RESUMEN
Camelina sativa is a hardy oilseed crop with seeds that contain high levels of ω3 polyunsaturated fatty acids and protein, which are critical components of fish feed. Camelina might thus be used as a cheaper and more sustainable supplement to fish-based products in aquaculture. Atlantic cod, Gadus morhua, is a species of interest in the aquaculture industry due to a decrease in wild populations and subsequent collapse of some cod fisheries. As cod are carnivorous fish, it is necessary to determine how this species physiologically tolerates plant-based diets. In this study, juvenile Atlantic cod were subjected to 13 weeks of either 15 or 30% camelina meal (CM)-supplemented diets or a control fish meal feed. Growth and food intake were evaluated and the mRNA expression of appetite-related hormones [pro-melanin-concentrating hormone (pmch), hypocretin (synonym: orexin, hcrt), neuropeptide Y (npy) and cocaine- and amphetamine-regulated transcript (cart)] was assessed using quantitative real-time PCR in brain regions related to food intake regulation (telencephalon/preoptic area, optic tectum/thalamus and hypothalamus). CM inclusion diets caused decreases in both growth and food intake in Atlantic cod. Optic tectum pmch transcript expression was significantly higher in fish fed the 30% CM diet compared to fish fed the 15% CM diet. In the hypothalamus, compared to fish fed the control diet, hcrt expression was significantly higher in fish fed the 30% CM diet, while npy transcript expression was significantly higher in fish fed the 15% CM diet. cart mRNA expression was not affected by diet in any brain region. Further studies are needed to determine which factors (e.g. anti-nutritional factors, palatability and nutritional deficits) contribute to reduced feed intake and growth, as well as the maximum CM inclusion level that does not negatively influence feed intake, growth rate and the transcript expression of appetite-related factors in Atlantic cod.
Asunto(s)
Regulación del Apetito/genética , Encéfalo/metabolismo , Brassicaceae , Dieta , Gadus morhua/genética , Alimentación Animal , Animales , Apetito/genética , Acuicultura/métodos , Suplementos Dietéticos , Femenino , Gadus morhua/metabolismo , Regulación del Desarrollo de la Expresión Génica , Hormonas Hipotalámicas/genética , Hormonas Hipotalámicas/metabolismo , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Masculino , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Neuropéptido Y/genética , Neuropéptido Y/metabolismo , Neuropéptidos/genética , Neuropéptidos/metabolismo , Orexinas , Precursores de Proteínas/genética , Precursores de Proteínas/metabolismoRESUMEN
Melanin-concentrating hormone (MCH) is classically known for its role in regulating teleost fish skin color change for environmental adaptation. Recent evidence suggests that MCH also has appetite-stimulating properties. The gonadotropin-releasing hormone (GnRH) peptide family has dual roles in endocrine control of reproduction and energy status in fish. Atlantic cod (Gadus morhua) are a commercially important aquaculture species inhabiting the shores of Atlantic Canada. In this study, we examine MCH and GnRH transcript expression profiles during early development as well as in central and peripheral tissues and quantify juvenile Atlantic cod MCH and GnRH hypothalamic mRNA expressions following food deprivation. MCH and GnRH3 cDNAs are maternally deposited into cod eggs, while MCH has variable expression throughout early development. GnRH2 and GnRH3 mRNAs "turn-on" during mid-segmentation once the brain is fully developed. For both MCH and GnRH, highest expression appears during the exogenous feeding stages, perhaps supporting their functions as appetite regulators during early development. MCH and GnRH transcripts are found in brain regions related to appetite regulation (telencephalon/preoptic area, optic tectum/thalamus, hypothalamus), as well as the pituitary gland and the stomach, suggesting a peripheral function in food intake regulation. Atlantic cod MCH mRNA is upregulated during fasting, while GnRH2 and GnRH3 transcripts do not appear to be influenced by food deprivation. In conclusion, MCH might be involved in stimulating food intake in juvenile Atlantic cod, while GnRHs may play a more significant role in appetite regulation during early development.
