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 889 毫秒
1.
17-estradiol, 17-20-dihydroxy-4-pregnen-3-one (17-20-P), and testosterone levels were measured in plasma samples obtained from vitellogenic coho salmon (Oncorhynchus kisutch) before and 32 days after injection of the aromatase inhibitor Fadrozole (AI). Plasma 17-estradiol levels decreased significantly 6 h after injection in all AI treated fish. The higher the dose the longer the maintenance of low plasma 17-estradiol levels. Inversely, plasma 17-20-P increased significantly 6 h after injection in all AI treated fish, and the higher the dose the longer the maintenance of high plasma 17-20-P levels. At 48 h after injection plasma testosterone levels were significantly higher in the AI treated groups. The oocyte maturation index showed that multiple injections with AI retarded oocyte development. Besides, oocyte diameter and GSI were lower in the same group, which presented high incidence of atresia of vitellogenic oocytes. The ovarian follicles and brain of the fish which received multiple injections secreted less 17-estradiol, in vitro. These findings suggest that aromatase inhibitors such as Fadrozole may have a potential as a tool to regulate sexual development in salmon.  相似文献   

2.
A cDNA encoding the subunit of thyrotropin (TSH) was isolated from a goldfish (Carassius auratus) pituitary gland cDNA library. By comparing the sequence with other teleost TSHs, a signal peptide of 19 amino acids and a mature hormone of 131 amino acids were predicted for goldfish TSH subunits. The resulting putative mature hormone of 131 amino acids had well-conserved cysteine positions and a putative N-linked glycosylation site; homology was 51–67% with TSHs from other teleosts, 38–43% with tetrapod TSHs, but only 27 and 29% with goldfish GTH-I and -II, respectively. We also examined the effects of thyroid hormones (TH) and thiourea (TU, an inhibitor of TH production) treatments on TSH and GTH subunit gene expressions in the goldfish pituitary gland. After thyroxine (T4) treatment, circulating T4 concentration increased and TSH mRNA level decreased. Supressing the amount of circulating T4 and triiodothyronine (T3) by TU treatment increased the TSH mRNA level. Moreover, T4 replacement therapy (simultaneous treatment of both TU and T4) caused a high level of circulating T4 and a low level of circulating T3, and a decrease in the TSH mRNA level. Thus, changing levels of circulating TH exert a negative feedback on the level of TSH subunit mRNA in goldfish in vivo. On the other hand, GTH subunit mRNA levels were not affected by changes in the levels of circulating TH.  相似文献   

3.
The objective of this study was to investigate the effects of sex steroids on spermiation in protandrous male black porgy, Acanthopagrus schlegeli. Experiments on common carp (Cyprinus carpio) were also conducted for comparison. Fifty male black porgy were divided into 5 groups and injected with a superactive analogue of mammalian luteinizing hormone releasing hormone (LHRH-A), 17,20,21-trihydroxy-4-pregnen-3-one (20-S), 17,20-dihydroxy-4-pregnen-3-one (17,20-DHP), 11-ketotestosterone (11-KT) or saline. The dosage of the sex steroids given on days 0, 2, 4 and 6 was 330, 330, 990 and 1980 µg kg-1 body weight, respectively. Milt volume and sperm concentrations were measured on days 0, 2, 4, 6, 8 and 10. Similar treatments were also conducted in 45 male common carp. Milt volume was significantly increased in black porgy after treatment with 20-S and 17,20-DHP; 17,20-DHP had stimulatory effects on spermiation at a lower dose (900 µg kg-1 body weight, p < 0.05) as compared to 20-S (1980 µg kg-1 body weight, p < 0.01). In the common carp, milt volume was also increased after treatment with LHRH-A and 17,20-DHP but not with 20-S. 17,20-DHP stimulated spermiation at a lower dose in common carp (330 µg kg-1 body weight) than in black porgy (990 µg kg-1 body weight). However, 11-KT did not stimulate spermiation in black porgy or common carp. The concentrations of plasma 11-KT could immediately reflect to the administration of exogenous 11-KT in black porgy.  相似文献   

