Fig. 3: ERα⁺ neuronal activity during fasting-induced torpor in vivo and warmth exposure ex vivo.

a Schematic and coronal sections showing the optical fiber placement to record ERα⁺ neuronal activity in the MPA in vivo during fasting-induced torpor bouts. Image representative of n = 5 mice. oc optic chiasm. Scale bar 200 um. b Diagram showing the experimental design for photometry recordings during fasting. Mice were food deprived for 38 h at the time of optic fiber connection. c Core body temperature in mice showing normothermia and hypothermia (<33 °C) during the recording period following a fast. d Representative fluorescence traces of an individual mouse showing normothermia (black) and hypothermia (pink) during a 10 min recording period. e Mean area under the curve (AUC), variance, baseline, base width of peaks, peak amplitude, and total peak area of fluorescence detected from ERα⁺ MPA neurons in fasted mice showing normothermia (black) and hypothermia (pink) during a 10-min recording period (n = 5 mice, 4 females and 1 male). f Brightfield and fluorescence imaging of ERα-ZsGreen reporter expression in the MPA. Images representative of 179 cells from 4 mice. Scale bar 20 µm, white arrowhead denotes cell of interest. g Representative whole-cell current clamp recordings of ERα neurons in the MPA exposed to 25 °C and 30 °C. h Pie chart showing percentages of neurons showing a temperature response (TR, > 41.4% increase in firing rate) or no response (NR) in the MPA (MPN and rostral MPA). i Volcano plots comparing gene expression in TR (n = 4 samples, 2 neurons per sample) versus NR (n = 3 samples, 2 neurons per sample) ERα neurons in the MPN and rostral MPA regions combined. All genes shown as dots, with color denoting not significant in two-tailed differential expression testing (adjusted p > 0.05 using the Benjamini–Hochberg procedure, gray), significant (adjusted p < 0.05, dark gray), and genes induced by warmth⁶⁶.