Asunto(s)
Regulación del Apetito/fisiología , Ingestión de Alimentos/fisiología , Gadus morhua/fisiología , Hormona Liberadora de Gonadotropina/análogos & derivados , Hormonas Hipotalámicas/genética , Melaninas/genética , Hormonas Hipofisarias/genética , Ácido Pirrolidona Carboxílico/análogos & derivados , ARN Mensajero/genética , Animales , Ayuno/fisiología , Femenino , Regulación del Desarrollo de la Expresión Génica , Hormona Liberadora de Gonadotropina/genética , Hormona Liberadora de Gonadotropina/metabolismo , Hormonas Hipotalámicas/metabolismo , Hipotálamo/fisiología , Masculino , Melaninas/metabolismo , Especificidad de Órganos , Hipófisis/fisiología , Hormonas Hipofisarias/metabolismo , Ácido Pirrolidona Carboxílico/metabolismo , ARN Mensajero/metabolismo , Reproducción/fisiología , Tálamo/fisiología , Distribución TisularRESUMEN
In order to better understand the role of melanin-concentrating hormone (MCH) in the regulation of appetite in fish, the mRNAs of two forms of MCH, prepro-MCH and MCH2, and two forms of MCH receptors, MCH-R1 and MCH-R2, were isolated from winter flounder (Pseudopleuronectes americanus). In addition, the mRNA expressions of these peptides and their receptors were determined under fed and fasted conditions. Both MCHs are expressed in forebrain and midbrain, as well as peripheral tissues including gut and gonads. Both MCH-Rs are ubiquitously expressed in the brain and periphery. Fasting induced an increase in the expression levels of MCH and MCH-R1 mRNAs in optic tectum/thalamus and hypothalamus but had no effect on either MCH2 or MCH-R2 mRNA expressions. Our results suggest that MCH and MCH-R1, but not MCH2 and MCH-R2 might have a role in the regulation of appetite in flounder.
Asunto(s)
Regulación del Apetito , Proteínas de Peces/fisiología , Lenguado/fisiología , Hormonas Hipotalámicas/fisiología , Melaninas/fisiología , Hormonas Hipofisarias/fisiología , Receptores de la Hormona Hipofisaria/fisiología , Secuencia de Aminoácidos , Animales , Encéfalo/metabolismo , Femenino , Proteínas de Peces/genética , Proteínas de Peces/metabolismo , Lenguado/genética , Lenguado/metabolismo , Privación de Alimentos , Expresión Génica , Hormonas Hipotalámicas/genética , Hormonas Hipotalámicas/metabolismo , Hipotálamo/metabolismo , Masculino , Melaninas/genética , Melaninas/metabolismo , Datos de Secuencia Molecular , Especificidad de Órganos , Filogenia , Hormonas Hipofisarias/genética , Hormonas Hipofisarias/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Receptores de la Hormona Hipofisaria/genética , Receptores de la Hormona Hipofisaria/metabolismo , Análisis de Secuencia de ADN , Homología de Secuencia de AminoácidoRESUMEN
cDNAs encoding for preproTRH and preproorexin were cloned in winter flounder, a species that undergoes a period of natural fasting during the winter. For both peptides, the deduced amino acid structure of the hormone precursor shows 30-70% similarities with their homologs in other fish species. RT-PCR studies show that these peptides are present not only in the brain, but also in several peripheral tissues, including gastrointestinal tract and testes. Fasting induced increases in both preproorexin and preproTRH expressions in the hypothalamus, but did not affect their expression levels in the telencephalon/preoptic area. In addition, the mRNA expressions of both preproorexin and preproTRH were higher in the winter than in the summer in both hypothalamus and telencephalon/preoptic area. Our results suggest that orexin and thyrotropin-releasing hormone (TRH) might have a role in the seasonal regulation of food intake in winter flounder.