Validation of Heterologous Radioimmunoassays (RIA) for Growth Hormone (GH) and Insulin-Like Growth Factor (IGF)-I in Phocid, Otariid, and Cetacean Species (original) (raw)
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Aquaculture Research, 2007
The purpose of the study was to investigate whether dietary ration or diet composition in£uence the relationship between plasma growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in Arctic charr (Salvelinus alpinus L.). The pattern of changes in plasma GH and IGF-1 concentrations was examined in ¢sh fed at di¡erent ration levels (0%, 0.35% and 0.70% BWday À1 ) for 5 weeks, and in ¢sh fed diets containing di¡erent lipid:crude protein (LCP) ratios. Ration level signi¢cantly a¡ected plasma GH and IGF-1 concentrations; at 5 weeks the levels of both hormones in the food-deprived group were signi¢cantly lower than in ¢sh fed the 0.70% BWday À1 ration. Also, plasma IGF-1 levels in ¢sh of each ration treatment group were signi¢cantly correlated with individual ¢nal body weight; no such correlation was found for GH. To examine the e¡ects of dietary LCP ratios, ¢sh were fed for up to 18 weeks, with one of four formulated diets that had LCP ratios (dry matter basis) of 0.35 (Diet 1), 0.43 (Diet 2), 0.51 (Diet 3) or 0.59 (Diet 4), or a commercial diet (Diet 5) which had an LCP ratio of 0.38. Statistical di¡erences in plasma GH and IGF-1 concentrations were found only after 18 weeks. Growth hormone was signi¢cantly lower in ¢sh fed Diets 1 and 2 compared with Diets 3 and 5, and IGF-1 was signi¢cantly lower in ¢sh fed Diet 1 compared with Diets 2 and 5. Signi¢cant correlations between plasma GH and IGF-1 concentrations were found only for ¢sh fed Diets 1 and 5, suggesting that the in£uence of diet composition on the relationship between GH and IGF-1varies with the dietary LCP ra-tio in this species. The decline in plasma IGF-1 concentrations during food deprivation is similar to that described in other species; however, the unexpected decrease in plasma GH during food deprivation in this study may represent a species-speci¢c response.
Growth hormone axis as marker of nutritional status and growth performance in fish
Aquaculture, 1999
The endocrine control of growth and metabolism is interrelated and many of the endocrine factors involved in the regulation of lipid and protein metabolism are also involved in nutrient utilization, immune system function and somatic growth. All these processes are impaired in catabolic states induced by fasting, protein deprivation and chronic liver diseases as a response to the consequential changes in the endocrine system. In this regard, it must be noted that concentrations of circulating metabolites may be quite different depending on the catabolic state. However, in all the metabolic disorders that shared an increased catabolismranabolism balance, plasma insulin levels are depressed, whereas those of GH are elevated. This hypersomatotropism, linked to growth retardation, is accompanied by a reduction of plasma IGF-I concentration, which reflects some refractoriness of liver to the anabolic action of GH. Changes in GH availability and liver GH-responsiveness can also be established as a function of age, fish species, and environ-Ž . mental factors photoperiod and temperature . In the present work, the regulation and mode of GH action is discussed in order to provide a useful tool to assess the nutritional status and growth performance of cultured fish. q 0044-8486r99r$ -see front matter q 1999 Elsevier Science B.V. All rights reserved.
