Low-arginine and low-protein diets induce hepatic lipid accumulation through different mechanisms in growing rats

• Published in: Nutrition & metabolism 2020-08, Vol.17 (1), p.60-60, Article 60
• Main Authors: Otani, Lila, Nishi, Hiroki, Koyama, Ayaka, Akasaka, Yuta, Taguchi, Yusuke, Toyoshima, Yuka, Yamanaka, Daisuke, Hakuno, Fumihiko, Jia, Huijuan, Takahashi, Shin-Ichiro, Kato, Hisanori
• Format: Article
• Language: English
• Subjects: Amino acids; Antibodies; Apolipoprotein A-IV; Apolipoproteins; Arginine; Arginine deficiency; Diet; Fatty acids; Fatty liver; Glucose; Hepatosteatosis; Homeostasis; Insulin; Insulin resistance; Insulin signaling; Lipids; Lipogenesis; Lipoproteins; Liver; Low density lipoproteins; Low protein diet; Malnutrition; Nutrient deficiency; Plasma; Polymerase chain reaction; Protein deficiency; Proteins; Rodents; Secretion; Triglycerides; Veins & arteries
• ISSN: 1743-7075; 1743-7075
• DOI: 10.1186/s12986-020-00477-5

Dietary protein deficiency and amino acid imbalance cause hepatic fat accumulation. We previously demonstrated that only arginine deficiency or total amino acid deficiency in a diet caused significant hepatic triglyceride (TG) accumulation in young Wistar rats. In this study, we explored the mechanisms of fatty liver formation in these models. We fed 6-week-old male Wistar rats a control diet (containing an amino acid mixture equivalent to 15% protein), a low-total-amino acid diet (equivalent to 5% protein; 5PAA), and a low-arginine diet (only the arginine content is as low as that of the 5PAA diet) for 2 weeks. Much greater hepatic TG accumulation was observed in the low-arginine group than in the low-total-amino acid group. The lipid consumption rate and fatty acid uptake in the liver did not significantly differ between the groups. In contrast, the low-total-amino acid diet potentiated insulin sensitivity and related signaling in the liver and enhanced de novo lipogenesis. The low-arginine diet also inhibited hepatic very-low-density lipoprotein secretion without affecting hepatic insulin signaling and lipogenesis. Although the arginine content of the low-arginine diet was as low as that of the low-total-amino acid diet, the two diets caused fatty liver via completely different mechanisms. Enhanced lipogenesis was the primary cause of a low-protein diet-induced fatty liver, whereas lower very-low-density lipoprotein secretion caused low-arginine diet-induced fatty liver.