Mothers undergo significant metabolic changes during pregnancy and lactation to support the development of their offspring. While many of these changes have been studied, little is known about how body temperature regulation and environmental temperature preferences are affected during and after pregnancy. A new study conducted by researchers at Baylor College of Medicine, alongside collaborating institutions, reveals that postpartum female mice exhibit altered temperature preferences, with brain changes mediating this shift. The findings were published in the journal Molecular Metabolism.
Throughout pregnancy, both humans and mice experience fluctuations in body temperature. Early in pregnancy, body temperature rises, returns to normal during late pregnancy, and then increases again during lactation. However, the underlying mechanisms driving these changes remain poorly understood.
Dr. Chunmei Wang, a co-corresponding author and assistant professor of pediatrics at the USDA/ARS Children’s Nutrition Research Center at Baylor, explained that the study aimed to uncover what changes in the brain are responsible for the new environmental temperature preferences in postpartum females.
The study revealed that postpartum female mice develop a preference for cooler environments starting from late pregnancy and continuing long after they have weaned their offspring. “For more than four weeks after weaning, female mice had a lower body temperature and preferred cooler environments,” said Wang. These mice no longer favored warmer conditions (30°C/86°F), but still avoided extreme cold (15°C/59°F).
To understand the biological mechanisms behind these preferences, the researchers focused on the preoptic area (POA) of the brain, a region responsible for sensing and regulating body temperature. They found that a decrease in a specific group of neurons—estrogen receptor alpha (ERα)-expressing neurons in the POA—was linked to the observed shift in temperature preference in postpartum female mice.
The researchers further investigated the role of ERαPOA neurons by studying virgin female mice with a deleted estrogen receptor alpha in these neurons. These altered mice also exhibited a preference for lower temperatures, similar to postpartum females, supporting the theory that changes in these neurons influence temperature preferences.
The research team also found that the ERαPOA neurons of postpartum females displayed altered responses to temperature. One subset of these neurons typically responds to warmth, while another is sensitive to cooler temperatures. Compared to non-pregnant females, the ERαPOA neurons of postpartum mice showed a reduced response to warmth and an enhanced response to cooler temperatures.
These findings suggest that the ability of ERαPOA neurons to sense warmth and cold is influenced by reproductive experience, ultimately leading to changes in temperature preference and warmth-seeking behavior in postpartum females.
The team is now focusing on further investigating the specific functions of each group of ERαPOA neurons in regulating body temperature and thermal preferences.
Other contributors to the study include Nan Zhang, Meng Yu, Qianru Zhao, Bing Feng, Yue Deng, Jonathan C. Bean, Qingzhuo Liu, Benjamin P. Eappen, Yang He, Kristine M. Conde, Hailan Liu, Yongjie Yang, Longlong Tu, Mengjie Wang, Yongxiang Li, Na Yin, Hesong Liu, Junying Han, Darah Ave Threat, Nathan Xu, Taylor Smiley, Pingwen Xu, and Lulu Chen. The research team is affiliated with Baylor College of Medicine, Huazhong University of Science and Technology, Hubei Branch of National Center for Clinical Medical Research of Metabolic Diseases, Louisiana State University, South-central Minzu University, and the University of Illinois.
This study was supported by grants from the USDA/CRIS, Pennington Biomedical Research Center institutional funding, and the National Natural Science Foundation of China.
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