4.
Full-grown immature Clarias batrachus oocytes respond in vitro to exogenous 17,20-dihydroxy-4-preg-nen-3-one ( 17,20-DP) by undergoing germinal vesicle breakdown (GVBD). Cytosolic extract (CE) prepared from 17,20-DP-induced oocytes has been shown to produce similar effect when microinjected into unstimulated immature oocytes of the same fish. A dose of 50 nl is enough to cause 100% GVBD after 4 h. Maturation-promoting factor was investigated from 17,20-DP-induced, immature and cycloheximide treated oocytes incubated in presence of [35S] methionine. When the proteins were extracted and analyzed on SDS-PAGE, two prominent bands corresponding to molecular weight 34- and 46-kDa were detected in the CE of mature oocytes. However, labelling of [35S] methionine was observed mainly in the region of 46 kDa protein band indicating de novo synthesis of this particular protein during l7,20-DP-induction. Further, immunoblotting study by using rabbit anti-cyclin B1 antibody has clearly demonstrated that the protein which is newly synthesized is highly homologous to Xenopus cyclin B1 and goldfish cyclin B.  相似文献   

5.
The cDNAs encoding the glycoprotein hormone -subunit (GP) and the gonadotropin II-subunit (GTH II) were cloned from the pituitary gland of the African catfish, Clarias gariepinus. Using RNase protection analysis, we studied the steady-state mRNA levels of GP as well as GTH II in the pituitary gland of adult male catfish. Castration of adult male catfish resulted in a significant decrease of GTH II mRNA levels, whereas there was no change in the GP mRNA levels. Treatment of intact males with a single dose of 11-ketotestosterone (11-KT) resulted in dose-dependent increases in mRNA levels of both GP and GTH II. We conclude that 11-KT, a prominent, non-aromatizable teleost androgen, has a stimulatory effect on the pituitary mRNA levels of GP and GTH II of adult male fish.  相似文献   

6.
Plasma levels of 17,20-dihydroxy-4-pregnen-3-one (17,20OHP), which is involved in the regulation of spermiation in male salmonid fish, increase dramatically at the time of spermiation. To advance the understanding of the regulation of 17,20OHP production during the spermatogenetic cycle in trout, we have studied the in vitro effect of gonadotropin type II (GtH II) and the precursor 17-hydroxy-4-pregnene-3,20-dione (17OHP) on the production of 17,20OHP. The sensitivity with which testes secreted 17,20OHP following stimulation with GtH II was maximum during spermatogenesis. The addition of 17OHP (10 to 1600 ng ml-1) to the culture medium of testes fragments induced a significant and dose-related increase in 17,20OHP secretion. Although the capacity to produce 17,20OHP was not saturated by the 17OHP concentrations used, the conversion rate was highest for tested at an immature stage. As to the regulation of 17OHP, in vivo, a single injection of partially purified salmon gonadotropin (50 ng g-1 body weight) induced a significant increase in the circulating levels of 17OHP of immature males. In conclusion, the maximum sensitivity to GtH II stimulation and the highest conversion rate of 17OHP to 17,20OHP in vitro, occurred before the dramatic increase in the 17,20OHP secretion observed in rainbow trout at the time of spermiation.  相似文献   

7.
Roach ovaries converted 17-hydroxyprogesterone to 17,20-dihydroxy-4-pregnen-3-one (17,20P) and to glucuronides of testosterone and 17,20P. Small amounts of 5-pregnane-3- and -3, 17, 20-triols, 7-hydroxy-5-reduced metabolites and 17,20-dihydroxy-4-pregnen-3-one (17,20P) were also formed. Rudd ovaries converted this substrate mainly to 17,20P, 5-pregnane-3- and -3,17,20-triols, 17,20-dihydroxy-5-pregnan-3-one and testosterone glucuronide. The main metabolites of progesterone with both species were 17,20P, 5-pregnane-3,17,20-triol and 7-hydroxy-5-reduced steroids. Rudd ovaries formed, in addition, 17,20-dihydroxy-5-pregnan-3-one from progesterone. The pattern of metabolites was markedly altered when the concentration of substrate was increased from 42ng to 1 µg or 100 µg. At the highest concentration, glucuronides and polar steroids were not detectable, while at low concentrations they accounted for over 50% of the metabolites. 20-Hydroxysteroid dehydrogenase was shown to have a very high capacity, producing 21–47 µg 17,20P from 100 µg 17-hydroxyprogesterone substrate with 200 mg ovarian tissue in 5h.  相似文献   

