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1.
The present study attempted for the first time to explore the importance of photoperiod in the regulation of seasonal ovarian functions in any subtropical major carp. Adult Indian major carp Catla catla were transferred to a long photoperiod (LP; LD 16:8) or a short photoperiod (SP; LD 8:16) for 30 days on 4 dates corresponding to the beginnings of 4 reproductive phases in an annual cycle, and responsiveness of the ovary was evaluated by comparison with the gonadal weight (I(G)), relative number of developing oocytes, serum levels of vitellogenin, and the activity of 2 important steroidogenic enzymes, that is, Delta(5)3beta-hydroxysteroid dehydrogenase and 17.beta-hydroxysteroid dehydrogenase, in the ovary of fish in a natural photoperiod. Exposure of fish to LP during the preparatory phase (February-March) resulted in a significant (p < 0.001) increase in the values of vitellogenin and in the activity of both the steroidogenic enzymes but not in the ovarian weight and in the relative number of different stages of oocytes. A more stimulatory influence of LP was noted during the prespawning phase (April-May), when precocious maturation of ovary was evident from a significant (p < 0.001) rise in the values of each studied features of ovarian functions. However, no ovarian response was found when the fish were transferred to LP during the spawning (July-August) and the postspawning (September-October) phases. On the other hand, the SP was found to have an inhibitory influence on ovarian growth and maturation during the prespawning and the spawning phases or to have no influences on ovarian functions during the preparatory and the postspawning phases of an annual cycle. The results of our study provide the first evidence that photoperiod per se plays an important role in the seasonal maturation of ovary in a subtropical freshwater major carp.  相似文献   

2.
Administration of ochratoxin A to pregnant rats from 6 to 12 days of gestation period, resulted in complete resorption of fetuses. On histological examination luteal degeneration was observed along with reduction in the weight of corpus luteum (mg/100 mg ovarian tissue) and pituitary gland. The enzyme delta 5-3 beta-hydroxy steroid dehydrogenase (delta 5-3 beta-OHD) and glucose-6-phosphate dehydrogenase were demonstrated histochemically in the ovary of pregnant rats. The activities of the enzymes were suppressed significantly in ochratoxin A treated rats. The same treatment also resulted in an accumulation of cholesterol and ascorbic acid in the ovary. Based on these results, it is suggested that resorption of fetuses in ochratoxin A treated rats may be related with a diminution in ovarian steroidogenesis possibly due to reduction in pituitary gonadotrophin secretion.  相似文献   

3.
The present article summarizes some of the studies available on steroid hormone conversion through the specific expression of steroidogenic enzymes in adipose tissue (adipose tissue intracrinology) and discusses the potential impact of local adipose tissue steroid metabolism on the regulation of adipocyte function and other metabolic parameters. Several studies have demonstrated significant steroid hormone uptake and conversion by adipose tissues from various body sites and in various cell fractions. Activities and/or mRNAs of aromatase, 3beta-hydroxysteroid dehydrogenase (HSD), 3alpha-HSD, 11beta-HSD, 17beta-HSD, 7alpha-hydroxylase, 17alpha-hydroxylase, 5alpha-reductase and UDP-glucuronosyltransferase 2B15 have been detected in adipose tissue or adipose cells. These studies have demonstrated potentially important roles for these enzymes in obesity, central fat accumulation, and the metabolic syndrome. Future studies on adipose tissue intracrinology will contribute further to our understanding of steroid action in adipocytes.  相似文献   

4.
Alterations of steroid hormone biosynthesis and metabolism are suspected to be involved in the pathogenesis of several diseases. Several polymorphisms of the enzymes involved in these processes have already been described and some could be associated with certain diseases. We attempted to examine the sequence variants of these genes in order to find novel variants by an in silico analysis. We analyzed the known human nucleotide sequences of the enzymes p450 side-chain cleavage enzyme, steroid 17-alpha-hydroxylase/17,20-lyase, 3-beta-hydroxysteroid dehydrogenase types 1 and 2, 21-hydroxylase, 11-beta-hydroxylase, aldosterone synthase, aromatase, 11-beta-hydroxysteroid dehydrogenase types 1 and 2, steroid 5-alpha-reductase types 1 and 2, steroid 5-beta-reductase, dehydroepiandrosterone sulfotransferase, 17-beta-hydroxysteroid dehydrogenase types 1–3. The analysis was performed using the National Center for Biotechnology Information Database by the search tool blastn. We found numerous sequence variants in both coding and non-coding sequences. The majority of these sequence variants have already been described, nevertheless, some appear as novel variants. Some of these may also have functional significance. We hypothesize over the possible significance of these findings and briefly review the available literature.  相似文献   

