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Dexamethasone inhibits osteoblastic differentiation by down-regulation of LIM mineralization protein 1

Liu Sucai, Zhang Zhiyong, Li En

Department of Biochemistry, Hebei Medical University,Shijiazhuang(050017)；The Fourth Hospital of Shijiazhuang,Shijiazhuang(050011)

Abstract

To investigate the mechanisms of the inhibition of osteoblastic differentiation by dexamethasone (DEX), the effects of different doses of DEX on the activity of alkaline phosphatase (ALP), the synthesis of osteocalcin (OC) and the expression of colaggen type I were observed in the cultured rat osteoblasts. THe LIM mineralization protein-1 (LMP-1) mNRA, a positive regulator of osteoblasts, was semi-quantified by RT-PCR. The results showed that a lower dose (10~(-9)mol/L) of DEX could enhance the activity of ALP, the synthesis of OC and the expression of collagen type I. However, a higher dose (10~(-7)mol/L) of DEX inhibited them and down-regulated the expression of LMP-1 mRNA in osteoblasts. It is suggested that DEX stimulates osteoblast differentiation at lower dose, while at higher dose it inhibits osteoblast differentiation. The inhibitory action of DEX on osteoblast differentiation might be mediated by the down-regulation of LMP-1 mRNA.

Key words: Dexa methasone;LIM mineralization protein 1 expression;Osteoblastic differentiation

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Citing This Article：

Liu Sucai, Zhang Zhiyong, Li En. Dexamethasone inhibits osteoblastic differentiation by down-regulation of LIM mineralization protein 1. Acta Physiol Sin 2002; 54 (1): (in Chinese with English abstract).