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  • 1
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    Ghrelin in neonatal rats: distribution in stomach and its possible role
    Bioscientifica ; 2002
    In:  Journal of Endocrinology Vol. 173, No. 2 ( 2002-05-1), p. 239-245
    Details
    In: Journal of Endocrinology, Bioscientifica, Vol. 173, No. 2 ( 2002-05-1), p. 239-245
    Kurzfassung: Ghrelin, a 28 amino acid peptide, has recently been isolated from the rat stomach as an endogenous ligand for the GH secretagogue receptor. The fact that administration of ghrelin, centrally or peripherally, stimulates both food intake and GH secretion suggests that stomach ghrelin has an important role in the growth of rats. We used immunohistochemistry and radioimmunoassay to determine the age at which ghrelin-immunostained cells begin to appear in the rat stomach. Ghrelin-immunoreactive cells were found to be expressed in the fetal stomach from pregnancy day 18. The number of ghrelin-immunoreactive cells in the fetal stomach increased as the stomach grew. The amount of ghrelin in the glandular part of the rat stomach also increased, in an age-dependent manner, from the neonatal stage to adult. Eight hours of milk restriction significantly decreased the ghrelin concentration in the stomachs of 1-week-old rats, and increased the ghrelin concentration in their plasma. Administration of ghrelin to 1- and 3-week-old rats increased plasma GH concentrations. The daily subcutaneous administration of ghrelin to pregnant rats from day 15 to day 21 of pregnancy caused an increase in body weight of newborn rats. In addition, daily subcutaneous administration of ghrelin to neonatal rats from birth advanced the day of vaginal opening from day 30.7+/-0.94 to day 27.9+/-0.05. These results suggest that ghrelin may be involved in neonatal development.
    Materialart: Online-Ressource
    ISSN: 0022-0795 , 1479-6805
    URL: Article
    DOI: 10.1677/joe.0.1730239
    Sprache: Unbekannt
    Verlag: Bioscientifica
    Publikationsdatum: 2002
    ZDB Id: 1474892-7
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
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    Role for central ghrelin in food intake and secretion profile of stomach ghrelin in rats
    Bioscientifica ; 2002
    In:  Journal of Endocrinology Vol. 174, No. 2 ( 2002-08-1), p. 283-288
    Details
    In: Journal of Endocrinology, Bioscientifica, Vol. 174, No. 2 ( 2002-08-1), p. 283-288
    Kurzfassung: Ghrelin, a 28-amino-acid peptide, has recently been isolated from the rat stomach as an endogenous ligand for the GH secretagogue receptor. We have reported previously that central or peripheral administration of ghrelin stimulates food intake, and the secretion of GH and gastric acid in rats. In the present study, we investigated how much endogenous centrally released ghrelin is involved in the control of food intake and body weight gain. We also examined the profile of ghrelin secretion from the stomach by RIA using two kinds of anti-ghrelin antiserum, one raised against the N-terminal ([Cys(12)]-ghrelin[1-11] ) region and one raised against the C-terminal ([Cys(0)]-ghrelin [13-28] ) region of the peptide. The former antibody recognizes specifically ghrelin with n- octanoylated Ser 3 (acyl ghrelin), and does not recognize des-acyl ghrelin. The latter also recognizes des-acyl ghrelin (i.e. total ghrelin). Intracerebroventricular treatment with the anti-ghrelin antiserum against the N-terminal region twice a day for 5 days decreased significantly both daily food intake and body weight. Des-acyl ghrelin levels were significantly higher in the gastric vein than in the trunk. Either fasting for 12 h, administration of gastrin or cholecystokinin resulted in increase of both acyl and des-acyl ghrelin levels. The ghrelin levels exhibited a diurnal pattern, with the bimodal peaks occurring before dark and light periods. These two peaks were consistent with maximum and minimum volumes of gastric content respectively. These results suggest that (1) endogenous centrally released ghrelin participates in the regulation of food intake and body weight, (2) acyl ghrelin is secreted from the stomach, (3) intestinal hormones stimulate ghrelin release from the stomach, and (4) regulation of the diurnal rhythm of ghrelin is complex, since ghrelin secretion is augmented under conditions of both gastric emptying and filling.