8.
In two separate spawning seasons, spermiating male Atlantic halibut were implanted with pellets containing gonadotrophin-releasing hormone agonist (GnRHa). Males were bled repeatedly, and milt samples were collected. Blood samples were assayed for free and conjugated steroids: testosterone, 11-ketotestosterone, 17,20-dihydroxy-4-pregnen-3-one (17,20-P), 17,20-dihydroxy-4-pregnen-3-one (17,20-P), 17,20,21-trihydroxy-4-pregnen-3-one and steroids with a 17,20 configuration. Towards the end of the first season, pellets were implanted into three wild-caught and three hatchery-reared males. No control fish were available. The major progestogen in plasma was identified as sulphated 5-pregnane-3,17,20-triol (3,17,20-P-5-S). Concentrations of this steroid were stimulated by the GnRHa. Sulphated 17,20-P was also identified in the plasma, but at 10-fold lower concentrations than 3,17,20-P-5-S. In the middle of the second season, pellets were implanted into five hatchery-reared males; five unimplanted males were used as controls. Levels of androgens fell following GnRHa treatment, levels of progestogens rose briefly, and there was a significant increase in the fluidity of the milt. Of all the measured steroids, free and sulphated 17,20-P showed the best correlation with milt fluidity.  相似文献   

9.
Changes in steroid hormone levels in the serum and ovarian fluid during overripening were studied in goldfish. Ovulated eggs retained in the ovarian cavity became overripe at around 12h after ovulation based on loss of fertilizability, with advanced degeneration by 24h. Blood and ovarian fluid were taken at 0, 3, 6, 12, 18 and 24h after ovulation. Both serum and ovarian fluid progesterone (P) showed a highly significant decline by 18h with a further decline by 24h; P levels were higher in the ovarian fluid. Serum 17,20-dihydroxy-4-pregnen-3-one(17,20-P) levels showed a progressive and more rapid decline, decreasing significantly by 12h with further decreases by 18h and 24h. Serum testosterone (T) levels increased significantly at 3h and remained high till 18h, thereafter they declined to the 0h level. No significant changes in estradiol-17 (E2) levels were observed in the serum, except for a significant difference between 6 and 24h. There were no significant changes in ovarian fluid E2, T or 17,20-P levels.The postovulatory follicles (POFs) showed degenerative changes which corresponded to the decline in P and 17,20-P. The hypothesis that overripening may be associated with declining levels of P or 17,20-P was tested in vivo by immersing just ovulated females (0h) in P or 17,20-P solutions for 12h, and in vitro by immersing just-ovulated eggs (0h) in ovarian fluid with an anti-serum against P (Anti-P). In the former, P at 0.05 ppm significantly enhanced the fertilization rate of ovulated eggs stripped from the females at 12h while 17,20-P did not produce a significant effect at the tested concentrations (0.025 and 0.05 ppm) on the fertilization rate. In the latter, anti-P significantly lowered the fertilization rate of 0h ovulated eggs after 6h incubation. The evidence suggests a role of P in the maintenance of viability of ovulated eggs.  相似文献   

10.
The mRNA expression of the LH- and FSH- subunits were measured in nesting and post-breeding male three-spined sticklebacks, Gasterosteus aculetaus, as well as in castrated and sham-operated nesting males. Furthermore, expression of an androgen induced kidney protein, spiggin, and 11-ketotestosterone (11KT) levels, were measured in the castrated and sham-operated males. Nesting males had significantly higher levels of both LH- and FSH- mRNA expression compared to post-breeding males. Furthermore, sham-operated males had significantly higher levels of LH- mRNA and spiggin mRNA expression than the castrated fish. Expression of FSH-, on the other hand, did not differ between castrated and sham-operated males. There were strong positive individual correlations between circulating levels of 11KT on the one hand and expressions of LH- and spiggin mRNA, whereas the correlation between 11KT levels and FSH- mRNA was weak. The negative effect of castration on -LH mRNA indicates that gonadal hormones stimulate this expression, whereas this was not the case for -FSH. The observed decline in -LH expression after the end of the breeding season may be the result of cessation of the gonadal stimulation of the pituitary. On the other hand, it is not likely that this can explain the decline in FSH- expression.  相似文献   

