult APPswe / PS1dE9 transgenic mice. Methods: Ten APPswe / PS1dE9 transgenic adult mice and 10 wild type (WT) adult mice were selected and divided into five groups: experimental group and control group, wild-type experimental group and control group, Low-dose isoproterenol (ISO) (2 mg / kg) was injected once daily for 4 weeks. In the control group, the same volume of saline was injected. After 4 weeks, the mice in each group were anesthetized and the surface electrocardiogram The heart rate, heart rate, heart weight and left ventricular mass were measured and the left ventricular mass index (LVW / BW) and total heart rate (HW / BW) were calculated. The HE staining was used to determine the pathological changes of cardiomyocytes. The expression of GRP78, JNK, P-JNK and CaMKII were detected by Western Blot and immunohistochemistry. Results: The APPswe / PS1dE9 transgenic mice showed significantly hypertrophy compared with WT hearts after induction with low doses of ISO. Compared with transgenic mice and WT mice, APPswe / PS1dE9 transgenic mice showed significant increases in HW / BW and LVW / BW (P <0.05). Compared with the transgenic control group and the WT experimental group and the WT group, the diameter of myocardial cells in APPswe / PS1dE9 transgenic group was significantly increased, the cell density was decreased, the capillary density was decreased, the interstitial cells were increased, Pitch becomes larger. The results of Western blot showed that the expressions of GRP78, p-JNK and CaMKII in APPswe / PS1dE9 transgenic group were significantly higher than those in transgenic group and WT (P <0.05, P <0.01), while there was no significant difference between WT and WT . The results of immunohistochemistry showed that the positive rate of GRP78 and CaMKⅡprotein in APPswe / PS1dE9 transgenic group was 80% in the cytoplasm of cardiomyocytes, which was significantly higher than that in the wild type experimental group (40%) (P <0.05) Was negative; transgenic experimental group p-JNK expression was 90%, JNK expression was 30%, the other three were negative. CONCLUSIONS: APPswe / PS1dE9 transgenic adult mice are more prone to myocardial hypertrophy after induction with lower doses of ISO than WT mice. Endoplasmic reticulum stress is involved in cardiac hypertrophy in APPswe / PS1dE9 transgenic adult mice.