5.
The case of a true hermaphrodite, with a normal ovary and an ovotestis is presented. The ovotestis was removed and incubated in vitro with tritiated steroids (testosterone, dehydroepiandrosterone, pregnenolone and 17 alpha-hydroxyprogesterone). Labeled metabolites were isolated and identified. Based upon these findings, a pathway of steroid biogenesis in this abnormal gonadal tissue is suggested. The ovotestis studied did not contain all the enzymes involved in ovarian steroidogenesis: 3 beta-hydroxysteroid dehydrogenase, isomerase, 17--20 desmolase and 17 beta-hydroxysteroid dehydrogenase were present, but other important enzymes, such as 16 and 17-hydroxylases, and aromatizing enzyme systems, were deficient or absent.  相似文献   

6.
In 5 placental homogenates the Km of steroid sulfatase for DHEA sulfate increased from 15.4 in Tris buffer to 26.8 microM in phosphate (both buffers 0.1 M, pH 7.4), P less than 0.05. In 3 pooled ovarian preparations the Km increased from 14.3 microM in Tris to 33.0 microM in phosphate, P less than 0.01. There was no significant difference between the ovarian and placental values for Km in either Tris or phosphate (P greater than 0.5), and the increase in the Km produced by phosphate in ovarian tissue was not significantly different from that in the placenta (P greater than 0.5). In the placentas the Vmax in Tris was 1420 pmol/min/mg protein and this fell to 523 pmol/min/mg protein in phosphate (P less than 0.005). The Vmax was 50-fold higher in the placenta than in the ovary in either Tris or phosphate (both P less than 0.001). In the ovary, the Vmax was 27.6 pmol/min/mg protein in Tris and 11.0 pmol/min/mg protein in phosphate (P less than 0.05). The reduction of Vmax produced by phosphate in the ovary was not significantly different from that in the placenta (P greater than 0.5). The slope of the 1/v vs 1/S plot (Km/Vmax) increased 4.7-fold in the placentas and 5.8-fold in the ovaries in phosphate over that in Tris (both P less than 0.001); the increase in the placentas was not significantly different from that in the ovaries (P greater than 0.5). Phosphate ion acts as a mixed inhibitor of both placental and ovarian steroid sulfatase.  相似文献   

7.
In human placenta, 3 beta-hydroxy-5-ene-steroid dehydrogenase and steroid 5----4-ene-isomerase, an enzyme complex found in microsomes and mitochondria, synthesizes progesterone from pregnenolone and androstenedione from fetal dehydroepiandrosterone sulfate. The dehydrogenase and isomerase activities of the mitochondrial enzyme were copurified (733-fold) using sequential cholate solubilization, ion exchange chromatography (DEAE-Toyopearl 650S), and hydroxylapatite chromatography (Bio-Gel HT). Enzyme homogeneity was demonstrated by a single protein band in SDS-polyacrylamide gel electrophoresis (monomeric Mr = 41,000), gel filtration at constant specific enzyme activity (Mr = 77,000), and a single NH2-terminal sequence. Kinetic constants were determined for the oxidation of pregnenolone (Km = 1.6 microM, Vmax = 48.6 nmol/min/mg) and dehydroepiandrosterone (Km = 2.4 microM, Vmax = 48.5 nmol/min/mg) and for the isomerization of 5-pregnene-3,20-dione (Km = 9.3 microM, Vmax = 914.2 nmol/min/mg) and 5-androstene-3,17-dione (Km = 27.6 microM, Vmax = 888.4 nmol/min/mg. Mixed substrate studies showed that the dehydrogenase and isomerase activities utilize their respective pregnene and androstene substrates competitively. Dixon analysis demonstrated that the product steroids, progesterone and androstenedione, are competitive inhibitors of the C-21 and C-19 dehydrogenase activities. Enzyme purified from mitochondria and microsomes had similar kinetic profiles with respect to substrate utilization, product inhibition, and cofactor (NAD+) reduction (mean Km +/- SD using C-19 and C-21 dehydrogenase substrates = 26.4 +/- 0.8 microM, mean Vmax = 73.2 +/- 1.3 nmol/min/mg). Pure enzyme from both organelles exhibited identical biophysical properties in terms of molecular weight and subunit composition, pH optima (pH 9.8, dehydrogenase; pH 7.5, isomerase), temperature optimum (37 degrees C), stability in storage and solution, effects of divalent cations, and the single NH2-terminal sequence of 27 amino acids. These results suggest that the mitochondrial and microsomal enzymes are the same protein localized in different organelles.  相似文献   