    Materialart: Online-Ressource
    ISSN: 0022-0795 , 1479-6805
    URL: Article
    DOI: 10.1677/joe.0.1740283
    Sprache: Unbekannt
    Verlag: Bioscientifica
    Publikationsdatum: 2002
    ZDB Id: 1474892-7
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
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    Amidated fish ghrelin: purification, cDNA cloning in the Japanese eel and its biological activity
    Bioscientifica ; 2003
    In:  Journal of Endocrinology Vol. 176, No. 3 ( 2003-03-1), p. 415-423
    Details
    In: Journal of Endocrinology, Bioscientifica, Vol. 176, No. 3 ( 2003-03-1), p. 415-423
    Kurzfassung: 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.
    Materialart: Online-Ressource
    ISSN: 0022-0795 , 1479-6805
    URL: Article
    DOI: 10.1677/joe.0.1760415
    Sprache: Unbekannt
    Verlag: Bioscientifica
    Publikationsdatum: 2003
    ZDB Id: 1474892-7
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
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    Gender and gonadal influences on ghrelin mRNA levels in rat stomach
    Oxford University Press (OUP) ; 2001
    In:  European Journal of Endocrinology ( 2001-06-1), p. 687-690
    Details
    In: European Journal of Endocrinology, Oxford University Press (OUP), ( 2001-06-1), p. 687-690
    Kurzfassung: OBJECTIVE: The recently isolated endogenous GH secretagogue, named ghrelin, is a gastric peptide of 28 amino acids with an n-octanoylation in the serine 3 that confers the biological activity to this factor. Ghrelin has been shown to directly stimulate GH release in vivo and in vitro and to be involved in the regulation of gastric acid secretion and motility. In the present work we have studied gender and gonadal dependency of ghrelin mRNA expression in rat stomach. DESIGN AND METHODS: We analysed ghrelin mRNA expression in rat stomach by Northern blot analysis. We also examined the effect of gonadal steroid deprivation on ghrelin mRNA expression. RESULTS AND CONCLUSIONS: The results obtained showed clearly that ghrelin gastric mRNA expression increased with age in young rats (up to 90 days old) but exhibited no significant sex difference at each age tested. Ghrelin mRNA levels were lowest at postnatal day 9, reaching a stable level of expression at day 40 in both female and male rats, although the increase in female rats appears much more gradual than that in males. Moreover, neither ovariectomy nor orchidectomy significantly modified ghrelin mRNA gastric levels in adult rats. In conclusion, these data indicate that ghrelin mRNA expression is associated with age and that a progressive increase is present from the perinatal period up to a stable level after puberty. Gonadal hormones did not alter ghrelin mRNA levels. Taken together, these data showed that ghrelin mRNA levels in young rats are age but not gender dependent, and are not influenced by gonadal steroids.
