The effect of long-term ovarian hormone deficiency on transforming growth factor-beta and bone matrix protein mRNA expression in rat femora.
Estrogen deficiency results in increased bone turnover and osteopenia. Decreased transforming growth factor beta (TGF-beta) has been implicated as having a role in ovariectomy (OVX)-induced bone loss; however the decrease in TGF-beta mRNA may simply be due to the reduction in cancellous bone volume that occurs following OVX. This investigation characterized the effect of long-term OVX (11.5 months) on mRNA levels for TGF-beta, osteocalcin (OC), and type I collagen (TYPE I) and expressed these data relative to the amount of cancellous bone surface. Additionally, the short-term effect of estrogen administration on TGF-beta, OC, and TYPE I mRNA was evaluated. OVX resulted in a 56% loss of bone surface. At the tissue level, TGF-beta was reduced, OC was increased, and TYPE I was unchanged. Expressed relative to bone surface, TGF-beta was unchanged and OC and TYPE I were significantly elevated. Four hours after estrogen administration, TGF-beta mRNA was unchanged compared to vehicle-treated controls. The data suggest that bone turnover is elevated after long-term OVX, but do not suggest a direct role of TGF-beta in OVX-induced bone loss.
Westerlind
K C
KC
Department of Orthopedic Research, Mayo Clinic and Foundation, Rochester, MN 55905.
Wronski
T J
TJ
Evans
G L
GL
Turner
R T
RT
D000375:Aging / Q000378:metabolism; D000818:Animals; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism*; D003094:Collagen / Q000096:biosynthesis; D015342:DNA Probes; D004054:Diethylstilbestrol / Q000494:pharmacology; D005260:Female; D005269:Femur / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D015675:Osteocalcin / Q000096:biosynthesis*; D010052:Ovariectomy; D010053:Ovary / Q000254:growth & development / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D016212:Transforming Growth Factor beta / Q000096:biosynthesis*
D015342:DNA Probes; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D015675:Osteocalcin; D004054:Diethylstilbestrol; D003094:Collagen