GLUCOCORTICOID-INDUCED OSTEOPENIA IN RATS - HISTOMORPHOMETRICAL AND MICROARCHITECTURAL CHARACTERIZATION AND CALCITONIN EFFECT

A glucocorticoid-induced osteopenia (GC-OP) model was developed in Wis tar male rats to use for in pi,lo screening of anti-osteoporotic candi dates. 1) Two week treatment with a wide dose range of methylprednisol one acetate (0.01 to 50 mg/kg, s.c., 3d a week) and histomorphometry o f the right tibia combined with histological study (n=3) allowed us to select 0.1 mg/kg as a proper dose to produce a measurable degree of o steopenia. 2) Eight week treatment with the selected dosing regimen (n =6) of the steroid and histomorphometry including strut analysis measu red the development of a characteristic osteopenia which can be descri bed briefly as ''uncut but thinning'' of trabecular bone structure, an d which was prevented by salmon catcitonin (0.33-10 U/kg, s.c., 5 time s/week) in a dose-dependent manner. The results indicate the usability of this osteopenic model not only for screening of anti-osteoporotics but also for study of the mechanism leading to CC-OF.