The influence of estrogen deficiency on the structural and mechanical properties of rat cortical bone

Shipov​, Anna; Zaslansky, Paul; Riesemeier, Heinrich; Segev, Gilad; Atkins, Ayelet; Kalish-Achrai, Noga; Weiner, Stephen; Shahar, Ron

Affiliations

¹Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel

²Department for Operative and Preventive Dentistry. Centrum für Zahn-, Mund- und Kieferheilkunde, Charité - Universitätsmedizin Berlin, Berlin, Germany

³BAM Federal Institute for Materials Research and Testing, Berlin, Germany

⁴Department of Chemistry and Bar Ilan Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat Gan, Israel

⁵Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel

Abstract and keywords

Background: Post-menopausal osteoporosis is a common health problem worldwide, most commonly caused by estrogen deficiency. Most of the information regarding the skeletal effects of this disease relates to trabecular bone, while cortical bone is less studied. The purpose of this study was to evaluate the influence of estrogen deficiency on the structure and mechanical properties of cortical bone.

Methods: Eight ovariectomized (OVH) and eight intact (control) Sprague Dawley rats were used.Structural features of femoral cortical bone were studied by light microscopy, scanning electron microscopy and synchrotron-based microcomputer-tomography and their mechanical properties determined by nano-indentation.

Results: Cortical bone of both study groups contains two distinct regions: organized circumferential lamellae and disordered bone with highly mineralized cartilaginous islands. Lacunar volume was lower in the OVH group both in the lamellar and disorganized regions (182 ± 75 µm³ vs 232 ± 106 µm³, P < 0.001 and 195 ± 86 µm³ vs. 247 ± 106 µm³, P < 0.001, respectively). Lacunar density was also lower in both bone regions of the OVH group (40 ± 18 ×10³ lacunae/mm³ vs. 47 ± 9×10³ lacunae/mm³ in the lamellar region, P = 0.003 and 63 ± 18×10³ lacunae/mm³ vs. 75 ± 13×10³ lacunae/mm³ in the disorganized region, P < 0.001). Vascular canal volume was lower in the disorganized region of the bone in the OVH group compared to the same region in the control group (P < 0.001). Indentation moduli were not different between the study groups in both bone regions.

Discussion: Changes to cortical bone associated with estrogen deficiency in rats require high-resolution methods for detection. Caution is required in the application of these results to humans due to major structural differences between human and rat bone.

Keywords: Estrogen; Disorganized bone; Rat; Lacunae; Ovariectomy

Links

DOI: 10.7717/peerj.10213

PubMed: 33520431

WoS: 000607472600003

History

Received: 2020-03-25

Accepted: 2020-09-28

Online: 2021-01-13

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