Brain Regulation of Growth Hormone Secretion and Food Intake in Fish

Peter, Richard; Chang, John P.

doi:10.1007/978-1-4615-4805-8_4

Cited by 11 publications

(8 citation statements)

References 65 publications

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“…Pharmacological treatments that elevate intracellular cAMP levels increase GH release, but cAMP does not participate in mediating sGnRH and cGnRH-II actions on GH secretion (reviewed in Wong et al 1994b;Peter and Chang 1999). In contrast to GTH-II release, cAMP-stimulated GH release is only additive to GnRH-and PKC-induced responses, indicating that these are parallel transduction systems in the somatotropes, and that the GH releasable pool may be partitioned between cAMP-and PKC-dependent elements ( Fig.…”

Section: Gh Releasementioning

confidence: 96%

“…GH release DA, via D1 receptor-mediated mechanisms, has been shown to be a major stimulatory factor for GH secretion (reviewed in Peng and Peter 1997;Peter and Chang 1999). D1 receptors have been localized to regions of the goldfish pitu- itary in which somatotropes are located .…”

Section: Gth-ii Releasementioning

confidence: 99%

“…Multiple SRIF forms and cDNAs encoding these isoforms are known to exist in goldfish, including SRIF 14 (reviewed in Lin et al 1998;Peter and Chang 1999). To date, SRIF signal transduction mechanisms in goldfish somatotropes have only been examined using SRIF 14 .…”

Section: Mechanisms Mediating Srif Inhibition Of Gh Secretionmentioning

confidence: 99%

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Signal transduction mechanisms mediating secretion in goldfish gonadotropes and somatotropes

Chang

Johnson²,

Goor³

et al. 2000

Biochem. Cell Biol.

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The intracellular signal transduction mechanisms mediating maturational gonadotropin and somatotropin secretion in goldfish are reviewed. Several major signaling mechanisms, including changes in intracellular [Ca2+], arachidonic acid cascades, protein kinase C, cyclic AMP/protein kinase A, calmodulin, nitric oxide, and Na+/H+ antiport, are functional in both cell types. However, their relative importance in mediating basal secretion and neuroendocrine-factor-regulated hormone release differs according to cell type. Similarly, agonist- and cell-type-specificity are also present in the transduction pathways leading to neuroendocrine factor-modulated maturational gonadotropin and somatotropin release. Specificity is present not only in the actions of different regulators within the same cell type and with the same ligand in the two cell types, but this also exists between isoforms of the same neuroendocrine factor within a single cell type. Other evidence suggests that function-selectivity of signaling may also result from differential modulation of Ca2+ fluxes from different sources. The interaction of different second messenger systems provide the basis by which regulation of maturational gonadotropin and somatotropin release by multiple neuroendocrine factors can be integrated at the target cell level.

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Section: Gh Releasementioning

confidence: 96%

Section: Gth-ii Releasementioning

confidence: 99%

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Signal transduction mechanisms mediating secretion in goldfish gonadotropes and somatotropes

Chang

Johnson²,

Goor³

et al. 2000

Biochem. Cell Biol.

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“…It is well documented that all vertebrate species ranging from fish to humans possess two (hypothalamus, GnRH1; midbrain, GnRH2) or, as in recently derived teleosts, three GnRH types (caudal olfactory bulbs, GnRH3) (1-3). GnRH1, GnRH2, and GnRH3, in addition to stimulating gonadotropes (follicle-stimulating hormone, FSH; luteinizing hormone, LH), are potent regulators of somatotropes [growth hormone (GH) cells], lactotropes [prolactin (PRL) cells], and somatolactin (SL)-containing cells in teleosts (4)(5)(6)(7)(8)(9). Because GnRH exerts its actions through binding to GnRH receptors (GnRH-Rs) (10), it is, therefore, conceivable that the three GnRH types have their respective cognate receptors expressed in different pituitary cells.…”

mentioning

confidence: 99%

Three GnRH receptor types in laser-captured single cells of the cichlid pituitary display cellular and functional heterogeneity

Parhar

Ogawa

Sakuma

2005

Proc. Natl. Acad. Sci. U.S.A.

