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Intermittent On/Off Prostaglandin E 2 and Risedronate Are Equally Anabolic as Daily PGE 2 Alone Treatment in Cortical Bone of Ovariectomized Rats
Author(s) -
Ma Yan Fei,
Pan Zeng,
Jee Webster S. S.,
Lin Chao Hua,
Liang Hao Hai,
Chen Hongka,
Pun Sunwah,
Li Xiao Jian
Publication year - 1997
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.1997.12.12.2108
Subject(s) - ovariectomized rat , endocrinology , medicine , prostaglandin e2 , anabolism , bone remodeling , bone resorption , osteoporosis , etidronic acid , cortical bone , chemistry , estrogen , anatomy
In this study, we evaluated the rat cortical bone changes after a two‐cycle, 60‐day each (ON/OFF/ON/OFF) treatment with either prostaglandin E 2 (OVX/c‐PGE 2 ) alone or in combination with risedronate (OVX/c‐PGE 2 +Ris), in comparison with daily treatment with PGE 2 for 240 days (OVX/PGE 2 −240d) in ovariectomized (OVX) rats. At the end of the study, we found that: (1) the overall effectiveness of the treatment on bone mass in the tibial shaft indicates the following ranking: OVX/PGE 2 −240d = OVX/c‐PGE 2 +Ris > OVX/c‐PGE 2 > OVX/c‐Ris ≥ OVX = aging; (2) the same bone mass and architecture were produced in the OVX/PGE 2 −240d and the OVX/c‐PGE 2 +Ris groups, but the histomorphometric profiles differed in that the former exhibited a higher bone turnover and index of resorption; (3) OVX/c‐PGE 2 +Ris treatment prevented endocortical bone loss and minimized trabecular bone loss during the OFF periods; and (4) the OVX/c‐PGE 2 alone treatment resulted in the accumulation of less total bone than OVX/PGE 2 −240d and OVX/c‐PGE 2 +Ris because it could not maintain most of the new subendocortical and marrow trabecular bone generated earlier. In summary, both continuous daily PGE 2 and two cycles ON/OFF combined PGE 2 and Ris treatments result in more bone mass than two cycles ON/OFF PGE 2 alone and Ris alone in estrogen‐deficient rats. This study showed that the anabolic effects of PGE 2 can be induced and maintained either by continuous administration or by cyclical PGE 2 +Ris.