孕鼠补充牛磺酸促进生长受限胎鼠神经元与神经干细胞增殖的最佳时机

Optimal timing of antenatal taurine supplementation for improvement of neuron and neural stem cell proliferation in fetal rats with intrauterine growth restriction

目的：探讨孕鼠补充牛磺酸促进胎儿生长受限（fetal growth restriction，FGR）胎鼠神经元及神经干细胞增殖的最佳时机。方法25只Sprague-Dawley孕鼠随机分为5组（每组5只），A组为对照组，B～E组均为FGR组采用全程低蛋白饮食法建立FGR胎鼠模型，且C～E组分别于妊娠第9、11、15天补充牛磺酸300 mg/（kg＆#183;d）。孕鼠自然分娩后，称量新生鼠出生体重，低于对照组新生鼠平均出生体重2个标准差，判定为FGR。每组5窝新生鼠，每窝随机抽取2只，每组10只，采用免疫组织化学方法检测新生鼠脑组织增殖细胞核抗原（proliferating cell nuclear antigen，PCNA）、脂肪酸结合蛋白7（fatty acid binding protein 7，FABP7）阳性表达情况。统计学方法采用单因素方差分析、LSD检验。结果 A、B、C、D、E组新生鼠平均出生体重分别为（6.61±0.45）、（4.65±0.23）、（5.37±0.17）、（5.74±0.21）和（5.00±0.24） g，B组低于A组（t=2.447），D和E组均高于B组（t值分别为2.306和2.306），D组高于C和E组（t值分别为2.306和2.306），差异均有统计学意义（P值均＜0.05）。新生鼠脑组织PCNA阳性表达主要位于细胞核内；A、B、C、D、E组每高倍镜视野（＆#215;400）PCNA阳性细胞个数分别为（31.03±5.38）、（46.49±4.38）、（59.65±5.37）、（67.76±5.84）和（53.53±6.94）个，B组多于A组（t=2.110），C、D和E组PCNA均多于B组（t值分别为2.110、2.110和2.131），D组多于C和E组（t值分别为2.101和2.110），差异均有统计学意义（P值均＜0.05）。新生鼠脑组织FABP7阳性表达主要位于细胞质中，A、B、C、D、E组的积分吸光度值分别为451733.1±141452.3、207232.2±60525.2、333766.6±68412.1、380647.4±131145.9、278967.1±127630.7，B组低于A组（t=3.165，P=0.000），C、D、E组均高于B组（t值分别为5.272，7.132和2.950，P值均＜0.05），D组高于C组，但差异无统计学意义（t=1.953，P＞0.05），D组高于E组，差异有统计学意义（t=4.182，P＜0.05）。结论孕鼠补充牛磺酸可促进FGR胎鼠神经元和神经干细胞增殖，在妊娠第11天时补充效果最显著，可能发挥促进脑发育的最佳效应。

ObjectiveTo determine the optimal timing of antenatal taurine supplementation to improve neuron and neural stem cell proliferation in fetal rats with intrauterine growth restriction.Methods Twenty-five pregnant SD rats were randomly divided into five groups （five rats in each group）： group A was the control group, group B to E were the fetal growth restriction （FGR） model groups with low-protein diet during the experiment, group C, D, and E were supplemented with taurine [300 mg/（kg＆#183;d）] at day 9, 11 and 15, respectively. The birth weight of newborn rats was measured after natural delivery. The rats with body weight two standard deviations lower than the average weight in group A were diagnosed as FGR. There were five litters of newborn rats in each group, and two were randomly selected from each litter, resulting in ten newborn rats in each group. Proliferating cell nuclear antigen （PCNA） and fatty acid binding protein 7 （FABP7） positive cell expression in newborn rat brain tissues were detected by immunohistochemistry. Single factor analysis of variance, LSD tests were used for statistical analysis.ResultsThe average birth weight of newborn rats in group A, B, C, D and E were （6.61±0.45）, （4.65±0.23）, （5.37±0.17）, （5.74±0.21）, and （5.00±0.24） g, respectively. Average birth weight was lower in group B than in group A （t=2.447）, higher in group D and E than in group B （t=2.306 and 2.306）, higher in group D than in group C and E （t=2.306 and 2.306）, and the differences were statistically significant （allP〈0.05）. The positive expression of PCNA in the brain of neonatal rats was mainly located in the nucleus. The number of PCNA positive cells in each high power field （＆#215;400） in group A, B, C, D and E was 31.03±5.38, 46.49±4.38, 59.65±5.37, 67.76±5.84, and 53.53±6.94, respectively. The number of PCNA positive cells in group B was higher than that in group A （t=2.110）, higher in groups C, D and E than in group B （t=2.110, 2.110 and 2.131）, higher in group D than in group C and E （t=2.101 and 2.110）, and the differences were all statistically significant （allP〈0.05）. The positive expression of FABP7 was mainly located in the cytoplasm of neonatal rat brain. The integral optical density （IOD） in group A, B, C, D, and E was 451 733.1± 141 452.3, 207 232.2±60 525.2, 333 766.6±68 412.1, 380 647.4±131 145.9, and 278 967.1±127 630.7, respectively. The IOD in group B was lower than that in group A （t=3.165,P=0.000）, higher in groups C, D and E than in group B （t=5.272, 7.132, 2.950）, and the differences were statistically significant （allP〈0.05）. Although the IOD in group D was higher than that in group C, the difference was not significant （t=1.953, P〉0.05）. The IOD in group D was higher than that in group E, and the difference was statistically significant （t=4.182,P〈0.05）.ConclusionsAntenatal taurine supplementation can promote neuron and neural stem cell proliferation in rats with FGR. The effect is most obvious on the 11th day of pregnancy, and may lead to the promotion of brain development.