Estrogen and androgen dynamics in the cynomolgus monkey

We studied the dynamics of androgen, estrogen, and cortisol (F) production, metabolism, and protein binding in cynomolgus monkeys (M. fascicularis) to provide baseline data and to compare these parameters with those obtained in other primates. Constant infusions of 3H-labeled androgens, 14C-labeled estrogens, and [3H]F were administered to 11 male cynomolgus monkeys (M. fascicularis) for 3.5 h. Blood samples were obtained from a peripheral vein during the infusion, and all urine was collected for 96 h. In each of 3 monkeys, a catheter was inserted into the hepatic vein, and during the infusions blood samples were obtained from the hepatic and peripheral veins and the femoral artery. All blood and urine samples were analyzed for radioactivity as testosterone (T), androstenedione (A), dihydrotestosterone (DHT), estradiol (E2), and estrone (E1). When indicated, blood samples were also analyzed for radioactivity as F. Blood samples taken before the infusions were analyzed for endogenous T, A, DHT, E1, E2, and F concentrations; percent free T, free E2, and free F; and sex hormone-binding globulin and F-binding globulin capacities. The mean +/- SE MCRs for T, A, E2, E1, and F were 44 +/- 4, 407 +/- 40, 175 +/- 17, 315 +/- 28, and 57 +/- 6 liters/day, respectively. The mean blood production rates were 128 +/- 19, 91 +/- 14, 3.3 +/- 0.5, and 9.2 +/- 1.1 micrograms/day and 13.4 +/- 1.9 mg/day for T, A, E2, E1, and F, respectively. The aromatization of androgens was 1.30 +/- 0.10% for A to E1 and 0.28 +/- 0.03% for T to E2. The percent free F (4.34 +/- 0.42%) was greater than the percent free T (1.73 +/- 0.16%) or free E2 (2.75 +/- 0.22%), and the concentration of F-binding globulin was greater than that of sex hormone-binding globulin (227 +/- 35 vs. 60 +/- 7 nM). In the three monkeys who had hepatic venous catheterization, the mean extraction, across the splanchnic bed of T was 32 +/- 3%, that of E was 62 +/- 2%, and that of cortisol was 12 +/- 5%. Across peripheral tissues (leg) the mean extractions were 13 +/- 1%, 18 +/- 1%, and 6 +/- 4%, respectively. In general, the dynamics of androgen, estrogen, and F production and metabolism are similar in male cynomolgus and rhesus monkeys and in man. The similarity is especially close for peripheral aromatization despite differences in adipose tissue content between man and nonhuman primates.     

Estrogen and androgen dynamics in liver disease

Constant infusions of 3H-androgen/14C-estrogen were given to 18 men with increased serum bilirubin concentrations and biopsy proven hepatic cirrhosis. From data obtained from the infusions and the radioimmunoassay of circulating endogenous steroid levels metabolic clearance rates (MCR), blood production rates (PB), aromatization rates (fraction of androgen infused into and measured as estrogen in blood; [p]And, Est BB) and conversion ratios (ratio of concentration of radioactivity of infused precursor to product steroid in blood; CRPREC,PROD were calculated. These data were compared to normal data obtained from similar studies in a group of normal men similar in age and weight. The mean concentrations of testosterone (T), and dihydrotestosterone (DHT), were decreased but those of estrone (E1) and estradiol (E2) were increased, and the concentration of androstenedione, (A), was similar compared to the normal values. Compared to the values in normal men the mean MCR of T was decreased those of A and E2 were normal, and that of E1 was slightly increased. However, the PB's of both estrogens were increased while that of A was normal T was decreased. The increase in the PB's of the estrogens could be explained on the basis of a marked increase in [p]And, Est BB probably due to a shift in blood flow from the liver to peripheral tissue. These findings were noted in men with alcoholic cirrhosis as well as cardiac cirrhosis and in 1 subject with infectious hepatitis. Abnormalities in steroid metabolism occur in men with several types of liver disease and are not limited to those with alcoholic liver disease.     

