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Involvement of PI3K, Akt and RhoA in Oestradiol Regulation of Cardiac iNOS Expression

[ Vol. 17 , Issue. 3 ]

Author(s):

Sonja Zafirovic*, Emina Sudar-Milovanovic, Milan Obradovic, Jelena Djordjevic, Nebojsa Jasnic, Milica Labudovic Borovic and Esma R. Isenovic   Pages 307 - 318 ( 12 )

Abstract:


Background: Oestradiol is an important regulatory factor with several positive effects on the cardiovascular (CV) system. We evaluated the molecular mechanism of the in vivo effects of oestradiol on the regulation of cardiac inducible nitric oxide (NO) synthase (iNOS) expression and activity.

Methods: Male Wistar rats were treated with oestradiol (40 mg/kg, intraperitoneally) and after 24 h the animals were sacrificed. The concentrations of NO and L-Arginine (L-Arg) were determined spectrophotometrically. For protein expressions of iNOS, p65 subunit of nuclear factor-κB (NFκB-p65), Ras homolog gene family-member A (RhoA), angiotensin II receptor type 1 (AT1R), insulin receptor substrate 1 (IRS-1), p85, p110 and protein kinase B (Akt), Western blot method was used. Coimmunoprecipitation was used for measuring the association of IRS-1 with the p85 subunit of phosphatidylinositol- 3-kinase (PI3K). The expression of iNOS messenger ribonucleic acid (mRNA) was measured with the quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemical analysis of the tissue was used to detect localization and expression of iNOS in heart tissue.

Results: Oestradiol treatment reduced L-Arg concentration (p<0.01), iNOS mRNA (p<0.01) and protein (p<0.001) expression, level of RhoA (p<0.05) and AT1R (p<0.001) protein. In contrast, plasma NO (p<0.05), Akt phosphorylation at Thr308 (p<0.05) and protein level of p85 (p<0.001) increased after oestradiol treatment.

Conclusion: Our results suggest that oestradiol in vivo regulates cardiac iNOS expression via the PI3K/Akt signaling pathway, through attenuation of RhoA and AT1R.

Keywords:

Cardioprotection, oestradiol, rat heart, inducible nitric oxide synthase, eNOS, CVS.

Affiliation:

Institute of Nuclear Sciences “Vinca”, Department of Radiobiology and Molecular Genetics, University of Belgrade, Belgrade, Institute of Nuclear Sciences “Vinca”, Department of Radiobiology and Molecular Genetics, University of Belgrade, Belgrade, Institute of Nuclear Sciences “Vinca”, Department of Radiobiology and Molecular Genetics, University of Belgrade, Belgrade, Institute of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Institute of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Institute of Histology and Embryology “Aleksandar D. Kostic”, Faculty of Medicine, University of Belgrade, Belgrade, Institute of Nuclear Sciences “Vinca”, Department of Radiobiology and Molecular Genetics, University of Belgrade, Belgrade

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