促红细胞生成素对窒息新生大鼠心肌细胞凋亡及内质网应激相关蛋白的影响

目的：研究促红细胞生成素（EPO）对窒息新生大鼠心肌细胞凋亡及内质网应激相关蛋白葡萄糖调节蛋白78（GRP78）和C/EBP同源蛋白（CHOP）的影响。方法：120只新生7日龄Sprague-Dawley（SD）大鼠随机分为假手术组、窒息组和EPO组，每组40只。制备新生鼠常压窒息模型；EPO组于造模后立即给予rhEPO 500 U/mL（10 mL/kg）腹腔注射，其余两组接受同剂量的生理盐水。各组在造模完成后2 h、6 h、12 h、24 h和48 h分别取8只大鼠采集心脏血及心肌组织，测定血清心肌酶肌酸激酶（CK）和乳酸脱氢酶（LDH）水平，检测心肌细胞凋亡情况及心肌组织GRP78、CHOP蛋白的表达。结果：与假手术组和EPO组相比，窒息组各时间点血清心肌酶CK和LDH升高，凋亡细胞增多，GRP78、CHOP表达上调（P<0.01）；上述各指标在EPO组的表达水平亦高于假手术组（P<0.01）；窒息后24 h心肌组织CHOP蛋白与心肌细胞凋亡指数AI呈正相关（r=0.942，P<0.01）。结论：EPO可能通过调节内质网应激相关细胞因子GRP78、CHOP，减少心肌细胞凋亡从而发挥对新生鼠缺氧缺血性心肌损伤的保护作用。

Effects of erythropoietin on cardiomyocyte apoptosis and endoplasmic reticulum stress-related proteins in neonatal rats with asphyxia

OBJECTIVE: To study the effects of erythropoietin (EPO) on cardiomyocyte apoptosis and endoplasmic reticulum stress (ERS)-related proteins, glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP), in neonatal rats with asphyxia. METHODS: A total of 120 newborn Sprague-Dawley rats (7 days old) were randomly divided into sham-operated (n=40), asphyxia (n=40) and EPO-treated asphyxia groups (n=40). A neonatal rat model of normobaric asphyxia was established in the asphyxia and EPO-treated asphyxia groups. The rats in the EPO-treated asphyxia group received intraperitoneal injection of recombinant human erythropoietin (500 U/mL) immediately after the model was established, while the other two groups received the same volume of normal saline (0.9%). Heart blood and myocardial tissue samples were collected from 8 rats in each group at 2, 6, 12, 24 or 48 hours after the model was established. Serum creatine kinase (CK) and lactate dehydrogenase (LDH) levels were measured; cardiomyocyte apoptosis was evaluated, and expression of myocardial GRP78 and CHOP was measured. RESULTS: Compared with the sham-operated and EPO-treated asphyxia groups, the asphyxia group had significantly increased serum CK and LDH levels, number of apoptotic cells, and expression of myocardial GRP78 and CHOP at each time point (P<0.01), and all the indices were significantly higher in the EPO-treated asphyxia group than in the sham-operated group (P<0.01). At 24 hours after asphyxia, the expression of myocardial CHOP was positively correlated with the myocardial apoptosis index (r=0.944, P<0.01). CONCLUSIONS: EPO exerts a protective effect on the myocardium of neonatal rats with hypoxic-ischemic injury by regulating ERS-related proteins GRP78 and CHOP and reducing cardiomyocyte apoptosis.