The Effect of Leptin on Rat Maxillary Alveolar Bone under Mechanical Stimuli

Mechanical stress is known to play an important role in bone remodeling and homeostasis, by influencing processes of bone formation and bone resorption. Some hormones have been shown to influence not only bone homeostasis but also mechanical stress-induced bone remodeling. For example, leptin, a hormone secreted by adipocytes that controls mammal's appetite, has been suggested to regulate bone volume. Here, we have investigated the effects of leptin on the remodeling of alveolar bone induced by experimental tooth movement in leptin receptor-defective Wistar fatty rats. Seven days after applying tractive force on a right maxillary first molar, a larger tooth displacement was observed in heterozygous (fa/+) compared to wild-type (+/+) animals. Histomorphometry demonstrated a significantly elevated osteoclast number in the alveolar bone of heterozygous (fa/+) (p<0.05) when compared to that in wild-type (+/+) rats, indicating that leptin receptor deficiency enabled rapid orthodontic tooth movement by accelerated bone resorption. Our findings suggested that leptin could influence mechanical stress-induced bone remodeling.