Fig. 7: Na_V1.3 is required for acclimation-induced, tonic warm-sensitive firing and heat tolerance.

a, LepR-Cre mice POA injected with Cre-dependent constructs encoding shRNAs against Scn3a or scrambled control (scram-Scn3a shRNA). b, Acclimated VMPO^LepR neurons labeled with GFP encoded within the shRNA constructs. Scale bars, 250 μm. ac, anterior commissure. c, Left: average I_NaP in VMPO^LepR neurons expressing Scn3a shRNA and scrambled control. Traces are presented as mean ± s.e.m. Right: quantification (mean ± s.e.m.) of I_NaP at −35 mV, showing a reduction of I_NaP in Scn3a shRNA expressing acclimated LepR⁺ neurons. Unpaired, two-tailed Student’s t-test, ^*P = 0.0174; n = 8/4 (Scn3a shRNA) and n = 8/3 (scram-Scn3a shRNA) cells. d, Firing frequency of acclimated VMPO^LepR neurons significantly reduced by the functional shRNAs. Unpaired two-tailed Student’s t-test, ^**P = 0.0044; n = 30/5 (Scn3a shRNA) and n = 20/3 (scram-Scn3a shRNA) cells. e, Distribution of temperature-insensitive, WSN and silent neurons within the acclimated VMPO^LepR neuron population expressing either Scn3a (n = 47/5) or scram-Scn3a (n = 19/3) shRNA. f, Na_V1.3^fl/fl and WT controls were injected with an AAV encoding the Cre recombinase into the POA (cKO). g, Most of the WT animals able to defend their body temperature within physiological range. In contrast, all but one of the Na_V1.3 cKO animals were unable to maintain their body temperature <41.5 °C (N = 9 for each group). h, Left: range of body temperatures of animals shown in g. Right: quantification of endurance time at 36 °C acclimation temperature of mice shown in g. Cut-off time was 72 h (dashed line). Mann–Whitney U-test, ^*P = 0.0155 (N = 9 each). i, Left: Allen Brain Atlas annotation of human POAs. Right: human tissue block covering POAs MnPO/MPA/OVLT (LFB/H&E stain). j, LEPR coexpression in human VMPO with RNAscope ISH. Left: PACAP + LEPR-tv1 (long isoform; coexpression in yellow). Middle: vGLUT2 + LEPR-alltv (all isoforms; coexpression in yellow). Right: LEPR-alltv + LEPR-tv1 (coexpression in yellow). Electrophysiological recordings were performed with fast synaptic transmission blockade and at 36 °C. Box plots show the median and IQR (Extended Data Fig. 10 and Supplementary Figs. 4 and 5).