Impactos da suplementação com extratos de linhaça ou amoreira sobre o sistema vascular de ratas wistar com deficiência estrogênica

Abstract

INTRODUCTION: Estrogen deficiency contributes to endothelial dysfunction by reducing nitric oxide bioavailability and increasing oxidative stress, favoring the development of cardiovascular diseases such as hypertension and atherosclerosis. Although clinical and experimental studies demonstrate the cardioprotective effects of estrogens, exogenous treatment with estradiol can increase the risk of developing cardiovascular diseases and breast cancer in some women, limiting its use in hormone replacement therapy. Thus, the search for natural products with potential antioxidant, anti-inflammatory, and vasodilator responses has been of great interest, aiming to bring benefits to the estrogen-deficient organism and consequently cardioprotection. OBJECTIVE: To identify the phenolic compounds present in flaxseed or mulberry extracts, as well as to investigate the vascular action of supplementation with these extracts in estrogen-deficient Wistar rats. METHODS: High-performance liquid chromatography (HPLC) was used to determine the phenolic compounds present in flaxseed and mulberry extracts. Adult Wistar rats were divided into five experimental groups, one group with animals in proestrus that underwent sham surgery and were treated with saline (SHAM) and four ovariectomized groups treated with saline (OVX); estradiol (E2; 5 μg/kg/day); flaxseed extract (Flaxseed; 400 mg/kg/day); or mulberry extract (Mulberry; 400 mg/kg/day). Concentration-response curves were performed to evaluate the contractile response triggered by phenylephrine and the vasodilatory response triggered by acetylcholine. Likewise, the effect of pre-incubation with indomethacin, L-NAME, and Tiron on the contractile response to phenylephrine in the thoracic aorta of the animals was evaluated. The concentration of hydroperoxides and the activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) were determined in the thoracic aorta. The data were analyzed using one-way or two-way ANOVA followed by the Bonferroni test, and were considered statistically significant if p<0.05. RESULTS: Through HPLC, trigonelline, gallic acid, and p-coumaric acid were observed in the flaxseed extract, while gallic acid, theobromine, chlorogenic acid, and syringic acid were identified in the mulberry extract. Estrogen deficiency increased vasoconstriction of the thoracic aortas in response to phenylephrine but did not alter vascular relaxation. Ovariectomy increased the production of free radicals after 8 weeks of estrogen deficiency. Treatment with estradiol or supplementation with flaxseed or mulberry extract in ovariectomized animals reduced the vascular contraction induced by phenylephrine in a manner dependent on the modulation of nitric oxide synthase and protection against oxidative damage. Supplementation with these extracts reduced the concentration of hydrogen peroxide, as well as supplementation with flaxseed extract increased the activity of the enzyme superoxide dismutase, in the thoracic aorta. CONCLUSION: The results suggest that supplementation with flaxseed or mulberry extracts can promote vascular protection in estrogen deficiency through the reduction of vascular contractile response and oxidative stress. Furthermore, supplementation with flaxseed extract demonstrated greater efficacy.