posted on 2021-12-29, 12:03authored byRun Li, Jie Xiao, Yong Cao, Qingrong Huang, Chi-Tang Ho, Muwen Lu
As
the major component in red chili peppers, capsaicin is useful
in the prevention of lipid metabolism disorders. In this study, the
attenuation effect of capsaicin on oleic acid (OA)-induced lipid accumulation
in HepG2 cells was evaluated with respect to circadian clock gene
expressions. Lipid profiles, including triacylglycerols, total cholesterols,
high-density lipoproteins, low-density lipoproteins, and aspartate
aminotransferase content, were measured using enzymatic assay kits.
The mitochondrial membrane potential, cellular redox status, and lipid
droplet morphology were also determined using different assay kits
and staining methods. The mRNA and protein expressions of core circadian
clock genes and major lipometabolism-related factors were assessed
using RT-qPCR and western blotting. Results showed that 50 μM
capsaicin alleviated the circadian desynchrony and inhibited OA-induced
ROS overproduction (from 166.44 ± 12.63% to 119.90 ± 5.43%)
and mitochondrial dysfunction (from 0.60 ± 0.08 to 0.83 ±
0.09, represented by the red/green fluorescence ratio) in HepG2 cells.
The amelioration effect of capsaicin on OA-induced lipid accumulation
was weakened after Bmal1-knockdown, demonstrating
that the rhythmic expression of the circadian clock gene is involved
in the regulation process of capsaicin in lipid metabolism.