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Ovariectomy-induced changes in aged beagles: histomorphometry of rib cortical bone
A K Wilson1, M H Bhattacharyya, S Miller
1Center for Mechanistic Biology and Biotechnology, Argonne National Laboratory, Illinois 60439, USA.
Calcified Tissue International
|March 21, 1998
Summary
Ovariectomy in aged female dogs significantly impacts rib cortical bone, increasing bone formation transiently and porosity long-term. This study highlights cortical bone
Area of Science:
- Bone Biology
- Skeletal Physiology
- Endocrinology
Background:
- Estrogen depletion is known to cause bone loss, particularly in cancellous bone.
- Cortical bone's response to estrogen depletion is less understood.
- Ovariectomy is a common model for studying estrogen deficiency in animal research.
Purpose of the Study:
- To investigate the effects of ovariectomy on cortical bone in aged female dogs.
- To analyze changes in cortical bone histomorphometry over time following ovariectomy.
- To determine if rib cortical bone is a responsive site to ovariectomy-induced skeletal changes.
Main Methods:
- Histomorphometric analysis of sequential rib biopsies from ovariectomized and sham-operated aged female dogs.
- Fluorochrome labeling (tetracycline, calcein, xylenol orange) to mark bone formation.
- Biopsies collected at baseline, 1, 4, and 8.5 months post-surgery.
Main Results:
- Ovariectomy did not affect histomorphometric indices at 1 month post-surgery.
- A transient, sixfold increase in cortical bone formation was observed at 4 months post-ovariectomy compared to controls (P < 0.001).
- Cortical porosity increased by 4 months and remained elevated at 8.5 months post-ovariectomy.
Conclusions:
- Rib cortical bone in aged female dogs is responsive to ovariectomy.
- Ovariectomy induces a transient increase in cortical bone formation and sustained elevation in cortical porosity.
- These findings contribute to understanding the skeletal effects of estrogen depletion on cortical bone.