Folic acid consumption reduces resistin level and restores blunted acetylcholine-induced aortic relaxation in obese/diabetic mice

Sai Wang Seto, Tsz Yan Lam, Penelope Mei Yu Or, Wayne Yuk Wai Lee, Alice Lai Shan Au, Christina Chui Wa Poon, Rachel Wai Sum Li, Shun Wan Chan, John Hok Keung Yeung, George Pak Heng Leung, Simon Ming Yuen Lee, Sai Ming Ngai, Yiu Wa Kwan

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20 Citations (Scopus)

Abstract

Folic acid supplementation provides beneficial effects on endothelial functions in patients with hyperhomocysteinemia. However, its effects on vascular functions under diabetic conditions are largely unknown. Therefore, the effect(s) of folic acid (5.7 and 71 μg/kg/day for 4 weeks) on aortic relaxation was investigated using obese/diabetic (+db/+db) mice and lean littermate (+db/+m) mice. Acetylcholine-induced relaxation in +db/+db mice was less than that observed in +db/+m mice. The reduced relaxation in +db/+db mice was restored by consumption of 71 μg/kg folic acid. Acetylcholine-induced relaxation (with and without folic acid treatment) was sensitive to NG-nitro-l-arginine methyl ester, 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one, geldanamycin and triciribine. In addition, acetylcholine-induced relaxation was attenuated by resistin. The plasma level of resistin in +db/+db mice was sevenfold higher than that measured in +db/+m mice, and the elevated plasma level of resistin in +db/+db mice was reduced by 25% after treatment with 71 μg/kg folic acid. Folic acid slightly increased the ratio of reduced glutathione to oxidized glutathione in +db/+db mice. Moreover, folic acid caused a reduction in PTEN (phosphatase and tensin homolog deleted on chromosome 10) expression, an increase in the phosphorylation of endothelial nitric oxide synthase (eNOSSer1177) and AktSer473, and an enhanced interaction of heat shock protein 90 (HSP90) with eNOS in both strains, with greater magnitude observed in +db/+db mice. In conclusion, folic acid consumption improved blunted acetylcholine-induced relaxation in +db/+db mice. The mechanism may be, at least partly, attributed to enhancement of PI3K/HSP90/eNOS/Akt cascade, reduction in plasma resistin level, down-regulation of PTEN and slight modification of oxidative state.

Original languageEnglish
Pages (from-to)872-880
Number of pages9
JournalJournal of Nutritional Biochemistry
Volume21
Issue number9
DOIs
Publication statusPublished - Sep 2010

Keywords

  • Acetylcholine
  • ENOS
  • Folic acid
  • PTEN
  • Relaxation

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Molecular Biology
  • Nutrition and Dietetics
  • Clinical Biochemistry

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