The Endocrinology of Growth, Development, and Metabolism in Vertebrates
Elsevier eBooks, 1993
I. INTRODUCTION Animal growth is influenced by a variety of genetic, extrinsic, and humoral factors. As such, disturbances in one, or combinations of these growth determinants, may result in changes to normal body growth. Poikilotherms exhibit fluctuations in growth due to alterations in environmental conditions (e.g., photoperiod, temperature, food availability) and changes in the hormonal milieu (e.g., during reproduction). These animals thus demonstrate periods of fast and slow growth; the latter usually occur during the winter months in temperate species. As may be expected, given the total numbers of species extant, poikilotherms are the most diverse of the vertebrates, inhabit a wide range of aquatic and terrestrial environments, and exhibit wide thermal preferences and hence rates of growth. Ectotherms also illustrate extremes in size and longevity, and recent studies appear to indicate that many species of poikilotherm exhibit indeterminate patterns of growth (e.g., the American alligator, Alligator mississippiensis, Jacobson and Kushlan, 1989; the wood turtle, Clemmys insculpta, Lovich et al., 1990; the sailfin molly, Poecilia latipinna, Snelson, 1982). Principal in coordinating the events surrounding animal growth are hormones, a fact adequately illustrated by growth cessation in many animals following extirpation of the hypophysis. While a number of hormones have been implicated in governing somatic growth and metabolism, the most significant is growth hormone (GH). In mammals, many of the actions of GH are mediated by the insulinlike growth factors (IGFs), and various studies have provided direct and indirect evidence in support of the existence of similar effector molecules in poikilotherms (see Etherton, Chapter 9, this volume, for discussion of IGFs). Since the major goal of intensive animal culture is to maximize efficiency of production, an understanding and application of those endocrine factors that influence metabolism and encourage somatic growth has obvious commercial implications. To a large degree, it is because of this economic potential that much of our current information upon the effects of GH upon growth in poikilotherms has been gained. The available data have proliferated during the last few years with the arrival of sensitive techniques for the detection of endogenous GH and the wider availability of recombinant derived
2015
The purpose of the study was to investigate whether dietary ration or diet composition in£uence the rela-tionship between plasma growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in Arctic charr (Salvelinus alpinus L.). The pattern of changes in plas-ma GH and IGF-1 concentrations was examined in ¢sh fed at di¡erent ration levels (0%, 0.35 % and 0.70%BWday1) for 5 weeks, and in ¢sh fed diets containing di¡erent lipid:crude protein (LCP) ratios. Ration level signi¢cantly a¡ected plasma GH and IGF-1 concentrations; at 5 weeks the levels of both hormones in the food-deprived group were signi¢-cantly lower than in ¢sh fed the 0.70%BWday1 ra-tion. Also, plasma IGF-1 levels in ¢sh of each ration
Molecular and Cellular Endocrinology, 2010
Contradictory studies suggest IGF-I in fish liver and gills is involved in osmoregulation, but nothing is known about the kidney and intestine's role nor about IGF-II's role in any organ. Tilapia were transferred from freshwater (FW) to seawater (SW) for 1 week (wk) and retransferred to FW for another week. At 4 h, 1 d, 2 d, 3 d and 1 wk after SW-transfer and FW-retransfer IGF-I, IGF-II and growth hormone receptor (GHR1) mRNA were measured by real-time PCR. Hepatic IGF-I, IGF-II and GHR1 mRNA were downregulated in parallel after SW-transfer, recovered and were again downregulated after FWretransfer. In gills, IGF-I, IGF-II and GHR1 were upregulated synchronously after SW-transfer and, partially also after FW-retransfer. The renal genes were downregulated after SW-transfer and partially upregulated after FW-retransfer. Persisting upregulation in intestinal IGF-I mRNA occurred after FW-retransfer. Thus, endocrine and auto/paracrine IGF-I and IGF-II seem to be involved in fish osmoregulation in an organ-specific manner.
General and Comparative Endocrinology, 2002
Regulation of somatolactin (SL) and the somatotropic axis was examined year-around at three different stocking times (spring, summer, and autumn) in a Mediterranean fish, the gilthead sea bream (Sparus aurata). The overall timing of plasma growth hormone (GH) increase was similar among trials (late spring-early summer), but the range of variation year-around was different and followed changes in food intake. Total plasma insulin-like growth factor-I primarily followed changes on growth rates, and a close positive correlation between IGF-I and thermal-unit growth coefficient (TGC) was found irrespective of fish stocking time. Thus, the activation of the somatotropic axis preceded always warm growth spurts, whereas the rise of SL in concurrence with low plasma cortisol levels was found at late autumn. This up-regulation of circulating SL titres preceded the winter inhibition of feeding, and it was more severe in big fish (spring and summer stocking times) than in small fish (autumn stocking time), growing with a relative high efficiency during the cold season despite of a severe hypertriglyceridemia and a high hepatosomatic index. These new insights provide good evidence for a different timing of GH and SL increases, and it is likely that the dominant role of SL in energy homeostasis is to be a mediator of the adaptation to fasting after replenishment of body fat stores, whereas GH and IGF-I are perceived as growth-promoting signals in times of food intake and increasing temperature and day-length.
Growth in teleosts is controlled in large part by the activities of the growth hormone (Gh)/insulin-like growth factor (Igf) system. In this study, we initially identified igf-binding protein (bp)1b, -2b, -4, -5a and -6b transcripts in a tilapia EST library. In Mozambique tilapia (Oreochromis mossambicus), tissue expression profiling of igfbps revealed that igfbp1b and -2b had the highest levels of expression in liver while igfbp4, -5a and -6b were expressed at comparable levels in most other tissues. We compared changes in hepatic igfbp1b, -2b and -5a expression during catabolic conditions (28 days of fasting) along with key components of the Gh/Igf system, including plasma Gh and Igf1 and hepatic gh receptor (ghr2), igf1 and igf2 expression. In parallel with elevated plasma Gh and decreased Igf1 levels, we found that hepatic igfbp1b increased substantially in fasted animals. We then tested whether systemic Gh could direct the expression of igfbps in liver. A single intraperitoneal injection of ovine Gh into hypophysectomized tilapia specifically stimulated liver igfbp2b expression along with plasma Igf1 and hepatic ghr2 levels. Our collective data suggest that hepatic endocrine signaling during fasting may involve posttranslational regulation of plasma Igf1 via a shift towards the expression of igfbp1b. Thus, Igfbp1b may operate as a molecular switch to restrict Igf1 signaling in tilapia; furthermore, we provide new details regarding isoform-specific regulation of igfbp expression by Gh.
General and Comparative Endocrinology, 1998
The ability of ovine growth hormone (oGH), recombinant bovine insulin-like growth factor I (rbIGF-I), recombinant human insulin-like growth factor II (rhIGF-II), and bovine insulin to increase hypoosmoregulatory capacity in the euryhaline teleost Fundulus heteroclitus was examined. Fish acclimated to brackish water (BW, 10 ppt salinity, 320 mOsm/kg H 2 O) were injected with a single dose of hormone and transferred to seawater (SW, 35 ppt salinity, 1120 mOsm/kg H 2 O) 2 days later. Fish were sampled 24 h after transfer and plasma osmolality, plasma glucose, and gill Na ؉ ,K ؉-ATPase activity were examined. Transfer from BW to SW increased plasma osmolality and gill Na ؉ ,K ؉-ATPase activity. Transfer from BW to BW had no effect on these parameters. rbIGF-I (0.05, 0.1, and 0.2 g/g) improved the ability to maintain plasma osmolality and to increase gill Na ؉ , K ؉-ATPase activity in a dose-dependent manner. oGH (0.5, 1, and 2 g/g) also increased hypoosmoregulatory ability but only the higher doses (2 g/g) significantly increased gill Na ؉ ,K ؉-ATPase activity. oGH (1 g/g) and rbIGF-I (0.1 g/g) had a significantly greater effect on plasma osmolality and gill Na ؉ ,K ؉-ATPase activity than either hormone alone. rhIGF-II (0.05, 0.1, and 0.2 g/g) and bovine insulin (0.01 and 0.05 g/g) were without effect. The results suggest a role of GH and insulin-like growth factor I (IGF-I) in seawater acclimation of F. heteroclitus. Based on these findings and previous studies, it is concluded that the capacity of the GH/IGF-I axis to increase hypoosmoregulatory ability may be a common feature of euryhalinity in teleosts. 1998 Academic Press General and Comparative Endocrinology 111, 103-112 (1998) Article No.
Fish Physiology and Biochemistry, 1993
Un dosage des somatomédines (IGF) plasmatiques de téléostéens a été mise au point, en utilisant une protéine du sérum de truite qui lie spécifiquement les IGF humains (Niu and Le Bail 1993). Pour éliminer les risques d'interférence dues aux protéines de liaison (IGF-BP), l'activité IGF des différents échantillons a été extraite à l'aide de SP Sephadex C-25 en condition acide. La contamination en IGF-BP de ces extraits est estimée à 5% par dosage de la liaison et n'est pas détectable en western ligand blot. L'IGF-I humain a été utilisée comme standard et comme traceur. La sensibilité du dosage est de 0.15–0.40 ng/ml (ED90) et l'ED50 varie entre 1 et 3 ng/ml. L'IGF-II humain est reconnue partiellement mais aucune réaction croisée n'est observée avec de l'insuline de différentes espèces ni avec les autres hormones testées. Les courbes d'inhibition obtenues avec les sera de mammifères et de téléostéens sont parallèles à la courbe standard. Ces résultats montrent que le dosage par protéine de liaison est capable de quantifier une activité de type IGF dans le sérum des téléostéen, et que le site de liaison des IGF est resté bien conservé au cours de l'évolution des vertébrés. En utilisant ce dosage, nous avons mesuré l'activité IGF et les niveaux d'hormone de croissance (GH) dans des plasmas de jeunes truites arc-en-ciel abattues toutes les heures et demie durant 24h. Les profils nycthémér-aux des deux hormones, qui sont de type pulsatile, apparaissent similaires. Une corrélation significative est observée entre les niveaux de GH et les activités IGF circulant une heure et demie plus tard. Des observations analogues ont été faites chez des truites adultes cathétérisées. Cependant, les niveaux plasmatiques de GH sont très différents d'un animal à l'autre, alors que les variations de l'activité IGF sont moins prononcées. Dans une troisième expérience, des truites ont été réparties en trois groupes: un groupe contrôle, un groupe traité avec de la GH bovine et un groupe soumis à un jeûne prolongé. Chez les animaux à jeun, les niveaux de GH augmentent alors que les activités IGF diminuent. Chez les animaux injectés avec de la GH, les activités IGF sont significativement plus élevées que chez les animaux témoins. Ces résultats suggèrent que, comme chez les mammifères, la sécrétion des IGF plasmatiques est contrôlée par les niveaux circulants de GH et que les variations de la réceptivité tissulaire à la GH dépendent de l'état nutritionnel des animaux. Using rainbow trout plasma protein (IGF-BP) which specifically binds human insulin-like growth factor (IGF) (Niu and Le Bail 1993), we have developed an assay to measure plasma IGF-like levels in different teleost species. Before the assay and to prevent interference by IGF-BP, IGF-like was extracted from all samples, using SP Sephadex C-25 in acidic conditions. After this treatment, contamination of the IGF fraction by IGF-BP which was estimated by binding assay, was approximately 5%, and was not detectable by western ligand blot. Human IGF-I was used as standard and labelled hormone. Sensitivity of the assay was 0.15–0.40 ng/ml (ED90) and ED50 was 1–3 ng/ml. hIGF-II crossreaction was partial and no significant displacement was observed with Insulin from different species or with other hormones. Inhibition curves were obtained with plasma IGF fractions (but not with tissue extracts) from teleost and mammals and are parallel to the standard curve. These results suggest that the protein binding assay can quantify an IGF-like factor in the plasma of teleost and that the binding sites of IGF are well conserved during vertebrate evolution. Using this IGF binding assay, IGF-like was measured in parallel with growth hormone (GH) in plasma from young rainbow trout killed every 1.5h throughout one day. The daily profiles for both hormones, which appear pulsatile, are similar. A significant correlation was observed between GH levels and IGF-like levels with a 1.5h delay. Analogous observations were obtained in individual catheterized adult rainbow trout. Although plasma GH levels differ greatly between fish, less variability is found with IGF-like. In a third experiment, rainbow trout were starved or submitted to bovine GH treatment for four weeks. Starved fish, in which plasma GH levels increased, had plasma IGF-like level significantly lower than in fed fish. In bGH injected fish, plasma IGF-like level was significantly higher than in non-injected fish. These results suggest that, as in mammals, IGF-like secretion depends on plasma GH level and could be modulated by the nutritional status of fish.