title: Skeletal effects of constant and terminated use of sodium risedronate in ovariectomized rats.
abstract: OBJECTIVE
  To study the skeletal effects of constant and terminated use of sodium risedronate (Ris) treatment in the ovariectomized (Ova) rats.
  
  
  METHODS
  Ris 5 micrograms.kg-1, s.c., twice a wk. The proximal tibial metaphysis (PTM) were processed undecalcified for quantitive bone histomorphometry.
  
  
  RESULTS
  (1) Placebo-treated (normal saline) Ova rats were characterized by decreased trabecular area (TA) on d 60, d 81, and d 150 compared with aging controls, and bone resorption was over formation with high bone turnover. (2) Ova rats were treated with Ris for 60, 81, and 150 d (Ris-on) increased. (TA 217%, 108%, and 101%) respectively, vs Ova rats and depressed bone turnover indices to aging control level, but bone mass did not maintain at high level in 150-d group as in the early stage. (3) Ova rats were pretreated with Ris for 60 d and then terminated (Ris-on/off), followed by sequential sacrifice of rats on 21 and 90 d. Withdrawal on 21 d showed the same results as the match-age Ris-on group. Withdrawal on 90 d still maintained cancellous bone mass at a high level vs 150 d Ris-on groups (+26%) and aging control group (+27%).
  
  
  CONCLUSIONS
  Regimen of Ris 60 d on then 90 d off prevented the development of osteoporosis in Ova rats.
authors.affiliation: Bone Biology Laboratory, Guangdong Medical College, Zhanjiang, China.
authors.forename: Q N
authors.initials: QN
authors.lastname: Li
authors.forename: N C
authors.initials: NC
authors.lastname: Liang
authors.forename: L F
authors.initials: LF
authors.lastname: Huang
authors.forename: T
authors.initials: T
authors.lastname: Wu
authors.forename: B
authors.initials: B
authors.lastname: Hu
authors.forename: L E
authors.initials: LE
authors.lastname: Mo
mesh_terms: D000818:Animals; D001862:Bone Resorption / Q000517:prevention & control; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000627:therapeutic use*; D012968:Etidronic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D015663:Osteoporosis, Postmenopausal / Q000517:prevention & control*; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D000068296:Risedronic Acid; D013977:Tibia
chemical_list: D002121:Calcium Channel Blockers; D000068296:Risedronic Acid; D012968:Etidronic Acid