17β-estradiol modulates cardioprotective effects of nutraceutical compounds

Cardiovascular disease rarely manifests in pre-menopausal women meanwhile, the incidence of these pathologies dramatically increases after the menopause suggesting the possibility that sex hormones could have a key role. 17β-estradiol is the main female circulating hormone in the premenopausal period and showed protective effects on the cardiovascular system. Moreover, recent evidences underlie the importance to take into account the gender in clinical studies as it can influence the response to cardiovascular medications. Therefore, we hypothesize that sex hormones can also influence the cardioprotective effects of nutraceutical compounds, such as sulforaphane, isothiocyanate present in Brassica vegetables. This study was designed to investigate the protective effects of sulforaphane in presence of 17β-estradiol against H2O2-induced oxidative damage in cardiomyocytes. 17β-estradiol enhanced sulforaphane cardioprotection against H2O2-induced cell death with respect to 17β-estradiol or sulforaphane alone, as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyl-tetrazolium bromide and lactate dehydrogenase assays. Moreover, 17β-estradiol boosted sulforaphane antioxidant activity, reducing intracellular reactive oxygen species and 8-hydroxy-2′-deoxyguanosine levels and increasing the expression of phase II enzymes. The observed effects seem to be not mediated by estrogen receptor α and β, as we used specific antagonists. Otherwise, ERK1/2 and Akt signaling pathways seem to be involved, as the treatment with specific inhibitors reduced the protective effect of sulforaphane/17β-estradiol co-treatment. Furthermore, estrogen receptor β and G protein-coupled receptor 30 seem to contribute to Akt activation, as using receptor specific agonists sulforaphane-induced Akt phosphorylation was enhanced. The activation of Akt kinase is also involved in the activation of Nrf2 transcription factor elicited by sulforaphane/17β-estradiol co-treatment, as treated cells with Akt-inhibitor, the co-treatment-induced Nrf2 activation was prevented. Our results demonstrated, for the first time, that estrogen could enhance sulforaphane protective effects, suggesting that nutraceutical efficacy might be modulated by sex hormones.