硝酸塩/亜硝酸塩の不足は代謝症候群,血管不全,心臓突然死を引き起こす  [in Japanese] Long-term dietary nitrite and nitrate deficiency causes metabolic syndrome, endothelial dysfunction, and cardiovascular death in mice  [in Japanese]

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Author(s)

    • 喜名 美香 Kina-Tanada Mika
    • 琉球大学大学院医学研究科 薬理学|琉球大学大学院顎顔面口腔再建学 Department of Pharmacology, Graduate School of Medicine, University of the Ryukyus|Department of Oral and Maxillofacial Functional Rehabilitation, Graduate School of Medicine, University of the Ryukyus
    • 新崎 章 Arasaki Akira
    • 琉球大学大学院顎顔面口腔再建学 Department of Oral and Maxillofacial Functional Rehabilitation, Graduate School of Medicine, University of the Ryukyus
    • 筒井 正人 Tsutsui Masato
    • 琉球大学大学院医学研究科 薬理学 Department of Pharmacology, Graduate School of Medicine, University of the Ryukyus

Abstract

<p>一酸化窒素(NO)はL-arginineからNO合成酵素(NOSs)を介して産生されが,最近,その代謝産物である亜硝酸塩(NO<sub>2</sub><sup>-</sup>)および硝酸塩(NO<sub>3</sub><sup>-</sup>)からNOが産生される経路が発見された.レタスやホウレン草などの緑葉野菜には硝酸塩が多く含有されている.しかし,硝酸塩/亜硝酸塩(NOx)の不足が病気を引き起こすか否かは知られていない.本研究では,『食事性NOxの不足は代謝症候群を引き起こす』という仮説をマウスにおいて検証した.私達は過去に,NOSs完全欠損マウスの血漿NOxレベルは野生型マウスに比して10%以下に著明に低下していることを報告した.この結果から,生体のNO産生は主として内在するNOSsによって調節されていること,外因性NO産生系の寄与は小さいことが示唆されたが,低NOx食を野生型マウスに長期投与すると意外なことに血漿NOxレベルは通常食に比して30%以下に著明に低下した.この機序を検討したところ,低NOx食負荷マウスでは内臓脂肪組織のeNOS発現レベルが有意に低下していた.重要なことに,低NOx食の3ヵ月投与は,内臓脂肪蓄積,高脂血症,耐糖能異常を引き起こし,低NOx食の18ヵ月投与は,体重増加,高血圧,インスリン抵抗性,内皮機能不全を招き,低NOx食の22ヵ月投与は,急性心筋梗塞死を含む有意な心血管死を誘発した.低NOx食負荷マウスでは内臓脂肪組織におけるPPARγ,AMPK,adiponectinレベルの低下および腸内細菌叢の異常が認められた.以上,本研究では,食事性NOxの不足がマウスに代謝症候群,血管不全,および心臓突然死を引き起こすことを明らかにした.この機序には,PPARγ/AMPKを介したadiponectinレベルの低下,eNOS発現低下,並びに腸内細菌叢の異常が関与していることが示唆された.</p>

<p>Nitric oxide (NO) is synthesized not only from L-arginine by NO synthases (NOSs), but also from its inert metabolites, nitrite and nitrate. Green leafy vegetables are abundant in nitrate, however whether or not a deficiency in dietary nitrite/nitrate spontaneously causes disease remains to be clarified. In this study, we tested our hypothesis that long-term dietary nitrite/nitrate deficiency induces metabolic syndrome (MetS) in mice. To this end, we prepared a low nitrite/nitrate diet (LND) consisting of an amino acid-based low nitrite/nitrate chow in which the contents of L-arginine, fat, carbohydrates, protein, and energy were identical with a regular chow, and potable ultrapure water. Nitrite and nitrate were undetectable in both the chow and the water. Intriguingly, in comparison with a regular diet, 3 months of the LND significantly elicited visceral adiposity, dyslipidaemia, and glucose intolerance; 18 months of the LND significantly provoked increased body weight, hypertension, insulin resistance, and impaired endothelium-dependent relaxations to acetylcholine; and 22 months of the LND significantly led to death due to cardiovascular disease, including acute myocardial infarction. These abnormalities were reversed by simultaneous treatment with sodium nitrate, and were significantly associated with endothelial NOS down-regulation, adiponectin insufficiency, and gut microbiota dysbiosis. These results provide the first evidence that long-term dietary nitrite/nitrate deficiency gives rise to MetS, endothelial dysfunction, and cardiovascular death in mice, indicating a novel pathogenetic role of the exogenous NO production system in MetS and its vascular complications.</p>

Journal

  • Folia Pharmacologica Japonica

    Folia Pharmacologica Japonica 151(4), 148-154, 2018

    The Japanese Pharmacological Society

Codes

  • NII Article ID (NAID)
    130006655003
  • NII NACSIS-CAT ID (NCID)
    AN00198335
  • Text Lang
    JPN
  • ISSN
    0015-5691
  • NDL Article ID
    028990358
  • NDL Call No.
    Z19-247
  • Data Source
    NDL  J-STAGE 
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