High Lipid Diet Research Articles

Methionine restriction reduced growth performance and exacerbated lipid deposition in hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂) under high-lipid diets by suppressing the lipid degradation pathways with the single-cell RNA-seq analysis

The experiment mainly focused on the liver of the hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂) with low methionine levels by single-cell RNA-seq under high-lipid diets. Both weight gain rate (WGR) and specific growth rate (SGR) in the MR group were obviously lower than the C group, and the intraperitoneal fat (IPF) in the MR group was obviously enhanced than HL and C groups, which led to more visible growth inhibition and lipid deposition. By using the scRNA-seq analysis, nine cell types were classified as: liver parenchymal cells, erythrocytes, hepatic stellate cells, cholangiocytes, macrophages, T cells, epidermal cells, eosinophil and fibroblasts. Lipid and carbohydrate metabolisms were mainly enriched in liver parenchymal cells. The lipid degradation pathways were obviously inhibited in the MR group, such as cholesterol degradation pathway. The lipid degradation genes were obviously decreased in the MR group. In conclusion, methionine restriction might suppress the lipid degradation pathways in liver parenchymal cells, led to obvious lipid deposition.

Effects of silybin on growth performance, antioxidant capacity and immunity in juvenile hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂) fed with high-lipid diets

This research examined the impacts of varying silybin dosages in high-lipid diets on the growth, hepatic histology, immunity, and immune-related gene expression of juvenile hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂). The grouper (with an initial body weight of 8.27 ± 0.08 g) were fed diets containing silybin at levels of 0 g/kg (S1, control group), 0.05 g/kg (S2), 0.10 g/kg (S3), 0.15 g/kg (S4), 0.20 g/kg (S5), 0.25 g/kg (S6), and 0.50 g/kg (S7) for 8 weeks. The study results suggest that the silybin-treated groups displayed an initial increase followed by a decrease in final body weight and specific growth rate, with the highest value observed in the group S5. In serum samples, silybin supplementation of high-lipid diets resulted in increased activities of alkaline phosphatase (AKP), superoxide dismutase (SOD) and catalase (CAT) enzymes, decreased activities of aspartate transaminase (AST) and alanine transaminase (ALT) enzymes and increased total antioxidant capacity (T-AOC) content. In liver, the addition of silybin to high-lipid diets increased SOD, CAT, and lysozyme (LYZ) enzyme activities, increased T-AOC and immunoglobulin M (IgM) contents, and decreased reactive oxygen species (ROS) and malondialdehyde (MDA) contents. Contrasted with the control group, the addition of silybin at 0.05–0.50 g/kg enhanced the hepatic histomorphology, for example, ameliorating the indistinctness of cell outlines and diminishing the hepatocyte vacuolation. Silybin treatment significantly upregulated the expression of liver sod, cat, gpx, nrf2, keap1, hsp70, hsp90, tlr22, myd88, il-1β, tnf-α and il-6(P < 0.05). Silybin treatment significantly upregulated the expression of tlr22, myd88, il-1β, tnf-α, and il-6 of head kidney (P < 0.05). After vibrio harveyi challenge, groups S5-S6 showed higher survival than the control. Incorporating silybin into high-lipid diets boosts grouper's growth, antioxidant, and immune abilities. Regression analysis implies adding 0.23 g/kg silybin to the diets of juvenile hybrid grouper.

Effects of dietary primary bile acids on the growth, intestinal morphology, gene expression, serum metabolites and intestinal microbiota in pearl gentian grouper fed a high lipid diet

The grouper aquaculture industry flavors high lipid diets for economic reasons, yet this inevitably produces negative effects on the growth performance and intestinal function. Bile acids have been extensively reported to mitigate the negative effects on fish fed a high lipid diet, but it remains unclear whether this mechanism is bile acid type dependent. Therefore, an eight-week feeding trial was conducted to investigate the response of growth and intestinal health parameters in pearl gentian grouper Epinephelus fuscoguttatus♂ × E. lanceolatus♀ fed with high lipid diets to different types of bile acids. A high lipid diet (diet HL) containing 167 g/kg crude lipid served as the control diet, and three of primary bile acids glycocholic acid, taurocholic acid, and cholic acid were added at a dose of 900 mg/kg to generate the bile acid diets HBG, HBT, and HBC, respectively. Results revealed that dietary supplementation with glycocholic acid, taurocholic acid, or cholic acid does not affect the feed intake and growth of pearl gentian grouper fed a high lipid diet, while increasing the relative abundance of intestinal opportunistic pathogens such as Staphylococcus and Pseudomonas in this species. Dietary supplementation with glycocholic acid or cholic acid decreases muscle layer thickness and villus height, while increases intestinal injury score. Grouper fed with taurocholic acid showed higher villus width and serum antioxidant enzyme activity, along with lower intestinal injury score and serum lipid peroxidation level. For the protein and gene involved in the PI3K/AKT/mTOR pathways, S6K1 signaling, and bile acids metabolism, grouper fed with taurocholic acid exhibited an increase in the protein expression of PP70 and the mRNA expression of nrf2, pi3k, pdk1, tsc2, akt, mtorc1, fxr and tgr5. Moreover, the serum metabolites can be significantly influenced by the intestinal bacteria. Overall, dietary supplementation of 900 mg/kg taurocholic acid is recommended when feeding high lipid diets to grouper.

