Effects of estrogen on the concentration of insulin-like growth factor-I in rat bone matrix.
Insulin-like growth factor-I (IGF-I) plays an important role in bone metabolism, but data on the regulation of IGF-I in bone tissue in vivo are still limited. In the present study, we examined the effects of ovariectomy (ovx) and estrogen replacement on the skeletal concentration of IGF-I in the femur shaft of 6-10 week-old female rats. Ovx had no consistent effect on bone matrix IGF-I concentration regardless of animal age at ovx. In contrast, administration of estradiol in doses that exceeded physiological replacement (50 and 150 nmol/kg per day, subcutaneously) significantly increased the bone matrix IGF-I concentration. These are the first in vivo data which demonstrate that estrogens are capable of increasing the concentration of IGF-I in bone tissue. However, this stimulatory effect appears to be limited to supraphysiological estrogen concentrations.
Erdmann
J
J
Department of Internal Medicine I, University of Heidelberg, Germany.
Storch
S
S
Pfeilschifter
J
J
Ochlich
P
P
Ziegler
R
R
Bauss
F
F
D000818:Animals; D001857:Bone Matrix / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000032:analysis / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D015914:Estrogen Replacement Therapy; D005260:Female; D005269:Femur / Q000187:drug effects / Q000378:metabolism; D007279:Injections, Subcutaneous; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D010052:Ovariectomy; D051381:Rats; D017208:Rats, Wistar; D013054:Spectrophotometry, Atomic
D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D002118:Calcium