虹鳟排卵前后血清中性类固醇激素浓度变化的研究   总被引：4，自引：0，他引：4  

赵维信 《水产学报》1987,11(3):205-213

对虹鳟(Salmo gairdneri)排卵前后血清17β-雌二醇(17β-E_2),睾酮(T)和17α-羟-20β-双氢孕酮(17α20βP)的含量进行了测定。17β-E_2从排卵前15天的18.1ng/ml急骤下降到排卵前3—6天的2ng/ml,并继续下降,至排卵时仅为0.9ng/ml。睾酮在虹鳟雌鱼血清中的含量很高,血清浓度从排卵前9天的峰值水平143.3ng/ml缓慢下降,排卵时为24.3ng/ml。17α20βP的血清浓度变化明显,排卵前15天,该激素浓度接近于基线水平或甚至低得不能被检测,排卵前9天开始迅速上升,到排卵前3天达到峰值350.6ng/ml,排卵时为302.2ng/ml。本研究进一步证实了17α20βP在鲑鳟鱼类卵母细胞最后成熟过程中的生理作用,是一种诱发卵母细胞成熟的类固醇激素。临排卵前,血清17β-E_2浓度的下降,可能调节了17α20βP大量分泌的时间;17α20βP的大量分泌是卵母细胞达到最后成熟和排卵不可缺少的一环。注射合成的大麻哈鱼(Oncorhynchus keta)促性腺激素释放激素(s-GnRH)及其类似物(s-GnRH-A),诱发虹鳟血清类固醇激素17β-E_2,睾酮和17α20βP的变化趋势与自然排卵时的变化相类似。经注射药物诱发排卵的鱼,较对照组提早一周排卵,而且排卵较同步和集中。  相似文献   

Differentiation and development of Leydig cell, and induction of spermatogenesis during testicular differentiation in the Japanese eel, Anguilla japonica     

H. Chiba  T. Miura  M. Nakamura  K. Yamauchi 《Fish physiology and biochemistry》1997,16(3):187-195

The initial appearance and the development of Leydig cells (LCs), the sites of steroid hormone production in the testis, were investigated ultrastructurally during testicular differentiation in the Japanese eel, Anguilla japonica. In addition, the effects of a single injection of human chorionic gonadotropin (HCG; 5 IU g body weight^-1) on histological changes of the testes and serum 11-ketotestosterone (11-KT) were examined at various stages (15–18, 20–23, 26–29, 32–35, 38–41 and 46–50 cm body length (BL)) of testicular differentiation. Testicular differentiation was morphologically characterized by the development of loose connective tissue on the medial side in animals 18–29 cm in BL. Ultrastructurally, LCs were first identified in the loose connective tissue of the testis of the 23 cm fish. In the testes of fish over 32 cm, clusters of LCs were distributed throughout the interstitial region accompanying the increase in number of spermatogonia. In fish larger than 32 cm, spermatogenesis was induced by administration of HCG; serum 11-KT levels were also raised. On the other hand, there was no effect on spermatogenesis or serum 11-KT levels in fish less than 29 cm, or in the controls. These result suggests that morphological differentiation of LCs occurs in testis of the 23 cm eel, and subsequently, the testes of eels of BL more than 32 cm acquire the capability to produce steroid hormones.  相似文献   