11.
Three experimental approaches were chosen to study the question if the progestin 17-hydroxy-20-dihydroprogesterone (1720OHP) is synthesised in testes of young Oncorhynchus mykiss, in which the absence of spermatozoa was verified histologically: first, in order to detect 20-hydroxysteroid dehydrogenase activity (20HSD), testes homogenates were incubated with 3H-labeled 17OHP.Metabolites were analysed by TLC, HPLC, and repeated crystallization to constant isotope ratios. One of the metabolites was identified as 1720OHP-3H, indicating that already immature testes contain 20HSD activity and are able to produce 20-reduced steroids. Second, 1720OHP was quantified by radioimmunoassay in incubates of testes fragments. The sensitivity of the gonads to gonadotropin II (GtH II) became evident when comparing incubations in the absence and presence of GtH II. Third, plasma levels of 1720OHP were significantly higher in animals injected with partially purified salmon gonadotropin, compared to controls. Thus, for the first time, it could be shown that 20HSD is present in testicular cells other than spermatozoa. Furthermore, 1720OHP is indeed secreted at a very early stage of testicular development; 1720OHP secretion is also responsive to GtH II. Future studies will have to show if the functions of this progestin include the stimulation of spermatogenesis.  相似文献   

12.
As part of a series of experiments concerning a possible pheromonal function of steroids and steroid glucuronides excreted by the sex organs of the African catfish,Clarias gariepinus, qualitative and quantitative studies, using GCMS, were carried out to examine the presence of the steroids, that can be synthesized by the ovary during oocyte maturation and ovulation, and of the corresponding steroid glucuronides, in the fluid surrounding the eggs in the ovarian cavity shortly after ovulation.Full mass spectra were obtained of 5-pregnane-3,17-diol-20-one, 5-pregnane-3,17,20-triol, 5-pregnane-3,6,17-triol-20-one, 5-pregnane-3,6,17,20-tetrol, 5-androstane-3,17-diol and 5-androstane-3,17-diol-11-one. After selected ion monitoring the following steroids could be detected by the presence of at least two characteristic ions at the expected retention time: 5-pregnane-3, 17,20-triol, etiocholanolone, 5-dihydrotestosterone, 5-androstane-3,11-diol-17-one, testosterone and estradiol. After treatment with -glucuronidase the following steroids could be determined in a similar way: 5-pregnane-3,17-diol-20-one, 5-pregnane-3,17,20-triol, 5-pregnane-3,17,20-triol, 5-pregnane-3,6,17-triol-20-one, 5-pregnane,3,6,17,20-tetrol, 5-androstane-3,17-diol, etiocholanolone, 5-dihydrotestosterone, testosterone and estradiol.The free steroids 5-pregnane-3,6,17,20-tetrol and 5-pregnane-3,6,17-triol-20-one and the steroid glucuronides of testosterone, 5-dihydrotestosterone and estradiol appeared to be the most abundant of these compounds. The results indicate that very polar steroids and steroid glucuronides, synthesized in the ovary, can be excreted via the ovarian fluid shortly before and during oviposition, and possibly function as sex attractants, inducing reproductive behaviour in male conspecifics.  相似文献   

