目的　探讨丙氨酰-谷氨酰胺(Ala-Gln)对低出生体重(LBW)新生大鼠缺氧后肠组织胰岛素样生长因子-1(IGF-1)及IGF-1受体(IGF-1R)水平的影响。方法　将孕鼠分别置于吸烟和非吸烟环境中饲养, 非吸烟条件下饲养孕鼠所分娩的新生大鼠设为A组; 将吸烟条件下饲养孕鼠所分娩的正常体重新生大鼠设为B组, LBW新生大鼠随机分为对照组(C组)、缺氧-复氧组(D组)和Ala-Gln组(E组); 每组24只。D、E组行缺氧-复氧操作连续3 d, 每天2次造模, E组在每日缺氧处理前腹腔注射Ala-Gln(10 mL/kg), C、D组以等量生理盐水行替代注射。各组于生后第4、7、10天分别处死8只大鼠取肠组织。采用ELISA法检测各组肠组织IGF-1水平; 免疫组化法检测各组肠组织IGF-1R水平。结果　A组与B组IGF-1及IGF-1R蛋白水平在各时间点差异无统计学意义(P>0.05)。C组IGF-1及IGF-1R蛋白水平呈上升趋势, 第7天时均较其他各组升高(P<0.05), 第10天时趋于正常水平, 与A、B组比较差异无统计学意义(P>0.05)。D组各时间点IGF-1及IGF-1R蛋白水平均明显低于C组(P<0.05)。E组在第4、7天IGF-1及IGF-1R蛋白水平低于C组(P<0.05), 但到第10天上升至接近C组水平, 且显著高于D组水平(P>0.05)。结论 宫内和生后缺氧易使LBW新生大鼠出现肠损伤, 肠道外给予大剂量Ala-Gln可减轻LBW新生大鼠缺氧性肠损伤程度, 对缺氧性肠损伤有一定保护作用。

Objective To study the effect of L-alanyl-L-glutamine (Ala-Gln) on the levels of insulin-like growth factor-1 (IGF-1) and IGF-1 receptor (IGF-1R) in the intestinal tissues of low-birth-weight (LBW) newborn rats with hypoxia/reoxygenation-induced intestinal injury. Methods Pregnant rats were fed with or without smoking. The rats born by those fed without smoking were included in group A; for the rats born by those fed with smoking, normal-birth-weight rats were included in group B, and LBW rats were randomly divided into control group (group C), hypoxia/reoxygenation (H/R) group (group D), and Ala-Gln group (group E). Each group consisted of 24 newborn rats. The rats in groups D and E received H/R treatment twice a day for three consecutive days to establish an intestinal injury model; the rats in group E were intraperitoneally injected with Ala-Gln (10 ml/kg) before daily H/R treatment, while those in groups C and D were given an equal dose of normal saline by intraperitoneal injections. On days 4, 7, and 10 after birth, 8 rats were sacrificed in each group to collect intestinal tissues. The IGF-1 levels in intestinal tissues were measured using ELISA, and IGF-1R levels were measured by immunohistochemistry. Results There were no significant differences in IGF-1 and IGF-1R levels between groups A and B at all time points. The levels of IGF-1 and IGF-1R in group C kept increasing, were higher than those in other groups on day 7 (P<0.05), and reached a normal level on day 10, without significant differences compared with those in groups A and B. Group D had significantly lower IGF-1 and IGF-1R levels than group C at all time points (P<0.05). The levels of IGF-1 and IGF-1R in group E were lower than those in group C on days 4 and 7 (P<0.05), but they increased to approximately the levels in group C and were significantly higher than those in group D on day 10. Conclusions Intrauterine and postnatal hypoxia may induce intestinal injury in LBW newborn rats, and parenteral administration of high-dose Ala-Gln can reduce hypoxia-induced intestinal injury. Therefore, Ala-Gln has a protective effect against hypoxia-induced intestinal injury.