Dietary high plant protein and high lipid impaired the intestine health of grouper by disrupting oxidative stress, immune response, and protein metabolism

This study aimed to investigate the molecular mechanisms underlying the detrimental effects of high lipid (HL) and high plant-protein (HP) diets on gut health in pearl gentian grouper, Epinephelus fuscoguttatus♂ × Epinephelus lanceolatus♀. Thus, grouper were randomly distributed into 12 plastic tanks, which were randomly assigned to four diet groups: control (C, 9.48 % lipid, 46.21 % protein), high lipid (HL, 16.70 % lipid, 46.37 % protein), high plant-protein (HP, 9.38 % lipid, 46.50 % protein), high lipid and high plant-protein (HLP, 16.67 % lipid, 46.54 % protein). After an 8-week feeding trial, the HL and HP treatments led to impaired growth performance, compromised gut structure, suppressed immune components, reduced antioxidant defense through the Keap/Nrf2 signaling, and inhibited protein metabolism via the PI3K/AKT/mTOR signaling. Notably, their combined effects (HLP) further exacerbated it. A significant decrease in the proportion of unclassified_Peptostreptococcaceae, Clostridium, and Curvibacter in all treatment groups. The Streptococcus, Lactobacillus, and Bosea were influenced by the interaction between dietary lipids and plant proteins. 14 metabolites that exhibited significant differences among all treatment groups, including arginine, prostaglandin B1, cortexolone, alpha-linolenic acid, and allocholic acid. The HL treatment primarily affected pathways related to lipid metabolism and immunomodulation, while the HP treatment predominantly influenced pathways associated with protein metabolism and immunomodulation. Our findings also indicated that the HP factor played a more prominent role in shaping the metabolic response of fish to the HLP intervention. Furthermore, a significant positive correlation between the Clostridium and the metabolites Cortexolone and Allocholic acid, while a negative correlation was observed between the Streptococcus, Lactobacillus, and Lactococcus and these metabolites. In conclusion, our study demonstrates that excessive inclusion of plant proteins and/or lipids negatively affects gut health in grouper by disrupting oxidative stress, immune response, and protein metabolism through modulation of the gut microbial-metabolite crosstalk.

Comparing effects of high starch diet or high lipid diet supplemented with different levels of zinc on intestinal barrier and microbe community in largemouth bass Micropterus salmoides

Zinc is essential for normal growth and reproduction in all animals and plays a crucial role in many biological processes. The present study aimed to compare the intervention effects of zinc on intestinal health in a high lipid diet or high starch diet. Seven iso-nitrogenous (∼520 g kg−1) diets were formulated containing a positive control diet (115 g kg−1 lipid + 115 g kg−1 starch + 20 mg kg−1 Zn), three high starch diets (HS, 166 g kg−1 starch) and three high lipid diets (HL, 182 g kg−1 lipid), with 0 (HS-LZn, HL-LZn), 20 (HS-MZn, HL-MZn) and 150 (HS-HZn, HL-HZn) mg kg−1 Zn being supplemented. High starch diet and high lipid diet promoted feed efficiency, as evidenced by the lower feed conversion ratio. Three-way factorial ANOVA analysis showed high starch diet (166 g kg−1) significantly decreased final body weight and weight gain compared to the normal starch level (115 g kg−1). Diamine oxidase in serum significantly increased in diets HS-LZn and HL-LZn. In addition, distal intestinal mucosal fold damage and inflammatory infiltration were observed in the HS-LZn, HS-HZn, HL-LZn and HL-HZn groups. Fish fed HL diets (HL-LZn, HL-MZn, HL-HZn) showed lower expressions of claudin 5 and claudin 34, and higher IgD and IgM. Diets HL-LZn and HL-MZn significantly up-regulated C4 and C7. Proinflammatory cytokines including il8, il1β and tnfα significantly up-regulated in diet HL-LZn, even higher than the HS-LZn. Intestinal microbial composition indicated the abundance of Cetobacterium in HL-LZn was significantly higher than the control and HL-MZn diets. Similarly, LEfSe showed that Cetobacterium (P = 0.039) significantly enriched in the HL-LZn group. This study clarified high energy diet induced intestinal damage, which can be alleviated by zinc.

