High lipid diets (HLD) and high plant-protein diets (HPD) exhibit potential fishmeal-saving effects but negatively impact liver health and growth performance in fish. We hypothesized that HLD and HPD impair liver health in pearl gentian groupers (Epinephelus fuscoguttatus♂ × Epinephelus lanceolatus♀) through the modulation of intestinal microbiota and bile acid (BA) metabolism. Four diet groups were tested: control diet (CD, 46.21% crude protein, 9.48% crude lipid), HLD (46.37% crude protein, 16.70% crude lipid), HPD (46.50% crude protein, 9.38% crude lipid), and high lipid-high plant-protein diet (HLPD, 46.54% crude protein, 16.67% crude lipid). A total of 300 fish (average body weight = 15.22 ± 0.03 g) were randomly divided into 4 diet treatments (ensuring 3 tanks replicates of each diet treatment, each tank containing 25 fish). After an eight-week feeding period, the HLD and HPD significantly decreased the final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR) and feed intake (FI) in comparison to CD group, with HLPD exacerbating these indicators (P < 0.05). Compared to CD group, the content of total cholesterol (T-CHO) and triglyceride (TG) in liver and serum were significantly increased in HLD group (P < 0.05). Compared to HPD group, the content of T-CHO in liver was significantly decreased, the content of TG in liver and serum were significantly increased in HLPD group (P < 0.05). HLD, HPD, and HLPD impaired liver health by inducing histological damage, inflammation, and oxidative stress. Compared to CD group, the mRNA relative expression of bile salt export pump (bsep) and multidrug resistance protein 3 (mdr3) were significantly increased in HLD group, whereas the mRNA relative expression of sterol-27-hydroxylase (cyp27a1), microsomal epoxide hydrolase (meh), apical sodium-dependent bile acid transporter (asbt), multidrug resistance-associated protein 3 (mrp3), farnesoid X receptor (fxr) and G protein-coupled bile acid receptor 5 (tgr5) were significantly decreased (P < 0.05). Compared to CD group, the mRNA relative expression of mdr3, asbt, mrp3, organic anion transporters 1 (oatp1), meh, fxr and tgr5 were significantly decreased in HPD group (P < 0.05). In summary, HLD affects intestinal microbiota, BA metabolism, and lipid metabolism, leading to lipid deposition and liver damage. HPD regulates gut microbiota, BA metabolism, inflammatory responses, and BA receptor expression, impairing grouper liver health. HLPD synergistically combines the adverse effects of HLD and HPD on grouper liver health.

中文翻译：

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日粮高脂质和高植物蛋白影响石斑鱼的生长性能、肝脏健康、胆汁酸代谢和肠道菌群


高脂饮食 （HLD） 和高植物蛋白饮食 （HPD） 具有潜在的鱼粉节省效果，但会对鱼类的肝脏健康和生长性能产生负面影响。我们假设 HLD 和 HPD 通过调节肠道微生物群和胆汁酸 （BA） 代谢损害珍珠龙胆石斑鱼 （Epinephelus fuscoguttatus♂ × Epinephelus lanceolatus♀） 的肝脏健康。测试了 4 个饮食组：对照饮食 （CD，46.21% 粗蛋白，9.48% 粗脂）、HLD （46.37% 粗蛋白，16.70% 粗脂）、HPD （46.50% 粗蛋白，9.38% 粗脂）和高脂植物蛋白饮食 （HLPD，46.54% 粗蛋白，16.67% 粗脂）。总共 300 条鱼 （平均体重 = 15.22 ± 0.03 g） 被随机分为 4 次饮食处理 （确保每个饮食处理的 3 个水箱重复，每个水箱包含 25 条鱼）。饲喂期 8 周后，与 CD 组相比，HLD 和 HPD 显著降低最终体重 （FBW） 、增重率 （WGR） 、比生长速率 （SGR） 和采食量 （FI），HLPD 加剧了这些指标 （P < 0.05）。与 CD 组相比，HLD 组肝脏和血清中总胆固醇 （T-CHO） 和甘油三酯 （TG） 含量显著升高 （P < 0.05）。与 HPD 组相比，HLPD 组肝脏中 T-CHO 含量显著降低，肝脏和血清中 TG 含量显著升高（P < 0.05）。HLD、HPD 和 HLPD 通过诱导组织学损伤、炎症和氧化应激来损害肝脏健康。 与CD组相比，HLD组胆盐输出泵（bsep）和多药耐药蛋白3（mdr3）的mRNA相对表达显著升高，而甾醇-27-羟化酶（cyp27a1）、微粒体环氧化物水解酶（MEH）、顶端钠依赖性胆汁酸转运蛋白（ASBT）、多药耐药相关蛋白3（MRP3）、法尼醇X受体（fxr）和G蛋白偶联胆汁酸受体5（TGR5）的mRNA相对表达显著降低（P < 0.05）。 与 CD 组相比，HPD 组 mdr3 、 asbt 、 mrp3 、 有机阴离子转运蛋白 1 （oatp1） 、 meh 、 fxr 和 tgr5 的 mRNA 相对表达显著降低 （P < 0.05）。综上所述，HLD 影响肠道菌群、BA 代谢和脂质代谢，导致脂质沉积和肝损伤。HPD 调节肠道微生物群、BA 代谢、炎症反应和 BA 受体表达，损害石斑鱼肝脏健康。HLPD 协同结合了 HLD 和 HPD 对石斑鱼肝脏健康的不利影响。