AJP - Endocrinology and Metabolism, Vol 264, Issue 2 E190-E196, Copyright © 1993 by American Physiological Society
Increased proliferation of osteoblast precursor cells in estrogen-deficient rats
D. Modrowski, L. Miravet, M. Feuga and P. J. Marie
Institut National de la Sante et de la Recherche Medicale Unite 349, Lariboisiere Hospital, Paris, France.
We have evaluated the in vivo and in vitro changes in osteoblast
characteristics induced by estrogen deficiency and 17 beta-estradiol (E2)
treatment in ovariectomized (OVX) rats. Estrogen deficiency induced
osteopenia and increased bone turnover, as evidenced by bone
histomorphometry at 1, 3, and 6 mo postovariectomy. Bone surface
osteoblastic cells (OB) isolated from tibias of OVX rats, OVX rats treated
with E2 (10 micrograms/kg body wt), and sham rats showed no difference in
alkaline phosphatase activity and osteocalcin production in vitro. In
contrast the proliferation rate of OB cells was higher in OVX rats compared
with sham rats at all time points post-surgery, as shown by [3H]thymidine
incorporation and cell number. The proliferation rate of alkaline
phosphatase-positive marrow cells was also higher in OVX rats compared with
sham rats. E2 treatment of OVX rats corrected histologic indexes of bone
resorption and formation and normalized OB cell proliferation. induced by
estrogen deficiency in OVX rats is related to an increased proliferation of
osteoblast precursor cells present in the marrow stroma and along the
endosteal bone surface.
