Turner R T, Evans G L, Wakley G K
Department of Orthopedic Surgery, Mayo Foundation, Graduate School of Medicine, Rochester, Minnesota.
J Bone Miner Res. 1993 Mar;8(3):359-66. doi: 10.1002/jbmr.5650080313.
Ovariectomy results in cancellous osteopenia in rat long bones, a condition that is prevented by treatment with estrogens. The purpose of these studies was to clarify the effects of estrogen on cancellous bone turnover using dynamic bone histomorphometry. Treatment of ovariectomized rats with diethylstilbestrol (DES) reduced the mineral apposition rate, double-label perimeter, osteoblast number, and osteoclast number, suggesting that the hormone had inhibitory effects on bone formation as well as bone resorption. However, we could not estimate the bone formation rate because of rapid resorption of tetracycline-labeled bone in the ovariectomized rat. The magnitude of loss was documented by a time course study: 58% of the tetracycline initially incorporated into the secondary spongiosa of the tibial metaphysis was resorbed after 11 days and 89% was resorbed after 22 days. Similarly, cancellous bone area was decreased by 67% after 11 days and by 88% after 22 days. Administration of either DES or tamoxifen (TAM) dramatically reduced resorption of tetracycline as well as the decrease in cancellous bone area. These results demonstrate that (1) estrogen prevents osteopenia in ovariectomized (OVX) rats, in part by inhibiting bone turnover, (2) TAM is an estrogen agonist on bone resorption, and (3) resorption of tetracycline-labeled bone leads to serious underestimation of the bone formation rate in OVX rats.
卵巢切除术会导致大鼠长骨出现松质骨减少症，而雌激素治疗可预防这种情况。这些研究的目的是使用动态骨组织形态计量学来阐明雌激素对松质骨转换的影响。用己烯雌酚（DES）治疗去卵巢大鼠可降低矿物质沉积率、双标记周长、成骨细胞数量和破骨细胞数量，这表明该激素对骨形成和骨吸收均有抑制作用。然而，由于去卵巢大鼠中四环素标记骨的快速吸收，我们无法估计骨形成率。通过一项时间进程研究记录了损失的程度：最初掺入胫骨近端干骺端次级海绵骨的四环素，11天后有58%被吸收，22天后有89%被吸收。同样，松质骨面积在11天后减少了67%，22天后减少了88%。给予DES或他莫昔芬（TAM）均可显著减少四环素的吸收以及松质骨面积的减少。这些结果表明：（1）雌激素可部分通过抑制骨转换来预防去卵巢（OVX）大鼠的骨质减少；（2）TAM在骨吸收方面是一种雌激素激动剂；（3）四环素标记骨的吸收会导致对OVX大鼠骨形成率的严重低估。
