Physiological adaptations during endurance training below anaerobic threshold in rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)To assess the effects of continuous exercise training at intensities corresponding to 80 and 90 % of the lactate minimum test (LM), we evaluated antioxidant activity, hormone concentration, biochemical analyses and aerobic and anaerobic performance, as well as glycogen stores, during 12 weeks of swimming training in rats. One-hundred rats were separated into three groups: control (CG, n = 40), exercise at 80 (EG80, n = 30) and 90 % (EG90, n = 30) of LM. The training lasted 12 weeks, with sessions of 60 min/day, 6 days/week. The intensity was based at 80 and 90 % of the LM. The volume did not differ between training groups ( of EG80 = 52 +/- A 4 min; of EG90 = 56 +/- A 2 min). The glycogen concentration (mg/100 mg) in the gastrocnemius increased after the training in EG80 (0.788 +/- A 0.118) and EG90 (0.795 +/- A 0.157) in comparison to the control (0.390 +/- A 0.132). The glycogen stores in the soleus enhanced after the training in EG90 (0.677 +/- A 0.230) in comparison to the control (0.343 +/- A 0.142). The aerobic performance increased by 43 and 34 % for EG80 and EG90, respectively, in relation to baseline. The antioxidant enzymes remain unchanged during the training. Creatine kinase (U/L) increased after 8 weeks in both groups (EG80 = 427.2 +/- A 97.4; EG90 = 641.1 +/- A 90.2) in relation to the control (246.9 +/- A 66.8), and corticosterone (ng/mL) increased after 12 weeks in EG90 (539 +/- A 54) in comparison to the control (362 +/- A 44). The continuous exercise at 80 and 90 % of the LM has a marked aerobic impact on endurance performance without significantly biomarkers changes compared to control.113718591870Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [04/01205-6, 06/58411-2

Importance of All and AT2 receptors in the nucleus of the solitary tract in cardiovascular responses induced by a high-fat diet

A high-fat diet (HFD) induces an increase in arterial pressure and a decrease in baroreflex function, which may be associated with increased expression of angiotensin type 1 receptor (AT1R) and pro-inflammatory cytokine genes and reduced expression of the angiotensin type 2 receptor (AT2R) gene within the nucleus of the solitary tract (NTS), a key area of the brainstem involved in cardiovascular control. Thus, in the present study, we evaluated the changes in arterial pressure and gene expression of components of the renin-angiotensin system (RAS) and neuroinflammatory markers in the NTS of rats fed a HFD and treated with either an AT1R blocker or with virus-mediated AT2R overexpression in the NTS. Male Holtzman rats (300-320 g) were fed either a standard rat chow diet (SD) or HFD for 6 weeks before commencing the tests. AT1R blockade in the NTS of HFD-fed rats attenuated the increase in arterial pressure and the impairment of reflex bradycardia, whereas AT2R overexpression in the NTS only improved the baroreflex function. The HFD also increased the hypertensive and decreased the protective axis of the RAS and was associated with neuroinflammation within the NTS. The expression of angiotensin-converting enzyme and neuroinflammatory components, but not AT1R, in the NTS was reduced by AT2R overexpression in this site. Based on these data, AT1R and AT2R in the NTS are differentially involved in the cardiovascular changes induced by a HFD. Chronic inflammation and changes in the RAS in the NTS may also account for the cardiovascular responses observed in HFD-fed rats