不同温度下雌激素对施氏鲟早期性腺发育及血清性激素的影响     

张颖  孙大江  曲秋芝  刘海金 《东北农业大学学报》2011,42(12):118-125

在不同养殖温度下注射外源雌激素后对孵化后90日龄的施氏鲟性未分化的仔鱼进行培育,研究早期性腺发育过程中组织结构和血清性激素含量的变化,以了解温度和外源雌激素对施氏鲟幼鱼性分化和性别比率的影响,探讨施氏鲟的早期性别控制方法和机制。在不同试验温度下,注射外源雌激素-17β-estradiol(E2)30 d后,使施氏鲟幼鱼的卵巢分化提前,但未能改变施氏鲟雌雄1∶1的性别比率。注射24 h后各温度组血浆T含量下降到0 ng.mL-1,显著低于对照组0.46 ng.mL-1的水平(P<0.05)。注射30 d后,血浆T含量有所回升,但以高温组21、24和27℃组的血浆T含量开始回升,27℃组回升幅度最大,与处理前水平无显著差异(P>0.05)。注射后24 h,各温度组血浆E2含量显著升高(P<0.05),7 d后开始缓慢降低,15 d后降到最低值后开始回升,30 d时血浆E2含量与对照组差异不显著(P>0.05)。与注射后血清T含量一样,以温度高组回升快,最快组为21℃组。结果表明,注射17β-E2不能改变施氏鲟的性别比率,但对施氏鲟血浆T和E2含量具有一定影响作用。  相似文献   

Regulation by gonadal steroids of estrogen and progesterone receptors along the reproductive tract in female lambs.   总被引：2，自引：0，他引：2  

A Meikle  EG Garófalo  M Rodríguez-Pi?ón  C Tasende  L Sahlin 《Acta veterinaria Scandinavica》2001,42(1):161-169

The regulation of estrogen and progesterone receptor (ER, PR) expression by estradiol (E2) and progesterone (P4) in the oviduct, uterus and cervix of female lambs was studied. The animals received three intramuscular injections of E2, P4 or vehicle with an interval of 24 h and they were slaugthered 24 h after the third injection. Determinations of ER and PR were performed by binding assays and mRNAs of ER alpha and PR by solution hybridization. High levels of ER and PR in both cervix and oviduct were found in the female lamb, differing from other mammalian species. No significant effects by either E2 or P4 treatment on ER and PR levels in the cervix and oviduct could be observed. E2 treatment increased the mRNA levels of ERa and PR more than 3-fold in the cervix, while P4 treatment increased the mRNA levels of ERa and PR in the uterus. The results show differential effects of gonadal steroids on sex steroid receptor expression along the reproductive tract in female lambs, suggesting that steroid target tissues can modulate responses to the same circulating levels of steroid hormones.  相似文献   

The duality of teleost gonadotropins   总被引：5，自引：0，他引：5  

Hiroshi Kawauchi  Kunimasa Suzuki  Hiromichi Itoh  Penny Swanson  Nobuko Naito  Yoshitaka Nagahama  Masumi Nozaki  Yasumitu Nakai  Seiga Itoh 《Fish physiology and biochemistry》1989,7(1-6):29-38

The duality of salmon gonadotropins has been proved by biochemical, biological, and immunological characterization of two chemically distinc gonadotropins. GTH I and GTH II were equipotent in stimulating estradiol production, whereas GTH II appears to be more potent in stimulating maturational steroid synthesis. The ratio of plasma levels and pituitary contents of GTHs and the secretory control by a GnRH suggest that GTH I is the predominant GTH during vitellogenesis and early stages of spermatogenesis in salmonids, whereas GTH II is predominant at the time of spermiation and ovulation. GTH I and GTH II are found in distinctly separate cells. In trout, GTH I is expressed first in ontogeny, whereas GTH II cells appear coincident with the onset of spermatogenesis and vitellogenesis, and increase dramatically at the time of final reproductive maturation. Comparison of the amino acid sequences of polypeptides and the base sequences of cDNA revealed that salmon GTH I β is more similar to bovine FSHβ than bovine LHβ and salmon GTH II β shows higher homology to bovine LHβ than to bovine FSHβ. The existence of two pituitary gonadotropins in teleosts as well as tetrapods suggests that the divergence of the GTH gene took place earlier than the time of divergence of teleosts from the main line of evolution leading to tetrapods.  相似文献   

Differential distribution and response to experimental sexual maturation of two forms of brain gonadotropin-releasing hormone (GnRH) in the European eel,Anguilla anguilla     

