Salih M A, Liu C C, Arjmandi B H, Kalu D N
Department of Physiology, University of Texas Health Science Center, San Antonio 78284-7756.
Bone Miner. 1993 Dec;23(3):285-99. doi: 10.1016/s0169-6009(08)80104-3.
This study was undertaken to examine the effects of ovariectomy and 17 beta-estradiol (E2) on the gene expression of type 1 collagen, osteocalcin and the protooncogen, c-myc, in cancellous bone. Female Sprague-Dawley rats, aged 95 days, were divided into 4 groups. Group 1 was sham operated and Groups 2-4 were ovariectomized. Groups 3 and 4 received daily injections of 160 ng and 1600 ng E2/kg body weight, respectively. Groups 1 and 2 received the solvent vehicle. All animals were sacrificed after 14 days. The femurs were dissected out and cancellous bone scraped from the distal metaphysis. RNA was isolated from the cancellous bone, immobilized on filters or size-fractionated by agarose gel electrophoresis and adsorbed on filters which were then hybridized with specific cDNA probes. Ovariectomy resulted in a significant increase in the mRNAs of type 1 collagen, osteocalcin and c-myc. The increase was suppressed in animals that received 17 beta-estradiol injections. In addition, ovariectomy caused the expected decrease in cancellous bone in the proximal tibia and increased osteoclast and osteoblast numbers. The ovariectomy-induced changes were prevented by 17 beta-estradiol administration. These findings suggest that the lack of ovarian hormones shortly after ovariectomy up-regulates and estrogen administration down-regulates the expression of important cancellous bone matrix proteins as well as the protooncogen, c-myc.
本研究旨在探讨卵巢切除及17β-雌二醇（E2）对松质骨中I型胶原蛋白、骨钙素及原癌基因c-myc基因表达的影响。将95日龄的雌性Sprague-Dawley大鼠分为4组。第1组为假手术组，第2 - 4组为卵巢切除组。第3组和第4组分别每日注射160 ng和1600 ng E2/kg体重，第1组和第2组注射溶剂载体。14天后处死所有动物，取出股骨，刮取远端干骺端的松质骨。从松质骨中提取RNA，固定于滤膜上，或经琼脂糖凝胶电泳进行大小分级后吸附于滤膜上，然后与特异性cDNA探针杂交。卵巢切除导致I型胶原蛋白、骨钙素及c-myc的mRNA显著增加，而接受17β-雌二醇注射的动物中这种增加受到抑制。此外，卵巢切除导致胫骨近端松质骨量预期性减少，破骨细胞和成骨细胞数量增加，而给予17β-雌二醇可防止卵巢切除引起的这些变化。这些发现表明，卵巢切除后不久卵巢激素缺乏会上调，而雌激素给药则下调重要松质骨基质蛋白以及原癌基因c-myc的表达。
