PI3K/Akt/GSK3β信号通路及内质网应激蛋白在大鼠难免性压疮形成中表达变化

目的：探讨磷脂酰肌醇3-激酶（PI3K）/蛋白激酶B（Akt）/糖原合成激酶3β（GSK3β）信号通路及内质网（ER）分子伴侣在大鼠难免性压疮中的表达变化。方法：54只雄性SD大鼠按照随机数字表法分为正常对照组（Con组），1个周期受压组（1c组）、3个周期受压组（3c组）、6个周期受压组（6c组）、9个周期受压组（9c组）和恢复期1 d组、3 d组、5 d组、7 d组，每组各6只。取各时间点受压部位肌肉组织，行HE染色观察组织的形态变化，SABC免疫组织化学法检测受压组织caspase-3的表达；蛋白质印迹（Western blotting）法检测受压组织中ER分子伴侣及Akt、GSK3β的变化。结果：HE染色结果显示，与Con组比较，各受压组局部肌肉组织呈现逐步退化的病理改变，在恢复组病理现象仍然存在；受压组和恢复组caspase-3蛋白表达均高于Con组，棕黄色颗粒表达主要在胞浆；Western blotting法检测受压组织中ER分子伴侣发现，其蛋白表达总体上呈上升趋势；与Con组比，受压组和恢复组p-Akt蛋白表达呈先上升后下降的趋势；与Con组比，受压组p-GSK3β蛋白表达首先表现为先上升后下降的趋势，在恢复组表达呈先下降后上升趋势。结论：难免性压疮难以愈合的原因可能与受压肌肉细胞凋亡有关；ER应激及PI3K/Akt/GSK3β信号通路可能参与了难免性压疮损伤过程。

Changes of the expression of signaling pathway of PI3K/Akt/GSK3β and endoplasmic reticulum stress in the formation of deep tissue injury of pressure ulcer in rats

Objective: To explore changes of the expression of signaling pathway of PI3K/Akt/GSK3β and expressions of ER chaperones in the deep tissue injury of pressure ulcer in rats. Methods: Fifty-four male Sprague-Dawley rats were divided into normal group and compressed groups (1 cycle, 3 cycles, 6 cycles, and 9 cycles group), natural recovery group as 1 day group, 3 days group, 5 days group and 7 days group according to the random number table, with six rats in each group. Muscle tissues underneath compression region and the same region normal group tissue were collected for analysis. Haematoxylin and eosin staining was carried out to examine the tissue histology; the expression of caspase-3 was assayed by immunohistochemical staining (Vectastain avidin-biotin complex, ABC); during different stages (experimental group and natual recovery group) the dynamic change of the ER chaperone such as GRP78, CHOP, caspase-12 and Akt, GSK3β, p-Akt, p-GSK3β in compressed muscle tissue were assayed by Western blot. Results: Under the light microscope of HE staining, the compressed muscle tissue of the experiment group showed a gradual degradation in the pathological changes, in recovery group, there were still signs of the pathlogical phenomenon; The immunohistochemical analysis indicated that the protein abundance of caspase-3 was elevated in the experiment group and natural recovery group compared with the control group, the detected immunoreactivity were generally distributed in cytoplasm. According to our immunoblot analysis, the protein expression of GRP78, CHOP, caspase-12 displayed a general ascending trend during different cycle; the protein expression of p-Akt showed first increased and then decreased; the protein expression of p-GSK3β offered first increased and then decreased with the time going, in recovery group p-GSK3β expression appeared first decreased and then increased with time going. Conclusion: The reasons of deep layer ulcers hard to heal may be related to muscle injury of the surrounding tissue; ERS and PI3K/Akt/GSK3β signaling pathway may involved in the procedure of deep ulcers.