The Transient Role of Calcium and Vitamin D During the Developmental Hair Follicle Cycle

The study investigated the role of 1,25-dihydroxyvitamin D3 and calcium in hair follicle cycling using calbindin-D9k knockout (KO) mice. Pups from KO mothers on a vitamin D-deficient, low-calcium diet developed transient alopecia starting at 13 days, with complete hair loss by 20-23 days and spontaneous recovery by 28 days. Histological analysis revealed dystrophic hair follicles, increased apoptosis, and hyperplastic epidermis. The alopecia was mitigated when mothers were fed a high-vitamin D/high-calcium diet. The findings suggested that maternal vitamin D and calcium levels were crucial for normal hair follicle development in calbindin-D9k KO pups.