Indole-3-carbinol (I3C) is a compound found in high concentrations in Brassica family vegetables, including broccoli, cauliflower and cabbage, and is regarded as a promising chemopreventive agent against various cancers. This study assesses the protective effect of I3C against diet-induced obesity in mice. Mice were randomly grouped to receive either a normal diet, high-fat (40% energy as fat) diet (HFD) or I3C-supplemented diet (1 g/kg diet) for 10 weeks. I3C supplementation significantly ameliorated HFD-induced increases in body weight gain, visceral fat pad weights and plasma lipid levels. The visceral adipose tissue mRNA levels of uncoupling proteins 1 and 3, crucial factors of thermogenesis, and their regulators such as sirtuin 1, peroxisome proliferator-activated receptor (PPAR) α and PPARγ coactivator 1α, which were down-regulated by HFD, were normalized by supplementation with I3C. In contrast, I3C supplementation significantly decreased expression levels of a key adipogenic transcription factor, PPARγ2, and its target genes, such as leptin and adipocyte protein 2, in the visceral adipose tissue of mice maintained on the HFD. Furthermore, HFD-induced up-regulation in mRNA levels of inflammatory cytokines (tumor necrosis factor α, interferon β and interleukin 6) was significantly ameliorated by I3C. These findings suggest that I3C has a potential benefit in preventing obesity and metabolic disorders, and the action for I3C in vivo may involve multiple mechanisms including decreased adipogenesis and inflammation, along with activated thermogenesis.
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