β-Cryptoxanthin Induces UCP-1 Expression via a RAR Pathway in Adipose Tissue

While β-cryptoxanthin is hypothesized to have a preventive effect on lifestyle-related diseases, its underlying mechanisms are unknown. We investigated the effect of β-cryptoxanthin on energy metabolism in adipose tissues and its underlying mechanism. C57BL/6J mice were fed a high-fat diet (60% kcal fat) containing 0 or 0.05% β-cryptoxanthin for 12 weeks. β-cryptoxanthin treatment was found to reduce body fat gain and plasma glucose level, while increasing energy expenditure. The expression of uncoupling protein (UCP) 1 was elevated in adipose tissues in the treatment group. Furthermore, the in vivo assays showed that the Ucp1 mRNA expression was higher in the β-cryptoxanthin treatment group, an effect that disappeared upon cotreatment with a retinoic acid receptor (RAR) antagonist. In conclusion, we report that β-cryptoxanthin reduces body fat and body weight gain and that β-cryptoxanthin increases the expression of UCP1 via the RAR pathway.