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Influence of a high-fat diet on cardiac iNOS in female rats

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Author(s)

Aleksandra Jovanovic, Emina Sudar-Milovanovic, Milan Obradovic, Samantha Jane Pitt, Alan James Stewart, Sonja Zafirovic, Julijana Stanimirovic, Djordje Radak, Esma R. Isenovic

School/Research organisations

Abstract

Overexpression of inducible nitric oxide synthase (iNOS) is a key link between high-fat (HF) diet induced obesity and cardiovascular (CV) disease. Several studies have reported that oestradiol has cardioprotective effects that may be mediated through reduction of iNOS activity/expression. In the present study, female Wistar rats were fed a standard diet or a HF diet (balanced diet for laboratory rats enriched with 42% fat) for 10 weeks. Gene and protein expression of iNOS were measured in heart tissue. HF diet-fed rats exhibited a significant increase in cardiac iNOS mRNA by 695% (p<0.05), iNOS protein level by 248% (p<0.01), without changes in nitrate/nitrite levels. Expression of CD36 protein in plasma membranes was increased by 37% (p<0.05), while the concentration of free fatty acids (FFA) was reduced by 25% (p<0.01) in HF diet-fed rats. Expression of the p50 subunit of nuclear factor-κB (NFκB-p50) in heart lysate was increased by 77% (p<0.01) in HF diet-fed rats. Expression and phosphorylation of protein kinase B (Akt) and extracellular signal-regulated kinases 1/2 (ERK1/2) in control and HF diet-fed rats were also examined. Expression of Akt and ERK1/2 were unchanged between the groups. There was a significant increase in the ratio of phospho-Akt/total Akt but not for phospho-ERK1/2/total ERK1/2/ in HF-fed rats. Estrogen receptor-α levels (by 50%; p<0.05) and serum oestradiol concentrations (by 35%; p<0.05) were examined and shown to be significantly reduced in HF diet-fed rats. Our results revealed that a HF diet led to increased iNOS expression, most likely via a mechanism involving Akt and NFκB-p50 proteins. Decreased levels of oestradiol and ERα protein in the HF-fed group, in combination with increased iNOS levels are consistent with the hypothesis that oestradiol has a cardioprotective effect through its ability to regulate iNOS expression.
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Details

Original languageEnglish
Pages (from-to)491-500
Number of pages10
JournalCurrent Vascular Pharmacology
Volume15
Issue number5
Early online date25 Oct 2016
DOIs
Publication statusPublished - 2017

    Research areas

  • Cardioprotection, Cardiovascular disease, Oestradiol, Inducible nitric oxide synthase, Obesity

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