Effect of swimming on prednisolone-induced osteoporosis in elderly rats

Open Access
Publisher Website
Google Scholar
Abstract
We investigated the possible ameliorating and preventive effect of swimming on prednisolone-induced osteoporosis in elderly rats. A total of 48 female Sabra strain rats were randomly assigned to the following groups and treatments: (1) control (C), (2) swimming (S), (3) prednisolone-treated (CP), and (4) swimming + prednisolone (SP). An additional 8 rats were sacrificed and examined at the onset of the study. Groups C and S were sham injected; groups CP and SP were injected with prednisolone (Ultracorten), 80 mg/kg three times per week for 10 weeks. Groups S and SP swam 1 h daily, 5 days per week for 10 weeks. SP rats swam simultaneously with prednisolone administration. At the end of the swimming period, in vivo bone mineral content (BMC) measurements were performed on rat vertebrae L4-5 by single-photon absorptiometry. Later, the humerus and femur were removed for the following measurements: morphometric, bone density (BD) by Compton scattering technique, bone ion content by atomic absorption, and hydration fraction by proton magnetic resonance (PMR). We found that the humeral BD of S rats was greater by 14%for group S over C and 3% greater for group SP over CP (P < 0.05). Vertebral BMC was higher by 15% in group S over C and 11% higher for group SP over CP (P < 0.05). Femoral calcium (mg/g dry bone) ion content was higher by 5% in group S over C and 8% in group SP over CP group (P < 0.05). The fraction of bound water was higher by 36% in group S over C and 8% in group SP over CP group (P < 0.05). The hydration properties of the femur were examined by PMR determining the longitudinal (T1) and transverse (T2) relaxation times, referring to the freedom of the hydrogen proton movement of water molecules within bone tissue. T2 relaxation time was found to be significantly greater in swimming rats compared to controls (27%) and 58% in group SP over CP. T1 relaxation time was found to be significantly higher (23%) in group C over S and 17% in group CP over SP (P < 0.05). No significant morphometric differences were found among the different treatment groups. These results support the notion that swimming partially prevents prednisolone-induced osteoporosis in elderly rats.
Funding Information
  • U.S.-Israel Binational Science Foundation (87-00186)