晚期糖基化终末产物及其受体在妊娠期糖尿病孕鼠的子鼠脑损伤中的作用

Roles of advanced glycation end products and its receptor on the fetal brain injury in pregnant rats with gestational diabetes mellitus

目的探讨晚期糖基化终末产物（AGE）及其受体（RAGE）在妊娠期糖尿病（GDM）孕鼠的子鼠脑损伤中的作用。方法对21只孕鼠进行1％链脲佐菌素（STZ）注射以诱导建立妊娠期糖尿病模型，依据建模后第3天的血糖水平将21只孕鼠分为重度GDM组7只（〉16．7mmol／L）和轻度GDM组7只（6．7～16．7mmol／L）；另7只孕鼠为重度GDM干预组（每Et定时给予复方多维元素片溶于蒸馏水灌胃）。另选5只健康孕鼠为空白对照组（腹腔内注射同体积柠檬酸缓冲液）。于孕第3、13、19天检测各组孕鼠尾静脉空腹血糖。应用ELASA法检测各组孕鼠血清AGE水平；高倍显微镜下观察子鼠脑组织的病理变化。采用免疫组化二步法检测RAGE蛋白的表达。结果（1）各组孕鼠孕前血糖水平比较，差异无统计学意义（P〉0．05）；重度GDM组和重度GDM干预组孕鼠孕3d及孕期平均血糖水平均明显高于空白对照组，差异有统计学意义（P〈0．05）；重度GDM组与重度GDM干预组比较，差异无统计学意义（P〉0．05）。（2）重度GDM组孕鼠血清AGE水平为（1037±38）ng／L，轻度GDM组为（880±34）ng／L，两组比较，差异有统计学意义（P〈0．05）；空白对照组为（857±32）ng／L，重度GDM干预组为（988±37）ng／L，两组比较，差异有统计学意义（P〈0．05）；重度GDM干预组与轻度GDM组比较，差异无统计学意义（P〉0．05）。（3）轻度GDM组＋重度GDM组＋空白对照组3组孕鼠的总体血清AGE水平，与孕期平均血糖水平呈显著正相关（r=0．603，P〈0．05）；与孕3d血糖水平呈显著正相关（r=0．704，P〈0．05）。（4）空白对照组子鼠脑神经细胞数量、形态分布正常；轻度GDM组子鼠脑神经细胞数量减少，胶质细胞增生肿胀；重度GDM组与重度GDM干预组子鼠脑神经细胞进一步减少，细胞周围呈大空泡样变，细胞变形，有的仅见细胞残骸，并可见胶质瘢痕形成。空白对照组子鼠脑组织中RAGE蛋白表达极弱，轻度及重度GDM组子鼠脑组织中RAGE蛋白表达明显增强；重度GDM干预组子鼠的RAGE蛋白表达强度介于重度GDM组与轻度GDM组之间。结论GDM孕鼠的子代脑发育异常与孕鼠血清AGE水平升高和子鼠脑组织中RAGE蛋白表达增强有关，提示AGE／RAGE通路可能在GDM孕鼠的子代脑损伤中起重要作用；微量营养素对宫内高血糖环境致子代的脑损伤具有保护作用。

Objective To study the roles of advanced glycation end products and its receptor on fetal brain injury of gestational diabetes mellitus （GDM） rats. Methods Twenty one adult pregnant Wistar rats were administered streptozotocin （STZ） intraperitoneally to induce GDM rats model. The fourteen pregnant rats were divided into two groups according to the fasting glucose on the 3^rd day of pregnancy：severe GDM group with the fasting glucose 〉 16. 7 mmol/L and mild GDM group with the fasting glucose between 6. 7 - 16, 7 mmol/L. Another seven pregnant rats were chosen as the severe GDM and intervention with micronutrient group, receiving gavage with micronutrient during the whole pregnancy. Five control rats received the same volume of citric acid buffer. All the pregnant rats were tested fasting glucose from the tail vein and their weight on the pregnant day 3,13 and 19. Maternal serum levels of AGE were measured by ELISA and RAGE levels in the embryonic brain tissues were tested by immunohistochemistry. Results （ 1 ）There was no statistically significant difference of pre-pregnancy fasting glucose level among all groups （ P 〉 0.05）. The fasting glucose levels on the 3^rd day and the mean fasting glucouse level of pregnancy in the severe GDM group and the severe GDM and intervention with micronutrient group were higher than those of the control group （ P 〈 0. 05 ）. And there was no significant difference between the severe GDM group and the severe GDM and intervention with micronutrient group （ P 〉 0. 05 ）. （ 2 ） The serum AGE levels in the severe GDM group and the mild GDM group were （ 1037 ± 38 ） ng/L and （ 880±34 ） ng/L respectively, with no significant difference （ P 〉 0. 05 ）. The serum AGE levels in the control group and the severe GDM and intervention with micronutrient group were （857±32） ng/L and （ 988 ± 37 ） ng/L, and the difference was statistically significant （ P 〈 0. 05 ） . The serum AGE levels in the severe GDM and intervention with mieronutrieut group and in the mild GDM group had no significant difference （ P 〉 0.05 ）. （ 3 ） The serum AGE levels in the severe GDM group, mild GDM group and the control group were positively associated with the mean glucose level of pregnancy （ r = 0. 603, P 〈 0. 05 ） and the grlucose on the 3^rd day of pregnancy （r =0. 704,P 〈0. 05）. （4）The fetal brain nerve cell number and morphology in the control group were normal. While in the mild GDM group fetal brain nerve ceils decreased, the proliferation and swelling of glial ceils were seen. In the severe GDM group and the severe GDM and intervention with micronutrient group, the fetal brain cells furtherly reduced, and large vacuole around the cells, deformation and debris of the cells were seen. Glial scar formation was visible in some fetal brain tissues. There was a few RAGE expression in the control fetal brain tissues. In the mild GDM group and the severe GDM group, RAGE expression increased significantly. And the RAGE expression intensity in the severe GDM and intervention with micronutrient group was between the severe and the mild GDM groups. Conclusions （ 1 ） Abnormal fetal brain development of GDM rats was associated with the increase of maternal serum AGE and the enhancement of RAGE expression in fetal brain tissues, which suggested that AGE/RAGE pathway may play an important role in the fetal brain injury of GDM rats. （2） Micronutrients can reduce the brain damage of GDM fetuses.