ABSTRACT
PURPOSE: The aim of this study was to investigate the alterations of growth and bone metabolism in SDR induced by dexa administration and to evaluate the effects of GH treatment in dexamethasone(dexa) induced growth and bone metabolism in SDR. METHODS: Forty-five female Sprague-Dawley rats(weight 150-170gm) were divided in 3 groups: Group 1(n=15) received normal saline as control, Group 2(n=15) received dexa(1mg/kg/day), Group 3(n=15) received dexa and rhGH(LG Chem, 1IU/kg/day) simultaneously. Group 2 and 3 were injected rhGH daily, 6 days per week. Each group was divided in three subgroups(n=5) and sacrificed at 4, 6, 8 weeks, respectively. RESULTS: In Group 2, the length of tibia and femur and tibia epiphyseal plate thickness decreased significantly at 4, 6, 8 weeks compared to Group 1, respectively. In Group 2, serum IGF-I and PICP level also decreased at 6, 8 weeks and serum ICTP level increased at 4, 6 weeks compared to Group 1 significantly. In Group 3, the length of tibia and femur increased at 4, 6, 8 weeks compared to Group 2 but there was no statistical significance. In Group 3, tibia epiphyseal plate thickness increased significantly at 6, 8 weeks compared to Group 1. In Group 3, serum IGF-I and PICP level increased significantly at 4, 6, 8 weeks respectively compared to Group 2. But serum ICTP level showed no changes between two groups. Serum PTH level increased in Group 2 compared to Group 1, and decreased in Group 3 compared to Group 2 but no statistical significance was noted, respectively. CONCLUSION: Our data suggest that dexa inhibits longitudinal bone growth and interferes with bone metabolism, both inhibiting bone formation and stimulating bone resorption in SDR. Simultaneous GH administration may abolish alterations of growth and bone metabolism induced by dexa in SDR.