Vitamin D deficiency-related muscle atrophy – an indirect effect of low vitamin D levels?

Background Vitamin D deficiency has been associated with a decrease in muscle force and fibre type II atrophy. Unknown are the effects of vitamin D deficiency on the skeletal muscle contractile properties. Methods To investigate the effects of vitamin D deficiency on the contractile properties and expression factors of the medial gastrocnemius muscle, female 3 week old Wistar rats were provided with special vitamin D deficient food, preventing hypocalcaemia and hyperparathyroidism, and raised in an UV free environment during 10 weeks. Results 10 weeks of vitamin D deficient food results in undetectable 25-hydroxy-vitamin D blood serum levels. Vitamin D deficiency was not accompanied with a change in muscle contractile properties, only the force frequency relation was shifted to the left. Furthermore no atrophy was observed in different muscles. mRNA expression of α-skeletal actin, MAFbx, MURF1, c-myc , CYP27B1 and VDR was not changed in the Gm. Conclusion Vitamin D deficiency per se does not result in a decrease in maximal force and muscle mass or atrophy but could be the result of associated hypocalcaemia and hyperparathyroidism.