13.
The plasma concentrations of fourteen ovarian steroids were measured in postvitellogenic African catfish,Clarias gariepinus, which had been injected with pimozide and LHRHa. Postvitellogenesis persisted for at least four hours after pimozide and LHRHa administration. During this stage a limited rise in the plasma gonadotropin (GTH) level was accompanied by an increase in the testosterone concentration. The estradiol level was high and remained high except for a passing drop during the stage of germinal vesicle migration. At the stage of germinal vesicle migration a strong increase in the plasma GTH level coincided with a maximum in the testosterone concentration and a concomitant increase in the levels of 17,20-dihydroxy-4-pregnen-3-one and of five 5-reduced pregnanes. During germinal vesicle breakdown the GTH concentration remained high, the plasma level of 17-hydroxyprogesterone tended to increase, and the levels of 5-pregnane-3, 17-diol-20-one, 5-pregnane-3,17,20-triol and 5-pregnane-3,17,20-triol reached a maximum. At pre-ovulation the GTH concentration did not change, and peak levels were reached of 17,20-dihydroxy-4-pregnen-3-one and 5-pregnane-3,6,17-triol-20-one. Shortly after ovulation the GTH concentration slightly decreased together with a sharp decline in the concentrations of 17,20-dihydroxy-4-pregnen-3-one and the 5-reduced steroids, with the exception of 5-pregnane-3,17,20-triol, 5-pregnane-3,6,17,20-tetrol and 5-dihydrotestosterone. The plasma concentrations of androstenedione, estrone, etiocholanolone and 5-androstane-3,17-diol showed marginal fluctuations during oocyte maturation and ovulation. Apart from 17,20-dihydroxy-4-pregnen-3-one, the 5-reduced pregnanes might be candidates for the function of oocyte maturation inducing hormone inC. gariepinus.  相似文献   

14.
In order to specify the timing of some changes in ovarian steroid production during the transition from vitellogenesis to ovulation, plasma hormones levels andin vivo andin vitro responses of the ovary to salmon gonadotropin (s-GtH) or dibutyryl-cyclic adenosine mono-phosphate (db-cAMP) were recorded in relationship with the state of germinal vesicle migration in the oocyte.In vivo, a small, but significant, increase of plasma 17-hydroxy-20-dihydroprogesterone (17, 20-OH-P) level was detected earlier (at the subperipheral germinal vesicle stage) than the increase of GtH level (detectable at the peripheral germinal vesicle stage) and the decline of oestradiol-17 (E2–17) (also detectable at the peripheral germinal vesicle stage). Negative correlations were established between E2–17 levels and GtH (=–0.53) or 17,20-OH-P (=–0,43) levels while a positive correlation occurred between 17,20-OH-P and GtH levels (=+0,54).In vivo no action of GtH on the decline of E2–17 levels was detected GtH did not stimulate 17,20-OH-P production, within 72h, in females at the end of vitellogenesis stage. It had significant effect in females at other stages closer to ovulation, but the pattern of responses changed according to the stage.In vitro db-cAMP like GtH was able to stimulate 17,20-OH-P output from ovarian follicles. The greatest response was observed at the later stage. (GVBD). Testosterone output was also increased by GtH, but the lowest response was observed at the later stage (GVBD). Androstenedione output was lower than testosterone output.In vitro, a small but significant decline of E2–17 output was induced by GtH. We conclude that substantial changes occur during the very last stages prior to ovulation, both in the steroidogenic potential of the ovary and in the ovarian sensitivity to GtH. 20-oxydoreductase is probably progressively induced during GV migration when GtH basal levels are increasing but still relatively low. Without minimizing the role of discrete pulses of GtH on this induction, we could expect synergic actions of other hormones. Thus a high testosterone/oestradiol ratio in the follicle environment favours 17,20-OH-P secretion.  相似文献   

15.
Goldfish, carp and trout gills were incubated with 3H-17-hydroxyprogesterone (17P). With goldfish gills, the metabolites were 17,20-dihydroxy-4-pregnen-3-one (17,20P; 82%), 17,20-dihydroxy-4-pregnen-3-one (17,20P; 8%), 11-ketotestosterone (KT) glucuronide (5.4%) and 17,20P glucuronide (0.2%). Sulfates were not detected. Carp gills converted 17P into 17,20P (11.2%), 17,20P (9.6%), KT (8.4%), glucuronides of 17,20P (1.3%) and 17,20P (1.6%) and sulfates of 17,20P (5.1%) and 17,20P (7.2%). 17,20P (38% free, 1.8% glucuronide and 21.1% sulfate) was the sole metabolite of 3H-17P in trout gill incubations. In the presence of high (10; µg ml-1) substrate concentration, cyprinid gills gave predominantly free 17,20P, while trout gills yielded only free 17,20P. Production of 17,20P, predominantly as its sulfate, from endogenous precursors was demonstrated in trout gills but was not stimulated by trout primary extract. Our results demonstrate for the first time the steroidogenic potential of teleost gills and suggest that they may play a role in secretion of pheromones in some species.  相似文献   