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The role of multiple gonadotropin-releasing hormone receptor (GnRH-R) types in the regulation of gonadotropic and nongonadotropic cells remains speculative. To address this issue, we developed a technology integrating laser-captured microdissection of single digoxigenin-labeled pituitary cells coupled with real-time quantitative PCR to examine the expression profiles of three endogenous GnRH-R types (R1, R2, and R3) in immature and mature males of tilapia Oreochromis niloticus. Here, in addition to gonadotropes (luteinizing and folicle-stimulating hormone, FSH), we show GnRH-Rs are also present in lactotropes, somatotropes, thyrotropes, melanotropes (melanocyte-stimulating hormone, MSH), corticotropes and somatolactin cells. Subpopulations of pituitary cells express single (42.9%), multiple (32.4%) or lack (24.7%) GnRH-Rs. In immature males, the percentage of FSH cells containing combinations of GnRH-Rs was significantly higher (R1؉R2: 24%, P < 0.05; R1؉R2؉R3: 25%, P < 0.01) than in mature males, whereas the percentage showing only R1 and R1 and R3 transcripts (P < 0.05) was higher in mature males. Significantly greater copies of R1 and R3 transcripts were found in MSH cells of immature and mature males, respectively (P < 0.05). GnRH-R transcripts in other pituitary cells (lactotropes, R1 and R2; somatolactin cells͞thyrotropes͞corticotropes, R1, R2, and R3) were significantly higher in mature males (P < 0.05) but were unaltered in somatotropes and luteinizing hormone cells. Thus, FSH and MSH cells are required for both reproductive states, whereas other pituitary cells are recruited only during testicular maturation. The differential expression of GnRH-Rs in gonadotropic and nongonadotropic cells demonstrates cellular and functional heterogeneity of mechanisms controlling normal sexual development.G protein ͉ in situ hybridization ͉ tilapia G onadotropin-releasing hormone (GnRH) is now recognized as a family of 16 multifunctional neuropeptides in vertebrates (1-3). It is well documented that all vertebrate species ranging from fish to humans possess two (hypothalamus, GnRH1; midbrain, GnRH2) or, as in recently derived teleosts, three GnRH types (caudal olfactory bulbs, GnRH3) (1-3). GnRH1, GnRH2, and GnRH3, in addition to stimulating gonadotropes (follicle-stimulating hormone, FSH; luteinizing hormone, LH), are potent regulators of somatotropes [growth hormone (GH) cells], lactotropes [prolactin (PRL) cells], and somatolactin (SL)-containing cells in teleosts (4-9). Because GnRH exerts its actions through binding to GnRH receptors (GnRH-Rs) (10), it is, therefore, conceivable that the three GnRH types have their respective cognate receptors expressed in different pituitary cells. Multiple GnRH-Rs have been cloned (10) and their transcripts identified in LH and GH cells (11), and GnRH-R proteins in LH, GH, and PRL cells (4) of teleosts. However, the distribution of GnRH-R transcripts in other endocrine cell types of the adenohypophysis has never been evaluated. Besides, it is unknown whether transcripts of multip...

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“…Among neuroendocrine regulatory systems in lower vertebrates, the control of GH secretion in the goldfish is one of the best characterized, both in terms of the involvement of multiple regulatory factors and the interactions of intracellular signal transduction pathways (19). Of the many known factors that directly stimulate GH release in goldfish, the actions of the two endogenous gonadotropin‐releasing hormones (salmon, sGnRH, and chicken, cGnRH‐II) are two of the best studied.…”

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confidence: 99%

Nitric Oxide Produced by a Novel Nitric Oxide Synthase Isoform is Necessary for Gonadotropin‐Releasing Hormone‐Induced Growth Hormone Secretion Via a cGMP‐Dependent Mechanism

Uretsky

Weiss²,

Yunker

et al. 2003

J Neuroendocrinology

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The involvement of nitric oxide (NO) in the regulation of goldfish growth hormone (GH) secretion was further characterized using primary cultures of dispersed goldfish pituitary cells. Western blots revealed the presence of an inducible nitric oxide synthase (iNOS)-like protein of approximately 120 kDa in cytosol/plasma membrane extracts. By contrast, brain NOS-immunoreactive proteins of approximately 120-140 kDa were occasionally detected in a cytoskeleton/organelle fraction but were absent from cytosol/plasma membrane extracts. The NO donor sodium nitroprusside (SNP) acutely increased GH secretion but this response was not observed in the presence of either a NO scavenger (PTIO) or a soluble guanylate cyclase inhibitor (ODQ). SNP also significantly increased the levels of cyclic (c)GMP in somatotrope-enriched cell populations. Treatments with 1400W (iNOS inhibitor), PTIO and rutin hydrate (NO scavengers) and ODQ abolished the acute GH-release response to two endogenous gonadotropin-releasing hormones (GnRH). 1400W, rutin hydrate, PTIO and ODQ alone did not significantly alter basal GH secretion. Together, these results establish that an iNOS-like peptide is constitutively present in the pituitary of the goldfish. Furthermore, these data suggest that NO, most likely through the generation of cGMP, is a necessary signal transduction component of GnRH-induced GH secretion.

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Brain Regulation of Growth Hormone Secretion and Food Intake in Fish

Cited by 11 publications

References 65 publications

Signal transduction mechanisms mediating secretion in goldfish gonadotropes and somatotropes

Signal transduction mechanisms mediating secretion in goldfish gonadotropes and somatotropes

Three GnRH receptor types in laser-captured single cells of the cichlid pituitary display cellular and functional heterogeneity

Nitric Oxide Produced by a Novel Nitric Oxide Synthase Isoform is Necessary for Gonadotropin‐Releasing Hormone‐Induced Growth Hormone Secretion Via a cGMP‐Dependent Mechanism

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