Somatostatin Inhibition of Growth Hormone Release in Goldfish: Possible Targets of Intracellular Mechanisms of Action

Kwong, Patrick; Chang, John P.

doi:10.1006/gcen.1997.6995

Cited by 25 publications

(8 citation statements)

References 55 publications

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“…Like norepinephrine in the present study, somatostatin and 5HT have been shown to reduce basal and stimulated GH release in the goldfish by action at the level of the pituitary (12–14, 19, 25). It has been shown that somatostatin 14 acts at sites subsequent to PKC activation, and elevations in the levels of cAMP and Ca 2+ to inhibit GH secretion ( 13). Interestingly, somatostatin 14 abolished the GH responses to forskolin and cAMP, but like NE in the present study, only partially reduced GH responses to Ca 2+ ionphores and PKC activators.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, multiple somatostatin isoforms and cDNAs have been identified in goldfish hypothalamus and pituitary ( 12). Mammalian somatostatin 14 , one of the somatostatin forms present in the goldfish, interacts at sites distal to activation of GnRH and D 1 receptor‐induced signal transduction mechanisms to reduce stimulated GH release ( 13). A combination of in‐vivo and in‐vitro studies have demonstrated that 5HT acts at the pituitary cell level to inhibit basal GH secretion and GnRH‐ and D 1 ‐induced GH release via 5HT‐2‐like receptors (( 14) and references within).…”

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confidence: 99%

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Norepinephrine Regulation of Growth Hormone Release from Goldfish Pituitary Cells. II. Intracellular Sites of Action

Yunker

Lee

Wong

et al. 2000

J Neuroendocrinology

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Previous results suggest that norepinephrine decreases growth hormone (GH) release in goldfish by means of alpha-2 adrenoceptor activation. The intracellular mechanisms by which norepinephrine inhibits GH release were examined in the present study using dispersed goldfish pituitary cells. In 2-h static incubation experiments, norepinephrine and the alpha-2 agonist clonidine decreased basal GH release and the GH responses to stimulation by the dopamine D1 agonist SKF38393 and two native gonadotropin-releasing hormones (GnRH). Norepinephrine also reduced GH responses to the adenylate cyclase activator forskolin, two protein kinase C (PKC) activators (phorbol ester and synthetic diacylglycerol), and two Ca2+ ionophores (ionomycin and A23187). Similarly, norepinephrine applied as a 1-h pulse in cell column perifusion experiments reduced basal GH release and abolished the GH response to a 5-min pulse of arachidonic acid. In goldfish, D1-stimulated GH release is mediated by AC-, arachidonic acid-and Ca2+-dependent pathways, whereas GnRH action is coupled to PKC-and Ca2+-dependent mechanisms. These results suggest that norepinephrine activation of alpha-2 receptors inhibits ligand-induced GH secretion by actions subsequent to activation of these second messenger cascades. To further characterize norepinephrine mechanisms of action on unstimulated hormone release, the ability of norepinephrine and an alpha-2 agonist to affect activation of two second messenger cascades under basal conditions was also investigated. Static incubation with clonidine reduced cAMP production in a time-and dose-dependent manner, suggesting that norepinephrine inhibitory action can also be expressed at the level of cAMP production. Resting intracellular free calcium levels in single, identified goldfish somatotropes was unaffected by norepinephrine. However, the inhibitory effects of norepinephrine on basal GH secretion was not observed in the presence of a voltage-sensitive Ca2+ channel agonist. Whether these channels are targets for norepinephrine action on unstimulated GH release requires further investigation.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Norepinephrine Regulation of Growth Hormone Release from Goldfish Pituitary Cells. II. Intracellular Sites of Action

Yunker

Lee

Wong

et al. 2000

J Neuroendocrinology

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“…To date, SRIF signal transduction mechanisms in goldfish somatotropes have only been examined using SRIF 14 . SRIF 14 reduces the GH responses to forskolin, a cAMP analog, PKC activators, Ca 2+ ionophores, a VSCC agonist, and an NO donor (Kwong and Chang 1997; (Yunker and Chang 1999b). Although SRIF and NE target mostly similar sites along the intracellular pathways leading to GH release, SRIF was able to further reduce basal GH release during maximal inhibition by NE (W.K.…”

Section: Mechanisms Mediating Srif Inhibition Of Gh Secretionmentioning

confidence: 96%

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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“…Regarding the mechanism of SS on inhibiting growth, it has been revealed that SS inhibited GH secretion with the involvement of cAMP, protein kinase C (PKC), and Ca 2+ in goldfish ( 279 ). Similarly, blockade using the PLC/IP/PKC pathway reversed SRIF-inhibited of GH release without affecting GHRH-stimulated of GH release in grouper ( 252 ).…”

Section: Neuropeptide Y and Somatostatin In Food Intake And Growth Of...mentioning

confidence: 99%

Recent advances in neuropeptide-related omics and gene editing: Spotlight on NPY and somatostatin and their roles in growth and food intake of fish

Huang

2022

Front. Endocrinol.

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Feeding and growth are two closely related and important physiological processes in living organisms. Studies in mammals have provided us with a series of characterizations of neuropeptides and their receptors as well as their roles in appetite control and growth. The central nervous system, especially the hypothalamus, plays an important role in the regulation of appetite. Based on their role in the regulation of feeding, neuropeptides can be classified as orexigenic peptide and anorexigenic peptide. To date, the regulation mechanism of neuropeptide on feeding and growth has been explored mainly from mammalian models, however, as a lower and diverse vertebrate, little is known in fish regarding the knowledge of regulatory roles of neuropeptides and their receptors. In recent years, the development of omics and gene editing technology has accelerated the speed and depth of research on neuropeptides and their receptors. These powerful techniques and tools allow a more precise and comprehensive perspective to explore the functional mechanisms of neuropeptides. This paper reviews the recent advance of omics and gene editing technologies in neuropeptides and receptors and their progresses in the regulation of feeding and growth of fish. The purpose of this review is to contribute to a comparative understanding of the functional mechanisms of neuropeptides in non-mammalians, especially fish.

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Somatostatin Inhibition of Growth Hormone Release in Goldfish: Possible Targets of Intracellular Mechanisms of Action

Cited by 25 publications

References 55 publications

Norepinephrine Regulation of Growth Hormone Release from Goldfish Pituitary Cells. II. Intracellular Sites of Action

Norepinephrine Regulation of Growth Hormone Release from Goldfish Pituitary Cells. II. Intracellular Sites of Action

Signal transduction mechanisms mediating secretion in goldfish gonadotropes and somatotropes

Recent advances in neuropeptide-related omics and gene editing: Spotlight on NPY and somatostatin and their roles in growth and food intake of fish

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