Direct stereological estimation of three-dimensional connectivity in rat vertebrae:​ effect of estrogen, etidronate and risedronate following ovariectomy

Boyce, R. W.; Wronski, T. J.; Ebert, D. C.; Stevens, M. L.; Paddock, C. L.; Youngs, T. A.; Gundersen, H. J. G.

Affiliations

¹Procter and Gamble Pharmaceuticals, Norwich, NY, USA

²Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA

³Stereological Research Laboratory, Institute of Pathology and Second Clinic of Internal Medicine. Institute of Experimental Clinical Research, University of Aarhus, Arhus, Denmark

Abstract and keywords

Newly developed unbiased stereological methods were employed to investigate the effects of estrogen deficiency on the three-dimensional connectivity of vertebral cancellous bone from ovariectomized (OVX) rats. The effects of two classes of antiresorptive agents, estrogen and bisphosphonates, on changes in connectivity in this animal model were also evaluated. Female rats were either sham-operated (sham-op) or surgically OVX at 90 days of age. OVX rats were administered either vehicle, estrogen (10 μg/kg 17-β estradiol, 5 days/week subcutaneously [SC], etidronate disodium (5 mg/kg SC) or risedronate (5 μg/kg SC). The bisphosphonates were administered daily for 1 week followed by 3 weeks with no treatment. Treatment duration was 360 days. Systematic random sections, 30-μm thick, were prepared from methylmethacrylate-embedded decalcified second lumbar vertebrae. Total trabecular number and connectivity density were estimated using the ConnEulor principle. Vertebral cancellous bone volume was estimated on undecalcified sections from the first lumbar vertebrae. Connectivity density and cancellous bone volume were significantly reduced (approximately 25% and 40%, respectively) in the OVX group compared with the sham-op group. Estrogen treatment essentially maintained connectivity and cancellous bone volume at the level of the sham-op rats. Connectivity density and total trabecular number were significantly increased in the etidronate- and risedronate-treated rats compared with both the sham-op and OVX rats. These data demonstrate that reduction in the three-dimensional connectivity of vertebral cancellous bone is a long-term consequence of ovariectomy in the rat. This reduction in connectivity can be effectively prevented by the administration of antiresorptive agents such as estrogen, etidronate and risedronate. The increase in connectivity in the bisphosphonate-treated groups compared with the sham-op group may be a reflection of the combined effects of these agents on resorptive cell recruitment and function in the growing rat skeleton. These results suggest that these agents may be clinically useful in preventing resorption-dependent perforation and loss of trabecular elements which may be an important component of estrogendeficiency-related bone loss in women.

Keywords: Connectivity; ConnEulor; Osteoporosis; Ovariectomized rat; Stereology; Cancellous bone microstructure

Links

DOI: 10.1016/8756-3282(94)00031-T

PubMed: 7756049

WoS: A1995RB63500005

History

Received: 1994-06-27

Accepted: 1994-11-01

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Cited By (11)

Year	Entry
2000	Ding M. Age variations in the properties of human tibial trabecular bone and cartilage. Acta Orthop Scand. 2000;71(suppl 292):1-45.
1995	Boyce RW, Ebert DC, Youngs TA, Paddock CL, Mosekilde L, Stevens ML, Gundersen HJG. Unbiased estimation of vertebral trabecular connectivity in calcium-restricted ovariectomized minipigs. Bone. June 1995;16(6):637-642.
1997	Odgaard A. Three-dimensional methods for quantification of cancellous bone architecture. Bone. 1997;20(4):315-328.
1998	Lane NE, Thompson JM, Haupt D, Kimmel DB, Modin G, Kinney JH. Acute changes in trabecular bone connectivity and osteoclast activity in the ovariectomized rat in vivo. J Bone Miner Res. February 1998;13(2):229-236.
2000	Kinney JH, Haupt DL, Balooch M, Ladd AJC, Ryaby JT, Lane NE. Three‐dimensional morphometry of the L6 vertebra in the ovariectomized rat model of osteoporosis: biomechanical implications. J Bone Miner Res. October 2000;15(10):1981-1991.
2001	Dempster DW, Cosman F, Kurland ES, Zhou H, Nieves J, Woelfert L, Shane E, Plavetić K, Müller R, Bilezikian J, Lindsay R. Effects of daily treatment with parathyroid hormone on bone microarchitecture and turnover in patients with osteoporosis: a paired biopsy study. J Bone Miner Res. October 2001;16(10):1846-1853.
2002	Borah B, Dufresne TE, Chmielewski PA, Gross GJ, Prenger MC, Phipps RJ. Risedronate preserves trabecular architecture and increases bone strength in vertebra of ovariectomized minipigs as measured by three‐dimensional microcomputed tomography. J Bone Miner Res. July 2002;17(7):1139-1147.
2003	Jiang Y, Zhao JJ, Mitlak BH, Wang O, Genant HK, Eriksen EF. Recombinant human parathyroid hormone (1–34) [teriparatide] improves both cortical and cancellous bone structure. J Bone Miner Res. November 2003;18(11):1932-1941.
2002	Lane NE, Kumer JL, Majumdar S, Khan M, Lotz J, Stevens RE, Klein R, Phelps KV. The effects of synthetic conjugated estrogens, a (cenestin) on trabecular bone structure and strength in the ovariectomized rat model. Osteoporos Int. October 2002;13(10):816-823.
2002	Follet H. Caractérisation Biomécanique Et Modélisation 3D Par Imagerie X Et IRM Haute Résolution De L’os Spongieux Humain: Evaluation Du Risque Fracturaire [PhD thesis]. Institut national des sciences appliquées de Lyon (INSA Lyon); 2002.
1998	Yeni YN. Fracture Mechanics of Human Cortical Bone: The Relationship of Geometry, Microstructure and Composition With the Fracture of the Tibia, Femoral Shaft and the Femoral Neck [PhD thesis]. Morgantown, WV: West Virginia University; 1998.