Role of nitric oxide synthase and beta-adrenoceptors in cardiac tissue of rats subjected to stress with access comfort food

Abstract

Understanding the mechanisms related to stress response occupies the attention of scientists and clinicians since the definition of the term stress by the endocrinologist Hans Selye in 1936. It is believed that at least one third of the diseases that lead people to seek medical care are related to stress. The current conditions of life in the Western world represent a major cause of stress in humans, the called psychosocial stress, caused by the accelerated process of urbanization and changing lifestyles. The endocrine stress response in humans and animals includes the activation of the hypothalamic-pituitary-adrenal (HPA), which stimulates the secretion of glucocorticoids by the adrenal cortex, and activation of the sympathetic nervous system-adrenal medulla that stimulates the release of catecholamines. The relationship between these two systems is of great physiological importance. In general, steroids hormones induce the refinement or the regulation of processes mediated by catecholamines. Authors proposed that glucocorticoids stimulate the consumption of high-calorie foods that, in turn, would protect the HPA axis dysfuncition associated with stress, depression and anxiety. In this study we will investigate the behavior of animals with chronic mild stress and unpredictable (CMSU) with access to comfort diet compared with the behavioral data of rats subjected to foot-shock stress on the same diet. Rats subjected to foot-shock stress have been used as experimental models to investigate adaptative mechanisms mainly in the cardiovascular system. Those animals present increased secretion of glucocorticoids, which interact with their receptors and regulate the expression of genes, including those codifying ²-adrenoceptors and nitric oxide synthases (NOS), thus affecting the synthesis of nitric oxide (NO), a signaling molecule that regulates a variety of cardiovascular functions. In this study we propose to analyze in cardiac tissue, the involvement of adrenoceptors ² and isoforms of NOS in adaptative processes triggered by foot-shock stress and CMSU in rats fed with comfort food. (AU)