Role of testosterone, estradiol-17β, and cortisol during vitellogenin synthesis in the catfish, Heteropneustes fossilis (Bloch)

Sundararaj, Bangalore I.; Goswami, Shashi V.; Lamba, Virender J.

doi:10.1016/0016-6480(82)90151-4

Cited by 38 publications

(24 citation statements)

References 28 publications

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“…The circulating levels of estrogens (Tam et al 1990) and cortisol Mackett et al 1992) in brook trout have been observed to be elevated when the fish were exposed to low environmental pH. The essential role of estrogen and the synergistic effects of cortisol in vitellogenesis have been well documented Sundararaj et al 1982). The higher plasma concentrations of glucose, amino acids, free fatty acids, and proteins in acid-treated brook trout (Tam et al 1988;Mackett et al 1992) could probably also enhance the synthesis of vitellogenin and the development of oocytes.…”

Section: Discussionmentioning

confidence: 95%

The development and maturation of vitellogenic oocytes, plasma steroid hormone levels, and gonadotrope activities in acid-stressed brook trout (Salvelinus fontinalis)

Tam¹,

Zhang²

1996

Can. J. Zool.

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Brook trout (Salvelinus fontinalis) were divided into a control group at neutral pH, a food-restricted control (pH-food control) group at neutral pH, and an acid-stressed (pH 4.15) group, and were maintained under these conditions from August 14 to November 1. The food for the pH-food control group was restricted to simulate the reduced food intake of the acid-stressed fish. Throughout September, oocyte development in the acid-stressed fish was accelerated and the oocytes weighed 36-54% more than those of the pH control fish. By late September these oocytes had reached ovulatory size. Then a shift from predominantly high estrogen to high 17~~,20/3-dihydroxy-4-pregnen-3-one levels occurred in the circulation. Ovulation followed and by October 19 all acid-stressed trout had ovulated. The same sequence of events occurred significantly later in the pH control fish and ovulation was not complete on November 1. Although their oocytes were larger than those of pH control fish in September, hormonal changes and ovulation in pH-food control fish occurred at the same time as in pH control fish. The results suggest that while the reduced food intake during acid stress might have contributed to accelerated oocyte growth, the full effect of chronic acid exposure was responsible for advancing oocyte development, maturation, and ovulation.Resume : Des Ombles de fontaine (Salvelinus fontinalis) ont Ct C sCparCs en trois groupes, un groupe tCmoin gardC h pH neutre (tCmoin pH), un groupe ttmoin gardC h pH neutre et soumis h des restrictions alimentaire (pH-nourriture) et un groupe soumis 2i un stress 2i l'acide (pH 4,15); les poissons ont Ct C gardCs dans ces conditions du 14 aoQt au le' novembre. Le rationnement de la nourriture chez le groupe tCmoin pH -nourriture servait h simuler la consornmation rCduite de nourriture chez les poissons stress& par l'acide. Jusqu'h la fin de septembre, le dCveloppement des ovocytes est devenu plus rapide chez les poissons soumis au stress et leurs ovocytes avaient une masse de 36-54% supCrieure h celle des poissons du groupe tkmoin pH. A la fin de septembre, ces ovocytes avaient atteint la taille des ovules. A ce moment, la concentration ClevCe d'oestrogkne a donnC place 2i une concentration ClevCe de 17a,20/3-dihydroxyprCgnkne-4 one-3 dans la circulation. L'ovulation a Ct C dCclenchCe et, dCjh le 19 octobre, tous les poissons stress& par l'acide avaient subi leur ovulation. Les CvCnements se sont produits selon la mCme skquence, mais significativement plus tard, chez les poissons du groupe tCmoin pH, et l'ovulation n'Ctait pas terminCe le le' novembre. Chez les poissons du groupe tCmoin pH-nourriture, les ovocytes Ctaient plus gros que ceux du groupe ttmoin pH en septembre, mais les changements hormonaux et l'ovulation de ces poissons ont eu lieu en mCme temps que chez les poissons du groupe ttmoin pH. Les rCsultats indiquent que si la consommation plus faible de nourriture durant un stress causC par l'acide peut contribuer h l'accC1Cration de la croissance des ovocytes, le dCveloppement accCl...

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Section: Discussionmentioning

confidence: 95%

The development and maturation of vitellogenic oocytes, plasma steroid hormone levels, and gonadotrope activities in acid-stressed brook trout (Salvelinus fontinalis)

Tam¹,

Zhang²

1996

Can. J. Zool.

