Postpartum females show shift in temperature preferences due to brain changes

Mothers experience major metabolic adaptations during pregnancy and lactation to support the development and growth of the new life. Although many metabolic changes have been studied, body temperature regulation and environmental temperature preference during and after pregnancy remain poorly understood. Researchers at Baylor College of Medicine and collaborating institutions show in the journal Molecular Metabolism that postpartum female mice develop new environmental temperature preferences and reveal brain changes mediating these changes.

In both humans and mice, body temperature increases during early pregnancy, drops to normal temperature during late pregnancy and then goes up again during lactation."

Dr. Chunmei Wang, co-corresponding author, assistant professor of pediatrics at USDA/ARS Children's Nutrition Research Center at Baylor

In this study, Wang and her colleagues investigated what changes occurred in the brain that mediated the new temperature preference. "We worked with mice and found that female mice prefer a cooler environment starting from late pregnancy and persisting in long-term postpartum," Wang said. "For more than four weeks post-weaning female mice had a lower body temperature and preferred cooler environments; they lost their typical preference for warm environments (30 °C/86 °F) but still avoided cold environments (15 °C/59 °F)."

To identify the biological underpinnings of these changes, the researchers studied the preoptic area (POA), a brain region important for sensing and regulating body temperature. "We discovered that the change in temperature preference in postpartum female mice was associated with a significant decrease in a particular group of neurons, estrogen receptor alpha (ERα)-expressing neurons in the preoptic area of the brain (ERα^POA neurons)," Wang said.

Supporting this finding, the researchers found that virgin females in which the estrogen receptor alpha had been deleted in ERα^POA neurons also preferred lower temperatures and avoided warmer locations, mimicking postpartum females.

Looking closely into the ERα^POA neurons, the researchers found that these neurons vary in their ability to sense warm or cold temperatures – one group of ERα^POA neurons can directly respond to warmth, while another group responds to cooler temperatures. "Interestingly, compared to female mice that had not been pregnant, ERα^POA neurons of postpartum females had reduced response to warmth and an enhanced response to cold," Wang said.

Together, the results support that the ability of ERα^POA neurons to sense warmth and cold is regulated by reproductive experience and leads to changes in temperature preferences that alter the animal's warmth-seeking behavior. Currently, the researchers are exploring the function of each group of ERα^POA neurons on the regulation body temperature and thermal preference.

Other contributors to this work 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, Lulu Chen and co-corresponding authors Tianshu Zeng and Yanlin He. The authors are affiliated with one or more of the following institutions: 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 work was supported by grants from the USDA/CRIS (3092-51000-062-04(B)S), Pennington Biomedical Research Center institutional funding and the National Natural Science Foundation of China.