Skeletal effects of constant and terminated use of sodium risedronate in ovariectomized rats.
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.
Li
Q N
QN
Bone Biology Laboratory, Guangdong Medical College, Zhanjiang, China.
Liang
N C
NC
Huang
L F
LF
Wu
T
T
Hu
B
B
Mo
L E
LE
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
D002121:Calcium Channel Blockers; D000068296:Risedronic Acid; D012968:Etidronic Acid