[The regulation of various organs by osteoblasts].

It has been recently demonstrated that osteocalcin, which is secreted from osteoblasts, plays a significant role in glucose metabolism, fat metabolism, mail fertility, and brain functions. It has been also revealed that fibroblast growth factor 23 (FGF23), which is secreted from osteocytes, has an important role in phosphate metabolism or calcium homeostasis. These findings suggest that bone is not only a target organ of hormones but also involved in regulating other organs as an endocrine organ. Bone forms regulatory network with various organs to maintain the whole body homeostasis. This review introduces the regulation of various organs by osteoblasts.