Low energy irradiation of narrow-range UV-LED prevents osteosarcopenia associated with vitamin D deficiency in senescence-accelerated mouse prone 6

Deficiency of vitamin D is an important cause of osteosarcopenia. The purpose of this study is to examine the effects of low energy narrow-range UV-LED on osteosarcopenia in animal models of senescence-accelerated mouse prone 6 (SAMP6). Preliminary experiments specified the minimum irradiance intensity and dose efficacy for vitamin D production (316 nm, 0.16 mW/cm 2 , 1,000 J/m 2 ). we set a total of 4 groups (n = 8 per group); vitamin D-repletion without UV irradiation (Vit.D+UV−), vitamin D-repletion with UV irradiation (Vit.D+UV +), vitamin D-deficiency without UV irradiation, (Vit.D−UV−), and vitamin D-deficiency with UV irradiation (Vit.D−UV +). Serum levels of 25(OH)D at 28 and 36 weeks of age were increased in Vit.D−UV+ group as compared with Vit.D−UV− group. Trabecular bone mineral density on micro-CT was higher in Vit.D−UV+ group than in Vit.D−UV− group at 36 weeks of age. In the histological assay, fewer osteoclasts were observed in Vit.D−UV+ group than in Vit.D−UV− group. Grip strength and muscle mass were higher in Vit.D−UV+ group than in Vit.D−UV− group at 36 weeks of age. Signs of severe damage induced by UV irradiation was not found in skin histology. Low energy narrow-range UV irradiation may improve osteosarcopenia associated with vitamin D deficiency in SAMP6.