Name: EMILLY MARTINELLI ROSSI

Publication date: 31/03/2020
Advisor:

Name	Role
LEONARDO DOS SANTOS	Advisor *

Examining board:

Name	Role
ANDRÉ SOARES LEOPOLDO	Internal Examiner *
ERICK ROBERTO GONÇALVES CLAUDIO	External Examiner *
GIRLANDIA ALEXANDRE BRASIL AMORIM	External Examiner *
LEONARDO DOS SANTOS	Advisor *
NAZARE SOUZA BISSOLI	Internal Examiner *

Summary: Physical exercise is an effective non-pharmacological approach for prevention and treatment of cardiovascular diseases. Also, because iron is essential element in many physiological processes including hemoglobin and myoglobin synthesis, thereby playing a role on oxygen transport, many athletes use iron supplement to improve training performance. In this sense, although iron deficiency can cause anemia and impair body homeostasis, on the other hand, its overload can be even more harmful to health. Indeed, iron overload is associated with oxidative stress and damage to various systems, including cardiovascular. Thus, we aimed to identify the influence of iron overload on the beneficial vascular effects promoted by aerobic physical training in rats. To investigate it, male Wistar rats were treated with 100 mg/kg/day iron-dextran or 0.9% saline, ip, five times a week for four weeks, and then underwent aerobic exercise protocol on a treadmill at moderate intensity, 60 min/day, five days a week for eight weeks, or kept without exercise for an equal period. After 13 weeks of the treatment protocol, the iron overload model was confirmed with increased serum levels of iron, transferrin saturation and iron deposition in the liver, gastrocnemius muscle and aorta. Confirming the efficiency of the physical exercise protocol, all exercised animals increased physical capacity at the end of the followup, evaluated as increased speed and maximum time to failure. We identified that the exercise reduced vasoconstrictor response of isolated aortic rings, associated with higher bioavailability of nitric oxide (NO) and reduced oxidative stress. Furthermore, the reduced vasoconstriction in the exercised group was reversed by incubation with superoxide dismutase (SOD) inhibitor, suggesting increased SOD activity, added to catalase overexpression given by the exercise was lost in iron overload rats and the catalase was overexpressed, reinforcing the oxidative defenses on the aorta of exercised animals. However, these benefits to the vasculature were not observed in rats previously subjected to iron overload. In conclusion, despite the known beneficial effects of aerobic exercise on vasculature, our results indicate that a previous state of iron overload is able to prevent the anticontractile effect mediated by increased NO bioavailability and by the improvement of the endogenous antioxidant responses normally promoted by exercise

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