Preventive role of exercise training in autonomic, hemodynamic, and metabolic parameters in rats under high risk of metabolic syndrome development

Abstract

Moraes-Silva IC, Mostarda C, Moreira ED, Silva KAS, dos Santos F, de Angelis K, Farah VMA V, Irigoyen MC. Preventive role of exercise training in autonomic, hemodynamic, and metabolic parameters in rats under high risk of metabolic syndrome development. J Appl Physiol 114: 786 -791, 2013. First published January 17, 2013 doi:10.1152/japplphysiol.00586.2012.-High fructose consumption contributes to metabolic syndrome incidence, whereas exercise training promotes several beneficial adaptations. In this study, we demonstrated the preventive role of exercise training in the metabolic syndrome derangements in a rat model. Wistar rats receiving fructose overload in drinking water (100 g/l) were concomitantly trained on a treadmill (FT) or kept sedentary (F) for 10 wk. Control rats treated with normal water were also submitted to exercise training (CT) or sedentarism (C). Metabolic evaluations consisted of the Lee index and glycemia and insulin tolerance test (kITT). Blood pressure (BP) was directly measured, whereas heart rate (HR) and BP variabilities were evaluated in time and frequency domains. Renal sympathetic nerve activity was also recorded. F rats presented significant alterations compared with all the other groups in insulin resistance (in mg·dl Ϫ1 ·min Ϫ1 : F: 3.4 Ϯ 0.2; C: 4.7 Ϯ 0.2; CT: 5.0 Ϯ 0.5 FT: 4.6 Ϯ 0.4), mean BP (in mmHG: F: 117 Ϯ 2; C: 100 Ϯ 2; CT: 98 Ϯ 2; FT: 105 Ϯ 2), and Lee index (in g/mm: F ϭ 0.31 Ϯ 0.001; C ϭ 0.29 Ϯ 0.001; CT ϭ 0.27 Ϯ 0.002; FT ϭ 0.28 Ϯ 0.002), confirming the metabolic syndrome diagnosis. Exercise training blunted all these derangements. Additionally, FS group presented autonomic dysfunction in relation to the others, as seen by an ϳ50% decrease in baroreflex sensitivity and 24% in HR variability, and increases in sympathovagal balance (140%) and in renal sympathetic nerve activity (45%). These impairments were not observed in FT group, as well as in C and CT. Correlation analysis showed that both Lee index and kITT were associated with vagal impairment caused by fructose. Therefore, exercise training plays a preventive role in both autonomic and hemodynamic alterations related to the excessive fructose consumption.fructose; exercise training; autonomic nervous system SEVERAL STUDIES HAVE SHOWN that poor eating habits and a large increase in fructose consumption in recent years has contributed to the epidemic of metabolic syndrome (2, 5). These unhealthy habits may result in physiological changes that contribute to a higher morbidity and mortality in humans (14). Among these changes, increase of blood pressure, plasma lipids, obesity, glucose intolerance, insulin resistance, and hyperinsulinemia are the most evident. Additionally, studies have shown an association between these factors as hyperinsulinemia and hypertension, in both humans and animals (10, 21, 36), indicating that once these alterations are present, the higher is the incidence of cardiovascular diseases.Autonomic nervous system dysfunction also accompanies these metabolic disturbances. Our research group has ...

Exercise Training Prevents Cardiovascular Derangements Induced by Fructose Overload in Developing Rats

“…The fructose overload induced glucose intolerance and/or insulin resistance, unfavorable changes in lipid profile, as well as an increase in adipose tissue in male and female adults and developing animals [6, 7, 8, 21]. Indeed, our study showed that physical training was able to prevent these metabolic alterations induced by fructose overload as previous reported by others studies [5, 17, 34, 35, 36]. …”

“…Moderate-intensity exercise training (40–60% maximal running speed, 0% inclination) was performed on a treadmill once a day at the same time every day, 5 days/week during 8 weeks, as described in detail elsewhere [5]. The protocol was initially carried out with the concurrent administration of fructose.…”

“…The recorded data were analyzed on a beat-to-beat basis to quantify changes in mean AP and heart rate (HR). HR variability (HRV) was determined by using the standard deviation of the basal HR recording period [5]. …”

“…The alpha index analysis evaluates short-term changes in the systolic blood pressure and in the RR interval. This method has been proposed to quantify cause-and-effect events linked with the baroreflex [5]. …”

“…The resulting increase in cases of morbidity and mortality such as obesity, hypertension and diabetes [2] have encouraged several studies to focus on the risk factors posed by this trend [3, 4] and the preventive strategies to fight them [5]. …”