PTH and osteoporosis: In accordance, Liu et al. have observed in a mouse model of dexamethasone-induced secondary osteoporosis that celastrol not only improves lipid metabolism and reduces hypercalciuria but also mitigates articular cartilage lesions, decreases NF-kB, MMP-1, and MMP-9 expression, and reduces serum PTH, TRACP-5b, CTX-I, as well as deoxypyridinoline (48).