目的：探讨重组人促红细胞生成素(rhEPO)对新生大鼠坏死性小肠结肠炎(NEC)的作用机制。方法出生48 h的新生SD大鼠60只随机分为正常对照组、NEC模型组及rhEPO干预1、2、3组。采用人工喂养、缺氧、冷刺激方法制备NEC模型；rhEPO干预组分别在鼠乳代乳品中加入rhEPO 0.1、1及10 U/ml干预3天，以苏木精-伊红(HE)染色，按Nadler标准行肠道组织病理学评分，免疫组化(二步法)检测大鼠肠道Bcl-2及活性caspase-3蛋白情况。采用图像分析系统对免疫组化的图像进行阳性表达积分光密度值测量。结果 NEC模型组大鼠造模24 h后出现腹胀、活动减少、反应迟钝，严重者出现皮肤苍白、皮温降低、呼吸节律改变，3组rhEPO干预组上述症状出现较晚且较轻。正常对照组、NEC模型组、干预1组、干预2组和干预3组新生大鼠NEC发生率分别为0%、60%、30%、18.2%和9.1%，组间差异有统计学意义(P=0.008)。5组新生大鼠肠道病理组织学评分、肠道Bcl-2表达以及活性caspase-3蛋白表达的差异均有统计学意义(P均<0.01)；NEC模型组肠道病理损伤最重，肠道活性caspase-3蛋白合成最多；予rhEPO干预后，肠道损伤有减轻趋势， Bcl-2表达上调，活性caspase-3合成减少。结论口服rhEPO能使肠道活性caspase-3蛋白合成减少，Bcl-2表达上调，降低NEC发生率，且对肠道的保护作用呈剂量依赖性。%Objectives To investigate the effect of rhEPO on newborn rats with necrotizing enterocolitis (NEC). Meth-ods Sixty newborn Sprague-Dewley (SD) rats at the age of 48 hours were randomly divided into 5 groups:control group, NEC group, and intervention groups 1, 2 and 3 treated with rhEPO. The rats were fed rat breast milk substitutes and stressed under hypoxia and cold exposure to establish NEC model. The rats with NEC were treated with different doses of rhEPO (0.1U/ml, 1U/ml and 10U/ml) in intervention groups. The expression of Bcl-2 and caspase-3 were measured by immunohistochemistry, and intestinal pathological changes were observed using HE staining. The value of positive expression was analyzed by IOD (integral optical density) image analysis system. Results Abdominal distention, decreased activity and unresponsiveness occurred in NEC rats 24 hours after stress exposure, and pale skin, decreased skin temperature and respiratory rhythm change were observed in severe cases. The symptoms appeared later and milder in three intervention groups. The NEC incidence of newborn rats was as followings:control group(0%), model group(60%), intervention group 1( 30%), intervention group 2(18.2%), intervention group 3(9.1%) and the difference was signiifcant between each group (P=0.008). The grades of intestinal injury, the expression of active caspase-3 and Bcl-2 were signiifcantly different among groups (P<0.01). Intestinal injury was the most severe and the expression level of active caspase-3 was the highest in NEC group. After rhEPO treatment, the intestinal injury and the production of active caspase-3 protein were decreased, and the expression of Bcl-2 was increased. Conclusions Oral rhEPO could decrease the ex-pression of intestinal active caspase 3, and increase the expression of Bcl-2. The protective effect of rhEPO on NEC is dosede-pendent.
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