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 ; Comparative effect of different doses intervals of thyroid hormone about cardiac structure and function, tolerance to exercise and serum levels from T3 and T4 in rats that received doxorubicin

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. ; Dissertação (Mestrado) ; Fundamento: O emprego de doxorrubicina está associado a inflamações teciduais que podem causar alterações estruturais e na função cardíaca. Os efeitos decorrentes da administração de diferentes intervalos de doses de hormônio tireoidiano na presença destas disfunções ainda não foram documentados. Objetivo: Analisar os efeitos de diferentes doses do hormônio tireoidiano (T4) administrado por via oral, nas alterações estruturais e função do coração, na tolerância ao exercício ...