Abstract The aim of this article was to investigate the mechanism of appetite suppression induced by high-fat diets (HFD) in blunt snout bream ( Megalobrama amblycephala ). Fish (average initial weight 40·0 ( sem 0·35) g) were fed diets with two fat levels (6 and 11 %) with four replicates. HFD feeding for 30 d could significantly increase the weight gain rate, but feeding for 60 d cannot. Food intake of M. amblycephala began to decline significantly in fish fed the HFD for 48 d. HFD feeding for 60 d significantly reduced the expression of neuropeptide Y and elevated the expression of cocaine- and amphetamine-regulated transcript (CART), actions both in favour of suppression of appetite. The activation of fatty acid sensing was partly responsible for the weakened appetite. In addition, inflammatory factors induced by the HFD may be involved in the regulation of appetite by increasing the secretion of leptin and then activating the mammalian target of rapamycin (mTOR). Lipopolysaccharide (LPS, 2·0 mg/kg of fish weight) was administered to induce inflammation, and sampling was performed after 3, 6, 9, 12, 18, 24 and 48 h of LPS injection. Within 6–24 h of LPS injection, the food intake and appetite of M. amblycephala decreased significantly, whereas the mRNA expression of leptin and mTOR increased significantly. Our results indicate that inflammatory cytokines may be the cause of appetite suppression in M. amblycephala fed a HFD.
Length–weight relationships (LWR), W = aLb, were estimated for nine fish species belonging to three orders, four families and nine genera from the Hunan Zhangjiajie Chinese Giant Salamander National Natural Reserve, in the northwestern part of Hunan Province of central China. Six of the species are endemic to China, of which three are also endemic to the Yangtze River. The r2 value ranged from 0.9546 to 0.9924. Values of b varied from 2.9177 to 3.6752. This study represents the first reference on LWR for nine species, and are new maximum length records for six species.
This experiment was performed to investigate the effects of replacing fish meal in the diet of Cyprinus carpio var. jian (average weight 19.44±0.06 g) by yeast hydrolysate (YH), on growth, intestinal histology and function. Six hundred fish were assigned into five groups and fed with five isonitrogenous and isocaloric diets replacing fishmeal by 0% (G1), 1% (G2), 3% (G3), 5% (G4) and 7% (G5) YH. YH supplementation at 3% level significantly increased average body weight, daily growth index, feed intake, condition factor, specific growth rate, intestinal villi length and digestive and brush-border enzymes activity compared to the control group (p<0.05). Moreover, YH supplementation significantly increased (p<0.05) intestinal lipase, γ-GT, Na+/K+-ATPase and AKP expression levels. Intestinal Claudin-7 and Occludin mRNA levels in fish of dietary group G5 were significantly higher (p<0.05) than that in the control group. Replacing fish meal with 3% YH increased growth performance, intestinal digestion and absorption, as well as improved intestinal villi length without triggering any negative effects on intestinal tight junction structure. Keywords: Enzyme activities, Growth, Intestinal histology, Jian carp, Tight junction structure, Yeast hydrolysate
This study was conducted to understand the effects of glycyrrhetinic acid, berberine, and resveratrol on growth and inflammatory signalling in channel catfish fed a high-fat diet (HFD). Fish (average weight, 20 ± 0.15 g) were distributed randomly in 15 tanks (11 fish per tank). Fish were allocated randomly to five experimental diets: (control diet (ND); high-fat diet (HFD); high-fat diet + 0.3 mg/kg glycyrrhetinic acid (HFD + GA); high-fat diet + 50 mg/kg berberine (HFD + B); and high-fat diet + 400 mg/kg resveratrol (HFD + R). Each diet was tested in triplicates for eight weeks. The final body weight (FBW), body weight gain (BWG), specific growth rate (SGR), and condition factor (CF) were significantly lower in fish fed HFD. In contrast, opposite trends were observed in the feed conversion ratio (FCR), hepatosomatic index (HSI), visceralsomatic index (VSI), and mesenteric fat index (MFI). Fish fed HFD showed a higher trend ( ) in plasma glucose, cortisol, aspartate aminotransferase (AST), alanine aminotransferase (ALT), liver total cholesterol (TC), triglycerides (TG), and low-density lipoprotein (LDL), while opposite trends were found in total protein (TP) and high-density lipoprotein (HDL). These parameters were all enhanced by feeding the additive-supplemented diets. Liver superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), plasma lysozyme (LYM), myeloperoxidase (MPO), alkaline phosphatase (AKP), acid phosphatase (ACP) activities, and immunoglobulin M (IgM) levels were all lower in fish fed HFD as compared to the control group. However, supplementing GA, berberine, and resveratrol restored these parameters to similar levels to the control group. Upregulated gene expression of interleukin 1β (IL-1ß), nitric oxide (NOS), nuclear factor-kappa B (NF-κB), X box-binding protein 1 (XBP1s), coupled with tumour necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ), was observed in fish fed HFD, whereas reverse trends were observed in the additive-supplemented groups as compared to the control group. Overall, glycyrrhetinic acid, berberine, and resveratrol could reduce endoplasmic reticulum stress and inflammation and enhance the immune response in channel catfish fed HFD.
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