16.
Rainbow trout ovarian follicles were incubated in vitro with tritiated 17,20-dihydroxy-4-pregnen-3-one (17,20-P; maturation-inducing steroid). Within 18–24 h, 56–66% had been converted to tritiated 17,20-dihydroxy-4-pregnen-3-one 20-sulfate (identification confirmed by HPLC) and 27% had been taken up (absorbed) by the follicles. Addition of 125 ng of cold (non-tritiated) 17,20-P to the incubations caused a decrease in the percentage of [3H]-17,20-P which was sulfated (56% 10%) and an increase in the percentage that was taken up (27% 57%). Seven steroids were tested for their effectiveness in decreasing the sulfation and increasing the uptake of tritiated [3H]-17,20-P. The order of effectiveness was in both cases the same: 17,20-P > cortisol > 11-deoxycortisol > 17,20,21-trihydroxy-4-pregnen-3-one > 17-hydroxy-4-pregnene-3,20-dione > 17-estradiol > testosterone. This indicated that the processes of sulfation and uptake of [3H]-17,20-P were related to each other and led to the hypothesis that, when cold 17,20-P is added to the medium, it reduces the proportion of [3H]-17,20-P which is sulfated and thus allows more free [3H]-17,20-P to enter the ovarian follicles. This hypothesis was supported by the finding that each ovarian follicle had the capacity in vitro to sulfate only ca. 2 ng of [3H]-17,20-P per 18h but a capacity to take up > 500 ng per 18h.Gonadotropin I, Gonadotropin II, forskolin and phorbol-12-myristate-13-acetate (which all have an affect on steroid biosynthesis) did not affect the amount of 17,20-P which was sulfated. Sulfating activity was localized in the thecal cell layer of the follicle. The yolk fraction was shown to be responsible for absorbing the [3H]-17,20-P.  相似文献   

17.
Changes in ovarian steroidogenesis accompanying oocyte maturation and ovulation were studied in the African catfish,Clarias gariepinus. Laboratory-reared females with postvitellogenic ovaries were treated with pimozide and LHRH-analogue. The plasma gonadotropin levels were determined by means of a homologous radioimmunoassay, the condition of the ovaries was studied by histological examination of the follicles, and the steroidogenetic capacity of the ovaries was analyzed byin vitro incubation of tissue fragments for 3 h with [3H]-pregnenolone and [3H]androstenedione as precursors. Data were collected at regular intervals between 0 and 16 h after pimozide-LHRH analogue administration.Until 4 h after the beginning of the experiments the plasma gonadotropin levels did not rise above 25 ng/ml, the ovaries remained in the stage of postvitellogenesis, and testosterone was the main end product of steroidogenesis. Four hours later the gonadotropin concentration in the blood had risen to more than 150 ng/ml, and the ovaries had entered the stage of germinal vesicle migration. At the same time steroidogenesis shifted towards the production of 17,20-dihydroxy-4-pregnen-3-one, 5-pregnane-3, 17-diol-20-one, 5-pregnane-3,6,17-triol-20-one, 5-pregnane-3,17,20-triol and 5-pregnane-3,6,17,20-tetrol. During the subsequent stage of germinal vesicle breakdown the plasma gonadotropin level remained high, and the synthesis of the C21-steroids showed a further increase. Simultaneously, the production of some C19-steroid glucuronides was enhanced. The preovulation and especially the postovulation stages were accompanied by a gradual decrease in steroidogenic capacity of the ovaries, even though the plasma gonadotropin level remained high. It is concluded that the prematuration surge of gonadotropin influences the activity of enzymes involved in steroidogenesis, leading to a reduced C17,20-lyase and to an augmented activity of the enzymes 20-hydroxysteroid dehydrogenase (HSD), 5-reductase, 3-HSD, 6-hydroxylase and UDP-glucuronosyltransferase. During ovulation the activity of all steroidogenic enzymes, including such key enzymes as 3-HSD and 17-hydroxylase, gradually decreases.Not only 17,20-dihydroxy-4-pregnen-3-one, but also the 5-reduced pregnanes may be involved in inducing oocyte maturation and/or ovulation. The very polar triol and tetrol products may function, together with the steroid glucuronides as sex pheromones.A preliminary account of these results was presented at the XIII Conference of European Comparative Endocrinologists, Belgrade, September 7–12, 1986  相似文献   

