Efeito comparativo de diferentes intervalos de doses do hormônio tireoidiano sobre a estrutura e função cardíaca, tolerância ao exercício e nos níveis séricos de T3 e T4 em ratos que receberam doxorrubicina

Abstract

Background: The use of doxorubicin is associated with tissue inflammation that can cause structural and cardiac function changes. The effects resulting from the administration of different doses interval of thyroid hormone in the presence of these dysfunctions have not yet been documented. Objective: To analyze the effects of different doses of thyroid hormone (T4) administered orally on structural changes and heart function and exercise tolerance, serum levels of T3 and T4, in Wistar rats treated with doxorubicin. Method: 40 Wistar rats were randomly divided into four groups: Control, Doxorubicin, Doxorubicin + Sodium Levothyroxine (5 µg/100g, three times/week) and Doxorubicin + Sodium Levothyroxine (5 µg/100g, seven times/week). Body, heart and free T3 and T4 measurements, exercise tolerance tests on an adapted treadmill and echocardiography were performed. Results: Thyroid hormone (TH) administered three times a week in rats that received doxorubicin caused an increase in serum T4 levels, which did not occur in the group that received thyroid hormone (TH) seven times a week. Only thyroid hormone (TH) administered seven times a week prevented the reduction in exercise tolerance and produced cardiac hypertrophy. Conclusion: The administration of 5 µg/100g of sodium levothyroxine seven times a week started after doxorubicin administration does not change the serum levels of tetraiodothyronine (T4) and triiodothyronine (T3), prevents reduction of exercise tolerance by 10% and causes heart hypertrophy in Wistar rats.