Fig. 3: LH^Penk neurons of PSS mice exhibit sensitized activity in response to HFD consumption.

a Schematic for the injection of AAV-DIO-GCaMP6f (left) and implantation of GRIN lens into the LH (right). b, c Confocal image showing GRIN lens placement on the GCaMP6f-expressing LH^Penk neurons. Scale bar, 250 μm (b). A sample image for data acquisition. Scale bar, 50 μm (c), replicated independently with similar results in 4 mice. d Schematic for GRIN lens-implanted mice exposed to HFD. e, f Example in vivo Ca²⁺ activity traces from LH^Penk neurons of control (e) and PSS mice (f) in response to the 1st HFD eating bout. g, h Mean z-score of the LH^Penk neuronal activity of control (g; n = 55 cells from four control Penk-Cre mice) and PSS mice (h; n = 54 cells from five PSS Penk-Cre mice) before and after the 1st HFD eating bout. Two-tailed paired t test; in (g) t₅₄ = −0.435, p = 0.665; in (h), t₅₃ = −4.233, ***p = 0.0000921. i, j Pie charts indicate the classification of LH^Penk neurons of control (i) and PSS mice (j) showing activated, inhibited, or unresponsive activity upon the 1st HFD eating bout. k, l Schematic for GRIN lens-implanted control (k) and PSS mice (l) in the presence of a novel object. In vivo Ca²⁺ activity is monitored in the presence of a novel object 24 h after PSS exposure. m, n As for (e, f), but in response to the 1st physical contact to a novel object. o, p Mean z-score of the LH^Penk neuronal activity of control (o; n = 45 cells from four control Penk-Cre mice) and PSS mice (p; n = 56 cells from five PSS Penk-Cre mice) before and after the 1st physical contact to a novel object. Two-tailed paired t-test; in (o), t₄₄ = −1.036, p = 0.306; in (p), t₅₅ = −1.602, p = 0.115. q, r As for (i, j), but upon the 1st physical contact with a novel object. n.s not significant. Data are presented as mean ± SEM.