Skeletal effects of constant and terminated use of risedronate on cortical bone in ovariectomized rats |
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Authors: | Qing-Nan Li Nian-Ci Liang Lian-Fang Huang Tie Wu Bin Hu Li-Er Mo |
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Institution: | (1) Bone Biology Laboratory, Guangdong Medical College, Zhanjiang 52403, China, CN;(2) Department of Pharmacology, Guangdong Medical College, Zhanjiang, China, CN;(3) Department of Chemistry, Guangdong Medical College, Zhanjiang, China, CN |
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Abstract: | To study the skeletal effects of continual and terminated use of risedronate treatment on cortical bone in ovariectomized
(Ovx) rats, we used risedronate (Ris), 5 μg · kg−1, by subcutaneous injections, twice per week. The middle part of the tibial shafts (Tx) were processed undecalcified for quantitive
bone histomorphometry. Cortical bone and the marrow areas of the tibial shaft did not change in either sham-Ovx or Ovx rats
during the 150-day experimental period. Continued administration of Ris for 150 days decreased the marrow area and increased
the percentage of cortical area compared with the matching sham and Ovx group. A decrease in bone formation indices in both
periosteal and endocortical surfaces of Tx in sham-operated rats between the age of 5 and 8 months was seen. Ovariectomy increased
the percentage of labeled perimeter in the periosteal area, and markedly increased the percentage of eroded perimeter in the
endocortical surface compared with sham control groups in 81 and 150 days. Bone formation indices of Ris treatment were increased
in periosteal surfaces, and percentages of eroded perimeter were decreased more in endocortical surfaces in 150 days than
in the matching sham and Ovx groups. These data matched our static data, which showed a significantly increased percentage
of cortical bone area and decreased percentage of marrow area. These bone gains were not maintained in the 90-day Ris withdrawal
group. For cancellous bone, the 60-day Ris-treated high bone mass was maintained in the withdrawal group and not maintained
in Ris continmuously treated group. These results indicate the effects of constant and terminated use of Ris in cortical bone
were different from those in trabecular bone in the proximal tibial metaphysis.
Received: Jan. 20, 1998 / Accepted: June 16, 1998 |
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Keywords: | : bisphosphonates ovariectomy osteoporosis risedronate |
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