Hyperthermal stress potentiates enhanced lipid utilisation in genetically improved farmed Tilapia, Oreochromis niloticus juveniles

The present experiment evaluated whether dietary protein (P) or lipid (L) is preferred as an energy source by genetically improved farmed tilapia (GIFT) reared at high temperatures. A 60-day feeding trial was conducted at 28.3 °C and 33.3 °C, testing five diets with varying protein (34,36,38 %) and lipid (8,10,12 %) levels, viz., P38L8, P36L8, P34L8, P34L10, P34L12. Parameters assessed included growth, body composition, serum lipids, enzyme activities, fatty acid profiles, and PPAR-α mRNA expression. Results indicated that the fish fed optimum protein and highest lipid level (P34L12) showed significantly higher (P < 0.05) weight gain percent and thermal growth coefficient. Increasing dietary lipid content reduced whole-body lipid deposition and mobilised serum triglycerides and cholesterol at higher temperatures (HT). Hepatic malic enzyme activity decreased with rising temperature and lipid content, while lipoprotein lipase activity in muscle increased. The fatty acid composition altered substantially with the changes in rearing temperature and diets. Unsaturated fats were preferred as direct fuels for β-oxidation, wherein the P34L12 groups preserved body (area %) EPA, DHA, and linolenic acid, especially at HT. The expression of PPAR-α, a lipolytic marker, was upregulated with increasing temperature and high dietary lipid content, peaking in P34L12 groups. The study concludes that high-lipid diets (12 %) are metabolically superior to high-protein diets for GIFT tilapia at elevated temperatures, optimising growth, enhancing metabolic efficiency, and maintaining essential fatty acid profiles under hyperthermal stress.

A field study to optimize protein and lipid levels in diet for cage-cultured subadult rockfish Sebastes schlegelii

A feeding trial was conducted to evaluate growth, body composition, serum biochemistry, digestion and metabolism, and oxidation resistence of S. schlegelii fed 9 diets in a 3×3 factorial design (protein levels: 44 %, 48 %, 52 %; lipid levels: 6 %, 10 %, 14 %), to optimize protein and lipid levels for practical feed formula. Rockfish (114.25 g) were stocked into 27 cages in an offshore system and fed test diets to satiation twice daily for 8 weeks. Growth increased but feed conversion rate decreased with dietary protein increasing. Increasing dietary protein to >48 % led to reduced feeding intake but increased protein efficiency ratio. Lipid efficiency ratio increased with dietary protein increasing but decreased with dietary lipid increasing. Hepatosomatic index decreased coupling with the increases in condition factor and liver lipid content as dietary lipid increased to 14 %. Intraperitoneal fat ratio increased with dietary lipid increasing. Increasing dietary protein to > 48 % significantly elevated serum total protein and glucose concentrations, hepatic glycogen synthase activity. High-protein (52 %) diets elevated serum albumin and urea nitrogen concentrations, hepatic pyruvate kinase and alanine aminotransferase (ALT) activities but downregulated hepatic growth-hormone (GH) receptor. Activities of trypsin, lipase, serum superoxide dismutase and total antioxidant capacity decreased with the dietary lipid increasing. Increasing dietary lipid to > 10 % reduced serum GH concentration, and high-lipid (14 %) diets significantly enhanced serum triglyceride concentration and hepatic transaminases activities, and resulted in a visual increase of adipocytes in liver. Serum cholesterol and low-density lipoprotein decreased as dietary protein increased to 48–52 % or dietary lipid >10 %. Hepatic succinate dehydrogenase activity and serum IGF-1 significantly increased while hepatic fatty acid synthetase decreased as dietary protein increased to >48 % or dietary lipid >10 %. High-protein (52 %) diet or high-lipid (14 %) diet elevated serum malonaldehyde concentration. These findings suggested 48 % protein and 10 % lipid were the optimal in diet for subadult S. schlegelii.

