Effects of angiotensin II and natriuretic peptides of the eel on prolactin and growth hormone release in the tilapia, Oreochromis mossambicus

Eckert, S M; Hirano, Tetsuya; Leedom, Thomas A.; Takei, Yoshiyuki; Grau, E. Gordon

doi:10.1016/s0016-6480(02)00630-5

Cited by 23 publications

(6 citation statements)

References 36 publications

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“…This temporal dynamics in PRL stimulation with leptin likely represents a classic biphasic response observed by many endocrine cells during stimulus-secretion coupling and is similar to that previously shown to occur with exposure to IGF-I, ghrelin, and angiotensin II in tilapia (Kajimura et al 2002, Eckert et al 2003, Kaiya et al 2003b.…”

Section: Discussionsupporting

confidence: 81%

Leptin stimulates pituitary prolactin release through an extracellular signal-regulated kinase-dependent pathway

Tipsmark

Strom

Bailey

et al. 2007

Journal of Endocrinology

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Leptin was initially identified as a regulator of appetite and weight control centers in the hypothalamus, but appears to be involved in a number of physiological processes. This study was carried out to examine the possible role of leptin in regulating prolactin (PRL) release using the teleost pituitary model system. This advantageous system allows isolation of a nearly pure population of lactotropes in their natural, in situ aggregated state. The rostral pars distalis were dissected from tilapia pituitaries and exposed to varying concentrations of leptin (0, 1, 10, 100 nM) for 1 h. Release of PRL was stimulated by leptin in a potent and concentration-dependent manner. A time-course experiment showed that the strongest response in PRL release with leptin occurs within the first hour (approximately sixfold), and stimulation was sustained after 16 h (approximately twofold). Many of the actions of leptin are mediated by the activation of extracellular signalregulated kinase (ERK1/2) but nothing is known about the cellular mechanisms by which leptin might regulate PRL secretion in vertebrates. We therefore tested whether ERK1/2 might be involved in the leptin PRL response and found that the ERK inhibitor, PD98059, hindered leptininduced PRL release. We further analyzed leptin response by quantifying tyrosine and threonine phosphorylation of ERK1/2 using western blots. One hour incubation with leptin induced a concentration-dependent increase in phosphorylated, and thus active, ERK1/2. Our data show that leptin is a powerful stimulator of in vitro PRL release and that its actions occur in part through stimulation of ERK1/2.

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Section: Discussionsupporting

confidence: 81%

Leptin stimulates pituitary prolactin release through an extracellular signal-regulated kinase-dependent pathway

Tipsmark

Strom

Bailey

et al. 2007

Journal of Endocrinology

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“…While there are some reports on pituitary roles for natriuretic peptide signaling, such as increasing GH secretion (Hartt et al 1995, Shimekake et al 1994, Eckert et al 2003 or inhibiting ACTH secretion (Guild & Cramb 1999), these effects may well be celltype specific and are not known to be recapitulated in humans. Genetically manipulated mouse models of disrupted Nppc or Npr2 also point to a pituitary role for CNP and GC-B (Chusho et al 2001, Tamura et al 2004, given the profound growth and reproductive disruption to these animals, yet these intriguing possibilities remain to be determined within a pituitary-specific context.…”

Section: Endocrine-related Cancermentioning

confidence: 99%

Expression of guanylyl cyclase-B (GC-B/NPR2) receptors in normal human fetal pituitaries and human pituitary adenomas implicates a role for C-type natriuretic peptide

