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.