Multipurpose Hormone
Scientists at Baylor College of Medicine have identified a new role for leptin: potent inhibitor of bone formation acting through the central nervous system (P. Ducy et al., "Leptin inhibits bone formation through a hypothalamic relay: a central control of bone mass," Cell, 100:197-207, Jan. 21, 2000). This is the first indication that the brain has a central role in controlling bone formation and density. The researchers worked with two groups of mice; one mutant strain was unable to make leptin, while the other group was unable to make the leptin receptor in the hypothalamus. Experiments showed that disrupting the leptin pathway triggered increased bone formation, so the mice were able to overcome their predisposition for low bone mass because they had no functional gonads. "Two arguments suggest that the function of leptin in bone formation is at least as important as its function in regulating body weight," ...
