低出生体质量追赶生长大鼠胰岛功能的变化

目的研究低出生体质量大鼠出生后追赶生长对其胰岛功能的影响。方法建立低出生体质量大鼠出生后高脂饮食追赶生长模型（模型组,出生体质量低于正常对照组平均值的2个标准差）,设立正常对照（正常组,出生后常规饲料喂养）。称量两组3、7、11、15周龄大鼠体质量和15周龄大鼠的附睾脂肪质量并进行比较。分别采用口服葡萄糖耐量试验（OGTT）和高胰岛素-正葡萄糖钳夹试验对两组15周龄大鼠的血糖调节功能和胰岛素敏感性进行评估。免疫荧光双标法观察两组16周龄大鼠胰岛结构改变。结果模型组15周龄大鼠体质量和附睾脂肪量明显高于正常组（P〈0.05）。模型组大鼠空腹及糖负荷后30、60、120 min血糖均显著高于正常组（P〈0.05）;稳态血糖和基础胰岛素均明显高于正常组（P〈0.05）,而葡萄糖输注率显著低于正常组（P〈0.05）。免疫荧光双标法观察发现,模型组大鼠胰岛结构散乱;与正常组比较,模型组大鼠胰岛内胰岛素面积占胰岛总面积的比例明显减小（0.59±0.09和0.73±0.08）（P〈0.05）。结论低出生体质量追赶生长大鼠的糖耐量减退,胰岛素敏感性下降;其机制可能与胰岛结构发生重构,β细胞团减少有关。

Changes of islet function of rats with lower birth weight and catch-up growth

Objective To investigate the effects of lower birth weight and catch-up growth on islet function of rats. Methods An animal model of lower birth weight (birth weight lower than 2 standard deviations of the average of control) and high fat diet was established (model group), and the other animal model of normal diet after normal birth was used as control (normal group). The body weight of rats aged 3, 7, 11 and 15 weeks and the weight of epididymal fat were recorded and compared in two groups. Glucose metabolism was evaluated by oral glucose tolerance test (OGTT), and insulin sensitivity was determined by hyperinsulinaemic-euglycaemic clamp test in two groups of rats aged 15 weeks. Double-label immunofluorescence assay was adopted to observe the islet architecture of two groups of rats aged 16 weeks. Results The body weight and weight of epididymal fat of rats aged 15 weeks in model group were significantly higher than those in normal group (P<0.05). Fasting blood glucose and blood glucose of 30, 60 and 120 min after glucose loading in model group were significantly higher than those in normal group (P<0.05), the steady-state blood glucose and basal insulin in model group were significantly higher than those in normal group (P<0.05), while the glucose infusion rate in model group was significantly lower than that in normal group (P<0.05). Double-label immunofluorescence assay revealed that the islet architecture of rats in model group was disrupted, and the ratio of area of insulin to total area of islet in model group (0.59±0.09) was significantly lower than that in normal group (0.73±0.08）(P<0.05). Conclusion Rats with lower birth weight and catch-up growth have impaired glucose tolerance and insulin resistance, which may be associated with the reconstruction of islet structure and reduction of β cell mass.