Measurement of retinoids and beta-carotene 15,15'-dioxygenase activity in HR-1 hairless mouse skin with UV exposure

We investigated the vitamin A status and beta-carotene 15,15'-dioxygenase activity in hairless mice with UV exposure to assess the regulation of vitamin A metabolism after UV irradiation. HR-1 hairless mice were irradiated with UV at 3 J/cm2 for 5 d. After UV irradiation, the mice were sacrificed and samples were obtained to analyze the retinoid concentration, expression of RXR-alpha, and beta-carotene 15,15'-dioxygenase activity. After UV exposure, the skin retinoid concentration was significantly lower as well as the expression of RXR-alpha. Higher skin beta-carotene dioxygenase activity was observed in the UV group as compared to the control group. We found no significant differences in the alpha-tocopherol concentration or acrolein levels in the skins of the two groups. In conclusion, the elevation of beta-carotene 15,15'-dioxygenase activity in hairless mice after UV exposure may be a response to reduction of the skin retinoid concentration.