IL-1β induces inflammatory responses in C57BL/6J mice. (A) Serum IL-6 level at 2 h after injection of PBS or IL-1β (PBS, n = 5 mice; IL-1β, n = 5 mice). Unpaired t test. (B) Core body temperature for 6 h after injection of PBS or IL-1β (5 μg/kg). (C) Minimum change in core body temperature at 1 h after PBS or IL-1β injection (PBS, n = 7 mice; IL-1β, n = 8 mice). Data are represented as individual mouse data points pooled from two independent experiments. Unpaired t test. (D) ΔHR for 60 min after PBS or IL-1β injection. (E) Area under the curve (AUC) of change in heart rate (ΔHR) after PBS or IL-1β injection (PBS, n = 3 mice; IL-1β, n = 6 mice). Data are represented as individual mouse data points. This experiment was completed once. Unpaired t test. (F) Serum corticosterone levels at 2 h after PBS or IL-1β injection (PBS, n = 3 mice; IL-1β, n = 3 mice). Data are represented as individual mouse data points. This experiment was completed once. (G) Representative images showing immunofluorescence (IF) staining of the labeled cells (tdTomato, red) co-stained with DAPI (blue) in the NTS and PVN. Scale bar, 200 μm for the NTS. Scale bar, 100 μm for the PVN. (H) Serum IL-6 level at 2 h after injection of saline or CNO in naïve TRAP2-Cre mice (saline, n = 3 mice; CNO, n = 6 mice). Data are represented as individual mouse data points. This experiment was completed once. (I) ΔHR for 60 min after saline or CNO injection in naïve TRAP2-Cre mice (saline, n = 3 mice; CNO, n = 3 mice). *P < 0.05; **P < 0.01. NTS, nucleus tractus solitarius.