Wnt-beta-catenin signaling in the pathogenesis of osteoarthritis

Osteoarthritis (OA) is a progressively degenerative joint condition that is influenced by various metabolic and structural factors. The canonical Wnt-frizzled-beta-catenin pathway has been implicated in the pathogenesis of OA. Products of the Wnt, frizzled, secreted frizzled-related protein (sFRP), Dickkopf and LDL-receptor-related protein gene families have crucial roles in the development and maintenance of bone, cartilage and joints. Increased levels of beta-catenin have been observed in degenerative cartilage, suggesting that a diminished capacity to limit Wnt signaling might contribute to cartilage loss. Polymorphisms in genes involved in Wnt signaling-particularly in the gene encoding sFRP-3-are associated with an increased susceptibility to the development of OA. At least one of these polymorphisms in the gene encoding sFPR-3 is associated with a reduced ability to limit beta-catenin signaling. In addition, the canonical Wnt signaling pathway is influenced by local factors, including alterations in glycosaminoglycan sulfation, cartilage matrix content, transforming growth factor beta and vitamin D. A higher circulating level of the Wnt inhibitor Dickkopf-1, for instance, is associated with slowed progression of hip OA. Hence, the sum of local and systemic factors contributes to the outcome of the Wnt-frizzled pathways. Further investigation is needed to fully define the role of Wnt signaling in OA.     

Estrogen and androgen regulation of protein synthesis by the immature rabbit epididymis

To obtain evidence of a physiological role for androgens and estrogens in the regulation of the epididymis of sexually immature rabbits, the effects of these hormones on [35S] methionine incorporation into epididymal proteins in vitro were examined. Two-dimensional polyacrylamide gel electrophoresis revealed that short term incubation with estradiol changed the patterns of radiolabeled proteins detected in tissue homogenates of epididymal segments from castrated rabbits compared to those in segments from castrated rabbits that were not exposed to exogenous estradiol. Most of the changes seen in corpus tissue affected proteins with a wide range of pI values and relatively high mol wt (greater than 40K). The effects on caput and cauda tissue proteins were seen over a wide pH and mol wt range. Castration abolished many of the regional differences in protein synthesis; these were restored by incubation with estradiol. Testosterone had little effect on the synthesis of tissue proteins, except for stimulation of the synthesis of a single protein (17K; pI 5.1) in all three segments and stimulation of a small group of proteins (less than 14K; pI 7.0-7.2) in the corpus. Estradiol had little effect on proteins secreted by epididymal segments. Testosterone, however, stimulated the synthesis of a number of unique proteins secreted by the caput and corpus and resulted in a pattern of radiolabeled proteins similar to that obtained with intact animals. Additional secretory proteins could be stimulated in caput, but not corpus, tissue minces from intact rabbits by exogenous testosterone. No androgen-specific synthesis of secretory proteins was detected in the cauda of either castrated or intact rabbits. Estradiol affected the synthesis of both secreted and tissue proteins in terms of influencing which epididymal segment was most active at incorporating [35S]methionine into radiolabeled proteins and which was least active. Testosterone had a similar influence on secreted proteins, but did not have any analogous effect on tissue proteins. These results indicate that testosterone and estradiol influence the synthesis of proteins by the immature rabbit epididymis and that both may, therefore, be important physiological regulators of epididymal development and/or function.     

Estrogen and androgen production rates in two brothers with Reifenstein syndrome

Defects of the androgen receptor in 46,XY individuals cause aberrant virilization that varies from a female phenotype to men with minor defects. More severely affected individuals also develop gynecomastia associated with enhanced estradiol secretion by the testis. However, the degree of breast development does not correlate with the rate of estrogen production, leading us to propose that feminization is a function of the degree of androgen resistance as well as the rate of estrogen formation. To test this hypothesis we measured estrogen and androgen formation in two brothers with perineoscrotal hypospadias and severe gynecomastia (the Reifenstein phenotype) due to a mutation that impairs androgen receptor function. Rates of estradiol production (60 and 70 micrograms/day) were elevated, but were not as high as in previously studied men with a similar phenotype. We conclude that the variable degree of feminization in this disorder cannot be explained by androgen resistance alone.     

