A novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats

Our goal in this study was to determine to what extent the physiologic consequences of ovariectomy (OVX) in bones are exacerbated by a lack of daily activity such as walking. We forced 14-week-old female rats to be inactive for 15 weeks with a unique experimental system that prevents standing and wa...

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Main Authors:	Miyagawa, Kazuaki, Kozai, Yusuke, Ito, Yumi, Furuhama, Takami, Naruse, Kouji, Nonaka, Kiichi, Nagai, Yumiko, Yamato, Hideyuki, Kashima, Isamu, Ohya, Keiichi, Aoki, Kazuhiro, Mikuni-Takagaki, Yuko
Format:	Online
Language:	English
Published:	Springer Japan 2010
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3132588/

id	pubmed-3132588
recordtype	oai_dc
spelling	pubmed-31325882011-08-24 A novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats Miyagawa, Kazuaki Kozai, Yusuke Ito, Yumi Furuhama, Takami Naruse, Kouji Nonaka, Kiichi Nagai, Yumiko Yamato, Hideyuki Kashima, Isamu Ohya, Keiichi Aoki, Kazuhiro Mikuni-Takagaki, Yuko Original Article Our goal in this study was to determine to what extent the physiologic consequences of ovariectomy (OVX) in bones are exacerbated by a lack of daily activity such as walking. We forced 14-week-old female rats to be inactive for 15 weeks with a unique experimental system that prevents standing and walking while allowing other movements. Tibiae, femora, and 4th lumbar vertebrae were analyzed by peripheral quantitative computed tomography (pQCT), microfocused X-ray computed tomography (micro-CT), histology, histomorphometry, Raman spectroscopy, and the three-point bending test. Contrary to our expectation, the exacerbation was very much limited to the cancellous bone parameters. Parameters of femur and tibia cortical bone were affected by the forced inactivity but not by OVX: (1) cross-sectional moment of inertia was significantly smaller in Sham-Inactive rat bones than that of their walking counterparts; (2) the number of sclerostin-positive osteocytes per unit cross-sectional area was larger in Sham-Inactive rat bones than in Sham-Walking rat bones; and (3) material properties such as ultimate stress of inactive rat tibia was lower than that of their walking counterparts. Of note, the additive effect of inactivity and OVX was seen only in a few parameters, such as the cancellous bone mineral density of the lumbar vertebrae and the structural parameters of cancellous bone in the lumbar vertebrae/tibiae. It is concluded that the lack of daily activity is detrimental to the strength and quality of cortical bone in the femur and tibia of rats, while lack of estrogen is not. Our inactive rat model, with the older rats, will aid the study of postmenopausal osteoporosis, the etiology of which may be both hormonal and mechanical. Springer Japan 2010-12-03 2011-07 /pmc/articles/PMC3132588/ /pubmed/21127921 http://dx.doi.org/10.1007/s00774-010-0241-9 Text en © The Japanese Society for Bone and Mineral Research and Springer 2010
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Miyagawa, Kazuaki Kozai, Yusuke Ito, Yumi Furuhama, Takami Naruse, Kouji Nonaka, Kiichi Nagai, Yumiko Yamato, Hideyuki Kashima, Isamu Ohya, Keiichi Aoki, Kazuhiro Mikuni-Takagaki, Yuko
spellingShingle	Miyagawa, Kazuaki Kozai, Yusuke Ito, Yumi Furuhama, Takami Naruse, Kouji Nonaka, Kiichi Nagai, Yumiko Yamato, Hideyuki Kashima, Isamu Ohya, Keiichi Aoki, Kazuhiro Mikuni-Takagaki, Yuko A novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats
author_facet	Miyagawa, Kazuaki Kozai, Yusuke Ito, Yumi Furuhama, Takami Naruse, Kouji Nonaka, Kiichi Nagai, Yumiko Yamato, Hideyuki Kashima, Isamu Ohya, Keiichi Aoki, Kazuhiro Mikuni-Takagaki, Yuko
author_sort	Miyagawa, Kazuaki
title	A novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats
title_short	A novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats
title_full	A novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats
title_fullStr	A novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats
title_full_unstemmed	A novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats
title_sort	novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats
description	Our goal in this study was to determine to what extent the physiologic consequences of ovariectomy (OVX) in bones are exacerbated by a lack of daily activity such as walking. We forced 14-week-old female rats to be inactive for 15 weeks with a unique experimental system that prevents standing and walking while allowing other movements. Tibiae, femora, and 4th lumbar vertebrae were analyzed by peripheral quantitative computed tomography (pQCT), microfocused X-ray computed tomography (micro-CT), histology, histomorphometry, Raman spectroscopy, and the three-point bending test. Contrary to our expectation, the exacerbation was very much limited to the cancellous bone parameters. Parameters of femur and tibia cortical bone were affected by the forced inactivity but not by OVX: (1) cross-sectional moment of inertia was significantly smaller in Sham-Inactive rat bones than that of their walking counterparts; (2) the number of sclerostin-positive osteocytes per unit cross-sectional area was larger in Sham-Inactive rat bones than in Sham-Walking rat bones; and (3) material properties such as ultimate stress of inactive rat tibia was lower than that of their walking counterparts. Of note, the additive effect of inactivity and OVX was seen only in a few parameters, such as the cancellous bone mineral density of the lumbar vertebrae and the structural parameters of cancellous bone in the lumbar vertebrae/tibiae. It is concluded that the lack of daily activity is detrimental to the strength and quality of cortical bone in the femur and tibia of rats, while lack of estrogen is not. Our inactive rat model, with the older rats, will aid the study of postmenopausal osteoporosis, the etiology of which may be both hormonal and mechanical.
publisher	Springer Japan
publishDate	2010
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3132588/
_version_	1611464562117181440

A novel underuse model shows that inactivity but not ovariectomy determines the deteriorated material properties and geometry of cortical bone in the tibia of adult rats

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