Dataset Information

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

ABSTRACT:

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 ± 18×10³lacunae/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.

SUBMITTER: Shipov A

PROVIDER: S-EPMC7811283 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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Publications

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

Shipov Anna A Zaslansky Paul P Riesemeier Heinrich H Segev Gilad G Atkins Ayelet A Kalish-Achrai Noga N Weiner Stephen S Shahar Ron R

PeerJ 20210113

<h4>Background</h4>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.<h4>Methods</h4>Eight ovariectomized (OVH) and eight intact (control) Sprague Dawley rats were ...[more]

PMID: 33520431

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Project description:Raman spectroscopy (RS) is sensitive to the accumulation of advanced glycation end-products (AGEs), and it measures matrix-sensitive properties that correlate with the fracture toughness of human cortical bone. However, it is unclear whether sugar-mediated accumulation of AGEs affects the fracture toughness of human cortical bone in a manner that is consistent with the negative correlations between amide I sub-peak ratios and fracture toughness. Upon machining 64 single-edge notched beam (SENB) specimens from cadaveric femurs (8 male and 7 female donors between 46 years and 61 years of age), pairs of SENB specimens were incubated in 15 mL of phosphate buffered saline with or without 0.1 M ribose for 4 weeks at 37 °C. After acquiring 10 Raman spectra per bone specimen (n = 32 per incubation group), paired SENB specimens were loaded in three-point bending at a quasi-static or a high loading rate approximating 10-4 s-1 or 10-2 s-1, respectively (n = 16 per incubation group per loading rate). While 2 amide I sub-peak ratios, I1670/I1640 and I1670/I1610, decreased by 3-5% with a 100% increase in AGE content, as confirmed by fluorescence measurements, the ribose incubation to accumulate AGEs in bone did not affect linear elastic (KIc) nor non-linear elastic (KJc) measurements of bone's ability to resist crack growth. Moreover, AGE accumulation did not affect the change in these properties when the loading rate changed. Increasing the loading rate increased KIc but decreased KJc. Ribose incubation did not affect mineral-related RS properties such as mineral-to-matrix ratios, Type B carbonate substitutions, and crystallinity. It did however increase the thermal stability of demineralized bone (differential scanning calorimetry), without affecting the network connectivity of the organic matrix (i.e., maximum slope during a hydrothermal isometric tension test of demineralized bone). In conclusion, RS is sensitive to AGE accumulation via the amide I band (plus the hydroxyproline-to-proline ratio), but the increase in AGE content due to ribose incubation was not sufficient to affect the fracture toughness of human cortical bone.

Dataset Information

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

Background

Methods

Results

Discussion

Publications

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

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