The role of bile acid in regulating head-kidney, spleen and skin immune function of on-growing grass carp (Ctenopharyngodon idella)

Bile acids (BA) are receiving a great deal of attention and interest as critical regulators of the immune system of immune organs. Nevertheless, there are few researches on the effect of BA on immunity of aquatic animals. Hence, the objective of this research was to evaluated the effects of BA supplementation on immune function and the mechanisms in immune organs [head-kidney (HK), spleen (SP) and skin (SK)] of grass carp (Ctenopharyngodon idella). A total of 540 fish (the average body weight was 179.85 ± 1.34 g) were randomly assigned to a normal diet group (NPNL: 29 % protein and 5 % lipid) and five low protein and high lipid diet groups (LPHL: 26 % protein and 6 % lipid) with graded levels of 0 (no supplement), 80, 160, 240 and 320 mg/kg BA for 50 days. Grass carp were subjected to a 14-day challenge with Aeromonas hydrophila after growth experiment. Results indicated that: (1) LPHL group (without BA supplementation) increased SK lesion morbidity compared to NPNL group, and LPHL+160 mg/kg BA supplementation improved the disease resistance; (2) LPHL group (without BA supplementation) decreased the levels of antimicrobial compounds and the gene expressions of antimicrobial peptides in immune organs compared to NPNL group, and LPHL+(160–240) mg/kg BA supplementation significantly increased (P < 0.05) lysozyme (LZ) and acid phosphatase (ACP) activities, complement (C3, C4) and immunoglobulin M (IgM) contents, as well as the gene expressions of hepcidin, antimicrobial peptide 2 A (Leap-2 A), Leap-2B, Mucin2, βdefensin-1 in immune organs of fish; (3) LPHL group (without BA supplementation) aggravated inflammatory response by upregulated pro-inflammatory factors and downregulated anti-inflammatory factors gene expressions compared to NPNL group, and LPHL+240 mg/kg BA supplementation significantly increased transforming growth factor (TGF)-β1, interleukin 11 (IL-11), −4/13 A, TOR, eIF4E-binding proteins (4E-BP)1, S6K1, but markedly reduced (P < 0.05) the gene expressions of tumor, necrosis factor α (TNF-α), interferon γ2 (IFN-γ2), IL-1β, IL-6, IL-8, IL-15, IL-17D, IL-12p35, nuclear factor kappa B p65 (NF-κB p65), c-Rel, inhibitor of κBα (IκBα), IκB kinase β (IKKβ), IKKγ in immune organs of fish. In conclusion, LPHL diet (without BA supplementation) increased SK lesion morbidity and impaired the immunity of immune organs. In addition, LPHL+(160–240) mg/kg BA supplementation enhanced the disease resistance and immunity of grass carp by inhibiting NF-κB signaling molecule and activating TOR signaling molecule.

Changes in ruminal fermentation and rumen bacteria population in feedlot cattle during a high lipid diet adaptation

Abstract This study aimed to investigate changes in feed intake and ruminal environmental parameters during a high-lipid diet transition in cattle. Eight Nellore steers were fed a control diet composed of 30% hay and 70% concentrate for 21 days, followed by the inclusion of 60 g/kg dry matter of soybean oil for 21 days. The DM intake expressed as a percentage of BW 21 days after lipid inclusion was lower (1.75% BW) than that observed during the control diet feeding (1.81% BW) (P&lt;0.01). Steers fed the control diet had a lower pH than the ruminal pH recorded on days 7, 14, and 21 after lipid inclusion (P=0.034). Lower total short-chain fatty acid production in the rumen and lower microbial nitrogen synthesis were observed on day 7 after lipid inclusion compared to values found when steers were fed the control diet and on days 14 and 21 after lipid inclusion (P=0.041). Lipid inclusion in the diet decreased the population of protozoa on days 7, 14, and 21 (P&lt;0.001). The abundances of R. albus and F. succinogenes were higher when steers were fed the control diet than the abundance observed on days 7, 14, and 21 after lipid inclusion in the diet (P&lt;0.05). The first seven days of lipid diet inclusion are considered the most critical for ruminal adaptation, involving reductions in fibrolytic bacteria and changes in fermentation parameters. After 14 days the rumen showed signs of recovery and adaptation.

Antidiabetic potential of sea fish mass by inhibiting di-peptidyl peptidase-IV and augmenting glucagon-like peptide-1 on high lipid diet and streptozotocin induced diabetic rats

Many studies have revealed that sea fish is a rich source of nutrients, especially protein and there peptide. In this study, antidiabetic activity of the fish masses of three sea-fishes ‘volavetki’ (Panna microdon, Bleeker 1849), ‘ruli’ (Coilia dussumieri, Valenciennes 1848), ‘tapra’(Opisthopterus tardoore, Cuvier 1829) and one fresh-water fish ‘murola’(Amblypharyngodon mola, Hamilton 1822),evaluated high lipid diet (HLD) and STZ induced Type 2 Diabetic Mellitus (T2DM) rats. Supplementation of sea-fish masses and antidiabetic effect was monitored by fasting plasma blood glucose and HbA1c. Also, insulin, c-peptide, glucagon-like peptide-1, dipeptidyl peptidase-IV, glucokinase, glucose-6 phosphatase, superoxide dismutase, glutathione peroxidase, catalase, plasma total cholesterol, low density lipoprotein, triglycerides, high density lipoprotein and histopathology of free radical activity of pancreatic tissues were evaluated. Out of four fish masses, volavetki sea fish masses oral supplementation resulted in significant reduction of plasma blood glucose, HbA1c of T2DM rat. All other parameters in T2DM rats were returned to near normal by treatment of volavetki sea fish mass. Our findings strongly indicated that volavetki sea fish highly showed antidiabetic activity.

