Endogenous Glucocorticoids and Bone.
While the adverse effects of glucocorticoids on bone are well described, positive effects of glucocorticoids on the differentiation of osteoblasts are also observed. These paradoxical effects of glucocorticoids are dose dependent. At both physiologicaland supraphysiological levels of glucocorticoids, osteoblasts and osteocytes are the major glucocorticoid target cells. However, the response of the osteoblasts to each of these is quite distinct. At physiology levels, glucocorticoids direct mesenchymal progenitor cells to differentiate towards osteoblasts and thus increase bone formation in a positive way. In contrast with ageing, the excess production of glucocorticoids, at both systemic and intracellular levels, appear to impact on osteoblast and osteocytes in a negative way in a similar fashion to that seen with therapeutic glucocorticoids. This review will focus on therole of glucocorticoids in normal bone physiology, with particular emphasis on the mechanism by which endogenous glucocorticoids impact on bone and its constituent cells.
Bone Research Program, ANZAC Research Institute , Sydney, Australia ; Concord Clinical School, The University of Sydney , Sydney, Australia.
Hong
H
Zhou
Concord Clinical School, The University of Sydney , Sydney, Australia ; Department of Endocrinology & Metabolism, Concord Hospital , Sydney, Australia.
Mark S
MS
Cooper
Bone Research Program, ANZAC Research Institute , Sydney, Australia ; Concord Clinical School, The University of Sydney , Sydney, Australia ; Department of Endocrinology & Metabolism, Concord Hospital , Sydney, Australia.
Markus J
MJ
Seibel
Wnt signaling; bone; glucocorticoids; mechanisms of action; osteoblasts; skeletal development