Patients taking glucocorticoid or glucocorticoid-like drugs for an extended period of time may develop osteoporosis, termed glucocorticoid-induced osteoporosis (GIOP). GIOP is the most common form of secondary osteoporosis, but the mechanism underlying its development is unclear. In the present study, we used prednisolone to treat zebrafish larvae to investigate GIOP. Our RNA deep-sequencing (RNA-seq) results show that prednisolone affects genes known to act in the extracellular region. Therefore the extracellular region, extracellular matrix, and collagen...