Sylvie Dufour  Maïté Montero  Nadine Le Belle  Marc Bassompierre  Judy A. King  Robert P. Millar  Richard E. Peter  Yves-Alain Fontaine 《Fish physiology and biochemistry》1993,11(1-6):99-106

Using specific radioimmunoassays for the two GnRH molecular forms present in the European eel, Anguilla anguilla, (mGnRH and cGnRH II), we compared their distributions in the pituitary and different parts of the brain of female silver eels, as well as the modifications of their levels in experimentally matured female eels (treated with carp pituitary extract). In control eels, mGnRH levels were higher than cGnRH II levels in the pituitary, olfactory lobes and telencephalon, di- and mesencephalon, while the opposite was found in the posterior part of the brain (met- and myelencephalon). Experimental sexual maturation of the gonads significantly increased mGnRH levels in the pituitary and anterior parts of the brain; such a positive effect was not observed on the low cGnRH II levels, which were, in contrast, reduced. These data indicate that the positive feedback of gonadal hormones on GnRH, that we previously demonstrated, would specifically affect the mGnRH form. The differential distribution and control of mGnRH and cGnRH II suggest that these two forms have different physiological roles in the eel. The large increase in mGnRH during sexual maturation suggests the prime implication of this form in the neuroendocrine control of reproduction.  相似文献   

Effect of cortisol on the metabolism of 17-hydroxyprogesterone by Arctic charr and rainbow trout embryos     

M.N. Khan  P.K. Reddy  R.L. Renaud  J.F. Leatherland 《Fish physiology and biochemistry》1997,16(3):197-209

The effect of cortisol on the in vitro metabolism of [³H]17-hydroxyprogesterone ([³H]17OHP) was studied during embryonic development of Arctic charr (Salvelinus alpinus) and rainbow trout (Oncorhynchus mykiss). In the absence of cortisol, rainbow trout embryos metabolized [³H]17OHP largely to androstenedione (A₄) and androstenetrione (11-KA) with a minor conversion to 17,20ß-dihydroxy-4-pregnen-3-one (17,20P). In the presence of cortisol, this biosynthesis was inhibited. On the other hand, cortisol had no apparent inhibitory effect on the nature of metabolism of [³H]17OHP by Arctic charr embryos. In these embryos [³H]17OHP was metabolized mainly to 17,20P with a minor conversion to A₄ and without the formation of 11-KA that was seen in rainbow trout.When incubated in the presence of [³H]cortisol both Arctic charr and rainbow trout embryos produced 11ß-hydroxyandrostenedione (11ß-OHA) as the major metabolite, with a minor conversion to an unknown steroid. The catabolism of the cortisol by salmonid embryos may reflect the ability of the embryo to inactivate or detoxify cortisol to protect itself from the adverse effects of this biologically potent steroid hormone The study indicates the existence of species-specific differences in the nature of metabolism of [³H]17OHP and the inhibitory effect of cortisol on this metabolism.  相似文献   

Evidence that 17α,20β,21-trihydroxy-4-pregnen-3-one is a maturation-inducing steroid in spotted seatrout     

Peter Thomas  John M. Trant 《Fish physiology and biochemistry》1989,7(1-6):185-191

