Studies on the Effects and Mechanisms of Vitamin A Nutritional Status on the Absorption and Metabolic Functions of Lipids.

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K11608
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 59040:Nutrition science and health science-related
• Research Institution: University of Nagasaki
• Principal Investigator: Suruga Kazuhito 長崎県立大学, 看護栄養学部, 准教授 (70315852)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: ビタミンA / 脂質代謝 / NAFLD / PPARα / LXR

Outline of Final Research Achievements

Vitamin A showed no inhibitory effect on the onset and progression of NAFLD in rats, but β-carotene suppressed the gene expressions related to hepatic inflammation and fibrosis, thereby inhibiting the progression of NAFLD. In addition, it was found that rats with NAFLD had both a decreased vitamin A storage capacity in the liver as well as a decreased ability to mobilize vitamin A from the liver to other tissues.
The expression levels of PPARα and LXR target genes in the liver and jejunum showed that the expression levels of each target gene increased with each agonist administration, even in vitamin A-deficient conditions. These results suggest the presence of substances other than vitamin A-derived metabolites as ligands for RXR in the functional expression of PPARα and LXR.

Free Research Field

栄養生理学

Academic Significance and Societal Importance of the Research Achievements

最近の研究ではビタミンAの潜在的な不足が種々の脂質代謝異常の発症や進展に関与する可能性が報告されている。本研究結果ではNAFLDモデルラットにおいてビタミンAの投与がNAFLDの発症・進展に対して予防効果を示さなかったが、顕著な肝臓ビタミンA貯蔵能の低下および肝外へのビタミンA動員機能の低下が認められた。また、脂質代謝調節に関与する核内受容体PPARαやLXRの機能発現に対してもビタミンA栄養状態は影響しない可能性が示された。これらの結果は、これまで報告されている脂質代謝調節におけるビタミンAの関連性について一部再検討する必要性を提示するものである。