    Materialart: Online-Ressource
    ISSN: 0804-4643 , 1479-683X
    URL: Article
    DOI: 10.1530/eje.0.1440687
    RVK:
    WA 15000
    Sprache: Unbekannt
    Verlag: Oxford University Press (OUP)
    Publikationsdatum: 2001
    ZDB Id: 1485160-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
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    Ghrelin-induced growth hormone secretion in humans
    Oxford University Press (OUP) ; 2000
    In:  European Journal of Endocrinology Vol. 143, No. 6 ( 2000-12-01), p. R11-R14
    Details
    In: European Journal of Endocrinology, Oxford University Press (OUP), Vol. 143, No. 6 ( 2000-12-01), p. R11-R14
    Kurzfassung: Ghrelin is a novel growth hormone (GH) releaser acylated peptide that has recently been purified from stomach, and which potently binds to the GH secretagogue receptor. Ghrelin releases GH in vitro and in vivo in animal models, however its actions, potency and specificity in humans are unknown. In the present study, 12 healthy subjects were studied: 6 underwent four tests with ghrelin administered i.v. at the dose of 0 (placebo), 0.25, 0.5 and 1 microg/kg which corresponds to 0, 18, 37 and 75 microg total dose. A further 6 volunteers underwent two tests on different days with ghrelin at the dose of 3.3 or 6.6 microg/kg which corresponds to 250 microg and 500 microg total dose. Ghrelin-mediated GH secretion showed a dose-response curve, in which 1 microg/kg was the minimally effective dose in some individuals, but not as a group. On the contrary, the total doses of 250 microg and 500 microg elicited a powerful GH secretion, with a mean peak of 69.8+/-9.2 microg/l and 90.9+/-16.9 microg/l respectively, and areas under the curve of 4435+/-608 and 6125+/-1008 microg/l per 120 min respectively. All of them statistically significant vs placebo and vs the 1 microg/kg dose. Ghrelin administration also elicited a relevant dose-response mediated prolactin secretion suggesting no specificity of its actions. No relevant side effects were observed with ghrelin apart from a hyperhydrosis episode in two individuals tested with the higher ghrelin doses. In conclusion, ghrelin is a potent releaser of GH in normal individuals, with a dose-response pattern of operation. No saturating dose was observed.
    Materialart: Online-Ressource
    ISSN: 0804-4643 , 1479-683X
    URL: Article
    DOI: 10.1530/eje.0.143r011
    RVK:
    WA 15000
    Sprache: Englisch
    Verlag: Oxford University Press (OUP)
    Publikationsdatum: 2000
    ZDB Id: 1485160-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
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    A transient ghrelin surge occurs just before feeding in a scheduled meal-fed sheep
    Elsevier BV ; 2002
    In:  Biochemical and Biophysical Research Communications Vol. 295, No. 2 ( 2002-07), p. 255-260
    Details
    In: Biochemical and Biophysical Research Communications, Elsevier BV, Vol. 295, No. 2 ( 2002-07), p. 255-260
    Materialart: Online-Ressource
    ISSN: 0006-291X
    URL: Article
    DOI: 10.1016/S0006-291X(02)00654-X
    RVK:
    WA 15000
    Sprache: Englisch
    Verlag: Elsevier BV
    Publikationsdatum: 2002
    ZDB Id: 1461396-7
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
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    Cellular mechanisms for synthesis and secretion of atrial natriuretic peptide and brain natriuretic peptide in cultured rat atrial cells.
    Ovid Technologies (Wolters Kluwer Health) ; 1992
    In:  Circulation Research Vol. 71, No. 5 ( 1992-11), p. 1039-1048
    Details
    In: Circulation Research, Ovid Technologies (Wolters Kluwer Health), Vol. 71, No. 5 ( 1992-11), p. 1039-1048
    Kurzfassung: To investigate the cellular mechanism for the synthesis and secretion of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), we examined the effects of vasoactive agents on the secretion rates and gene expression of ANP and BNP in cultured rat atrial cells. Endothelin (10(-7) M, +61%), 12-O-tetradecanoylphorbol 13-acetate (TPA, 10(-6) M, +62%), the calcium ionophore A23187 (10(-6) M, +95%), and Bay K 8644 (10(-6) M, +34%) (p 〈 0.05 each) all increased the secretion of ANP into the culture media in a dose-dependent fashion. On the other hand, endothelin (10(-7) M, +57%) and TPA (10(-6) M, +55%) (p 〈 0.01 each) increased the secretion of BNP in a dose-dependent manner, whereas A23187 (10(-6) M, -45%, p 〈 0.001) suppressed the secretion of BNP in a dose-dependent manner, and Bay K 8644 caused no significant effects on BNP secretion. The molecular forms of intracellular ANP were exclusively gamma-ANP, whereas those of BNP were gamma-BNP and its carboxy terminal 45-amino-acid peptide, BNP-45. The ratio of media to cell contents was much higher in BNP than in ANP. Northern blot analysis revealed that both ANP mRNA and BNP mRNA levels were significantly increased by 10(-7) M endothelin (ANP mRNA, +52%; BNP mRNA, +36%; p 〈 0.05 each) and 5 x 10(-5) M 1-oleoyl-2-acetylglycerol (ANP mRNA, +296%; BNP mRNA, +133%; p 〈 0.01 each) but not by 10(-6) M A23187. Thus, the secretion of ANP is stimulated by both the elevation of [Ca2+]i and the activation of protein kinase C, whereas its synthesis is increased mainly by the activation of protein kinase C. The synthesis and secretion of BNP are augmented by the activation of protein kinase C rather than the elevation of [Ca2+] i. Furthermore, the processing and secretion of ANP and BNP may be regulated in different manners.
