Vitamin D and/or calcium deficient diets may differentially affect muscle fiber neuromuscular junction innervation.

Introduction: There is evidence that supports a role for Vitamin D (Vit. D) in muscle. The exact mechanism by which Vit. D deficiency impairs muscle strength and function is not clear.

Methods: Three-week-old mice were fed diets with varied combinations of Vit. D and Ca deficiency. Behavioral testing, genomic and protein analysis, and muscle histology were performed with a focus on neuromuscular junction (NMJ) -related genes.

Results: Vit. D and Ca deficient mice performed more poorly on given behavioral tasks than animals with Vit. D deficiency alone. Genomic and protein analysis of the soleus and tibialis anterior muscles revealed changes in several Vit. D metabolic, NMJ-related, and protein chaperoning and refolding genes.

Conclusions: These data suggest that detrimental effects of a Vit. D deficient or a Vit. D and Ca deficient diet may be a result of differential alterations in the structure and function of the NMJ and a lack of a sustained stress response in muscles. Muscle Nerve 54: 1120-1132, 2016.