首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
Runx2 integrates estrogen activity in osteoblasts   总被引:6,自引:0,他引:6  
  相似文献   

3.
4.
5.
6.
7.
8.
9.
Genomic and non-genomic effects of estrogens on endothelial cells   总被引:7,自引:0,他引:7  
  相似文献   

10.
11.
12.
The sex steroid hormones, androgens and estrogens, via their respective nuclear receptors, regulate bone mineral density in humans and mice. Very little is known about the direct targets of the androgen and estrogen receptors in bone cells. First, models of hormone and receptor deficiency in mouse and human bone are discussed. This review then focuses on the direct targets of the receptors in osteoblasts and osteoclasts. A direct target of a NR is defined here as a gene that is regulated by NR binding to the DNA (either through DNA binding or association with a DNA binding protein) at an enhancer or promoter of that gene. The experimental evidence that illustrates androgen and estrogen gene regulation in osteoblasts and osteoclasts will be summarized and compared with the phenotype of the hormones in vivo.  相似文献   

13.
14.
15.
The results of the measurement of 19-nortestosterone in the testiscular artery and vein of the stallion, the very low levels of this steroid in the peripheral blood of geldings and the similar patterns of increase in the peripheral levels of 19-nortestosterone and testosterone after hCG stimulation, show that 19-nortestosterone, like testosterone, is essentially synthesized in the testis. This testicular origin was confirmed by the ability of testicular tissue to synthesize 19-norandrogens from [4-14C]androgens in vitro. 19-Nortestosterone was 50% conjugated in the peripheral blood and almost entirely conjugated after biosynthesis in vitro. The sequence of appearance of steroids in the peripheral blood after a single injection of 10,000 IU hCG suggests that, in the equine testis, 19-norandrogens are produced by a specific C10-19 desmolase (estrene synthetase), stimulable by hCG. 19-Nortestosterone was aromatized into estradiol-17 beta by stallion testicular microsomes. The affinity of the aromatase for 19-nortestosterone was very low compared to that for testosterone. At low and presumably physiological levels, and at a high testosterone/19-nortestosterone ratio, testosterone did not inhibit 19-nortestosterone aromatization by more than 53%. Thus, 19-nortestosterone may be aromatized in vivo in the testis in spite of the endogenous concentrations of androgens. However, the low velocity of 19-nortestosterone aromatization by testicular microsomes at roughly physiological concentrations suggests that 19-norandrogen aromatization may only participate slightly in the testicular estrogen production. These results suggest that in the equine testis, two aromatizing enzyme systems may exist: one which aromatizes both androgens and 19-norandrogens, and a minority system more specific for 19-norandrogens.  相似文献   

16.
Follicular fluid was aspirated from preovulatory follicles of women under ovarian stimulation for in vitro fertilization and analyzed by a highly specific technique based on gas chromatography-mass spectrometry associated with stable isotope dilution. 19-Nortestosterone and 19-norandrostenedione were identified and quantified for the first time in human follicular fluid. There was a strong positive correlation between 19-nortestosterone and estradiol-17 beta and between 19-norandrostenedione and estrone concentrations, thus indicating a common cellular origin. The accumulation of 19-norsteroids in follicular fluid confirms that they are weakly active intermediates in the multistep enzymatic conversion of androgen to estrogen. Testosterone concentrations were significantly lower than those obtained by radioimmunoassay; cross-reaction with substantially higher levels of 19-nortestosterone seems to be at the origin of this discrepancy. Androstenedione concentrations were similar to those reported in the literature and it was therefore confirmed that an estradiol/androstenedione concentration ratio above 20 is favourable for oocyte cleavage. Other and some newly estimated androgens are: testosterone sulfate, 5-androstene-3 beta, 17 beta-diol 3-sulfate and disulfate, dihydrotestosterone sulfate, epitestosterone, 19-hydroxyandrostenedione, 5 alpha-androstane-3 alpha, 17 beta-diol, 5 alpha-androstane-3 beta, 17 beta-diol, 5 alpha-androstane-3,17-dione and androsterone. Dehydroepiandrosterone sulfate was by far the most abundant androgen in this type of follicles.  相似文献   

17.
18.
19.
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号