Capsaicin

The HepG2 cell was purchased from Bioresource Collection and Research Center and cultured in DMEM medium (Hyclone) supplemented with 5% fetal bovine serum, 100 units/ml penicillin, and 100 μg/ml streptomycin. Cells were maintained in a humidified atmosphere composed of 5% CO₂ and 95% air at 37°C. Cells were plated in 3 cm culture dishes at 1 x 10⁵ cells per dish 24 h before they were treated with or without capsaicin (Sigma) and SMFs for 72 h. The SMF groups were placed on cylindrical permanent magnets (Fig 1D) derived from the rare earth material neodymium iron boron. The magnetic flux density of ~ 0.5 T was measured in the center of the cylindrical magnet by means of a digital gaussmeter (Model: TM-701; Kanetec Co., Japan). TRPV1 antagonist SB-705498 (Targetmol) was incubated with the cells 30 min before SMF and capsaicin treatments.

The mice were randomly allocated into four groups (n=6 per group): (1) Control group (CON); (2) lipopolysaccharide-treated group (LPS); (3) capsaicin diet group (CAP); (4) capsaicin diet + lipopolysaccharide-treated group (CAP+LPS). The mice of Control and LPS groups were fed standard laboratory chow (Department of Laboratory Animal Science of China Medical University). The mice in the CAP and CAP+LPS groups were fed standard laboratory chow plus 0.005% capsaicin (Targetmol, Boston, MA, USA). All mice were fed for 4 months. During the last 5 days, mice in LPS and CAP+LPS groups received lipopolysaccharide (Beijing Solarbio Science & Technology Co., Ltd., Beijing, China) once daily via intraperitoneal injection. The following doses of LPS were used according to previous methods: 0.052/0.104/0.208/0.415/0.83 mg/kg (5-day) (Wickens et al., 2017 (link)). The CON and CAP groups were injected with an equal volume of saline in the same manner. Body weight was measured after behavioral testing.