Alleviating effects of guar gum on high-fat diet-induced liver injury in common carp (Cyprinus carpio)

This research aimed to determine the effect of dietary guar gum inclusion in high-lipid diets on the liver health of common carp (Cyprinus carpio). Four high-fat diets (10 % crude lipid) containing 0 % (HF), 0.3 % (HFG0.3), 1 % (HFG1), and 3 % (HFG3) of guar gum and a normal-lipid diet (5 % crude lipid; Control) were formulated. The tested diets were evenly and randomly distributed to fifteen tanks, with each tank containing thirty fish (4.53 ± 0.05 g). Fish were fed until apparent satiation for eight weeks. Compared to HF, diets HFG0.3, HFG1, and HFG3 significantly improved feed efficiency, with the HFG0.3 diet enhancing weight gain rate and specific growth rate. The results indicated that HF induced gut dysbiosis, hepatic lipid accumulation, oxidative stress, inflammation, and disturbance in hepatic lipid and cholesterol metabolism. Compared to the HF diet, diets HFG0.3, HFG1, and HFG3 substantially decreased hepatic lipid accumulation and malonaldehyde content, increased catalase activity and the expression of AMP-activated protein kinase (AMPKα2), peroxisomal proliferator-activated receptor alpha (PPARα), cholesterol 7alpha-hydroxylase, and decreased the expression of interleukin-1β (IL-1β). Moreover, the HFG0.3 and HFG1 diets dramatically increased nuclear factor erythroid 2-related factor 2 and liver X receptor expression and decreased protein carbonyl contents and expression of IL-8, nuclear factor kappa B (NF-κB p65), and tumor necrosis factor α. Furthermore, the HFG1 diet significantly increased carnitine palmitoyltransferase 1 and peroxisomal proliferator-activated receptor gamma coactivator 1 expression and reduced expression levels of fibroblast growth factor 19, farnesoid X receptor, and sterol regulatory element-binding protein type 1. The linear discriminant analysis effect size (LEfSe) analysis showed that HFG 0.3 and HFG1 substantially increased the enrichment of beneficial microbiota (e.g., lactic acid bacteria, Cetobacterium, and Fusobacterial) and decreased the enrichment of harmful microbiota (e.g., Proteobacteria, Acinetobacter, and Pseudomonas) compared to HF. These results suggested that guar gum can mitigate high-fat diet-induced liver damage in fish.

Protein-sparing effects of lipids in the diet of golden pompano (Trachinotus ovatus): evaluation of growth, feed utilization, and lipid metabolism.

To investigate the influences of dietary protein and lipid levels on the growth, feed utilization, morphometric parameters, body composition, serum biochemical parameters, and lipid metabolism of golden pompano (Trachinotus ovatus), nine test diets containing three protein levels (35%, 40%, and 45%) and three lipid levels (8%, 13%, and 18%) were designed in the present study. Each diet (named D1-D9) was randomly assigned to feed triplicate groups of golden pompano juvenile (initial weight ~ 70 g) for 50 days. The results showed that the dietary lipid levels positively correlated with weight gain, specific growth rate, and protein efficiency ratio (PER), suggesting that the high lipid diets (18%) can be efficiently utilized in this fish species. The dietary protein levels have no significant influences on the growth and feed utilization except for the PER. Increasing dietary protein levels resulted in a decrease in hepatosomatic index (HSI), viscerosomatic index (VSI), and intestinal somatic index (ISI), while the dietary lipid level did not have a significant impact on morphological indices except for ISI. The dietary protein and lipid levels had no significant influences on the contents of crude lipid, crude ash, and moisture of whole body, while the crude protein contents was significantly affected by the dietary protein levels. Serum biochemical indexes, including cholesterol (CHO), triglycerides (TG), high-density lipoprotein cholesterol (HDL), and low-density lipoprotein cholesterol (LDL), as well as HDL/LDL ratio were significantly affected by the dietary lipid levels, but not by the dietary protein levels. The expression levels of genes and their associated proteins involved in hepatic lipogenesis (Srebp-1c and Fas) and fatty acids β-oxidation (Pparα and Cpt-1) were up-regulated with increasing dietary lipid levels, while the former was up-regulated, and the latter was down-regulated with increasing dietary protein levels. Considering the present results in terms of growth performance, feed utilization, morphometric parameters, and lipid metabolism, the recommended dietary protein and lipid levels for golden pompano are 40% and 18%, respectively. The findings suggested that this species exhibits a significant protein-sparing effect on lipid utilization.