8.
In human pregnancy, placental 3 beta-hydroxy-5-ene-steroid dehydrogenase and steroid 5----4-ene-isomerase produce progesterone from pregnenolone and metabolize fetal dehydroepiandrosterone sulfate to androstenedione, an estrogen precursor. The enzyme complex was solubilized from human placental microsomes using the anionic detergent, sodium cholate. Purification (500-fold, 3.9% yield) was achieved by ion exchange chromatography (Fractogel-TSK DEAE 650-S) followed by hydroxylapatite chromatography (Bio-Gel HT). The purified enzyme was detected as a single protein band in sodium dodecylsulfate-polyacrylamide gel electrophoresis (monomeric Mr = 19,000). Fractionation by gel filtration chromatography at constant specific enzyme activity supported enzyme homogeneity and determined the molecular mass (Mr = 76,000). The dehydrogenase and isomerase activities copurified. Kinetic constants were determined at pH 7.4, 37 degrees C for the oxidation of pregnenolone (Km = 1.9 microM, Vmax = 32.6 nmol/min/mg) and dehydroepiandrosterone (Km = 2.8 microM, Vmax = 32.0 nmol/min/mg) and for the isomerization of 5-pregnene-3,20-dione (Km = 9.7 microM, Vmax = 618.3 nmol/min/mg) and 5-androstene-3,17-dione (Km = 23.7 microM, Vmax = 625.7 nmol/min/mg). Mixed substrate analyses showed that the dehydrogenase and isomerase reactions use the appropriate pregnene and androstene steroids as alternative, competitive substrates. Dixon analyses demonstrated competitive inhibition of the oxidation of pregnenolone and dehydroepiandrosterone by both product steroids, progesterone and androstenedione. The enzyme has a 3-fold higher affinity for androstenedione than for progesterone as an inhibitor of dehydrogenase activity. Based on these competitive patterns of substrate utilization and product inhibition, the pregnene and androstene activities of 3 beta-hydroxy-5-ene-steroid dehydrogenase and steroid 5----4-ene-isomerase may be expressed at a single catalytic site on one protein in human placenta.  相似文献   

9.
Summary Histochemical evidence is presented for the occurrence of specific steroid 3-ol dehydrogenase activities in steroidogenic cells of the human ovary, testes and adrenal. The enzymes in the cells of the corpus luteum and adrenal show similar dehydrogenase reactions with some steroid substrates and are inhibited by progesterone, a known physiologic steroid. Theca cells have an activity which is less readily demonstrated and apparently inhibited by both progesterone and DHA. The ovarian hilus cells and the interstitial cells of the testis contain steroid dehydrogenase activity which is inhibited by DHA and not by progesterone. The cellular specificity suggests that the type of activity plays a major role in determining the type of hormone production. The specificity of the steroid inhibitors suggests the possibility of intracellular feedback mechanisms which control the amount of hormone produced.Supported by USPHS Grant No. AMO 3806-07.  相似文献   

