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Objective To determine the effect of long-term use of methylprednisolone on bone biomechanics of rats. Methods Thirty-eight 3-month-old female SD rats were chosen. They were randomly divided into basal control group (B group, 8 rats were sacrificed at the beginning of the experiment as baseline), normal control group ( C group, 10 rats were given intraperitoneal injection of 75mg/kg normal saline), low dose methylprednisolone group(L group, 10 rats were given intraperitoneal injection of 50 mg/kg methylprednisolone), and high dose methylprednisolone groug (H group, 10 rats were given intraperitoneal injection of 75 mg/kg methylprednisolone). Methylprednisolone was given in L group and H group for 3 days, and stopped for a week. Then the intraperitoneal injection was given once a week according to the plan. After 24 weeks of the treatment, the femurs and the lumbar spine L3 were collected for biomechanical experiment. Results (1) Compared to that in C group, the body weight in L group and H group decreased obviously after the experiment (P <0. 05). (2) Compared to those in C group, structural mechanical parameters (load and rigidity) and material mechanical parameters (breaking strength and modulus of rigidity) of the femurs in L group and H group significantly decreased (P <0. 05). (3) Compared to those in C group, structural mechanical parameters (load and rigidity) and material mechanical parameters (breaking strength and modulus of rigidity) of the L3 in L group and H group significantly decreased (P < 0. 05 ). Conclusion The long-term use of methylprednisolone, regardless of dose, results in the decrease of bone quality of the femur and the lumbar spine of rats. [ABSTRACT FROM AUTHOR]

Objective To investigate the preventive effect of stanozolol on retinoic acid-induced bone lesion in rats using bone mineral density (BMD), biomechanics, and bone histomorphometry methods. Methods Twenty-four 4-month-old virgin female Sprague-Dawley rats were randomly divided into control group, retinoic acid (RA) group, and stanozolol group. Rats in control group were given vehicle. Rats in RA groups were given RA of 70 mg* kg 1 ⋅ d-1. Rats in stanozolol group were given RA of 70 mg ⋅ kg-1 ⋅ d-1 and stanozolol of 0. 5 mg ⋅ kg-1 ⋅ d-1. All the rats were oral gavaged at 5 mL⋅ kg-1 for 28 days. At the experimental endpoint, bone mineral density (BMD) of the right femur was examined, and biomechanical properties and bone histomorphometric parameters of the proximal tibial metaphysis ( PTM) and the tibial shaft (Tx) were measured. Results Compared to those in control group, BMD decreased by 10. 2%, and biomechanical properties including elastic load, maximum load, break load, rigid coefficient, and bending energy decreased by 39. 1%, 32. 9%, 36. 4%, 40. 2%, 38. 0% in femur in RA group, respectively (P <0.01). Compared to those in control group, the static parameters including total tissue area, trabecular area, and trabecular perimeter decreased by 31. 6%, 40. 0%, and 36. 2% (P < 0. 01), and the dynamic parameters including percent labeled perimeter (% L. Pm), bone formation rate (BFR/TV, BFR/BV, and BFR/BS) decreased by 57. 1%, 69. 9%, 62.0%, and 65. 8%, respectively, in PTM in RA group (P < 0. 01). Compared to those in control group, the static parameters (the total tissue area and cortical area) and the dynamic parameters of periosteum of Tx significantly decreased, while the dynamic parameters of endosteum of Tx significantly increased in RA group. Compared to those in RA group, the elastic load, rigid coefficient, and bending-energy increased by 22. 2%, 22. 9%, and 17. 7%, respectively, in the femurs in stanozolol group. No significant changes of BMD and histomorphometric parameters in PTM and Tx were found in stanozolol group. Conclusion Stanozolol can partially relieve bone damage induced by RA in rats. [ABSTRACT FROM AUTHOR]