Obesity, chronic metabolic disorder characterized by abnormal or excessive fat accumulation inrelation to lean tissue, is considered a global epidemic that occurs in developed and undevelopedcountries, affecting all age groups. It is associated with numerous comorbidities, representing major public health problem. Different authors suggest that obesity is related to cardiovascular alterations and several factors, such as changes in the beta-adrenergic system, have been suggested as responsible for the alterations in cardiac performance in animal models of obesity. This pathway plays an important role in neuroendocrine regulation of heart function and it is formed by beta-adrenergic receptors, G-protein, adenylate cyclase and cAMP. The heart is composed of threebeta-adrenoceptor subtypes, ß1, ß2 e ß3, being ß1 subtype predominant and the most importantone in cardiac performance regulation. After the binding of adrenergic agonist upon ß1 and ß2receptors, they are coupled to activating G-protein (Gs), promoting the binding of G-protein to adenylate cyclase; activation of this enzyme promotes the formation of cAMP, which stimulates PKA, leading to phosphorylation of regulatory proteins involved in cardiac excitation-contraction-relaxation coupling. It was found in the literature only one study that evaluated the isolated behavior of beta-adrenergic pathway in experimental models of non-genetic obesity, using rabbits fed unsaturated high-fat diet for 12 weeks; Carroll et al. analyzed the number of beta-adrenoceptors and adenylate cyclase activity and found that obesity did not alter these components of beta-adrenergic pathway. It is well established in the literature the association of saturated fatty acids and increased cardiovascular disease risk. Therefore, due to the harmful association between saturated fatty acids and heart, and due to the absence of studies that assessed the relationship between obesity by saturated high-fat diet and myocardial ß-adrenergic pathway, the aim of this study is to test the hypothesis that obesity by saturated high-fat diet causes changes in the behavior of myocardial ß-adrenergic pathway.
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