10.
Seven multiforms of indanol dehydrogenase were isolated in a highly purified state from male rabbit liver cytosol. The enzymes were monomeric proteins with similar molecular weights of 30,000-37,000 but with distinct electrophoretic mobilities. All the enzymes oxidized alicyclic alcohols including benzene dihydrodiol and hydroxysteroids at different optimal pH, but showed clear differences in cofactor specificity, steroid specificity, and reversibility of the reaction. Two NADP+-dependent enzymes exhibited both 17 beta-hydroxysteroid dehydrogenase activity for 5 alpha-androstanes and 3 alpha-hydroxysteroid dehydrogenase activity for 5 beta-androstan-3 alpha-ol-17-one. Three of the other enzymes with dual cofactor specificity catalyzed predominantly 5 beta-androstane-3 alpha,17 beta-diol dehydrogenation. The reverse reaction rates of these five enzymes were low, whereas the other two enzymes, which had 3 alpha-hydroxysteroid dehydrogenase activity for 5 alpha-androstanes or 3(17)beta-hydroxysteroid dehydrogenase activity for 5 alpha-androstanes, highly reduced 3-ketosteroids and nonsteroidal aromatic carbonyl compounds with NADPH as a cofactor. All the enzymes exhibited Km values lower for the hydroxysteroids than for the alicyclic alcohols. The results of kinetic analyses with a mixture of 1-indanol and hydroxysteroids, pH and heat stability, and inhibitor sensitivity suggested strongly that, in the seven enzymes, both alicyclic alcohol dehydrogenase and hydroxysteroid dehydrogenase activities reside on a single enzyme protein. On the basis of these data, we suggest that indanol dehydrogenase exists in multiple forms in rabbit liver cytosol and may function in in vivo androgen metabolism.  相似文献   

11.
12.
Human brain short chain L-3-hydroxyacyl-CoA dehydrogenase (SCHAD) was found to catalyze the oxidation of 17beta-estradiol and dihydroandrosterone as well as alcohols. Mitochondria have been demonstrated to be the proper location of this NAD+-dependent dehydrogenase in cells, although its primary structure is identical to an amyloid beta-peptide binding protein reportedly associated with the endoplasmic reticulum (ERAB). This fatty acid beta-oxidation enzyme was identified as a novel 17beta-hydroxysteroid dehydrogenase responsible for the inactivation of sex steroid hormones. The catalytic rate constant of the purified enzyme was estimated to be 0.66 min-1 with apparent Km values of 43 and 50 microM for 17beta-estradiol and NAD+, respectively. The catalytic efficiency of this enzyme for the oxidation of 17beta-estradiol was comparable with that of peroxisomal 17beta-hydroxysteroid dehydrogenase type 4. As a result, the human SCHAD gene product, a single-domain multifunctional enzyme, appears to function in two different pathways of lipid metabolism. Because the catalytic functions of human brain short chain L-3-hydroxyacyl-CoA dehydrogenase could weaken the protective effects of estrogen and generate aldehydes in neurons, it is proposed that a high concentration of this enzyme in brain is a potential risk factor for Alzheimer's disease.  相似文献   

13.
1. The temperature dependence of the kinetics of glyceraldehyde-3-phosphate dehydrogenase from white muscle of carp and skeletal muscle of pig was examined. 2. The Km values of carp muscle enzyme were stable over the temperature range 5-35 degrees C, but increased for pig muscle enzyme with increasing temperature. 3. The Arrhenius plot for pig muscle enzyme is linear but non-linear for carp muscle enzyme. 4. The differences indicate that glyceraldehyde-3-phosphate dehydrogenase from white carp muscle may contribute to the adaptive mechanism of carp to varied temperature conditions.  相似文献   

