谷氨酰胺对新生大鼠坏死性小肠结肠炎肠道组织Caspase 3及增殖细胞核抗原表达的影响

Effect of glutamine on the expression of Caspase 3 and proliferating cell nuclear antigen in the intestinal tissue of neonatal rats with necrotizing enterocolitis

目的观察坏死性小肠结肠炎(NEC)新生大鼠肠道组织含半胱氨酸的天冬氨酸蛋白水解酶3(Caspase 3)与增殖细胞核抗原(PCNA)的表达情况,并探讨谷氨酰胺(Gln)对NEC大鼠肠道组织的保护作用。方法 36只新生SD大鼠随机分为对照组、NEC模型组和Gln+NEC模型组,每组12只。对照组予鼠乳代乳品人工喂养3天;NEC模型组采用鼠乳代乳品喂养+缺氧+冷刺激,连续3天建立NEC模型;Gln+NEC模型组建立NEC模型的同时,给予鼠乳代乳品加Gln喂养。各组大鼠均在3天后处死,HE染色后对其回肠进行病理评分,采用免疫组织化学方法检测肠组织Caspase 3和PCNA的表达情况。结果 NEC模型组肠组织Caspase 3表达指数为(77.3±8.6)%,高于对照组及Gln+NEC模型组[(18.9±3.4)%、(50.3±6.2)%],Gln+NEC模型组高于对照组,差异有统计学意义(P<0.05)。NEC模型组肠组织PCNA表达指数为(15.0±1.9)%,低于对照组及Gln+NEC模型组[(34.2±5.8)%、(24.0±3.9)%],Gln+NEC模型组低于对照组,差异有统计学意义(P<0.05)。NEC模型组肠道组织病理评分与Caspase 3表达指数(r=0.769,P=0.005)、Caspase 3/PCNA表达指数比(r=0.835,P=0.002)成正相关,与PCNA表达指数成负相关(r=-0.698,P=0.014)。结论 Caspase 3可能通过表达上调、PCNA通过表达下调参与NEC的疾病过程,细胞增殖和凋亡失衡与NEC的发生发展有一定关系。Gln在一定范围内抑制细胞凋亡、促进细胞增殖,可能是治疗NEC的有效措施之一。

Objective To study the expressions of cysteinyl aspartate specific proteinase 3（ Caspase 3） and proliferating cell nuclear antigen（ PCNA） in intestinal tissue of neonatal rats with necrotizing enterocolitis（ NEC）, and the protective effect of glutamine（ Gln） on NEC.Methods Thirty-six neonatal Sprague-Dawley（ SD） rats were randomly assigned into 3 groups at 48 h after birth（ 12 in each group）. The control group were fed with milk replacer. The NEC group were fed with milk replacer and experiencing cold exposure after hypoxic-reoxygenation twice a day for 3 days,The Gln ＋ NEC group were fed with milk replacer plus Gln and experiencing cold exposure after hypoxicreoxygenation twice a day for 3 days. All the rats were sacrificed and intestinal tissues obtained at day3 of the establishment of model. The histological changes of ileal tissues were studied using hematoxy lin-eosin（ HE） staining. The expressions of Caspase 3 and PCNA were detected using immunohistochemical（ IHC） method. Results Caspase 3 expression in NEC group（ 77. 3 ± 8. 6） % was significantly higher than the control group（ 18. 9 ± 3. 4） % and Gln ＋ NEC group（ 50. 3 ± 6. 2） %（ P〈0. 05）. Also,Caspase 3 in Gln ＋ NEC group was significantly higher than the control group（ P〈0. 05）.PCNA expression in the NEC group（ 15. 0 ± 1. 9） % was significantly lower than the control group（ 34. 2 ± 5. 8） % and the Gln ＋ NEC group（ 24. 0 ± 3. 9） %（ P〈0. 05）. PCNA expression in the Gln ＋ NEC group was significantly lower than the control group（ P〈0. 05）. The pathological score of the intestinal tissues was significantly correlated with Caspase 3 expression（ r = 0. 769,P = 0. 005）,Caspase3 / PCNA ratio（ r = 0. 835,P = 0. 002） and PCNA expression（ r =- 0. 698,P = 0. 014） in the NEC group. Conclusions Up regulation of Caspase 3 and down regulation of PCNA might be correlated with the process of NEC. Gln might be effective in prevention and healing of NEC by inhibiting apoptosis and promoting cell proliferation.