Release of Pituitary Gonadotrophins GtH I and GtH II in the Rainbow Trout (Oncorhynchus mykiss): Modulation by Estradiol and Catecholamines

Saligaut, Christian; Linard, Boris; Mañanós, Evaristo L.; Kah, Olivier; Breton, Bernard; Govoroun, Marina

doi:10.1006/gcen.1997.7033

Cited by 103 publications

(68 citation statements)

References 29 publications

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“…Another action demonstrated for estrogens in teleost fish is the positive and negative feedback on the brain-pituitary complex (Saligaut et al 1998) and in this context the distribution of ER has been characterized (Anglade et al 1994, Linard et al 1996. RT-PCR analysis of seabream brain only detected ER but further studies will be required to completely exclude the possibility that ER is also present.…”

mentioning

confidence: 99%

Two estrogen receptors expressed in the teleost fish, Sparus aurata: cDNA cloning, characterization and tissue distribution

Socorro¹,

Power²,

Olsson³

et al. 2000

Journal of Endocrinology

124

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Estrogen is an essential hormone for many reproductive and non-reproductive functions. The function of estrogen in the reproductive cycle of seabream (Sparus aurata), a protandrous hermaphrodite teleost fish, is complex but it is understood to be involved in sex inversion, a process that occurs in some individuals during the second reproductive season. Estrogen action is mediated by two estrogen receptor (ER) subtypes designated alpha and beta. As a step to understanding the mechanisms of estrogen action during natural and induced sex reversal in seabream, we have isolated two cDNAs encoding distinct forms of ER homologous to mammalian ER and ER . The seabream ER clone (sbER 1), which was truncated in the A/B domain, corresponded to a variant differing in five amino acids from another recently cloned sbER . The ER clone (sbER ) encoded a protein 559 amino acids long and showed only 40% identity to sbER . Northern blot analysis of liver and ovary mRNA indicated the presence of several transcripts of the two receptor subtypes. PCR analysis showed that the two receptors differed in their expression pattern. sbER had a more restricted distribution, occurring mainly in testis, liver and heart, and sbER was present in most tissues, being more abundant in ovary, testis, liver, intestine and kidney. The presence in seabream of two ERs with several ER transcripts and their pattern of distribution are consistent with the widespread effects of estrogen in different tissues.

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mentioning

confidence: 99%

Two estrogen receptors expressed in the teleost fish, Sparus aurata: cDNA cloning, characterization and tissue distribution

Socorro¹,

Power²,

Olsson³

et al. 2000

Journal of Endocrinology

124

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“…In some fish species, 5-HT and DA regulate secretion of gonadotropin releasing hormone (GnRH) and gonadotropin (GTH), respectively (Billard et al, 1984;Khan and Thomas, 1992;Saligaut et al, 1998). If the levels of 5-HT or DA were altered, secretion of GnRH or GTH could be disrupted.…”

Section: Discussionmentioning

confidence: 99%

“…Because DA and 5-HT are associated with secretion of GnRH and GTH in fish (Billard et al, 1984;Khan and Thomas, 1992;Saligaut et al, 1998), it is assumed that a sexual difference in monoamine content does exist, at least in the hypothalamus or pituitary, which secrete GnRH and GTH, respectively. In the present study, however, we measured whole-brain monoamine concentrations, and so we could not detect a possible region-specific alteration of monoamines in the brain.…”

Section: Discussionmentioning

confidence: 99%

Alteration of monoamine concentrations in the brain of medaka, Oryzias latipes, exposed to tributyltin

Nakayama¹,

Oshima²,

Tachibana³

et al. 2007

Environmental Toxicology

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ABSTRACT:We measured the concentrations of monoamines in the brain of Japanese medaka, Oryzias latipes, exposed to tributyltin (TBT). Fish were exposed to 0, 1, 5, 25, or 125 g g À1 of TBT via the diet for 21 days. After the administration period, six males and six females in each treatment group were dissected and their brains were collected. The following monoamines were analyzed: dopamine (DA), norepinephrine (NE), epinephrine (E), and 5-hydroxytryptamine (5-HT). The metabolites of DA, 3,4-dihydroxyphenylacetic acid and homovanilic acid, and the metabolite of 5-HT, 5-hydroxyindolacetic acid were also analyzed. The concentration of DA in the brain of male medaka and the concentrations of 5-HT and NE in the female brains were significantly decreased by exposure to 125 g TBT g À1. The concentrations of 5-HT and NE in males and of DA in females were slightly decreased by 125 g g À1 of TBT, although the differences were not statistically significant. The present study demonstrates that TBT alters monoamine concentrations in the brain of medaka. # 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 53-57, 2007.

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“…The observed increases in LH levels can be suppressed by treatment with estradiol, testosterone, or both. FSH is also controlled by steroid-dependent negative feedback loops in rainbow trout (49), salmon (50), and goldfish (51). The negative feedback effects of steroids may be mediated primarily at the levels of the hypothalamic GnRH neurons (52-54), because both in vivo and in vitro studies have shown that the expression of LHβ mRNA or FSHβ mRNA is often unchanged or increases following exposure to estradiol, testosterone, or both (49,53,55).…”

Section: Feedback Regulation Of Hagfish Gth Synthesis and Secretionmentioning

confidence: 99%

The hagfish heart

Davison¹

2015

Hagfish Biology

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The hypothalamic-pituitary system is considered to be a seminal event that emerged prior to or during the differentiation of the ancestral agnathans (jawless vertebrates). Hagfishes as one of the only two extant members of the class of agnathans are considered the most primitive vertebrates known, living or extinct. Accordingly, studies on their reproduction are important for understanding the evolution and phylogenetic aspects of the vertebrate reproductive endocrine system. In gnathostomes (jawed vertebrates), the hormones of the hypothalamus and pituitary have been extensively studied and shown to have well-defined roles in the control of reproduction. In hagfish, it was thought that they did not have the same neuroendocrine control of reproduction as gnathostomes, since it was not clear whether the hagfish pituitary gland contained tropic hormones of any kind. This review highlights the recent findings of the hypothalamic-pituitary-gonadal endocrine system in the hagfish. In contrast to gnathostomes that have two gonadotropins (GTH: luteinizing hormone and follicle-stimulating hormone), only one pituitary GTH has been identified in the hagfish. Immunohistochemical and functional studies confirmed that this hagfish GTH was significantly correlated with the developmental stages of the gonads and showed the presence of a steroid (estradiol) feedback system at the hypothalamic-pituitary levels. Moreover, while the identity of hypothalamic gonadotropin-releasing hormone (GnRH) has not been determined, immunoreactive (ir) GnRH has been shown in the hagfish brain including seasonal changes of ir-GnRH corresponding to gonadal reproductive stages. In addition, a hagfish PQRFamide peptide was identified and shown to stimulate the expression of hagfish GTHβ mRNA in the hagfish pituitary. These findings provide evidence that there are neuroendocrine-pituitary hormones that share common structure and functional features compared to later evolved vertebrates.

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Release of Pituitary Gonadotrophins GtH I and GtH II in the Rainbow Trout (Oncorhynchus mykiss): Modulation by Estradiol and Catecholamines

Cited by 103 publications

References 29 publications

Two estrogen receptors expressed in the teleost fish, Sparus aurata: cDNA cloning, characterization and tissue distribution

Two estrogen receptors expressed in the teleost fish, Sparus aurata: cDNA cloning, characterization and tissue distribution

Alteration of monoamine concentrations in the brain of medaka, Oryzias latipes, exposed to tributyltin

The hagfish heart

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