14.
Gonadotropin and steroid hormone levels in both peripheral and ovarian venous blood were measured in samples obtained from 20 Japanese patients with polycystic ovary syndrome (PCOs) and 10 normal women in early follicular phase (normal women) by radioimmunoassay. The change in the amount of steroid hormone following intravenous human menopausal gonadotropin (HMG) or dexamethasone administration was investigated. The mean concentration in patients with PCOs was significantly higher than the concentrations found in normal women for LH (p less than 0.001), but not for FSH in peripheral blood. Significantly elevated ovarian venous steroid hormone levels in PCOs were found for 17 alpha-hydroxypregnenolone (p less than 0.05), progesterone (p less than 0.05), 17 alpha-hydroxyprogesterone (p less than 0.01), 4 delta-androstenedione (p less 0.01), testosterone (p less than 0.01), estrone (p less than 0.01) and estradiol (p less than 0.05), but not for dehydroepiandrosterone-sulfate (DHEAS). The ovarian dehydroepiandrosterone (DHEA) level was slightly elevated in PCOs. The concentration of ovarian 4 delta-androstenedione in PCOs reached twelve times as much as that in normal women. After the administration of HMG, all of the ovarian venus steroid hormone levels were elevated slightly and without significance in the short observation time for 10 min. The DHEAS level was suppressed while the ovarian DHEA level remained high in PCOs following dexamethasone administration. These findings seem to indicate there is no adrenal involvement and no adrenal-like component in the ovary of PCOs, and no evidence of 3 beta-hydroxysteroid dehydrogenase and/or aromatase deficiency in this study. The increase in the steroid hormone secretion in PCOs is explained by the increase in ovarian production in polycystic enlarged ovaries.  相似文献   

15.
WE have reported1 studies on luteinized rat ovary in which we found that an approximate doubling of the rate of steroid synthesis following stimulation with luteinizing hormone was not associated with any change in the tissue NADPH/NADP+ concentration ratio. We concluded that it was unlikely that luteinizing hormone brought about the increase in steroid synthesis solely by increasing the production of NADPH by glucose 6-phosphate dehydrogenase or another cytoplasmic NADPH-linked dehydrogenase, as had been suggested2,3.  相似文献   

16.
1. The activity of 20α-hydroxy steroid dehydrogenase in rat ovarian corpora lutea increased at least 50-fold between 2 days before and 2 days after parturition, and then fell gradually during lactation. The activity of 3β-hydroxy Δ5-steroid dehydrogenase decreased by 50% at parturition but remained constant at other times. 2. The 20α-hydroxypregn-4-en-3-one/progesterone concentration ratio in the ovary fell tenfold between 1 day before and 1 day after parturition, in contrast with the increase of the ratio for these steroids in plasma. 3. Pregnenolone was metabolized in intact cells or cell-free systems either to pregn-5-ene-3β,20α-diol and then to 20α-hydroxypregn-4-en-3-one by 20α-hydroxy steroid dehydrogenase and 3β-hydroxy Δ5-steroid dehydrogenase respectively, or directly to progesterone by the latter enzyme. The relative activities of these pathways appeared to reflect the relative amounts of the two enzymes and the concentrations of their respective coenzymes NADPH and NAD+. 4. From these and other observations it was concluded that the cessation of progesterone secretion, which precedes parturition and lactogenesis at the end of pregnancy, is partly due to the redirected metabolism of pregnenolone away from progesterone and towards 20α-hydroxypregn-4-en-3-one as the secreted end product. This is primarily the consequence of the sharp increase in the activity of 20α-hydroxy steroid dehydrogenase. This mechanism is super-imposed on the already declining rate of net Δ4-steroid release by the ovary. 5. A relationship of these pathways to subcellular compartments of luteal cells is proposed.  相似文献   

17.
The investigations on enzymes related to glutathione like glutathione-S-transferase (GST) and glutathione peroxidase (GSH-Px) have been carried out mostly in human and rat ovaries, however the studies on these enzymes in ruminants are relatively absent. In the present study the changes in the activity of these enzymes, in different sizes of follicles from goat and sheep ovaries of different reproductive stages, were investigated. The results demonstrated that the activity of the enzyme GST increased with the increase in size of the follicles from small to large follicles of follicular phase ovary and from small to medium follicles of luteal phase ovary in both the species, thereafter it decreased in large follicles of luteal phase ovary. There was increasing pattern in the activity of GSH-Px in the follicular phase follicles and a decreasing pattern in the luteal phase follicles from both the species. Thus the changes in the activity of glutathione related enzymes namely GST and GSH-Px in different size follicles from both the species during different reproductive phases are evident from the results. It is reasonable, therefore, to assume that these enzymes may have functional role in the steroid hormone metabolism in ruminant ovary as reported in human ovary.  相似文献   