A high-cholesterol zebrafish diet promotes hypercholesterolemia and fasting-associated liver steatosis

Zebrafish are an ideal model organism to study lipid metabolism and to elucidate the molecular underpinnings of human lipid-associated disorders. Unlike murine models, to which various standardized high lipid diets such as a high-cholesterol diet (HCD) are available, there has yet to be a uniformly adopted zebrafish HCD protocol. In this study, we have developed an improved HCD protocol and thoroughly tested its impact on zebrafish lipid deposition and lipoprotein regulation in a dose- and time-dependent manner. The diet stability, reproducibility, and fish palatability were also validated. Fish fed HCD developed hypercholesterolemia as indicated by significantly elevated ApoB-containing lipoproteins (ApoB-LPs) and increased plasma levels of cholesterol and cholesterol esters. Feeding of the HCD to larvae for 8 days produced hepatic steatosis that became more stable and sever after 1 day of fasting and was associated with an opaque liver phenotype (dark under transmitted light). Unlike larvae, adult fish fed HCD for 14 days followed by a 3-day fast did not develop a stable fatty liver phenotype, though the fish had higher ApoB-LP levels in plasma and an upregulated lipogenesis gene fasn in adipose tissue. In conclusion, our HCD zebrafish protocol represents an effective and reliable approach for studying the temporal characteristics of the physiological and biochemical responses to high levels of dietary cholesterol and provides insights into the mechanisms that may underlie fatty liver disease.

Study of the Effect of Palmitic Acid on the Expression of Myostatin mRNA and its Cytotoxic Properties in the Culture of Myoblast Cells and the Possibility of Exogenous Regulation

Objective: To study the cytotoxic effect of palmitic acid on myoblasts in vitro and the influence of this toxicant on the expression of myostatin mRNA in myoblast culture. Methods: To research the protective action against these processes of a compound with antioxidant activity, for which 2-ethyl-6-methyl-3-hydroxypyridine malate (ethoxidol) was chosen. Results: Our studies have shown that palmitic acid has a noticeable cytostatic effect on myoblasts in vitro, significantly suppressing their proliferation: the rate of MTT recovery in myoblasts treated with palmitate was only 9.6% of that rate in control myoblasts. In experiments, it was shown that palmitic acid slightly activated the expression of myostatin mRNA. At the same time, the protective effect of 2-ethyl-6-methyl-3-hydroxypyridine malate was not so pronounced. Conclusion: The results of our research indicate that the activation of myostatin synthesis is not one of the main causes of the development of myodystrophy in obese people or people following a high-lipid diet, while the direct cytotoxic effect of palmitic acid on myoblasts is. It is obvious that the use of antioxidants such as ethoxide has a protective effect on myoblasts in the experiment and may have a certain potential in clinical practice.

Gckr depletion leads to growth retardation and diet-dependent visceral obesity in red crucian carp (Carassius auratus red var.)

There exists a notable contrast in the carbohydrate utilization capacity between fish and mammals. In mammals, the glucokinase regulatory protein (GCKR) is known to exert inhibitory effects on glycolysis by binding to glucokinase (GCK), but its role in fish remains unexplored. In this study, the function of gckr in red crucian carp (Carassius auratus red var.), hereafter referred to as RCC, was investigated through its knockout. Under normal dietary conditions, the growth rate of gckr knockout RCC was significantly lower compared to wild-type (WT) RCC reared in the same environment. Subsequent analysis found that gckr knockout RCC exhibited significantly higher serum glucose levels at 1 h post-feeding or glucose injection (hpi), while the difference was abolished at 3 h. Therefore, the metabolic characteristics at 1 and 3 hpi were evaluated between WT and gckr knockout RCC. The results revealed that gckr knockout led to impaired insulin signaling and glycolysis, as evidenced by a reduction in serum insulin level, hepatic insulin receptor a and pyruvate kinase expression, GCK contents, and pyruvate levels at 1 hpi. Additionally, gckr knockout resulted in compromised gluconeogenesis, as indicated by a significant decrease in hepatic expression of fructose-1,6-bisphosphatase 1 and glucose-6-phosphatase at 1 hpi, while it did not affect glycogen accumulation after glucose injection. Regarding lipid metabolism, gckr knockout caused a transient decrease in triglyceride level and reduced expression of fatty acid synthase after glucose injection. Moreover, decreased hepatic peroxisome proliferator activated receptor alpha (ppara) transcripts and proteins were observed in gckr knockout RCC at 1 dpi, indicating a reduced capacity for β-oxidation due to Gckr deficiency. Interestingly, when fed a high-lipid diet, gckr knockout resulted in a significant increase in visceral mass with higher triglyceride level, accompanied by attenuated PPARα signaling. Taken together, this study provides evidence that Gckr-mediated maintenance of Gck contributes to the facilitation of postprandial glycolysis, gluconeogenesis, lipogenesis, and fatty acid β-oxidation in RCC. This study further suggests that enhancing glycolysis may promote growth and liver health in fish under high lipid dietary conditions.

