[Effects of simulated weightlessness on the expression of cyclooxygenase-2 in rat calvarial osteoblasts induced by fluid shear stress].
OBJECTIVE
To investigate the effect of simulated weightlessness on mechanotransduction in rat calvarial osteoblasts.


METHODS
Osteoblasts were isolated from neonatal rat calvariae and then were set to two groups. One was cultured in clinostat to simulate the weightlessness environment. Another was cultured in 1 G gravitational environment. After 60 h, osteoblasts were treated with 0.5 Pa or 1.5 Pa FSS in a flow chamber. The FSS treatment time was set to 30 min and 60 min, respectively. The specimens of each group were obtained for immunohistochemistry staining and determination of expressions of cyclooxygenase-2 (COX-2) in osteoblasts.


RESULTS
In osteoblasts cultured in 1 G gravitational environment, COX-2 expression was increased remarkably from 30 min to 60 min with the treatment of FSS (P<0.01). There was no clear difference between the expression of COX-2 after treatments of 0.5 Pa or 1.5 Pa FSS; In cells cultured in simulated weightlessness environment, no detectable expression of COX-2 was found with the treatment of 0.5 Pa FSS. The expression of COX-2 was only detected after 60 min treatment of 1.5 Pa FSS, but the level of expression was decreased significantly (P<0.01).


CONCLUSIONS
These results demonstrated that the mechanotransduction in osteoblasts was down-regulated in simulated (correction of stimulated) weightlessness.
Zhang
Shu
S
Department of Aerospace Biodynamics, The Fourth Military Medical University, Xi'an, China. shuzhang@163.net
Wu
Xing-yu
XY
Li
Ying-hui
YH
Xie
Li-qin
LQ
D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D015870:Gene Expression; D006112:Gravitation; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008465:Mechanoreceptors / Q000502:physiology*; D010006:Osteoblasts / Q000502:physiology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D012212:Rheology; D012399:Rotation; D015398:Signal Transduction / Q000502:physiology*; D012886:Skull / Q000166:cytology; D013314:Stress, Mechanical; D018474:Weightlessness Simulation
D007527:Isoenzymes; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases