Diet and exercise modulate gh-igfs axis, proteolytic markers and myogenic regulatory factors in juveniles of gilthead sea bream (Sparus aurata)

© 2021 by the authors.The physiological and endocrine benefits of sustained exercise in fish were largely demonstrated, and this work examines how the swimming activity can modify the effects of two diets (high-protein, HP: 54% proteins, 15% lipids; high-energy, HE: 50% proteins, 20% lipids) on different growth performance markers in gilthead sea bream juveniles. After 6 weeks of experimentation, fish under voluntary swimming and fed with HP showed significantly higher circulating growth hormone (GH) levels and plasma GH/insulin-like growth-1 (IGF-1) ratio than fish fed with HE, but under exercise, differences disappeared. The transcriptional profile of the GH-IGFs axis molecules and myogenic regulatory factors in liver and muscle was barely affected by diet and swimming conditions. Under voluntary swimming, fish fed with HE showed significantly increased mRNA levels of capn1, capn2, capn3, capns1a, n3, and ub, decreased gene and protein expression of Ctsl and Mafbx and lower muscle texture than fish fed with HP. When fish were exposed to sustained exercise, diet-induced differences in proteases’ expression and muscle texture almost disappeared. Overall, these results suggest that exercise might be a useful tool to minimize nutrient imbalances and that proteolytic genes could be good markers of the culture conditions and dietary treatments in fish.This study was supported by the projects from the “Ministerio de Economía y Competitividad” (MINECO) AGL2015-70679-R and RTI2018-100757-B-I00 to J.G. and J.B., and the “Xarxa de Refèrencia d’R+D+I en Aqüicultura” and the 2017SGR1574 from the “Generalitat de Catalunya”. M.P.- A., I.G.-P. and E.J.V. were supported by predoctoral fellowships from the MINECO, BES-2016-078697, PRE2019-089578 and BES-2013-062949, respectively

A long-term growth hormone treatment stimulates growth and lipolysis in gilthead sea bream juveniles

The enhancement of the endocrine growth hormone (GH)/insulin-like growth factor I (IGF-I) system by the treatment with a sustained release formulation of a recombinant bovine GH (rBGH), is a good strategy to investigate growth optimization in aquaculture fish species. To further deepen into the knowledge of rBGH effects in fish and to estimate the growth potential of juveniles of gilthead sea bream, the present work evaluated rBGH injection on growth, GH/IGF-I axis and lipid metabolism modulation, and explored the conservation of GH effects provoked by the in vivo treatment using in vitro models of different tissues. The rBGH treatment increased body weight and specific growth rate (SGR) in juveniles and potentiated hyperplastic muscle growth while reducing circulating triglyceride levels. Moreover, the results demonstrated that the in vivo treatment enhanced also lipolysis in both isolated hepatocytes and adipocytes, as well as in day 4 cultured myocytes. Furthermore, these cultured myocytes extracted from rBGH-injected fish presented higher gene expression of GH/IGF-I axis-related molecules and myogenic regulatory factors, as well as stimulated myogenesis (i.e. increased protein expression of a proliferation and a differentiation marker) compared to Control fish-derived cells. These data, suggested that cells in vitro can retain some of the pathways activated by in vivo treatments in fish, what can be considered an interesting line of applied research. Overall, the results showed that rBGH stimulates somatic growth, including specifically muscle hyperplasia, as well as lipolytic activity in gilthead sea bream juveniles.E.J.V., E.L. and M.P.-A. were supported by predoctoral fellowships from the “Ministerio de Economía y Competitividad” (MINECO). This study was supported by the projects from the MINECO AGL2012-39768 and AGL2015-70679-R to J.G., and AGL2014-57974-R to I.N. and E.C., and the “Xarxa de Refèrencia d'R+D+I en Aqüicultura” and the 2014SGR-01371 from the “Generalitat de Catalunya”.Peer reviewe

Regulation of gh expression in gilthead sea bream pituitary

This is the 10th volume of Advances in Comparative Endocrinology, a series of books that collect the communications presented at the congresses of the Iberian Association for Comparative Endocrinology (AIEC). This round number marks roughly 20 years since the foundation of AIEC and the beginning of the biennial meetings organized by AIEC affiliated groups. In 2005, our Comparative Endocrinology and Integrative Biology group CEIB-CCMAR organized the 5th AIEC meeting and it was a pleasure to welcome the 12th AIEC Congress back again to Faro, Portugal, in 2019 (26-28 September). Volume X includes contributions resulting from plenary, keynote, oral or poster presentations, and authored by almost 150 senior or young scientists and students, which show the latest advances in the fields of reproduction, energy metabolism, genomics, evolution, stress, immune response and growth in both vertebrates and invertebrates. Studies range from fundamental questions on endocrinology to environmental challenges, animal production and welfare, or the mechanisms of disease, and reach beyond the Iberian borders. In addition to Portugal and Spain, the science presented here comes from institutions in Canada, Chile, France, Norway and USA. About 30% of the communications result from international cooperation, and over 55% were direct collaborations between institutions. AIEC aims to promote collaborations and its congresses are a privileged stage for networking.Supported by funds from the Ministerio de Ciencia, Innovación y Universidades (MICIUN) (AGL2017-89436-R and RTI2018- 100757-B-I00), 2017SGR-1574 and XRAq. M.P-A and S.B-P are recipients of a FPI fellowship from the MICIUN (BES-2016-078697 and PRE2018-085580 respectively).Peer reviewe

Recombinant bovine growth hormone (rBGH) enhances somatic growth by regulating the GH-IGF axis in fingerlings of gilthead sea bream (Sparus aurata)

The growth hormone (GH)/insulin-like growth factors (IGFs) endocrine axis is the main growth-regulator system in vertebrates. Some authors have demonstrated the positive effects on growth of a sustained-release formulation of a recombinant bovine GH (rBGH) in different fish species. The aim of this work was to characterize the effects of a single injection of rBGH in fingerlings of gilthead sea bream on growth, GH-IGF axis, and both myogenic and osteogenic processes. Thus, body weight and specific growth rate were significantly increased in rBGH-treated fish respect to control fish at 6 weeks post-injection, whereas the hepatosomatic index was decreased and the condition factor and mesenteric fat index were unchanged, altogether indicating enhanced somatic growth. Moreover, rBGH injection increased the plasma IGF-I levels in parallel with a rise of hepatic mRNA from total IGF-I, IGF-Ic and IGF-II, the binding proteins IGFBP-1a and IGFBP-2b, and also the receptors IGF-IRb, GHR-I and GHR-II. In skeletal muscle, the expression of IGF-Ib and GHR-I was significantly increased but that of IGF-IRb was reduced; the mRNA levels of myogenic regulatory factors, proliferation and differentiation markers (PCNA and MHC, respectively), or that of different molecules of the signaling pathway (TOR/AKT) were unaltered. Besides, the growth inhibitor myostatin (MSTN1 and MSTN2) and the hypertrophic marker (MLC2B) expression resulted significantly enhanced, suggesting altogether that the muscle is in a non-proliferative stage of development. Contrarily in bone, although the expression of most molecules of the GH/IGF axis was decreased, the mRNA levels of several osteogenic genes were increased. The histology analysis showed a GH induced lipolytic effect with a clear decrease in the subcutaneous fat layer. Overall, these results reveal that a better growth potential can be achieved on this species and supports the possibility to improve growth and quality through the optimization of its culture conditions.E.J.V. and E.L. are supported by a predoctoral fellowship from the “Ministerio de Ciencia e Innovación” (MICINN), and A.M. by the University of Barcelona (APIF-2012). This study was supported by the project AGL2012-39768 (MICINN) to J.G., and the “Xarxa de Refèrencia d’R+D+I en Aqüicultura” and the 2014SGR-01371 from the “Generalitat de Catalunya”.Peer reviewe

A Review on the key factors that control muscle development and growth in gilthead sea bream

Trabajo presentado en el 11º Congreso de la Asociación Ibérica de Endocrinología Comparada (AIEC), celebrado en Vigo (España), del 13 al 15 de julio de 2017Unlike mammals, many fish species are indeterminate growers. Muscle growth involves hypertrophy and hyperplasia that continue during the whole life of the fish, processes that can be modulated by different factors. Growth hormone (GH)/insulinlike growth factors (IGFs) endocrine axis is the main intrinsic factor. Diet composition and physical activity are important external regulators not only of the fish somatic growth but also of muscle characteristics. Over the last years, we have been investigating in gilthead sea bream (Sparus aurata) the possibility to increase growth with different approaches: injection of recombinant bovine GH (rBGH), moderated and sustained swimming activity or diet supplementation. We have determined biometrical parameters, hormones levels, gene and protein expression of growth, myogenesis, proteolysis or osteogenesis gene markers in white muscle, liver or bone, and also analyzed muscle histology. In the different models we have found that an increase in body weight up to 30% can be obtained, and the ratio of circulating GH/IGF-I has appeared as a very good indicator of the growing condition. Moreover, the effects of these factors on the expression of GH and IGF-I receptors, binding proteins and specific regulators in the different tissues will be discussed as have helped to understand how this complex scenario can determine the enhancement of growth and quality of the fish; thus, contributing to the improvement of aquaculture production. Acknowledgements: to Elanco Animal Health for kindly providing the rBGH.Supported by MINECO (AGL2012-39768, AGL2014-57974-R and AGL2015- 70679-R) and Catalonian Government (2014SGR-01371 and XRAq).Peer reviewe

Gilthead sea bream ghrelin characterization and transcriptional regulation during fasting and refeeding

Trabajo presentado en el 11º Congreso de la Asociación Ibérica de Endocrinología Comparada (AIEC), celebrado en Vigo (España), del 13 al 15 de julio de 2017Ghrelin hormone in vertebrates is involved in the regulation of different important functions, such as feed intake, energy metabolism, intestinal motility or digestive enzymes activity, but also has an effect promoting growth through stimulation of growth hormone (GH) expression in the pituitary. However, the functions of ghrelin and its tissue distribution seem to be species-specific and may differ substantially among vertebrates. The aim of this work was to identify and study the responses of ghrelin to different nutritional conditions in an important Mediterranean fish species, gilthead sea bream (Sparus aurata). To achieve this goal, first the phylogeny of S. aurata ghrelin among vertebrates was analyzed, and then a tissue screening by real-time quantitative PCR (qPCR) was performed. Afterwards, the effects of fasting and refeeding on ghrelin gene expression in key tissues and also its plasmatic levels were determined. The results revealed that S. aurata ghrelin is well conserved among fish species, and it is mainly expressed in stomach, pyloric caeca and intestine. Furthermore, in the experiment with juveniles, ghrelin’s gene expression was up-regulated in response to fasting and downregulated with refeeding, suggesting that this hormone may have an important role regulating the physiological functions related to nutritional state, such as feed intake and growth among others.Supported by MICINN (AGL2014-57974-R and AGL2015-70679-R) and Catalonian Government (2014SGR-01371 and XRAq).Peer reviewe

A review on the key factors that control muscle development and growth in gilthead sea bream

Trabajo presentado en el 11º Congreso de la Asociación Ibérica de Endocrinología Comparada (AIEC), celebrado en Vigo (España), del 13 al 15 de julio de 2017Unlike mammals, many fish species are indeterminate growers. Muscle growth involves hypertrophy and hyperplasia, processes that can continue during the whole life of the fish and are highly modulated. Growth hormone (GH)/insulin-like growth factors (IGFs) endocrine axis is the main intrinsic factor controlling growth. Diet composition and physical activity are important external regulators not only of the fish somatic growth, but also of muscle characteristics. Over the last years, we have been investigating in gilthead sea bream (Sparus aurata) the possibility to enhance growth using different approaches: injection of recombinant bovine GH (rBGH), moderated and sustained swimming activity or diet supplementation. We have determined biometrical parameters, hormones’ levels, gene and protein expression of growth, myogenesis, proteolysis and osteogenic gene markers in white muscle, liver or bone, and also analyzed muscle histology. In the different models we have found that an increase in body weight up to 30% can be achieved, and the ratio of circulating GH/IGF-I has appeared as a very good indicator of the growing condition. Moreover, the effects of these factors on the expression of GH and IGF-I receptors, binding proteins and specific regulators in the different tissues have been explored. All this has been performed in an attempt to understand how this complex scenario can determine the optimization of growth and quality of the fish, thus, contributing to the improvement of aquaculture productionPeer reviewe

Regulation of GH expression in gilthead sea bream pituitary

Trabajo presentado en el XII Conference of the Iberian Association for Comparative Endocrinology (AIEC), celebrado en Faro (Portugal), del 26 al 28 de septiembre de 2019The GH/IGF-I system is the main endocrine regulator of growth in vertebrates. But, how correlated is the pituitary expression of GH and that of the other components of the system with the animal growth condition? To answer this we have analyzed the changes on pituitary GH and related molecules expression upon different experimental conditions in vivo and in vitro in gilthead sea bream (Sparus aurata). Gilthead sea bream juveniles were treated with recombinant bovine GH (rbGH, Posilac), were fasted during 21 days and refed for 7 days, or were fed a diet containing an amino acid (AA) derivative. Moreover, adult fish pituitaries were treated in vitro with different hormones and AA. Pituitary GH expression in rbGH-treated fish was down-regulated reaching the lowest values after 6 weeks of injection and maintaining low levels during the rest of the experiment, suggesting that sustained high levels of exogenous GH provoked a clear depression on GH synthesis and secretion. On the contrary, 21-days fasting triggered an increase of pituitary GH expression parallel to plasma levels, while GH and IGF-I receptors expression strongly decreased, and refeeding partially recovered the basal levels. The adaptation to food deprivation determined a simultaneous increase of GH gene and protein expression to facilitate its energy mobilization function. Dietary supplementation for 8 weeks with an AA derivative also provoked a tendency to increase GH expression. Finally, hemi-pituitaries treated with Ghrelin or the AA Lysine and Leucine increased, while IGF-I or Somatostatin decreased GH expression. In summary, considering the difficulties to analyze GH circulating levels, these results indicate that pituitary GH expression can be a useful parameter to understand the effects of different physiological conditions on GH/IGF-I system in fis

Characterization and nutritional regulation of ghrelin and its receptors in Gilthead sea bream (Sparus aurata)

Trabajo presentado en el 29th Conference of European Comparative Endocrinologists (CECE), celebrado en Glasgow, del 19 al 22 de agosto de 2018Ghrelin is a peptide hormone that regulates different physiological processes in vertebrates (feeding, metabolism, intestinal activity and growth hormone (Gh) secretion). However, specific actions of this hormone have been reported to change among species. The objective of this work was to characterize preproghrelin and Ghrelin receptors (ghsrs) sequences, and to study their responses to fasting and refeeding in gilthead sea bream (Sparus aurata) juveniles. Structural and phylogenetic analysis of the S. aurata preproghrelin was accomplished, and its expression analyzed in main tissues. Fish were fasted for 21 days and then refed and sampled at 2, 5, 24 h, and 7 days afterwards. Plasma levels of Ghrelin, Gh and insulin-like growth factor (Igf-1), and preproghrelin, ghsrs and members of the Gh/Igf-1 axis gene expression were determined in key tissues. preproghrelin and its receptors presented a good conservation among fish, being highly expressed in stomach and pyloric caeca, and in the pituitary and brain, respectively. Fasting caused a growth recession while increased Ghrelin plasma levels, which rapidly recovered at 5 h postprandial. Gh plasma levels were also increased by fasting, and slowly recovered after refeeding. Contrarily, circulant Igf-1 followed an inverse pattern, suggesting important changes in the Gh/Igf ratio by nutritional status. In agreement with the plasma levels, fasting up-regulated gh expression in pituitary until 1 day after refeeding, when lowest igf-1 expression in the liver was observed. Moreover, the expression profile of hepatic Gh receptors resulted to be inverse to that if circulating Gh levels. Altogether, this study demonstrates the important role of Ghrelin concerning nutritional status, suggesting an orexigenic function in gilthead sea bream, and an interaction with pituitary Ghsrs and Gh/Igf-1 axis to promote optimal growth in this speciesSupported by funds from the MINECO (AGL2014-57974-R and AGL2015-70679-R) and Generalitat de Catalunya (2014SGR-01371 and XRAq)Peer reviewe