title: Intermittent on/off prostaglandin E2 and risedronate are equally anabolic as daily PGE2 alone treatment in cortical bone of ovariectomized rats.
abstract: 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 E2 (OVX/c-PGE2) alone or in combination with risedronate (OVX/c-PGE2+Ris), in comparison with daily treatment with PGE2 for 240 days (OVX/PGE2-240d) 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/PGE2-240d = OVX/c-PGE2+Ris > OVX/c-PGE2 > OVX/c-Ris > or = OVX = aging; (2) the same bone mass and architecture were produced in the OVX/PGE2-240d and the OVX/c-PGE2+Ris groups, but the histomorphometric profiles differed in that the former exhibited a higher bone turnover and index of resorption; (3) OVX/c-PGE2+Ris treatment prevented endocortical bone loss and minimized trabecular bone loss during the OFF periods; and (4) the OVX/c-PGE2 alone treatment resulted in the accumulation of less total bone than OVX/PGE2-240d and OVX/c-PGE2+Ris because it could not maintain most of the new subendocortical and marrow trabecular bone generated earlier. In summary, both continuous daily PGE2 and two cycles ON/OFF combined PGE2 and Ris treatments result in more bone mass than two cycles ON/OFF PGE2 alone and Ris alone in estrogen-deficient rats. This study showed that the anabolic effects of PGE2 can be induced and maintained either by continuous administration or by cyclical PGE2+Ris.
authors.affiliation: Radiobiology Division, University of Utah School of Medicine, Salt Lake City 84112, USA.
authors.forename: Y F
authors.initials: YF
authors.lastname: Ma
authors.forename: Z
authors.initials: Z
authors.lastname: Pan
authors.forename: W S
authors.initials: WS
authors.lastname: Jee
authors.forename: C H
authors.initials: CH
authors.lastname: Lin
authors.forename: H H
authors.initials: HH
authors.lastname: Liang
authors.forename: H
authors.initials: H
authors.lastname: Chen
authors.forename: S
authors.initials: S
authors.lastname: Pun
authors.forename: X J
authors.initials: XJ
authors.lastname: Li
mesh_terms: D000818:Animals; D015519:Bone Density / Q000187:drug effects*; D016723:Bone Remodeling / Q000187:drug effects; D001842:Bone and Bones / Q000187:drug effects / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000627:therapeutic use*; D015232:Dinoprostone / Q000008:administration & dosage / Q000627:therapeutic use*; D004334:Drug Administration Schedule; D004359:Drug Therapy, Combination; D012968:Etidronic Acid / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D010024:Osteoporosis / Q000188:drug therapy; D010052:Ovariectomy; D010053:Ovary / Q000502:physiology; D010120:Oxytocics / Q000008:administration & dosage / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D000068296:Risedronic Acid; D013997:Time Factors; D015430:Weight Gain / Q000187:drug effects
chemical_list: D002121:Calcium Channel Blockers; D010120:Oxytocics; D015232:Dinoprostone; D000068296:Risedronic Acid; D012968:Etidronic Acid