Estrogen receptors and signaling pathways in lactotropes and somatotropes

Estrogens are crucial determinants in the regulation of anterior pituitary function and maintenance of tissue homeostasis. Estrogen actions in this gland are exerted through both classical and non-classical mechanisms of action. This review summarizes the expression of classical α- and β-estrogen receptors and variant isoforms of estrogen receptors in anterior pituitary cell subpopulations. We also analyze estrogen receptor signaling pathways involved in estrogenic actions in the anterior pituitary gland, especially in lactotropes and somatotropes. Complex interactions between multiple signaling pathways are involved in estrogen regulation of hormone secretion, cell proliferation and cell death in this gland. Insight into these pituitary responses to estrogens would help to understand pituitary function and tumorigenesis.     

Estrogen receptor-alpha gene deficiency enhances androgen biosynthesis in the mouse Leydig cell

Leydig cells, which produce the primary male steroid hormone testosterone (T), express the two estrogen receptor (ER) subtypes, ERalpha and ERbeta, and have the capacity to convert testosterone to the natural estrogen 17beta-estradiol. Thus, Leydig cells are subject to estrogen action. The development of transgenic mice that are homozygous for targeted deletion of genes encoding the ER subtypes provides an opportunity to examine the role of estrogen in Leydig cell function. In this study androgen biosynthesis was analyzed in Leydig cells from mice that were homozygous for targeted deletion of the ERalpha gene (alphaERKO). T production by alphaERKO Leydig cells was 2-fold higher than that in wild-type (WT) cells. Serum T levels were accordingly higher in alphaERKO compared with WT mice (5.1 +/- 1.1 vs. 2.2 +/- 0.4 ng/ml; P 相似文献   

Comparison of androgen metabolites in benign prostatic hypertrophy (BPH) and normal prostate.

5 alpha-Dihydrotestosterone (DHT) and androstanediols (diols) have been measured in human prostate tissue. DHT levels in surgical specimens of prostate from 8 patients with BPH averaged 5.6 +/- 0.93 S.E. ng/g and were significantly greater than (P less than 0.01) values of 2.1 +/- 0.32 S.E. ng/g in 6 normal prostates obtained post-mortem from males less than 50 yrs old. Androstanediols averaged 2.3 +/- 0.35 S.E. ng/g in the BPH specimens compared to values of 10.2 +/- 2.4 S.E. ng/g in the normal prostates (P less than 0.01). This significantly higher (P less than 0.001) ratio of diols/DHT in the normal (5.1 +/- 0.93 S.E.) compared to the BPH prostate (0.45 +/- 0.08 S.E.) suggests that a decrease in 3-hydroxysteroid oxido-reductase, which converts DHT to diol, may be an important clue to the pathogenesis of BPH.     

Estrogen receptor expression in chronic hepatitis C and hepatocellular carcinoma pathogenesis