Ovarian steroidogenesis during final oocyte maturation (FOM) in the spotted seatrout (Cynoscion nebulosus) was investigated by incubating ovarian fragments with tritiated pregnenolone, followed by chromatographic separation of the radioactive products. The major tritiated steroid produced during FOM comigrated with 17α,20β,21-trihydroxy-4-pregnen-3-one (20β-dihydro-11-deoxycortisol, 20β-S) on HPLC and TLC. Only minor amounts of radioactive material coeluted with 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-P), 11-deoxycorticosterone (DOC), estradiol-17β and testosterone standards in the HPLC system. Additional chromatography by TLC confirmed the presence of radioactive estradiol-17β and testosterone but not 17α,20β-P and DOC. All the ovarian steroids producedin vitro during FOM were assayed for their ability to induce germinal vesicle breakdown (GVBD) of spotted seatrout oocytes. Twenty grams of ovarian tissue were incubated with human chorionic gonadotropin and exogenous pregnenolone. The steroidal products were purified by HPLC and TLC. Most of the maturation-inducing activity was confined to steroidal material which comigrated in these systems with 20β-S. This material was active at a concentration of 1 ng steroid/ml medium in the GVBD assay. Smaller amounts of material which coeluted with 11-deoxycortisol, DOC, 17α,20β-P and several minor unidentified fractions induced GVBD at concentrations of 10 ng steroid(s)/ml. The structure-activity relationships of authentic steroids in inducing GVBD of spotted seatrout oocytes was investigated. Hydroxylation at the 17α, 20β or 21 positions increased potency to induce GVBD. Steroids with multiple hydroxyl groups at the 17α and 20β positions (17α, 20β-P) and at the 17α, 20β, and 21 positions (20β-S) had maximum biological activity in the GVBD bioassay. The results suggest that 20β-S is a major maturation-inducing steroid in spotted seatrout.  相似文献   

Isolation of a novel hepatic CYP2-related protein from channel catfish, Ictalurus punctatus     

E.J. Perkins  B.C. DeBusk  D. Schlenk 《Fish physiology and biochemistry》2000,22(3):199-206

Channel catfish (Ictalurus punctatus) have been previously shown to express two major cytochrome P450 (CYP) protein bands that are cross-reactive with anti-CYP2K1 (rainbow trout, Oncorhynchus mykiss) antibodies on Western blots. These proteins appear to be the major constitutive CYPs in channel catfish and show distinct sex- and age-specific variations in expression. Because I. punctatus is an important agricultural and ecological commodity, and because it displays a high degree of resistance to the toxic effects of many pesticides, the molecular and catalytic characteristics of its biotransformation systems are of interest to those in areas of environmental science and aquaculture research. Using a chromatographic method similar to that employed in the purification of other fish CYP2 enzymes, a single CYP2-related protein (CM-HA3) was isolated from channel catfish hepatic microsomes. The isolated protein displays a relative molecular mass of approximately 47 kDa, and a CO-reduced difference spectrum _max of 449.6 nm. The sequence of 15 residues at the amino-terminal of CM-HA3 is 27% identical to both CYP2K1 and CYP2M1 isoforms of rainbow trout. Correlational analysis was employed to characterize potential substrates for this isoform, but no significant relationship was observed with E₂ hydroxylation, testosterone hydroxylation, or 7-ethoxycoumarin O-deethylase activities. These data indicate that CM-HA3 is a CYP2 family protein, with as yet uncharacterized substrate specificities.  相似文献   

Involvement of steroid hormones in the preovulatory gonadotropin surge in female goldfish     

Makito Kobayashi  Katsumi Aida  Isao Hanyu 《Fish physiology and biochemistry》1989,7(1-6):141-146

Goldfish,Carassius auratus, spawn several times within a spawning season. A gonadotropin (GtH) surge occurs at the time of ovulation in this cyprinid species. This ovulatory GtH surge mediates the processes of final oocyte maturation and ovulation, and occurs at the end of each spawning cycle. Within a cycle, there is a shift in the predominant plasma steroid from estradiol to testosterone, and finally 17α, 20β-dihydroxy-4-pregnen-3-one at the time of the ovulatory GtH surge. High levels of testosterone were always observed before ovulation. When ovariectomized or sexually regressed female goldfish were implanted with testosterone, they exhibited a GtH surge which was similar to those normally observed at ovulation. These results strongly suggest that elevated plasma testosterone is an important physiological requirement for the occurrence of the GtH surge.  相似文献