Thompson¹,

Chand²,

King³

et al. 2012

Endocrine-Related Cancer

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C-type natriuretic peptide (CNP/Nppc) is expressed at high levels in the anterior pituitary of rats and mice and activates guanylyl cyclase B receptors (GC-B/Npr2) to regulate hormone secretion. Mutations in NPR2/Npr2 can cause achondroplasia, GH deficiency, and female infertility, yet the normal expression profile within the anterior pituitary remains to be established in humans. The current study examined the expression profile and transcriptional regulation of NPR2 and GC-B protein in normal human fetal pituitaries, normal adult pituitaries, and human pituitary adenomas using RT-PCR and immunohistochemistry. Transcriptional regulation of human NPR2 promoter constructs was characterized in anterior pituitary cell lines of gonadotroph, somatolactotroph, and corticotroph origin. NPR2 was detected in all human fetal and adult pituitary samples regardless of age or sex, as well as in all adenoma samples examined regardless of tumor origin. GC-B immunoreactivity was variable in normal pituitary, gonadotrophinomas, and somatotrophinomas. Maximal transcriptional regulation of the NPR2 promoter mapped to a region within K214 bp upstream of the start site in all anterior pituitary cell lines examined. Electrophoretic mobility shift assays revealed that this region contains Sp1/Sp3 response elements. These data are the first to show NPR2 expression in normal human fetal and adult pituitaries and adenomatous pituitary tissue and suggest a role for these receptors in both pituitary development and oncogenesis, introducing a new target to manipulate these processes in pituitary adenomas.

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“…Medium samples were stored at 20 C until required for analysis for GH and PRL (PRL 188 ) by homologous radioimmunoassay (Ayson et al 1993) as modified by Yada et al (1994). Release of GH and PRL was expressed as ng/ 100 g body weight, because significant correlation was observed between the amounts of hormone released from the pituitary and body weight (Eckert et al 2002). Group comparisons were performed using one-way ANOVA, followed by the least significant test or by Mann-Whitney U-test for each time point.…”

Section: In Vitro Effects Of Eel Ghrelin On the Secretion Of Gh And Pmentioning

confidence: 99%

Amidated fish ghrelin: purification, cDNA cloning in the Japanese eel and its biological activity

Kaiya¹,

Kojima²,

Hosoda³

et al. 2003

Journal of Endocrinology

136

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We purified ghrelin from stomach extracts of a teleost fish, the Japanese eel (Anguilla japonica) and found that it contained an amide structure at the C-terminal end. Two molecular forms of ghrelin with 21 amino acids were identified by cDNA and mass spectrometric analyses: eel ghrelin-21, GSS(O-n-octanoyl)FLSPSQRPQGKDKKPP RV-amide and eel ghrelin-21-C10, GSS(O-n-decanoyl) FLSPSQRPQGKDKKPPRV-amide. Northern blot and RT-PCR analyses revealed high gene expression in the stomach. Low levels of expression were found only in the brain, intestines, kidney and head kidney by RT-PCR analysis. Eel ghrelin-21 increased plasma growth hormone (GH) concentrations in rats after intravenous injection; the potency was similar to that of rat ghrelin. We also examined the effect of eel ghrelin on the secretion of GH and prolactin (PRL) from organ-cultured tilapia pituitary. Eel ghrelin-21 at a dose of 0·1 nM stimulated the release of GH and PRL, indicating that ghrelin acts directly on the pituitary. The present study revealed that ghrelin is present in fish stomach and has the ability to stimulate the secretion of GH from fish pituitary. A novel regulatory pathway of GH secretion by gastric ghrelin seems to be conserved from fish to human.

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Effects of angiotensin II and natriuretic peptides of the eel on prolactin and growth hormone release in the tilapia, Oreochromis mossambicus

Cited by 23 publications

References 36 publications

Leptin stimulates pituitary prolactin release through an extracellular signal-regulated kinase-dependent pathway

Leptin stimulates pituitary prolactin release through an extracellular signal-regulated kinase-dependent pathway

Expression of guanylyl cyclase-B (GC-B/NPR2) receptors in normal human fetal pituitaries and human pituitary adenomas implicates a role for C-type natriuretic peptide

Amidated fish ghrelin: purification, cDNA cloning in the Japanese eel and its biological activity

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