Objective: To investigate the effect of heat exposure during the second week of pregnancy on placental development and intrauterine growth of fetal rats.
Methods: 24 pregnant rats were either exposed or not to a temperature of 35∓1 degrees celsius; during the second week of pregnancy. The body weight gain of the pregnant rats was measured regularly, and in late pregnancy, the pregnant rats were dissected and the number, weight, length, tail length, appearance of the offspring rats, number of live and still births, and the placental weight were recorded. The expressions of HSP70, Bax and Bcl-2 in the placenta were determined.
Results: Compared with the control group, the pregnant rats in heat exposure group had significantly lower body weight at the end of pregnancy and gestational weight gain, and the body weight, body length and tail length of the offspring rats were also significantly lower or smaller (P<0.05). The placental weight was comparable between the two groups. The placental expressions of HSP70,Bax,and Bcl-2 were significantly higher in the heat exposure group than in the control group (P<0.05).
Conclusion: Heat exposure during the second trimester of pregnancy has adverse effects on placental development and intrauterine growth of the fetal rats by inducing heat shock response of placental tissue and apoptosis of the placental cells.
目的: 探讨孕中期热暴露对大鼠胎盘和子代宫内生长发育的影响。
方法: 24只健康清洁级SD大鼠受孕后随机分为对照组和热暴露组，每组12只。对照组孕鼠孕期全程在23±1 ℃的环境中饲养，热暴露组大鼠受孕后先在23±1 ℃的环境中饲养，妊娠第8~13天饲养温度调高至35±1 ℃，妊娠第14天回至23±1 ℃的环境中饲养。测量孕鼠不同妊娠时段的的体质量变化，在孕末期行剖腹取胎，检测仔鼠的数量、体质量、身长、尾长、外观、活/死胎数、胎盘质量及胎盘组织HSP70、Bax、Bcl-2等蛋白表达。
结果: 热暴露组孕鼠孕末期体质量及孕期体质量增加值均小于对照组，且差异均有统计学意义（均P < 0.05）；热暴露组仔鼠的体质量、身长、尾长均小于对照组，且差异均有统计学意义（均P < 0.05）；两组仔鼠胎盘质量的比较差异无统计学意义；热暴露组胎盘HSP70表达（HSP70/actin）和Bax/Bcl-2均高于对照组，且差异均有统计学意义（P < 0.05）。
结论: 孕中期热暴露会影响大鼠胎盘及子代宫内的生长发育，会诱发胎盘组织的热休克反应及加速胎盘组织细胞的凋亡。