1321-P: Reproductive Experience Impairs Warm Sensing in Female Mice

The maternal body experiences drastic alterations in energy balance during pregnancy and lactation, but little is known about the long-term metabolic changes after this reproductive experience. Here we systemically compared the metabolic phenotypes in reproductive experienced (RE) female mice vs. virgin females, and found that RE mice showed a chronic hypothermia when housed at the room temperature (24°C) . In a warm sensing test, virgin females show clear preference to 30 °C ambient temperature vs. the room temperature, while RE mice lose this preference. In a cold sensing test, both virgin and RE females showed similar preference to the room temperature vs. 15 °C ambient temperature. Immunofluorescence staining revealed that expression of estrogen receptor alpha (ERα) in the medial preoptic area (MPA) was significantly decreased in the RE mice compared to virgins. Electrophysiological recordings demonstrated that the warm-sensing property of ERα neurons in the MPA were impaired in RE mice. Our results indicate that reproductive experience impairs the thermoregulation in female mice, associated with defective warm sensing of ERα neurons in the MPA.