What is the mechanism by which prednisolone causes osteoporosis?

Powerful&PoorlyKnown: Steroid hormones (all derivatives of cholesterol) analogous to cortisol induce greater activity of osteoclasts (bone degrading cells) vs. Osteoblasts (bone forming cells). This has long been observed, both in spontaneously occurring & iatrogenic (doc, medication induced) cushing's disease. However, like many other issues, though always happens, this does not mean all the details are understood.