Effects of Low-Lipid Diets on Growth, Haematology, Histology and Immune Responses of Parr-Stage Atlantic Salmon (Salmo salar).

Lipids in fish diets provide energy and play important roles in immunity and metabolism. Atlantic salmon, a species that migrates from freshwater to seawater, requires high energy, especially during smoltification. Juvenile teleosts have low lipid requirements, and a high dietary lipid content is known to have negative effects on their growth and digestion. Therefore, this study evaluated the effect of two commercial rainbow trout feeds (low-lipid, 13.41% and 14.6%) on the growth and immune responses of early parr-stage Atlantic salmon compared to commercial salmon feed (high-lipid, 29.52%). Atlantic salmon parr (weight: 14.56 ± 2.1 g; length: 11.23 ± 0.44 cm) were randomly divided into three groups and fed either one of two commercial rainbow trout feeds (RTF1 and RTF2) or the commercial salmon feed (ASF) for 12 weeks. At the end of the feeding trial, growth, haematology, histology and gene expression analyses were performed. There were no significant differences in weight gain rates or feed efficiency between the groups (p > 0.05). Superoxidate dismutase, glutathione peroxidase, lysozyme and immunoglobulin M activities were not different among the experimental groups (p > 0.05). A histological examination of the liver and intestinal tissues showed no pathological symptoms of inflammatory response or lipid accumulation in any of the groups. In an intestinal transcriptome analysis using RNA-seq, the expression levels of several genes linked to lipids, immune-related proteins, cytokines and chemokines did not differ significantly between the groups (p > 0.05). Commercial rainbow trout feed with low lipid content has no clear negative impact on the development of Atlantic salmon during the early parr stage (14.5 to 39.6 g). This study provides basic information for the development of economical feed for early parr-stage Atlantic salmon.

Molecular characterization of vascular endothelial growth factor b from spotted sea bass (Lateolabrax maculatus) and its potential roles in decreasing lipid deposition

Vascular endothelial growth factor B (VEGFB), a member of the VEGF family, exhibits limited angiogenic activity in mammals but plays an unexpected role in targeting lipids to peripheral tissues. However, its role in lipid metabolism in fish is unknown. In this study, the vegfb gene was cloned and characterized from spotted sea bass (Lateolabrax maculatus). It encodes 254 amino acids and possesses the typical characteristics of the Vegfb family, demonstrating high homology with those from other vertebrate species. The vegfb gene exhibits the highest expression levels in the liver, followed by the gills, intestine, and adipose tissues in spotted sea bass. In vivo, high-lipid diets decreased vegfb expression and increased lipid deposition in liver of fish. In vitro, palmitic acid + oleic acid treatment or vegfb knockdown significantly increased TG and TC contents, promoting lipid droplet deposition in hepatocytes. Vegfb overexpression has the opposite effects, inhibiting lipid deposition and downregulating fatty acid transport and adipogenesis genes. In contrast, the vegfb knockdown significantly upregulated the expression levels of c/ebpα, plin2, and dgat1 (P < 0.05). These results demonstrate that Vegfb may play an important role in reducing lipid deposition by regulating fatty acid transport and adipogenesis in the hepatocytes of spotted sea bass.