18.
The female bambooleaf wrasse, Pseudolabrus japonicus, spawns daily during the spawning season, and exhibits a diurnal rhythm of ovarian development. In the present study, we have investigated: (1) circulating levels of 17a, 20-dihydroxy-4-pregnen- 17,20-P) and 17,20,21-trihydroxy-4-pregnen-3-one (20-S) in females sampled at different times of the day during spawning season in captivity, and (2) in vitro production of 17,20-P and 20-S by follicle-enclosed oocytes at seven different develo tal stages. In addition, we developed a microtiter plate enzyme-linked immunosorbent assay (ELISA) for 17,20-P. Serum levels of 17,20-P and 20-S showed similar diurnal changes; substantial increases in these levels occurred around the time of germinal vesicle breakdown (GVBD). In vitro experiments showed that massive production of 17,20-P and 20-S occurred in follicles collected just before or during GVBD. Further, acute decreases in 17,20-P and 20-S production were found in the ovarian follicles just prior to ovulation, suggesting inactivation of the maturation-inducing hormone (MIH). These results, taken together with our previous data on the occurrence of GVBD in vitro, suggest a role for both 17,20-P and 20b-S as MIHs in the bambooleaf wrasse.  相似文献   

19.
Maturation-inducing steroid (MIS) in the Indian female catfish,Clarias batrachus, was purified and characterized from the incubation medium in which fully grown but immature folliculated oocytes were incubated with salmon gonadotropin (SG-G100) for 36 h. Maturation-inducing (MI) activity of residues obtained at various steps of extraction and purification was assessed byin vitro germinal vesicle breakdown (GVBD) assay using folliculated oocytes ofC. batrachus. The post incubation medium was extracted with diethyl ether. The ether phase was partitioned using 50% methanol plus n-hexane. The methanol phase which had MI activity was fractionated into 7 fractions using reverse-phase high-performance liquid chromatography. Of these 7 fractions, fraction 3 was found to be active in having MI ability and identified as 17 ,20-dihydroxy-4-pregnen-3-one (17,20-diOHprog). The authenticity of 17,20-diOHprog as the major follicular mediator of gonadotropin-induced oocyte maturation was further confirmed by thin-layer chromatography (TLC) in which fraction 3 was run along with authentic 17,20-diOHprog standard. This investigation gives a direct evidence that 17,20-diOHprog is the major naturally occurring MIS in Indian female catfish,C. batrachus.  相似文献   

20.
Testosterone, 3,17-dihydroxy-5-pregnen-20-one, 17,20-dihydroxy-4-pregnen-3-one (17,20P) and 5-pregnane-3,17,20-triol were identified as the major metabolites of [3H] 17-hydroxyprogesterone in ovarian incubations of the European catfish Silurus glanis. 17,20P and the reduced triol were present only in ovaries from fish primed with carp hypophysial homogenate (chh) while testosterone yields were significantly higher in controls than in treated fish. 11-Ketotestosterone, 11-hydroxytestosterone and 17,20-dihydroxy-4-pregnen-3-one (17,20P) were identified as the major metabolites of [3H]17-hydroxyprogesterone in in vitro incubations of testes of a spermiating catfish. There was no significant production of conjugates or other water soluble metabolites by either sex. The stimulation of plasma 17,20P, 17,20P and 11-hydroxytestosterone by chh in primed but not control males suggests that the role of these steroids in spermiation should be further examined.  相似文献   

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