Mice with circadian gene Period and Cryptochrome mutations develop high bone mass
early in life. Such a phenotype is accompanied by an increase in osteoblast numbers in
mutant bone and cannot be corrected by leptin intracerebroventricular infusion. Thus, the
molecular clock plays a key role in leptin-mediated sympathetic regulation of bone
formation. Indeed, we found that leptin-dependent sympathetic signaling induces the
expression of AP1 and circadian genes in bone and in osteoblasts with similar kinetics, and …