18.
An NAD+-linked 17 beta-hydroxysteroid dehydrogenase was purified to homogeneity from a fungus, Cylindrocarpon radicicola ATCC 11011 by ion exchange, gel filtration, and hydrophobic chromatographies. The purified preparation of the dehydrogenase showed an apparent molecular weight of 58,600 by gel filtration and polyacrylamide gel electrophoresis. SDS-gel electrophoresis gave Mr = 26,000 for the identical subunits of the protein. The amino-terminal residue of the enzyme protein was determined to be glycine. The enzyme catalyzed the oxidation of 17 beta-hydroxysteroids to the ketosteroids with the reduction of NAD+, which was a specific hydrogen acceptor, and also catalyzed the reduction of 17-ketosteroids with the consumption of NADH. The optimum pH of the dehydrogenase reaction was 10 and that of the reductase reaction was 7.0. The enzyme had a high specific activity for the oxidation of testosterone (Vmax = 85 mumol/min/mg; Km for the steroid = 9.5 microM; Km for NAD+ = 198 microM at pH 10.0) and for the reduction of androstenedione (Vmax = 1.8 mumol/min/mg; Km for the steroid = 24 microM; Km for NADH = 6.8 microM at pH 7.0). In the purified enzyme preparation, no activity of 3 alpha-hydroxysteroid dehydrogenase, 3 beta-hydroxysteroid dehydrogenase, delta 5-3-ketosteroid-4,5-isomerase, or steroid ring A-delta-dehydrogenase was detected. Among several steroids tested, only 17 beta-hydroxysteroids such as testosterone, estradiol-17 beta, and 11 beta-hydroxytestosterone, were oxidized, indicating that the enzyme has a high specificity for the substrate steroid. The stereospecificity of hydrogen transfer by the enzyme in dehydrogenation was examined with [17 alpha-3H]testosterone.  相似文献   

19.
A method involving the use of isolated cholesterol ester-storage granules as substrate is described for the assay of cholesterol esterase in rabbit ovarian tissues. Activities of cholesterol esterase 100-200-fold higher than those previously reported in ovarian tissues were measured by using this method. In addition to that of cholesterol esterase, activities of cholesterol ester synthetase, cholesterol side-chain cleavage enzyme and 3beta-hydroxy steroid dehydrogenase were determined in rabbit ovarian interstitial tissue and corpora lutea. Activities of these enzymes are in general compatible with the flows through them measured under a variety of conditions both in vivo and in vitro. It is concluded that, in the rabbit ovarian tissues investigated, these enzymes are capable of catalysing the conversions usually attributed to them.  相似文献   

20.
Temkin S  Nacharaju VL  Hellman M  Lee YC  Abulafia O 《Steroids》2006,71(11-12):1019-1023
In the ovary cortisol-cortisone inter-conversion is catalyzed by the enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD). Its role in carcinomas of human ovary is unknown. The majority of ovarian cancers are derived from ovarian surface epithelium and the inflammation caused by successive ovulation seems to a play a role in the development of cancer. Cortisol is known to act as anti-inflammatory agent and its metabolism by type 1 and type 11beta-HSD may control the inflammatory action by cortisol in ovary. We undertook this study to investigate type 2 11beta-HSD activity which functions exclusively oxidative direction, in normal ovarian tissue compared to ovarian epithelial cancer. Ovarian tissue was obtained from patients undergoing hysterectomy for both benign and malignant disease. Tissue was placed immediately on dry ice and subsequently transferred to a freezer where they were maintained at -70 degrees C. NAD dependent 11beta-HSD activity was then determined in this tissue. T-test was performed to determine statistical significance. Mean type 2 enzyme activity was 0.87 +/- 1.65 pmol/min g tissue in normal ovarian tissue versus a mean enzyme activity of 2.96 +/- 1.37 pmol/mim g tissue in from cancer specimens. This difference was statistically significant with a p-value of 0.03. Type 2 1beta-HSD activity in ovarian cancer specimens was significantly higher than enzyme activity measured in normal post-menopausal ovarian tissue. Decreased cortisol levels due type 2 1beta-HSD activity may play a role neoplastic transformation as well as tumor proliferation in ovarian cancer by eliminating anti-inflammatory action of cortisol.  相似文献   

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