Influence of dietary vitamin D deficiency on bone strength, body composition, and muscle in ovariectomized rats fed a high-fat diet.

Objective: Vitamin D deficiency is associated with a greater risk for osteoporosis and also influences skeletal muscle functions. The aim of this study was to investigate the influence of vitamin D restriction on ovariectomized (OVX) rats fed a high-fat diet.

Methods: Twenty-four 13-wk-old female rats were ovariectomized, and another 6 received a sham operation (Sham). The OVX rats were divided into four groups and fed experimental diets: a basic control diet (OVX-Cont), a basic control diet with vitamin D restriction (OVX-DR), a high-fat diet (OVX-F), and a high-fat diet with vitamin D restriction (OVX-FDR).

Results: At 28 d after starting the experimental diets, the fat mass was significantly increased in the OVX-F and OVX-FDR groups compared with OVX-Cont group, whereas the muscle mass was significantly decreased in the OVX-F and OVX-FDR groups compared with the OVX-Cont group. Compared with the OVX-Cont group, the bone mineral content of the femur was significantly lower in the OVX-DR and OVX-FDR groups, and the bone mineral density of the femur was significantly lower in the OVX-DR group. Myogenin is one of the muscle-specific transcription factors. The levels of mRNA expression of myogenin in the soleus and gastrocnemius muscles from the OVX-DR and OVX-FDR groups were reduced markedly compared with those from the OVX-Cont group.

Conclusion: We provided evidence that a high-fat diet with vitamin D restriction influences bone and muscle metabolism using OVX rats. Further studies on vitamin D deficiency in the regulation of muscle as well as bone metabolism would provide valuable data for the prevention of osteoporosis and sarcopenia.