    Materialart: Online-Ressource
    ISSN: 0009-7330 , 1524-4571
    URL: Article
    DOI: 10.1161/01.RES.71.5.1039
    RVK:
    XA 10000
    Sprache: Englisch
    Verlag: Ovid Technologies (Wolters Kluwer Health)
    Publikationsdatum: 1992
    ZDB Id: 1467838-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
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    Ghrelin enhances glucose-induced insulin secretion in scheduled meal-fed sheep
    Bioscientifica ; 2006
    In:  Journal of Endocrinology Vol. 189, No. 1 ( 2006-04), p. 67-75
    Details
    In: Journal of Endocrinology, Bioscientifica, Vol. 189, No. 1 ( 2006-04), p. 67-75
    Kurzfassung: The purpose of this study was to investigate the effects of physiologic levels of ghrelin on insulin secretion and insulin sensitivity (glucose disposal) in scheduled fed-sheep, using the hyperglycemic clamp and hyperinsulinemic euglycemic clamp respectively. Twelve castrated Suffolk rams (69.8 ± 0.6 kg) were conditioned to be fed alfalfa hay cubes (2% of body weight) once a day. Three hours after the feeding, synthetic ovine ghrelin was intravenously administered to the animals at a rate of 0.025 and 0.05 μg/kg body weight (BW) per min for 3 h. Concomitantly, the hyperglycemic clamp or the hyperinsulinemic euglycemic clamp was carried out. In the hyperglycemic clamp, a target glucose concentration was clamped at 100 mg/100 ml above the initial level. In the hyperinsulinemic euglycemic clamp, insulin was intravenously administered to the animals for 3 h at a rate of 2 mU/kg BW per min. Basal glucose concentrations (44± 1 mg/dl) were maintained by variably infusing 100 mg/dl glucose solution. In both clamps, plasma ghrelin concentrations were dose-dependently elevated and maintained at a constant level within the physiologic range. Ghrelin infusions induced a significant (ANOVA; P 〈 0.01) increase in plasma GH concentrations. In the hyperglycemic clamp, plasma insulin levels were increased by glucose infusion and were significantly ( P 〈 0.05) greater in ghrelin-infused animals. In the hyperinsulinemic euglycemic clamp, glucose infusion rate, an index of insulin sensitivity, was not affected by ghrelin infusion. In conclusion, the present study has demonstrated for the first time that ghrelin enhances glucose-induced insulin secretion in the ruminant animal.
    Materialart: Online-Ressource
    ISSN: 0022-0795 , 1479-6805
    URL: Article
    DOI: 10.1677/joe.1.06310
    Sprache: Unbekannt
    Verlag: Bioscientifica
    Publikationsdatum: 2006
    ZDB Id: 1474892-7
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
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    Effects of ghrelin on food intake and neuroendocrine function in sheep
    Elsevier BV ; 2004
    In:  Animal Reproduction Science Vol. 82-83 ( 2004-7), p. 183-194
    Details
    In: Animal Reproduction Science, Elsevier BV, Vol. 82-83 ( 2004-7), p. 183-194
    Materialart: Online-Ressource
    ISSN: 0378-4320
    URL: Article
    DOI: 10.1016/j.anireprosci.2004.05.001
    Sprache: Englisch
    Verlag: Elsevier BV
    Publikationsdatum: 2004
    ZDB Id: 1495854-5
    SSG: 22
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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