Effects of thiazolidinediones on bone mass and its mechanism

Thiazolidinediones (TZDs) are ligands of peroxisome proliferators-activated receptor (PPAR)-γ.In vhro studys show that activation of PPAR-γ by TZDs caused increase of bone marrow adiposity and decrease of osteoblastogenesis,therefore resulted in bone loss.The Health,Aging,and Body Composition (Health ABC) study and A Diabetes Outcome Progression Trial (ADOPT) demonstrate that TZDs can reduce bone mineral density and increase the bone fracture rate in limbs.The molecular mechanisms remained unclear,they maybe relate to:PPAR-γ inhibits osteogenesis indirectely by reducing the expression of Runx2 and osreris;downregulates cytokines and signal molecules related to osteogenesis;inhibits the expression of osteocalcin gene,stimulates apoptosis of osteoblast. Key words: PPAR-γ; Thiazolidinediones; Bone loss