Intervention timing of strontium treatment on estrogen depletion-induced osteoporosis in rats: bone microstructure and mechanics.
OBJECTIVE
To evaluate the effect of intervention timing of Sr treatment on trabecular bone microstructure and mechanics.


METHODS
Ninety female rats were randomly divided into three batches with three groups in each batch. Each group was divided according to the initiation timing of vehicle or strontium compound (SrC), which was at week 0 (early), 4 (mid-term) and 8 (late) after the ovariectomy, respectively. The treatment lasted for 12 weeks. The trabecular bone biomechanical properties, trabecular bone tissue mechanical properties, trabecular bone microstructure, and bone remodeling were analyzed with mechanical testing, nanoindentation, microCT, and histomorphometry, respectively. The osteoblast and osteoclast phenotypic genes were analyzed with real-time polymerase chain reaction (PCR).


RESULTS
Early and mid-term Sr treatment significantly increased biomechanical properties of trabecular bone, which was associated with increased microarchitecture parameters, increased bone formation parameters and up-regulation of osteoblast-related gene expression. Late Sr treatment failed to exert a beneficial effect on any of those parameters.


CONCLUSIONS
The beneficial effect of Sr was dependent on the intervention timing in ovariectomized rats.
Department of Spine Surgery, Shenzhen People's Hospital, Jinan University Second College of Medicine, Shenzhen, China; Research Center for Human Tissues and Organs Degeneration, Chinese Academy of Science, Shenzhen, China.
Songlin
S
Peng
X Sherry
XS
Liu
Shishu
S
Huang
Haobo
H
Pan
Wanxin
W
Zhen
Guangqian
G
Zhou
K D K
KD
Luk
X Edward
XE
Guo
W William
WW
Lu
D000818:Animals; D001862:Bone Resorption / Q000517:prevention & control; D001842:Bone and Bones / Q000187:drug effects*; D019245:Compressive Strength / Q000187:drug effects; D005260:Female; D006801:Humans; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects; D015663:Osteoporosis, Postmenopausal / Q000188:drug therapy*; D010052:Ovariectomy; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013324:Strontium / Q000008:administration & dosage* / Q000097:blood
D013324:Strontium
bone mechanics; bone microstructure; bone remodeling; osteoporosis; strontium