Calcitriol and energy metabolism.

Calcitriol, a calcitrophic hormone that can be suppressed by high dietary calcium, favors fatty acid synthesis and inhibits lipolysis via non-genomic modulation of Ca(2+) influx. Calcitriol also suppresses UCP2 expression via the nVDR and thereby increases energy efficiency. Calcitriol exerts a dose-dependent impact on adipocyte apoptosis and regulates adipose tissue fat depot location and expansion by promoting glucocorticoid production and release. Recent data also demonstrate a pivotal role of calcitriol in the modulation of cytokines, with potential roles in energy metabolism in adipocytes, macrophages, and skeletal muscle.