Effects of dietary lipid and protein levels on metamorphosis, growth, metabolism and gut microbiota of tadpole (Lithobates catesbeianus)

Tadpole cultivation is a crucial step in the artificial production of bullfrogs (Lithobates catesbeiana), but its feed nutrition is poorly understood. This study examined how dietary lipid and protein levels affect metamorphosis, growth and intestinal health of tadpole. Six groups of tadpoles were fed six diets with two lipid levels (7% and 10%) and three protein levels (36%, 40% and 44%) for 70 days. The results showed that at 7% lipid level, increasing protein enhanced metamorphosis rate and mean weight of tadpoles, reaching the optimal value at 40% protein (P < 0.05). At 10% lipid level, increasing protein also improved mean weight, peaking at 40% protein. Dietary nutrition also influenced liver amino acid and lipid metabolism directly. At 7% lipid level, increasing protein significantly increased the activities of hepatic enzymes GLS, PDH, ALT, AST, etc. (P < 0.05), and up-regulated the expression of hepatic genes fas, accb, fadd6 and cpt1a involved in lipid metabolism (P < 0.05). At 10% lipid level, increasing protein also up-regulated fadd6 and cpt1a genes (P < 0.05), but down-regulated acadl gene. Meanwhile, increasing dietary lipid level elevated TG and T-CHO levels in liver. Increasing dietary protein enhanced gut microbiota richness, while increasing lipid reduced it. Moreover, different gut microbiota groups had distinct biomarkers, such as Rikenellaceae, Desulfovibrionaceae, Burkholderiales and Bacteroidales, which were related to amino acid or lipid metabolism. In summary, under the test conditions, 7% lipid and 40% protein in diet are suitable levels, which can promote metamorphosis, growth and metabolism of tadpoles, and are more economical than high-lipid and high-protein diets.

To Study the Evidence of Linking Adipokines (Adiponectin, Leptin) with Metabolic Syndrome: A Systematic Review

Background: A growing body of world health has shown that there is a correlation between derangement of adipokines section and metabolic syndrome, but a small number of studies also refused the data. Considering these aspects, this study is intense in pursuing precise knowledge regarding the same and the conclusion. Aim and Objective: This study investigates the connection between markers of metabolic syndrome and adipokines, particularly leptin and adiponectin. Methods: PubMed, Scopus, and Web of Science databases were used for a thorough literature review. From 2013 to 2023, the terms “adipokines and metabolic syndrome”, “adiponectin and metabolic syndrome”, and “leptin and metabolic syndrome” were searched. This review made use of the preferred reporting items for systematic review and meta. Results: About 3448 previous studies were searched, of which 85 studies fulfilled the inclusion and exclusion criteria. A total of 85 papers comprised this systematic review, and we examined 60 of them. An overvalue of most studies showed that decreased adiponectin levels are linked with a higher risk of metabolic syndrome. However, patients with metabolic syndrome had higher risk levels of both leptin and the leptin-adiponectin ratio. Conclusions: Obesity affects the generation of adipokines, which regulates the many factors of the metabolic syndrome, through unique and linked pathways. Therefore, we conclude that obesity resulting from a high-fat, high-sugar, high-lipid diet may affect various organs, increasing the risk of metabolic diseases and the underlying causes of insulin resistance and triggering an inflammatory response.

Black Soldier Fly Oil in Different Lipid Diets Could Regulate Tissue Lipid Metabolism and Fatty Acid Composition of Juvenile Mirror Carp

In the present study, our aim was to assess the effect of dietary black soldier fly oil (BSFO) with different lipid contents on the growth performance, body composition, lipid metabolism, and related gene expression in juvenile mirror carp (Cyprinus carpio var. specularis). An 8-week feeding trial was conducted using four isonitrogenous diets (32.0% crude protein) containing two lipid levels: 6% (control (CT) group) and 9% (high lipid (HL) group), both using soybean oil as the oil source. The other two diets contained BSFO on the basis of 6% and 9% lipid, referred to as (CT + BSFO) and (HL + BSFO) groups. The results showed that final body weight, weight gain rate, specific growth rate, protein retention ratio, and feed utilization were significantly increased by using higher dietary lipid levels (P&lt;0.05). Additionally, the gene expression of lipid synthesis markers was significantly up-regulated in intra-peritoneal fat but significantly down-regulated in the hepatopancreas due to increased dietary lipid level (P&lt;0.05). No negative effects on feed utilization or growth performance were observed in fish fed diets containing BSFO. However, the intra-peritoneal fat index, adipocyte size, and hepatopancreas lipid content were significantly decreased in the CT + BSFO group compared to the CT group (P&lt;0.05). Furthermore, BSFO also up-regulated the expression of lipid lipolysis markers in the hepatopancreas and intra-peritoneal fat (P&lt;0.05). Moreover, the use of BSFO also increased the content of n-3 polyunsaturated fatty acid (PUFA) while reducing the content of n-6 PUFA in the muscle (P&lt;0.05). In conclusion, HL diets improved the growth of the fish and increased the lipid deposition. BSFO in the diet resulted in a reduction of lipid deposition in the hepatopancreas and intra-peritoneal fat, likely due to an increase in lipid oxidation.