Stress-induced cardiometabolic perturbations, increased oxidative stress and ACE/ACE2 imbalance are improved by endurance training in rats.

AIMS: To investigate the effects of endurance training on stress-induced cardiometabolic perturbations given the elevated release of stress hormones and subsequent glucose homeostasis perturbations. MATERIALS AND METHODS: Rats were randomized into non-trained rats, rats submitted to endurance training, non-trained rats submitted to stress, and trained rats submitted to stress. Endurance training was applied for 8 weeks, while chronic stress was applied at the 4th, 5th, and 6th weeks of the training period. Two weeks after the last stressor stimuli, rats were euthanized, and blood and heart were collected for biochemical tests. KEY FINDINGS: Exacerbated corticosterone levels were observed in both stressed groups, and chronic stress per se impaired glucose tolerance and insulin sensitivity. Training reduced circulating adrenaline, even though noradrenaline levels were elevated in the blood and heart of trained rats. While stress-induced high circulating serotonin levels were further increased by endurance training, cardiac serotonin levels were attenuated in trained rats. Endurance training mitigated the stress-induced higher circulating lipids. Cardiac TBARs and GPx activity increased in trained rats while CAT and GPx were reduced in response to chronic stress. Endurance training not only attenuated the stress-induced higher circulating ACE/ACE2 ratio but also reduced ACE/ACE2 balance in the heart. Glucose intolerance, insulin resistance, and altered stress hormones release were linked to impairment of cardiometabolic responses, elevated oxidative stress, and dysregulation of ACE/ACE2 ratio. SIGNIFICANCE: Endurance training mitigated the stress-related pathophysiological responses, which could be related to improvements in the antioxidant capacity and the balance of ACE/ACE2 activity.

Blockade of AT1 type receptors for angiotensin II prevents cardiac microvascular fibrosis induced by chronic stress in Sprague-Dawley rats.

To test the effects of chronic-stress on the cardiovascular system, the model of chronic mild unpredictable stress (CMS) has been widely used. The CMS protocol consists of the random, intermittent, and unpredictable exposure of laboratory animals to a variety of stressors, during 3 consecutive weeks. In this study, we tested the hypothesis that exposure to the CMS protocol leads to left ventricle microcirculatory remodeling that can be attenuated by angiotensin II receptor blockade. Male Sprague-Dawley rats were randomly assigned into four groups: Control, Stress, Control + losartan, and Stress + losartan (N = 6, each group, losartan: 20 mg/kg/day). The rats were euthanized 15 days after CMS exposure, and blood samples and left ventricle were collected. Rats submitted to CMS presented increased glycemia, corticosterone, noradrenaline and adrenaline concentration, and losartan reduced the concentration of the circulating amines. Cardiac angiotensin II, measured by high-performance liquid chromatography (HPLC), was significantly increased in the CMS group, and losartan treatment reduced it, while angiotensin 1-7 was significantly higher in the CMS losartan-treated group as compared with CMS. Histological analysis, verified by transmission electron microscopy, showed that rats exposed to CMS presented increased perivascular collagen and losartan effectively prevented the development of this process. Hence, CMS induced a state of microvascular disease, with increased perivascular collagen deposition, that may be the trigger for further development of cardiovascular disease. In this case, CMS fibrosis is associated with increased production of catecholamines and with a disruption of renin-angiotensin system balance, which can be prevented by angiotensin II receptor blockade.

Sensitivity and reproducibility of a PCR assay for Leishmania detection using skin biopsy imprints on filter paper.

The sensitivity and reproducibility of a PCR targeted to amplify the conserved 120 base-pair region of minicircles from Leishmania kDNA was defined using DNA extracted from skin biopsy imprints on filter paper. Seventy-seven patients with cutaneous leishmaniasis from an endemic region of Leishmania (Viannia) braziliensis in Brazil underwent skin biopsy of the ulcer border. Tissue samples were imprinted on filter paper and then, they were stored at -20 degrees C. Imprints on filter paper were stored at 4 degrees C. Samples were processed at three laboratories; Lab1 and Lab2 performed the PCR-kDNA assay using DNA extracted from the filter paper, and Lab3 processed PCR-kDNA using DNA from fresh-frozen tissue used as a gold standard. All samples were codified to maintain blinding during lab processing. Fifty-three (68.8%) patients had parasites isolated and identified by isoenzymes as L. (V.) braziliensis. The positivity of PCR-kDNA was similar between the three laboratories: 87.0, 85.7 and 88.3% (Lab1, Lab2 and Lab3, respectively). The sensitivity of PCR-kDNA in culture-proven cases was better, and showed similar results in all laboratories: 95.8, 95.8 and 97.9% (Lab1, Lab2 and Lab3, respectively). Data from the 77 enrolled patients showed an overall percent agreement of 80.5% (Kappa=0.173) for the filter-paper approach between Lab1 and Lab2. Percent agreement between Lab1 and Lab3 was 83.1% (Kappa=0.22), and it was 94.8% between Lab2 and Lab3 (Kappa=0.77). Fifteen patients were diagnosed in just one of the two laboratories that used DNA extracted from filter paper. We conclude that the sensitivity of the filter paper approach is satisfactory and could be used in clinical trials and field work. Reproducibility could be improved using two separate imprints from the same biopsy sample.