Data suggest that early exposure to high fructose intake produced marked alterations in metabolic and cardiovascular function. When stimulated by NaCl, the fructose-fed subjects showed further impairment in cardiac function.
The aim of this study was examine the effects exercise training into prevent the hepatic steatosis induced by a high fructose intake in rats from weaning to adulthood. Weaned male Wistar Rats with 21 days old (50‐60g) were divided into (n=5 each): Sedentary control (SC); Trained control (TC); Sedentary fructose (SF) and Trained fructose (TF). Fructose‐drinking rats received D‐fructose during 8 weeks (100 g/l). The trained animals were assigned to a treadmill training protocol during 1 h/day, 5 days/week for 8 weeks. Measurements of triglyceride concentrations, white adipose tissue and piruvate tolerance test and glucose tolerance test were carried out to evaluate metabolic profile. At the end of the e experimental protocol, the animals were euthanized and a piece of the liver was collected for histological evaluation. Fructose induced dyslipidemia and glucose intolerance in SF and TF groups. Moreover, SF showed a decrease in the pyruvate tolerance test when compared to SC. Despite it was not observed significant changes in body weight between the groups, fructose induced an increase in adiposity mass. The liver weight was not different between the groups, however fructose induced an increase in % of liver fat cells in SF when compared to SC (8.3% ± 0.48 vs. 5.6% ± 0.61, p<0.001) and in TF compared to TC (3.5% ± 0.2 vs. 1.9% ± 0.30, p<0.0001). When we compared TC vs. SC the percentage was significantly higher in AS (5.6% ± 0.61 vs. 1.9% ± 0.30, p<0.0001). And the last analysis showed higher percentage in SF when compared with TF (8.2% ± 0.48 vs. 3.5% ± 0.23, p<0.0001) Findings indicate that a high fructose diet significantly increase the percentage of fat in the liver, which may lead to Hepatic Steatosis. This study suggests that physical exercise can be used as a non‐pharmacological treatment, since we found a decrease in the percentage of fat in the liver in trained animals. Grant Funding Source: Supported by MACKPESQUISA/PIBIC CNPQ
Beta‐adrenoceptors (β‐AR) play an important role in cardiac autonomic function. There are three β‐AR subtypes (β(1), β(2), β(3)) described and identified. β(3) when stimulated, induce negative inotropic effects in order to protect the heart from catecholamine overstimulation. The aim of this study was to determine the cardiac autonomic modulation in experimental model of β3 adrenergic receptor absence. Knockout and wild type mice for β3 receptor were used (ARβ3KO and WT, respectively). The male animals with 8 weeks old were submitted to catheterization of carotid artery. This catheter was connected to a transducer and continuous signals of blood pressure (BP) and heart rate (HR) were recorded and analyzed by Windaq® software. The variability of resultant signal was evaluated in time and frequency domain by Fourier Fast Transform. Although there were no difference in BP and HR between the groups, the HR and BP variance are respectively 113% and 96% higher on ARβ3KO. Moreover, the LF component for HR (24.62 ± 3.4 vs. 7.90 ± 1.8 ms²) and BP (38.04 ± 8.1vs. 20.32 ± 2.8 mmHg²) were increased in ARβ3KO when compared with WT. The sympathetic‐vagal balance was increased in ARβ3KO (1.58 ± 0.28) when compared to WT (0.61 ± 0.09). In conclusion, our data showed that the absence of β3 receptor determined an increase in cardiac sympathetic modulation confirming the cardioprotective role this receptors.
Administration of a diet rich in fructose initiates a series of metabolic events resulting in hypertriglyceridemia, hypertension and glucose intolerance. The purpose of this study was to evaluate the cardiovascular and autonomic modulation induced by fructose intake during 8 weeks. Weaned (21 days old) male Wistar rats (50–60g) were divided in 2 groups and they were followed for 8 weeks: Control (CG) and Fructose (FG, 10% in drinking water). Arterial pressure (AP) and heart rate (HR) were directly recorded using a data acquisition system (Windaq, 2 KHz) in conscious and awake rats. Cardiac autonomic modulation was evaluated using spectral analysis of HR variability and after pharmacological blockade (Atenolol, 8mg/Kg and Atropine, 4mg/Kg). FG showed an increase of mean AP (120±3.1 mmHg) when compared to CG (98±1.6 mmHg). No changes in heart rate were observed, although autonomic balance increased in FG (0.12±0.02) compared to CG (0.04±0.01). Sympathetic tonus was increased in FG (86±7.2 bpm) when compared with CG (49±3.6 bpm) with no differences in vagal tonus. However, intrinsic HR was significantly lower in FG (375±7.2 bpm) when compared with CG (405±8.2 bpm). In conclusion, these data suggest that metabolic changes induced by frutose‐rich diet during life spam in rats are accompanied by hypertension associated with sympathetic overactivity.Supported by: FAPESP(2009/52556‐7) and PIBIC/Mackpesquisa
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