EGG WHITE HYDROLYSATE INHIBITS THE VASCULAR DYSFUNCTION AND THE RAISE ON BLOOD PRESSURE AFTER LONG-TERM ALUMINUM EXPOSURE IN RATS

Abstract

Aluminum (Al) adverse effects have been related with increased oxidative stress and inflammation. We have evaluated the effects of an egg white hydrolysate (EWH) on blood pressure and vascular effects after Al exposure. Three-month-old male Wistar rats were divided into four groups and treated orally for 42 days: a) Control - ultrapure water; b) AlCl3 - 100 mg/kg bw; c) Hydrolysate - 1 g/kg/day of EWH; d) Hydrolysate + Al. Systolic blood pressure (SBP) was measured by plethysmography. Vascular function was studied in aortic and mesenteric resistance arteries (MRA) in isolated organ bath. Concentration-response curves to acetylcholine and sodium nitroprusside were performed. Vasoconstrictor response to phenylephrine (PHE) in presence and absence of endothelium and in presence of NOS inhibitor (L-NAME), potassium channels blocker (TEA), NAD(P)H oxidase (NOX) inhibitor (apocynin)¸ superoxide dismutase (SOD)¸ non-selective COX inhibitor (indomethacin)¸ selective COX-2 inhibitor (NS 398)¸ were analyzed. We have measured: systemic and vascular reactive oxygen species (ROS)¸ lipid peroxidation and antioxidant capacity¸ situ vascular O2- production¸ NOX activity and the quantitative real time PCR for NOX1 and NOX2. Results were expressed as mean and SEM&decil; compared by t-test and ANOVA followed by Bonferroni test (P<0.05). EWH prevented: a) the increased SBP observed after Al exposure (Ct: 117.2 ± 1.09; Al: 132.4 ± 5.20*; Hydrolysate: 117.6 ± 3.12#; Hydrolysate + Al: 118.4 ± 1.93# mmHg, n=8 * vs Ct; #vs Al); b) the endothelial relaxation dysfunction; c) the increased vasoconstrictor response to PHE; d) restored the endothelium vasoconstrictor - modulation¸ nitric oxide bioavailability and potassium channels involvement; e) prevented the increased ROS production from NOX and contractile prostanoids from COX-2; f) inhibited the increased plasmatic and aortic ROS production and lipid peroxidation as well as the imbalance on antioxidant capacity; g) prevented the vascular O2- production and the increased NOX 1 mRNA expressions. As a conclusion¸ the EWH seems to be able to counteract the vascular toxic effects of Al¸ which points to a possible therapeutic effect based on functional foods against a highly widespread environmental contaminant.

Supported by CNPq (203440/2014-5)¸ CAPES and MINECO (AGL2012-32387; AGL AGL2017-89213; CSIC - Intramural 201570I028)