Influence of Dietary Inositol Supplementation on Growth, Liver Histology, Lipid Metabolism, and Related Genes Expression on Juvenile Hybrid Grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatu) Fed High-Lipid Diets

Abstract

An 8-week feeding trial was conducted to investigate the effects of dietary inositol on growth performance, lipid metabolism, and expression of lipid related genes of hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatu) (initial body weight 6.76 ± 0.34 g). Six isonitrogenous and isolipidic (16.35%) diets were formulated to contain graded levels of inositol (0.17 g/kg (J1), 0.62 g/kg (J2), 1.03 g/kg (J3), 1.78 g/kg (J4), 3.43 g/kg (J5), and 6.59 g/kg (J6)). The results indicated that (a) weight gain rate appeared gradually increasing trend and significant increase in four inositol treatments (J3, J4, J5, and J6) ( P < 0.05 ). Protein efficiency ratio was slightly improved in the J4 group ( P < 0.05 ), but there was no significant difference exhibiting in survival rate between the inositol-treated groups and the control group ( P > 0.05 ). (b) In serum, dietary inositol significantly reduced the contents of triglyceride (TG), total cholesterol (TC), low-density lipoprotein, and clearly increased the content of high-density lipoprotein ( P < 0.05 ). In the liver, dietary inositol significantly decreased contents of TG, TC, and very low-density lipoprotein ( P < 0.05 ). The activities of lipoprotein lipase, hepatic lipase, and adipose triglyceride lipase were slightly improved in the inositol-treated groups ( P < 0.05 ). (c) With increasing of inositol supplement, decreasing of lipid droplet could be observed in hepatocyte. (d) In the liver, dietary inositol significantly downregulated the mRNA levels of fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), 6-phosphogluconate dehydrogenase (6PGD), and sterol regulatory element-binding protein-1 (SREBP1) ( P < 0.05 ), while it remarkably upregulated the mRNA levels of lipoprotein lipase (LPL), hormone-sensitive lipase (HSL), and carnitine palmitoyl transferase1 (CPT1) ( P < 0.05 ). In summary, dietary inositol improved growth and reduced lipid composition in the liver of hybrid grouper through decreasing of fatty acid synthesis and increasing of lipid catabolism. Under the experimental conditions, broken-line regression analysis showed that 1.23~1.67 g/kg dietary inositol was recommended in juvenile grouper high-lipid diets.

Inositol Inclusion Affects Growth, Body Composition, Antioxidant Performance, and Lipid Metabolism of Largemouth Bass (Micropterus salmoides)

“…Additionally, the WGR, SGR, and FER of largemouth bass feedin a diet supplemented with 250 mg/kg inositol increased significantly. These results were consistent with the study on golden pompano (Trachinotus ovatus) [15], juvenile barramundi (Lates calcarifer Bloch) [25], juvenile tilapia (Oreochromis niloticus × Oreochromis aureus) [26], juvenile Chinese mitten crab (Eriocheir sinensis) [27], and Juvenile hybird grouper (Brown-marbled Grouper Epinephelus fuscoguttatus ♀ × giant grouper E. lanceolatus ♂) [28]. Studies have pointed out that inositol is involved in the synthesis of phosphatidyl inositol, and phosphatidyl inositol could generate inositol triphosphate through phosphorylation, which could regulate the concentration of calcium ions and control the release of acetylcholine.…”

Effects of High-Lipid Dietary Protein Ratio on Growth, Antioxidant Parameters, Histological Structure, and Expression of Antioxidant- and Immune-Related Genes of Hybrid Grouper

“…In this study, paraffin sections of liver were prepared to evaluate the efficacy of protein levels in a high-lipid diet on hepatic histologic changes. Previous studies have shown that the liver could be damaged by high-lipid diets [59] or environmental toxicants manifested by nuclear hypertrophy, karyolysis, indistinguishable cell contours, extensive hepatocellular vacuolation and other phenomena [2,60,61]. Similar symptoms were observed in the control group of this study but the 420 g/kg group reduced the histological abnormalities caused by the high-lipid diet.…”

“…This indicates that T-AOC is largely influenced by the activity of these two enzymes. Studies have shown that, when large amounts of oxygen radicals are present in the body [2,41], if the antioxidant capacity of the fish's antioxidant system is weak, it fails to scavenge ROS in time, which in turn causes oxidative damage to cells and promotes lipid peroxidation [42]. In the tissues and organs of the body, the concentration of MDA, the end product of lipid peroxidation, is not only a direct reflection of the antioxidant capacity of the tissues and organs, but also a measure of the antioxidant capacity of the body [42].…”

“…The hybrid grouper (♀Epinephelusfuscoguttatus × ♂E. lanceolatus) is a new species of grouper crossed from giant grouper (E. lanceolatus) as the male parent and brown-marbled grouper (E. fuscoguttatus) as the female parent, which belongs to the Perciformes, Suborder Perciformes, Serranodae and Grouper [1,2]. It is favored by consumers and farmers due to its fast growth rate, strong disease resistance and high return on agricultural investment, and has a large consumer market in southern China [3].…”