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. 2015 Dec;31(4):180-7.
doi: 10.5625/lar.2015.31.4.180. Epub 2015 Dec 22.

Supraphysiologic glucocorticoid administration increased biomechanical bone strength of rats' vertebral body

Azam Najar  1 , Mohammadjavad Fridoni  2 , Fatemesadat Rezaei  3 , Saba Bayat  4 , Mohammad Bayat  3
Affiliations

Supraphysiologic glucocorticoid administration increased biomechanical bone strength of rats' vertebral body

Azam Najar et al. Lab Anim Res. 2015 Dec.

Abstract

The aim of this study is to assess the effects of different glucocorticoid administration protocols on biomechanical properties of the first lumbar vertebral body in rats. We divided 40 male rats into the following groups: control, dexamethasone (7 mg/week), dexamethasone (0.7 mg/week), methylprednisolone (7 mg/kg/week), methylprednisolone (5 mg/kg twice weekly), dexamethasone (7 mg/kg three times per week), dexamethasone (0.7 mg/kg three times per week, and low-level laser treated rats. Lumbar vertebrae in rats were exposed to the pulsed laser. We conducted a biomechanical test to examine the mechanical properties of vertebral body in rats' lumbar bone. Supraphysiologic glucocorticoid administration protocols did not impair the biomechanical properties of rats' vertebral bodies compared to control and laser-treated rats. Supraphysiologic glucocorticoid administration caused an anabolic effect on the vertebral bodies.

Keywords: Glucocorticoid administration; biomechanical properties; cancellous bone; low-level laser therapy; rat.

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Conflict of interest statement

Conflict of interests: The authors declare that there is no financial conflict of interests to publish these results.

Figures

Figure 1
Figure 1. Schematic representation of the load-deformation curve of L1 vertebral body. The graph illustrates various biomechanical characteristics derived from the material-testing machine and its computer, in which an increasing load is placed on the tissue while isplacement is monitored. Bending stiffness, shown as the maximum slope on the linear portion of the load vs. the displacement curve, is derived from the linear portion of the curve. Energy absorption is the area under the curve.
Figure 2
Figure 2. The comparison of the mean values(±SEM ) of the weights of rats at the beginning of the study and at the end of the study; 0.05, 0.01, 0.001.
Figure 3
Figure 3. Bending stiffness (N/mm2) of L1 vertebral body of the groups studied. Values are mean±SEM for five animals per group. Statistical comparisons made against control rats (ANOVA test). control group=control (1); 2=Dex 7 mg/kg, I; 3=Dex 0.7 mg/kg I,4=Met 7 mg/kg, I; 5=Met 5 mg/kg, II; 6=Dex 7 mg/kg, III; 7=Dex 0.7 mg/kg, III; 8=low-level laser-treated rats; 0.05, 0.01, 0.001.
Figure 4
Figure 4. Maximum force (N) of L1 vertebral body of the groups studied. Values are mean±SEM for five animals per group. Statistical comparisons made against control rats (ANOVA test). control group=control (1); 2=Dex 7mg/kg, I; 3=Dex 0.7 mg/kg I, 4=Met 7 mg/kg, I; 5=Met 5 mg/kg, II; 6=Dex 7 mg/kg, III; 7=Dex 0.7 mg/kg, III; 8=low-level laser-treated rats; 0.05, 0.01, 0.001.
Figure 5
Figure 5. Stress high load (N/mm2) of L1 vertebral body of the groups studied. Values are mean±SEM for five animals per group. Statistical comparisons made against control rats (ANOVA test). control group=control (1); 2=Dex 7 mg/kg, I; 3=Dex 0.7 mg/kg I, 4=Met 7 mg/kg, I; 5=Met 5 mg/kg, II; 6=Dex 7 mg/kg, III; 7=Dex 0.7 mg/kg, III; 8=low-level laser-treated rats; 0.05, 0.01, 0.001.
Figure 6
Figure 6. Energy absorption up to maximum force (N mm) of L1 vertebral body of the groups studied. Values are mean±SEM for five animals per group. Statistical comparisons made against control rats (Statistical comparisons made against control rats (Kruscall wallis and Mann Whitney U test). *P<0.007. control group=control (1); 2=Dex 7 mg/kg, I; 3=Dex 0.7 mg/kg I, 4=Met 7 mg/kg, I; 5=Met 5 mg/kg, II; 6=Dex 7 mg/kg, III; 7=Dex 0.7 mg/kg, III; 8=low-level laser-treated rats; 0.05, 0.01, 0.001.
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