Glucocorticoid-induced osteopenia in rats: histomorphometrical and microarchitectural characterization and calcitonin...

A glucocorticoid-induced osteopenia (GC-OP) model was developed in Wistar male rats to use for in vivo screening of anti-osteoporotic candidates. 1) Two week treatment with a wide dose range of methylprednisolone acetate (0.01 to 50 mg/kg, s.c., 3 d a week) and histomorphometry of 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 osteopenia. 2) Eight week treatment with the selected dosing regimen (n = 6) of the steroid and histomorphometry including strut analysis measured the development of a characteristic osteopenia which can be described briefly as "uncut but thinning" of trabecular bone structure, and which was prevented by salmon calcitonin (0.33-10 U/kg, s.c., 5 times/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 GC-OP.