Efeitos do treinamento físico aeróbio em parâmetros do desempenho miocárdico e indicadores de estresse oxidativo em ratos submetidos a estresse de contenção

Abstract

Introduction: It is not new that stress is present in our society, high and sustained levels of this condition maintained for a long period can result in overload with pathological manifestations in different organs and systems. However, regular physical exercise is associated with a series of health benefits that can mitigate or normalize numerous conditions generated by different diseases and/or physiologically aggravating conditions. Objective: To evaluate changes in myocardial performance and indicators of oxidative stress in rats subjected to restraint stress. Methods: pathogen-free Wistar rats (n: 40) were randomized into four distinct groups, each containing 10 animals: control (C), trained (T), stressed (E) and stressed and trained (ET). The physical training protocol was conducted through swimming in a pool with pool water being constantly agitated with the aid of a pump and with a temperature between 32-34°C. After a week of adaptation, the animals exercised for 12 weeks, 5 days a week, 60 minutes/day. For stress induction, the animals were contained individually in an opaque PVC cylinder measuring 20 cm long and 6 cm in diameter, with closed ends and holes allowing air circulation for 1 hour per day, 5 days per day. week for 12 weeks. After completion of the experimental protocol, the following parameters were analyzed: body mass, physical fitness, stress intensity, cardiac biometry, blood pressure, ventricular function and myocardial contractility. Results: No significant differences (p>0.05) were found in the physical capacity of the animals before the protocol. However, after 12 weeks of training, groups T (before: 102 ± 9, after: 291 ± 23; seconds) and ET (before: 93 ± 8, after: 274 ± 36; seconds) increased physical capacity by 65 ± 2 % and 61 ± 8% respectively without differing from each other. No differences were found (*p> 0.05) after the intervention period in C (before: 86 ± 17, after: 101 ± 17; seconds) and E (before: 96 ± 12, after: 105 ± 11; seconds ) which also did not differ from each other, but were lower (p<0.05) than groups T and ET. Considering corticosterone levels, the relative values ​​of group E (335 ± 9 nmol/L) were higher (p>0.05) than groups C (141 ± 3 nmol/L), T (174 ± 3 nmol/L) and ET (231 ± 7 nmol/L), which also differed from each other. as demonstrated, group E's glucose values ​​were higher (p<0.05) at all times after glucose overload compared to groups C, T and ET, which did not differ (p>0.05). Regarding systolic blood pressure, no significant differences were observed between the animals over the weeks in both groups C and T. However, the systolic blood pressure of animals in group E increased significantly from the 6th week onwards in relation to the first week, unlike the ET group, which showed an increase only in the 12th week in relation to the 1st week. Additionally, the blood pressure of the ET group was higher than that of groups C and T, but lower than that of group E, demonstrating an attenuation in the development of hypertension. No changes were identified in cardiac masses and myocardial contractility between the groups, however, considering indicators of ventricular function, it is worth mentioning that the values ​​corresponding to the E and E/A wave of group E were higher than those of groups C, T and ET which it was also higher than groups C and T, which did not differ from each other. Considering the histomorphometric parameters, both nuclear volume and collagen content in group E were higher than groups C, T and ET, which did not differ from each other. The TBARS concentration values ​​in group E (0.74 ± 0.07 µmols/mg) were higher (p<0.05) than groups C (0.49 ± 0.03 µmols/mg), T (0.42 ± 0.02 µmols/mg) and ET (0.43 ± 0.05 µmols/mg) which did not differ (p>0.05) from each other. Similarly, the concentration of oxidized proteins in groups E (1.47 ± 0.29 nmol/ml) was higher (p<0.05) than groups C (0.76 ± 0.04 nmol/ml), T (0.72 ± 0.02 nmol/ml) and ET (0.69 ± 0.05 nmol/ml) which did not differ (p>0.05) which also did not differ from each other. Conclusion: The set of data presented in the present study indicates that the association between restraint stress and physical training induces greater stress intensity, however it promoted the attenuation of arterial hypertension and restriction of ventricular filling without promoting changes in myocardial contractility parameters.