AIM To investigate gender-specific liver estrogen receptor(ER) expression in normal subjects and patients with hepatitis C virus(HCV)-related cirrhosis and hepatocellular carcinoma(HCC).METHODS Liver tissues from normal donors and patients diagnosed with HCV-related cirrhosis and HCV-related HCC were obtained from the NIH Liver Tissue and Cell Distribution System. The expression of ER subtypes, ERα and ERβ, were evaluated by Western blotting and real-time RT-PCR. The subcellular distribution of ERα and ERβ was further determined in nuclear and cytoplasmic tissue lysates along with the expression ofinflammatory [activated NF-κB and IκB-kinase(IKK)] and oncogenic(cyclin D1) markers by Western blotting and immunohistochemistry. The expression of ERα and ERβ was correlated with the expression of activated NF-κB, activated IKK and cyclin D1 by Spearman's correlation. RESULTS Both ER subtypes were expressed in normal livers but male livers showed significantly higher expression of ERα than females(P 0.05). We observed significantly higher m RNA expression of ERα in HCV-related HCC liver tissues as compared to normals(P 0.05) and ERβ in livers of HCV-related cirrhosis and HCV-related HCC subjects(P 0.05). At the protein level, there was a significantly higher expression of nuclear ERα in livers of HCV-related HCC patients and nuclear ERβ in HCV-related cirrhosis patients as compared to normals(P 0.05). Furthermore, we observed a significantly higher expression of phosphorylated NF-κB and cyclin D1 in diseased livers(P 0.05). There was a positive correlation between the expression of nuclear ER subtypes and nuclear cyclin D1 and a negative correlation between cytoplasmic ER subtypes and cytoplasmic phosphorylated IKK in HCV-related HCC livers. These findings suggest that dysregulated expression of ER subtypes following chronic HCVinfection may contribute to the progression of HCVrelated cirrhosis to HCV-related HCC.CONCLUSION Gender differences were observed in ERα expression in normal livers. Alterations in ER subtype expression observed in diseased livers may influence genderrelated disparity in HCV-related pathogenesis.     

Studies on the pathogenesis of the incomplete forms of androgen resistance in man

The affinity and turnover of the specific dihydrotestosterone binding protein have been assessed in fibroblasts cultured from genital skin from a variety of control subjects and from 4 patients with incomplete hereditary male pseudohermaphroditism due to androgen resistance (incomplete testicular feminization and Reifenstein syndrome). Whereas the amount of dihydrotestosterone binding in the 4 mutant cell strains is low, both the affinity of the protein for dihydrotestosterone as assessed by the concentration at which half-maximal binding occurs (averaging 0.2 nM) and the turnover of the binding protein (average half-life of 11--13 h) are within the normal range. Since no qualitative abnormality could be detected, these data suggest that the mutations in these two disorders affect the synthesis of the dihydrotestosterone binding protein.     

Estrogen signaling ability in human endometrial cancer through the cancer-stromal interaction

The estrogen pathway plays an important role in the etiology of human endometrial carcinoma (EC). We examined whether estrogen biosynthesis in the tumor microenvironment promotes endometrial cancer. To examine the contribution of stromal cells to estrogen signaling in EC, we used reporter cells stably transfected with the estrogen response element (ERE) fused to the destabilized green fluorescent protein (GFP) gene. In this system, the endometrial cancer stromal cells from several patients activated the ERE of cancer cells to a variable extent. The GFP expression level increased when testosterone, a substrate for aromatase, was added. The effect was variably inhibited by aromatase inhibitors (AIs), although the response to AIs varied among patients. These results suggest that GFP expression is driven by estrogen synthesized by aromatase in the endometrial cancer stromal cells. In a second experiment, we constructed an adenovirus reporter vector containing the same construct as the reporter cells described above, and visualized endogenous ERE activity in primary culture cancer cells from 15 EC specimens. The GFP expression levels varied among the cases, and in most primary tissues, ERE activities were strongly inhibited by a pure anti-estrogen, fulvestrant. Interestingly, a minority of primary tissues in endometrial cancer showed ERE activity independent of the estrogen-ER pathway. These results suggest that AI may have some therapeutic value in EC; however, the hormonal microenvironment must be assessed prior to initiating therapy.     

Toll样受体信号传导在关节炎发病中的作用

最近的研究证据显示：Toll样受体（TLR）是固有免疫的关键性识别结构。TLR的活化启动了炎症性细胞因子、趋化因子、组织破坏性酶和Ⅰ型干扰素的产生;同时,TLR的信号传导可以通过上调抗原递呈细胞的共刺激分子在适应性免疫系统的活化和发展中扮演重要作用。鉴于TLR信号传导在连接固有免疫和适应免疫中具有重要作用,可以推测TLR信号传导的失调可能与自身免疫性疾病的发生有关。本文将就由对应配体激活的TLR信号转导通路进行一些总结,最后讨论TLR传导通路在类风湿性关节炎致病机制中的作用。