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“…Such observations have similarly been made with catfish. 22 When administered alone, cortisol suppressed the catfish plasma Vtg protein. 24 Since cortisol is a hormone produced in excess during stress, its seemingly deleterious effects in teleost reproduction in vivo 25,26 and its inability to induce Vtg protein in vitro 27 appear convincing.…”

Section: Introductionmentioning

confidence: 99%

“…Vtg gene expression is more complicated than originally thought. The effects of ambient temperature, 12 androgens, 13 a pituitary factor, 9,14,15 growth hormone, 14 pituitary homogenate, 15 prolactin, [16][17][18] thyroid hormone, 19,20 and glucocorticoids such as dexamethasone 21 and cortisol, 22 on vitellogenesis have called for a reinterpretation of hormone-induced Vtg gene expression.…”

Section: Introductionmentioning

confidence: 99%

Vitellogenesis and Vitellogenin Uptake into Oocytes

Ding¹

2005

Hormones and Their Receptors in Fish Reproduction

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The yolk proteins found in the oocyte of oviparous animals are synthesized by the liver as a large lipophosphoglycoprotein precursor, vitellogenin (Vtg), which represents a vital, sole source of nutrient for the developing larvae. Vitellogenesis underlies early development of oviparous animals. The Vtg gene is extremely sensitive to estrogen and other steroid hormones. Thus, vitellogenesis is a useful model for studying hormonal regulation of eukaryotic gene expression. The Oreochromis aureus vitellogenin, OaVtg gene spans 9 kb and contains 34 exons. Although the OaVtg promoter has a nonconsensus TATA, this promoter is capable of driving basal transcription. Two imperfect estrogen response elements, ERE p (proximal) and ERE d (distal), located in the promoter at Ϫ532 and Ϫ1352 elicit a significant increase in estrogen-dependent reporter gene activity. Competition gel mobility shift assays have demonstrated that ERE p and a novel ERE exon2 (located within exon 2) exhibit specific binding of estrogen receptor. Thus, nonconsensus OaVtg EREs contribute to the estrogen-dependent regulation of the OaVtg gene in vivo. During estrogen-induced vitellogenesis, the massive rate of transcription and translation of Vtg followed by its secretion into the blood makes this a major circulating protein that is taken up by membrane-bound vitellogenin receptors (VtgR) found on oocytes. The VtgR, which belongs to the low density lipoprotein receptor family, interacts with the N-terminal region of Vtg Hormones and Their Receptors in Fish Reproduction Downloaded from www.worldscientific.com by UNIVERSITY OF BIRMINGHAM LIBRARY -INFORMATION SERVICES on 03/20/15. For personal use only. Vitellogenesis and Vitellogenin Receptor 255via electrostatic attraction. Once in the oocytes, Vtg is cleaved into yolk proteins (lipovitellin and phosvitin), which are stored as nutrients for the developing embryo.

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“…This indicates that Vtg isoforms may have different roles during oocyte maturation and embryonic development [5]. Vitellogenin genes are present in both females and males but the lack of estrogens in the males prevents the expression of the protein under normal conditions [16]. …”

Section: Introductionmentioning

confidence: 99%

Untitled

Berg

Modig

Olsson

2004

Reprod Biol Endocrinol

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This study was performed to investigate stress effects on the synthesis of egg yolk precursor, vitellogenin (Vtg) in Arctic char (Salvelinus alpinus). In particular the effect of cortisol (F) was determined since this stress hormone has been suggested to interfere with vitellogenesis and is upregulated during sexual maturation in teleosts. Arctic char Vtg was purified and polyclonal antibodies were produced in order to develop tools to study regulation of vitellogenesis. The Vtg antibodies were used to develop an enzyme-linked immunosorbent assay. The corresponding Vtg cDNA was cloned from a hepatic cDNA library in order to obtain DNA probes to measure Vtg mRNA expression. Analysis of plasma from juvenile Arctic char, of both sexes, exposed to different steroids showed that production of Vtg was induced in a dose dependent fashion by 17beta-estradiol (E2), estrone and estriol. Apart from estrogens a high dose of F also upregulated Vtg. In addition, F, progesterone (P) and tamoxifen were tested to determine these compounds ability to modulate E2 induced Vtg synthesis at both the mRNA and protein level. Tamoxifen was found to inhibit E2 induced Vtg mRNA and protein upregulation. P did not alter the Vtg induction while F reduced the Vtg protein levels without affecting the Vtg mRNA levels. Furthermore the inhibition of Vtg protein was found to be dose dependent. Thus, the inhibitory effect of F on Vtg appears to be mediated at the post-transcriptional level.

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Role of testosterone, estradiol-17β, and cortisol during vitellogenin synthesis in the catfish, Heteropneustes fossilis (Bloch)

Cited by 38 publications

References 28 publications

The development and maturation of vitellogenic oocytes, plasma steroid hormone levels, and gonadotrope activities in acid-stressed brook trout (Salvelinus fontinalis)

The development and maturation of vitellogenic oocytes, plasma steroid hormone levels, and gonadotrope activities in acid-stressed brook trout (Salvelinus fontinalis)

Vitellogenesis and Vitellogenin Uptake into Oocytes

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