Melatonin could be a novel drug for preventing bone loss of astronauts during space flight. Here we used goldfish scales as a bone model of coexisting osteoclasts and osteoblasts and demonstrated that melatonin synthesis decreased under microgravity. Melatonin treatment of scales stimulated expression of Calcitonin, an osteoclast-inhibiting hormone, and decreased expression of an osteoclastogenesis promotor. This is the first study to report the inhibitory effect of melatonin on osteoclast activation, which is cancelled by microgravity.

Source: Melatonin is a potential drug for the prevention of bone loss during space flight