Leptin directly regulates bone cell function in vitro and reduces bone fragility in vivo

Abstract

Fat mass is an important determinant of bone density, but the mechanism of this relationship is uncertain. Leptin, as a circulating peptide of adipocyte origin, is a potential contributor to this relationship. Recently it was shown that intracerebroventricular administration of leptin is associated with bone loss, suggesting that obesity should be associated with low bone mass, the opposite of what is actually found. Since leptin originates in the periphery, an examination of its direct effects on bone is necessary to address this major discrepancy. Leptin (>10-11 M) increased proliferation of isolated fetal rat osteoblasts comparably with IGF-I, and these cells expressed the signalling form..