Combined Exercise Training Promotes More Benefits on Cardiovascular Autonomic Modulation in Ovariectomized Rats Than Isolated Aerobic or Resistance Training.

Introduction: Cardiovascular risk increase after ovarian deprivation has been extensively demonstrated by our research group through cardiovascular autonomic analysis. Interventions involving different types of exercises, such as resistance exercises or combined exercises (aerobic and resistance) have been widely recommended to prevent or minimize neuromuscular decline in postmenopausal women, which is aggravated by a sedentary lifestyle. Experimentally, the cardiovascular effects of resistance or combined training, as well as comparison between aerobic, resistance, and combined training, in ovariectomized animals are scarce. Purpose: In this study, we hypothesized that the combination of aerobic and resistance training may be more effective in preventing muscle mass loss, as well as improving cardiovascular autonomic modulation and baroreflex sensitivity, than aerobic or resistance training individually in ovariectomized rats. Animals and Methods: Female rats were divided into 5 groups: sedentary (C); ovariectomized (Ovx); trained ovariectomized submitted to aerobic training (OvxAT); resistance training (OvxRT); combined training (OvxCT). Exercise training lasted 8 weeks, with the combined group alternating between aerobic training and resistance training every other day. At the end of the study, glycemia and insulin tolerance were evaluated. Arterial pressure (AP) was directly recorded. Baroreflex sensitivity was assessed by heart rate response to changes in arterial pressure. Cardiovascular autonomic modulation was evaluated by spectral analysis. Results: Combined training was the only training regime that increased baroreflex sensitivity for tachycardic response and reduced all systolic blood pressure variability parameters. Furthermore, all animals submitted to exercise training on a treadmill (OvxAT and OvxCT) presented lower systolic, diastolic, and mean pressure, as well as improvements in the autonomic modulation for the heart. Conclusion: Combined training showed to be more effective than isolated aerobic and resistance training, mixing the isolated benefits of each modality. It was the only modality able to increase baroreflex sensitivity to tachycardic responses, reduce arterial pressure and all parameters of vascular sympathetic modulation.

Chronic exposure to PM2.5 aggravates SLE manifestations in lupus-prone mice.

BACKGROUND: Air pollution causes negative impacts on health. Systemic lupus erythematosus (SLE) is an autoimmune disease with diverse clinical manifestations and multifactorial etiology. Recent studies suggest that air pollution can trigger SLE and induce disease activity. However, this association has not been deeply investigated. Thus, the aim of this study was to evaluate whether exposure to fine particulate matter (PM2.5) exacerbates SLE manifestations, focusing on renal complications, in a lupus-prone animal model. Female NZBWF1 mice were exposed daily to 600 µg/m3 of inhaled concentrated ambient particles (CAP) or filtered air (FA). Survival rate, body weight, weight of organs (kidney, spleen, thymus, liver and heart), blood cell count, proteinuria, kidney stereology, renal histopathology, gene expression and oxidative stress were analyzed. RESULTS: Female NZBW mice exposed to CAP showed decreased survival, increased circulating neutrophils, early onset of proteinuria and increased kidney weight with renal cortex enlargement when compared to NZBW mice exposed to FA. CONCLUSIONS: This work shows that air pollution aggravates some SLE manifestations in lupus-prone mice. These results reinforce the need of reducing air pollutant levels in order to promote a better quality of life for individuals diagnosed with SLE.

Effect of aerobic exercise training on regional blood flow and vascular resistance in diabetic rats.

BACKGROUND: Hyperglycemia has been associated with decreased blood flow in various organs, leading to tissue damage and dysfunctions. Exercise training (ET) is known to promote beneficial changes in the autonomic nervous system and may have effects on circulation. The aim of this study was to evaluate coronary and renal blood flows and vascular resistances after ET in diabetic rats. METHODS: Thirty-two rats were divided into four groups (n = 8): sedentary control (SC), trained control (TC), sedentary diabetic (SD), trained diabetic (TD). Diabetes was induced by an injection of streptozotocin (STZ, 50 mg/kg). The ET was performed on a treadmill for 10 weeks. The blood flows were measured using colored microspheres. RESULTS: The diabetic groups presented hyperglycemia (blood glucose >350 mg/dL) and ET did not change this parameter. The SD group showed reduced renal blood flow when compared to SC group, and ET was able to normalize this parameter in TD rats (SC: 4.3 ± 0.5; TC: 2.9 ± 0.3; SD: 1.9 ± 0.4; TD: 3.2 ± 0.4 mL/min/g). TD group presented increased coronary blood flow in relation to SD group (SC: 2.3 ± 0.23; TC: 2.8 ± 0.5; SD: 1.2 ± 0.4; TD: 3.0 ± 0.4 mL/min/g). The heart and kidneys vascular resistance were increased in SD group when compared to SC group, and ET was able to reverse these changes. CONCLUSIONS: Given the relevance of cardiomyopathy and nephropathy in mortality of diabetics, our results demonstrated that ET is effective in improving coronary and renal blood flows and vascular resistances in STZ-diabetic rats, reinforcing the positive role of this approach in preventing hyperglycemia-induced long-term organ damage.

Diabetic hyperglycemia attenuates sympathetic dysfunction and oxidative stress after myocardial infarction in rats.

BACKGROUND: Previous research has demonstrated that hyperglycemia may protect the heart against ischemic injury. The aim of the present study was to investigate the association between hyperglycemia and myocardial infarction on cardiovascular autonomic modulation and cardiac oxidative stress profile in rats. Male Wistar rats were divided into: control (C), diabetic (D), myocardial infarcted (MI) and diabetic infarcted rats (DMI). METHODS: Diabetes was induced by streptozotocin (STZ, 50 mg/Kg) at the beginning of the protocol and MI was induced by left coronary occlusion 15 days after STZ. Thirty days after streptozocin-induced diabetes, cardiovascular autonomic modulation was evaluated by spectral analysis, and oxidative stress profile was determined by antioxidant enzyme activities and superoxide anion, together with protein carbonylation and redox balance of glutathione (GSH/GSSG). RESULTS: The diabetic and infarcted groups showed decreased heart rate variability and vagal modulation (p < 0.05); however, sympathetic modulation decreased only in diabetic groups (p < 0.05). Sympatho/vagal balance and vascular sympathetic modulation were increased only in the MI group (p < 0.05). Diabetes promoted an increase in catalase concentration (p < 0.05). Glutathione peroxidase activity was increased only in DMI when compared to the other groups (p < 0.05). Superoxide anion and protein carbonylation were increased only in MI group (p < 0.05). Cardiac redox balance, as evaluated by GSH/GSSG, was lower in the MI group (p < 0.05). CONCLUSIONS: These data suggest that hyperglycemia promotes compensatory mechanisms that may offer protection against ischemia, as demonstrated by increased antioxidants, decreased pro-oxidants and protein damage, possibly related to the improvements in both redox balance and sympathetic modulation to the heart.