Chronic stress, but not hypercaloric diet, impairs vascular function in rats.

The aim of this study was to evaluate vascular and metabolic effects of chronic mild unpredictable stress (CMS) and hypercaloric diet (HD) without carbohydrate supplementation in rats. Male Sprague-Dawley rats were randomly assigned to four groups: Control, HD, CMS, and HD plus CMS. CMS consisted of the application of different stressors for 3 weeks. The rats were killed 15 days after CMS exposure. The HD group presented higher plasma lipid concentrations, without changes in fasting glucose concentration, glucose tolerance test, and vascular function and morphology, in comparison with the control group. Stressed rats presented higher fasting blood concentration of insulin, higher homeostasis model assessment index values and area under the curve in an oral glucose tolerance test, in comparison with non-stressed rats. CMS increased the plasma concentrations of corticosterone and lipids, and the atherogenic index values, without change in high-density lipoprotein level. CMS increased intima-media thickness and induced endothelium-dependent supersensitivity to phenylephrine, and lowered the relaxation response to acetylcholine in the thoracic aorta isolated from rats fed with control or HD, in comparison with non-stressed groups. CMS effects were independent of diet. In non-stressed rats, the HD induced dyslipidemia, but did not change glucose metabolism, vascular function, or morphology. The data from this study indicate that CMS promotes a set of events which together can contribute to impair function of the thoracic aorta.

Proatherosclerotic effects of chronic stress in male rats: altered phenylephrine sensitivity and nitric oxide synthase activity of aorta and circulating lipids.

The aim of this study was to analyze the effects of chronic mild unpredictable stress (CMS) on the vasoconstrictor response and morphology of the thoracic aorta and serum lipid profiles in rats. Male Sprague-Dawley rats were submitted to CMS, which consisted of the application of different stressors for 7 days per week across 3 weeks. The rats were sacrificed 15 days after CMS exposure. CMS induced supersensitivity to the vasoconstrictor effect of phenylephrine in endothelium-intact thoracic aortic rings without changes in aortic rings without endothelium, or pre-incubated with nitric oxide (NO) synthesis inhibitor. Rats submitted to CMS showed hypertrophy of the intima and tunica media of thoracic aorta, increased serum levels of triglycerides, total cholesterol, very low-density lipoprotein cholesterol, low-density lipoprotein cholesterol and atherogenic index, without changes in high-density lipoprotein cholesterol levels, when compared with control rats. These data indicate that CMS induces physiological and morphological changes that may contribute to the development of atherosclerosis by mechanisms related to deficiency in NO production and dyslipidemia.