Abstract:

Abstract: Objective To investigate the preventive effect of Strontium ranelate on stress-absence induced osteoporo⁃
sis in tail-suspended rat. Methods A total of 30 SD rats with average age of 6 month were randomly divided into 3 groups
(n=10 in each group): Group A was normal control group while rats in group B and C were subjected to tail suspension test to
establish stress absence models. Rats in group C were administered with Strontium ranelate [1 g/(kg·d） ]. All rats were sacri⁃
ficed 4 weeks later. Left femurs were harvested for bone mineral density (BMD) test and prepared for undecalcified tissue sec⁃
tion and thereby bone histomorphometry assessment. Bone marrow from right femurs and tibias were cultured and induced to⁃
wards osteogenic-differentiation. The expression levels of osteocalcin in the fourth-passage cultured bone marrow cells and
in blood serum were detected separately. Results Rats in group B showed markedly decreased BMD comparing to those in
group A and C（P＜0.05） . Trabecular volume (BV/TV), number (Tb.N) and thickness (Tb.Th) in group B were lower than
those in group A and C; erosion percentage (Er.Pm) and osteoclast number (Oc.N) in group B and C were higher than those in
group A; comparing to those in group B, bone formation rate (BFR/BV), labeled percentage (L.Pm), were higher in group C,
coupled with decreased Er.Pm and Oc.N（P＜0.05） . mRNA expression levels of OCN in group B and C were higher than
those of group A. But its level in plasma were lower in group B than those in group A and C（P＜0.05） . Conclusion Tail
suspension could induce osteosporosis. Strontium ranelate prevent bone loss in stress-absence osteoporosis in rat induced by
tail-suspension for 4 weeks, which might be partially through upregulating the expression of OCN, thereby promoting bone
formation.

Key words: osteoporosis, organometallic compounds, thiophenes, rats, Sprague-Dawley, Strontium ranelate