School of Human Sciences, The University of Western Australia, Perth, 6009, Australia.
Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, 6009, Australia.
Reprod Sci. 2021 Feb;28(2):416-425. doi: 10.1007/s43032-020-00291-7. Epub 2020 Aug 17.
Physiological adaptations during heat exposure are critical in pregnancy. Maternal thermoregulation has to accommodate the increased metabolic load of the developing fetus. Here, we assess the consequences of intermittent heat exposure, as occurs in heat waves, for maternal adaptations during pregnancy, and chronic feto-placental outcomes. Following timed mating, C57BL/6J mice were allocated to either standard animal housing temperature conditions (SH) or housing at a temperature within the thermoneutral zone (TNZ). A subset of the TNZ group was exposed to 37 °C for 8 h a day from E15.5 to E17.5 to simulate a heat wave (HW). Maternal weight gain, food intake, rectal temperature, and nesting behaviors were measured across gestation. Fetal and placental tissues were collected at E18.5. With heat exposure, maternal rectal temperature increased while food intake and nest complexity decreased. Maternal daily weight gain initially decreased due to heat exposure, but on the last day of exposure, it was comparable to the other experimental groups. These maternal responses during heat exposure impacted on the fetus, with restrictions in placental and fetal development evident just before birth. Thus, the vascular portion of the placenta, and the relative fetal head size, was smaller. Furthermore, SH and TNZ animals demonstrated distinct differences in food intake and nesting behavior during pregnancy, reinforcing the need for caution in extrapolating from animal models to humans when housing occurs outside of thermoneutral zone conditions. This study highlights the direct effects of temperature conditions on health in pregnancy and provides a foundation for future studies to investigate fetal health consequences that are associated with intermittent heat exposure.
热暴露期间的生理适应在妊娠中至关重要。母体体温调节必须适应发育中胎儿增加的代谢负荷。在这里，我们评估了间歇性热暴露（如热浪期间发生的情况）对妊娠期间母体适应和慢性胎-胎盘结局的影响。在定时交配后，将 C57BL/6J 小鼠分配到标准动物饲养温度条件（SH）或处于热中性区（TNZ）内的饲养条件下。TNZ 组的一部分从 E15.5 到 E17.5 每天暴露于 37°C 8 小时，以模拟热浪（HW）。在整个妊娠期测量母体体重增加、食物摄入量、直肠温度和筑巢行为。在 E18.5 收集胎儿和胎盘组织。暴露于热时，母体直肠温度升高，而食物摄入量和巢的复杂性降低。由于热暴露，母体每日体重增加最初减少，但在暴露的最后一天，与其他实验组相当。这些母体在热暴露期间的反应影响了胎儿，在出生前就明显限制了胎盘和胎儿的发育。因此，胎盘的血管部分和相对胎儿头部大小较小。此外，SH 和 TNZ 动物在妊娠期间表现出明显不同的食物摄入量和筑巢行为，这强调了在热中性区条件以外的环境中饲养时，从动物模型推断到人类时需要谨慎。本研究强调了温度条件对妊娠健康的直接影响，并为未来研究提供了基础，以研究与间歇性热暴露相关的胎儿健康后果。
