Effects of dietary arginine levels and carbohydrate-to-lipid ratios on mRNA expression of growth-related hormones in largemouth bass, Micropterus salmoides.
Gen Comp Endocrinol
; 179(1): 121-7, 2012 Oct 01.
Article
en En
| MEDLINE
| ID: mdl-22906421
Utilizing the tissue samples and growth data collected from our two preceding researches in largemouth bass (LMB), we have investigated effects of dietary arginine (Arg) levels and carbohydrate-to-lipid (CHO/LIP) ratios on the GH, IGF-I and insulin expression in related tissues to find possible relationships between the nutrient intake, growth performance and transcript level. Hepatic IGF-I and pituitary GH mRNA levels were significantly up-regulated by lower dietary Arg levels from 1.94% to 3.01% and by higher levels from 2.76% to 3.01%, respectively, while Brockmann body (BB)-containing tissue insulin mRNA expression was not affected. Dietary CHO/LIP ratios ranging from 0.32 to 5.17 (w/w) affected pituitary GH, liver IGF-I and BB-containing tissue insulin mRNA expression in a ratio-specific pattern. The lower ratios from 0.32 to 2.36 significantly up-regulated GH and insulin transcript levels, but significantly down-regulated IGF-I transcript levels; the higher ratios did no longer exert any further effects on them. Meanwhile, two strong positive correlations (r=0.892, r=0.885) between hepatic IGF-I transcript levels and specific growth rates of tested fish were observed with varying dietary Arg levels and CHO/LIP ratios, respectively. These findings indicate that in LMB dietary Arg levels and CHO/LIP ratios regulate differentially the endocrine system of GH, IGF-I and insulin at transcription level; this system, in turn, plays a fundamental role in the regulation of the nutrient metabolism and somatic growth; and that hepatic IGF-I mRNA abundance should be a more reliable index to assess growth and nutritional fitness than the others, at least in LMB.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Arginina
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Lubina
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Factor I del Crecimiento Similar a la Insulina
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Hormona del Crecimiento
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Regulación de la Expresión Génica
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Metabolismo de los Hidratos de Carbono
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Metabolismo de los Lípidos
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Insulina
Límite:
Animals
Idioma:
En
Revista:
Gen Comp Endocrinol
Año:
2012
Tipo del documento:
Article
Pais de publicación:
Estados Unidos