O polimorfismo VAL16ALA do gene da superóxido dismutase dependente de Manganês (SOD-2), marcadores de estresse oxidativo e hipertensão em uma população auto declarada negra de Uruguaiana-RS

Abstract

The inequities that affect the black population have been present since the last century, and social and environmental factors negatively affect the health conditions of this population. Brazilian blacks are more susceptible than Caucasians to clinical cardiovascular disease, including heart failure, stroke, myocardial infarction, and also have a higher prevalence of hypertension. However, the mechanism involved in these phenomena is not fully understood, since blacks have lower rates of metabolic syndrome. Oxidative stress can affect the pathophysiology of several diseases, such as cardiovascular, neurodegenerative and even some types of cancer, being related to the aging process. Thus, both the excess of generated reactive species and the ineffective availability of antioxidants (enzymatic and non-enzymatic) can compromise the redox balance and favor the emergence or worsening of diseases. Superoxide Dismutase (SOD) is an enzyme that plays an important role in antioxidant defenses, responsible for catalyzing the dismutation of the superoxide radical into hydrogen peroxide and molecular oxygen. Its manganese-dependent mitochondrial form, known as MnSOD or SOD2, is synthesized in the cytosol and becomes active after being carried into the mitochondria. MnSOD is synthesized by the SOD2 gene which may have structural mutations and single nucleotide polymorphisms. In the Val16Ala polymorphism there is a substitution of a thymine (T) for a cytosine (C) in the coding sequence, which converts the codon GTT (valine) to GCT (alanine). The presence of the C allele results in the production of an enzyme with an altered conformation. A total of 158 individuals participated in the study, 100 of which were hypertensive and 58 were non-hypertensive, the polymerase chain reaction (PCR) determined the Val16Ala polymorphism, biochemical parameters were evaluated using a semi-automated equipment and the oxidative stress analyzes were analyzed with the aid of a spectrophotometer using standard techniques. Significant differences were found in TAC where the Val/Ala genotype showed higher TAC levels when compared to Val/Val; IMA the Val/Ala genotype showed increased levels when compared to Ala/Ala; TBARS the Val/Ala genotype showed higher levels 9 when compared to Ala/Ala; carbonyl, the Val/Val genotype showed higher levels when compared to Ala/Ala; and Nox the Val/Val genotype showed lower levels when compared to Ala/Ala. The results of the logistic regression analysis indicated that the SOD Val/Val genotype is a risk factor independent of the other variables for hypertension. Our data suggest that the Val16Ala polymorphism of the MnSOD gene is associated with hypertension, and the Val/Val genotype is considered to be at risk for developing hypertension in blacks.