Jpn. J. Pharmacol. 79 (3), 379-386 (1999)

Glucocorticoid-Induced Secondary Osteopenia in Female Rats: A Time Course Study as Compared With Ovariectomy-Induced Osteopenia and Response to Salmon Calcitonin

Takaya Nitta, Tohru Fukushima, Hiromichi Nakamuta and Masao Koida (*)

Department of Pharmacology, Faculty of Pharmaceutical Sciences, Setsunan University, Nagaotogecho 45-1, Hirakata, Osaka 573-0101, Japan
(*) To whom correspondence should be addressed.

Abstract: Previously we reported that 8-week treatment with methylprednisolone acetate (MPA: 0.1 mg/kg, s.c., 3 days a week) of male rats caused a novel type of osteopenia whose development was prevented by salmon calcitonin (SCT) in a dose-dependent manner. In this study, to compare the MPA-inducible osteopenia with the ovariectomy (OVX)-inducible one, female rats were used instead of male rats and a time-course study of development was made. MPA treatments for 1, 2, 4 and 8 weeks histologically induced characteristic osteopenic changes in a time-dependent manner that were histomorphometrically detectable in tibiae within 4 weeks as reduced bone mass, accelerated bone resorption, and suppressed bone formation and mineralization. Node-strut analysis revealed that the connectivity of the trabecular structure remained unaffected. Such MPA-induced changes in the trabecular structure, to be defined as thinned-but-uncut, is in a good contrast with OVX-induced unthinned-but-cut structure, although the latter osteopenic changes became detectable 2 weeks earlier. Another previous finding confirmed herein was that MPA-induced osteopenia in female rats was also completely masked by SCT (10 U/kg, s.c., 5 days a week). The results indicate that the MPA-inducible secondary osteopenic model in either sex of rats would be usable for testing anti-osteopenic drugs.

Keywords: Glucocorticoid, Secondary osteopenia, Anti-osteoporotics, Calcitonin, Ovariectomy

Copyrightę The Japanese Pharmacological Society 1999

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