Atherogenic effects of chronic stress on thoracic aorta rats / Efeitos aterogenicos do estresse cronico em aorta toracica de ratos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Metabolic and vascular complications can result in atherosclerosis, which constitutes a great problem of public health, associated to approximately half of the deaths related to the cardiovascular illnesses in the occidental world. Therefore to the establishment of guidelines for treatment and prevention of cardiovascular diseases, it is important to study risk factors associated to this pathology. Chronic stress and hypercaloric diet ingestion have been recognized as risk factors for cardiovascular diseases because of its potential deleterious effect on the cardiovascular system. The aim of this work was to evaluate, in rats, the atherogenic effects of chronic mild unpredictable stress (CMS) associated or not to the ingestion of hypercaloric diet on the sensitivity of right atria and thoracic aorta to catecholamines, on the vascular morphology and the influence of lipids in the possible functional and morphological vascular alterations. In order to evaluate the mechanisms related to the effects of chronic stress, associated or not to the consumption of hypercaloric diet, we present in the chapters 1 and 2, results of in vitro studies. In the chapter 1, it was shown that CMS promotes supersensitivity to phenylephrine in thoracic aorta isolated from rats, increases the endothelium and tunica media thickness, atherogenic dyslipidemia, and higher atherogenic index, in comparison with the control group, without alteration in the atrial sensitivity to noradrenaline. These alterations seem to be related to the inhibition of endothelial nitric oxide production and to the increase in the seric levels of low-density lipoprotein (LDL) in rats submitted to the CMS. In chapter 2, it was shown that in non-stressed-animals, hypercaloric diet promoted an increase in the adiposity and seric levels of LDL, without alterations in the levels of total cholesterol, triglicerides and without functional or structural changes in the thoracic aorta. The CMS promoted vascular supersensitivity to phenylephrine, increased the endothelium and tunica media thickness and increased the seric levels of LDL in rats treated with hypercaloric diet and control diet, in comparison with the groups that were not submitted to stress. Furthermore, the CMS promoted contrary alterations on the adiposity in the groups treated with control and hypercaloric diet, decreasing the adiposity in the first one and increasing it in the second group, in comparison with the respective groups treated with the same diet, but not submitted to the CMS. Considering that in spite of high levels of LDL, there were no functional or morphological changes in the thoracic aorta from rats treated with hypercaloric diet and not submitted to the CMS, and that despite the biggest rise in the LDL levels in stressed rats treated with hypercaloric diet, there was no difference between this group and stressed rats treated with control diet in the functional and morphological changes observed in the thoracic aorta as well in the corticosterone levels, the results presented in the chapter 1 and 2, indicate that chronic stress seems to increase the atherogenic effects of the LDL.

ASSUNTO(S)

lipoproteins lipoproteinas endothelium sistema cardiovascular cardiovascular system aterosclerose atherosclerosis endotelio

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