宫内发育迟缓大鼠第36周胰岛素合成相关基因的表达

目的研究宫内发育迟缓（IUGR）大鼠第36周胰腺组织中胰岛素合成相关基因表达的变化。方法将20只体重250-270g的8-10周健康雌性SD大鼠，饲养于无特定病原体（SPF）级动物房，适应性饲养2周后将雌雄鼠合笼，以发现阴栓当天记为雌鼠受孕第1天，雌鼠受孕后随机数字表法分为造模组（n=10）和对照组（n=10）。采用孕中晚期热量限制的方法建立IUGR大鼠模型。造模组孕鼠自妊娠11d起给予对照组总热量50％饲料，新生鼠出生体重低于对照组新生鼠平均体重2个标准差者人选为IUGR组；对照组新生鼠即为正常组，对照组孕鼠自由进食。两组每窝各保留8只新生鼠继续饲养，仔鼠21d断奶后以标准饲料喂养至36周。选取第36周（中老年阶段）雄鼠为研究对象，实施腹腔葡萄糖耐量及胰岛素释放试验，运用逆转录聚合酶链反应（RT-PCR）方法检测胰腺组织中胰岛素合成相关基因胰岛素基因1（Insulinl）、胰岛素基因2（Insulin2）以及胰-十二指肠同源盒基因-1（PDX-I）]的表达情况。两组间比较采用t检验分析。结果第36周，IUGR组大鼠胰重及胰重／体重比值明显低于正常组分别为（4971±525）比（5844±398）mg和（0．58±0．05）％比（0．69±0．04）％，t=-2．65、-3．39，均P〈0．05]。糖负荷后各时点（30、60、120、180min）血糖值IUGR组均明显高于正常组分别为30min：（17．9±1．5）比（16．1±1．1）mmol／L，60min：（13．4±1．1）比（11．7±1．4）mmol／L，120min：（10．1±0．8）比（8．6±1．0）mmol／L，180min：（8．9±1．0）比（7．6±0．9）mmol／L，t=2．31、2．37、2．77、2．34，均P〈0．05]；糖负荷后各时点胰岛素分泌水平两组大鼠差异无统计学意义（t=1．66、-0．10、-0．65、-0．83、-0．58，均P〉0．05）。IUGR组大鼠胰腺组织中Insulinl基因表达较正常组明显减少（0．79±0．17比1．25±0．28，t=-2．78，P〈0．05），而Insulin2、PDX-1基因表达差异均无统计学意义（t=-1．65、-1．46，均P〉0．05）。结论IUGR大鼠第36周糖耐量减退，胰腺组织中Insulinl基因表达下调。

Expression of genes relevant to insulin synthesis in intrauterine growth retardation rats at 36 weeks

Objective To investigate the expression of genes relevant to insulin synthesis of intrauterine growth retardation（IUGR） rats at 36 weeks. Methods Twenty healthy female SD rats （250 - 270 g; 8-10 weeks old） were housed in the SPF animal room. After two weeks acclimatization, male and female rats were placed in same cage overnight for mating. Day 1 of pregnancy was defined as the day on which vaginal plugs were found. Female rats were grouped into normal controls （n = 10 ） and model group （n = 10 ） according to random number table. The IUGR rat model was established by maternal nutrition restriction during mid- to late-gestation. Pregnant rats received 50% of their daily food intake beginning from day 11 through day 21 of gestation, compared with their control counterparts who had free access to rat chow. The birth weights of the offsprings born to semistarvation mothers were more than two times of standard deviation below the mean values of the birth weights of the control group with IUGR. The litter size was randomly reduced to eight at birth to assure uniformity of litter size between IUGR and control litters. Two groups of pups were fostered to their mothers until they were weaned at day 21, and then all the pups were fed with standard rat chow until 36 weeks of life. Male offsprings at 36 weeks of age were selected asresearch subjects. Intraperitoneal glucose tolerance test （IPGTT） and insulin releasing test （IRT） were performed in IUGR and normal groups. RT-PCR was applied to detect the expression of pancreas genes such as lnsulinl, Insulin2 and PDX-1. The t test was used in the comparison between two groups. Results At 36 weeks of age, body weight, pancreas weight and pancreas/body weight in IUGR group were much lower than those in normal group （ （4971 ± 525 ） and （ 5844 ± 398 ） mg, （0. 58 ± 0. 05 ） % and （0. 69 ± 0.04 ） % respectively, t = -2.65 and -3.39, both P 〈 0.05）. Glucose evels at 30, 60, 120 and 180 rain after glucose load were significantly higher in IUGR group （ 30 rain ： （ 17.9 ± 1.5 ） vs （ 16. 1 ± 1.1 ） retool/L, 60 min： （13.4±1.1） vs （11.7±1.4） mmol/L, 120min： （10.1 ±0.8） vs （8.6±1.0） retool/L, 180min： （8.9±1.0） vs （7.6 ±0.9） mmol/L, t =2.31,2.37,2.77,2.34, all P 〈0.05）, indicated glucose tolerance was impaired in IUGR rats. In addition, there was no significant difference in the insulin levels at the time points during glucose tolerance test between normal and IUGR rats （t = 1.66, -0. 10, -0. 65, - 0. 83, - 0. 58, P 〉 0. 05 ）. In IUGR rats, the expressions of lnsulinl mRNA were reduced markedly than those in the controls （0.79 ±0.17 vs 1.25 ±0.28, t = -2.78, P 〈0.05）. Although no significant differences were observed in gene expression of Insulin2 mRNA and PDX-1 mRNA （ both P 〉 0. 05 ） . Conclusions The IUGR rats had deteriorated glucose tolerance at 36 weeks of age with decreased gene expression of Insulinl in panereas.