title: [The effect of estrogen on new bone formation in the implanted bone matrix in aged male rats].
abstract: OBJECTIVE
  To study the effect of estrogen on new bone formation in the implanted bone matrix in aged male rats and on general bone metabolism.
  
  
  METHODS
  The aged male rats were implanted with slices of bone matrix and subcutaneously injected with estrogen, androgen or the solvent for five weeks. The changes in bone histomorphometry, bio-mechanical parameters and urine deoxypyridinoline (Dpd) levels were observed as indexes of bone reabsorption. Calcium, organic phosphate, and alkalphophatase levels in serum and urine were also studied.
  
  
  RESULTS
  (1) The areas of new bone formation were significantly larger in estrogen and androgen groups than in the control but without difference between estrogen and androgen groups. (2) The number of osteoclasts was higher in estrogen and androgen groups than in the control (P < or = 0.002) but without difference between estrogen and androgen groups. (3) Urine Dpd/Cr ratio was lower in estrogen and androgen groups than in the control and higher in the control than that obtained 5 weeks ago but without difference between estrogen and androgen groups.
  
  
  CONCLUSIONS
  Estrogen and androgen are able to stimulate new bone formation in the implanted bone matrix and inhibit the reabsorption rate of systemic bones in aged male rats, but there was no difference between estrogen and androgen in these two respects under the conditions of this experiment.
authors.affiliation: Department of Nephrology, China-Japan Friendship Hospital, Beijing 100029.
authors.forename: C
authors.initials: C
authors.lastname: Zhang
authors.forename: J
authors.initials: J
authors.lastname: Lin
authors.forename: Y
authors.initials: Y
authors.lastname: Jin
mesh_terms: D000728:Androgens / Q000494:pharmacology; D000818:Animals; D001842:Bone and Bones / Q000378:metabolism; D004967:Estrogens / Q000494:pharmacology*; D008297:Male; D010012:Osteogenesis / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000728:Androgens; D004967:Estrogens