Disuse osteopenia is accompanied by downregulation of gene expression for bone proteins in growing rats

G. K. Wakley, J. S. Portwood, R. T. Turner
2006 American Journal of Physiology. Endocrinology and Metabolism  
Disuse osteopenia is accompanied by downregulation of gene expression for bone proteins in growing rats. Am. J. Physiol. 263 (Endocrinol. Metab. 26): E1029-E1034, 1992.-Unilateral sciatic neurectomy (USN) resulted in cortical osteopenia in tibiae from the sciatic nerve-sectioned limb of growing rats. The bone deficit resulted from decreased periosteal addition; there were no changes in the indexes of bone resorption. The periosteal bone formation rate was reduced in the nerve-sectioned limb
more » ... -sectioned limb within 7 days of sciatic neurectomy, and this decrease persisted for at least 56 days. Steady-state mRNA levels for bone proteins were determined in periosteum isolated from tibiae and femurs 7 and 14 days after sciatic nerve section. Nerve section resulted in decreased levels of mRNA for osteocalcin, alkaline phosphatase, and possibly the prepro-cu (I)-subunit of type I collagen (collagen). The effects were more pronounced in tibiae than femurs, corresponding to the greater degree of immobility induced by USN in the former bone. The results demonstrate that decreased bone formation preceeds establishment of disuse cortical osteopenia in growing rats with no evidence for a change in bone resorption. Furthermore, the decreased bone formation is associated with, and may be due to, reduced mRNA levels for matrix proteins and other important bone proteins. messenger ribonuclease for osteocalcin; type I collagen; alkaline phosphatase; immobilization; sciatic neurotomy; rat bone 0193~l&B/92 $2.00
doi:10.1152/ajpendo.2006.263.6.e1029 fatcat:mmyryiq37jbirkgvuctzysu2ya