富生酮氨基酸饮食改善高脂诱导小鼠非酒精性脂肪肝

Ketogenic essential amino acid replacement diet ameliorates nonalcoholic fatty liver disease in high-fat diet mice

摘要:

目的  探讨富生酮氨基酸（KAA）饮食对高脂诱导小鼠非酒精性脂肪肝的影响及机制。方法  C57BL雄性小鼠随机分4组，给予常规饮食（NC）、高脂饮食（HFD）、富生酮氨基酸高脂饮食（HFDKAAR）以及高脂喂养8周后改为富生酮氨基酸高脂饮食（HFD→HFDKAAR）喂养。每周测进食量、体重，16周后行腹腔内注射葡萄糖耐量实验后处死小鼠，测肝重量、内脏脂肪重量、肝脂质沉积、Kupffer细胞聚集及肿瘤坏死因子-α（TNF-α）和白介素-1β（IL-1β）mRNA表达。结果  各组小鼠摄入热卡比较差异无统计学意义。与NC组比较，HFD组小鼠体重和内脏脂肪重量增加，伴随胰岛素抵抗，肝脂质沉积和Kupffer细胞数量显著增加，TNF-α和IL-1β mRNA表达增加（P <0.05）。与HFD组比较，HFDKAAR及HFD→HFDKAAR组小鼠体重、内脏脂肪下降，胰岛素抵抗均减轻（P <0.05），肝脏Kupffer细胞的数量及脂质沉积减少，TNF-α和IL-1β mRNA的高表达均被逆转（P <0.05）。结论  高脂膳食能诱导出非酒精性脂肪肝小鼠模型，富生酮氨基酸饮食可抑制高脂诱导的肝脏Kupffer细胞的表达，显著改善高脂饮食诱导的肥胖、胰岛素抵抗、肝脂质沉积，减轻肝脏的炎症损伤。

Abstract:

Objective To reveal the effects of ketogenic amino acid (KAA) replacement diet in the high-fat diet-induced nonalcoholic fatty liver disease in mice. Methods C57BL male mice were randomly fed with a conventional diet (NC group), high-fat diet (HFD group) or KAA-fortified HFD (HFDKAAR group); and 8 weeks after HFD initiation, the HFD-fed mice were randomly divided into two groups: one group of mice was fed the same HFD, the other group was fed HFDKAAR (HFD→HFDKAAR). The metabolic status and biochemical evaluations were performed 16 weeks after the initiation of experimental food. Blood glucose was measured by intraperitoneal glucose tolerance test. Insulin levels in plasma were measured using ELISA, the insulin resistance index (IRI) and area under curve (AUC) were calculated. The mesenteric and epididymal fat tissues and liver were weighed. Frozen liver sections were used for evaluation of hepatic steatosis and accumulation of Kupffer cells labeled by f4/80 via Oil Red O staining and immunofluorescence method respectively. The expressions of TNF-α and IL-1β mRNA were measured by real-time qPCR. Results All the mice ate almost similar calories. Compared to the NC group, the HFD-fed mice displayed significantly heavier body weight and intra-abdominal fat weight, severer hepatic steatosis, deterioration of glucose tolerance, and significantly-enhanced macrophage accumulation in liver; interestingly, these changes were reversed after rich-KAA diet administration. Furthermore, real-time qPCR showed hepatic TNF-α and IL-1β mRNA expressions were up-regulated in the HFD fed mice (P < 0.05), these changes were dramatically ameliorated by taking rich-KAA diet (P < 0.05). Conclusions Our data demonstrate that rich-KAA diet could significantly ameliorate HFD-induced hepatic steatosis, obesity and glucose intolerance via normalizing the macrophage accumulation. KAA replacement diet could be a potential nutritional intervention for treatment in patients with metabolic defects.