TESTOSTERONE DEPRIVATION IMPAIRS CARDIAC CONTRACTILE FUNCTION IN ORCHIECTOMIZED WISTAR RATS
Introduction: Several studies have linked low levels of testosterone with increased symptoms of cardiac disease; however the effects of testosterone deficiency on the heart have not been completely elucidated.
Objective: To evaluate the influence of testosterone deprivation on cardiac function.
Methods: A total of 11 ninety-day old male Wistar rats were used in this study. Animals were randomly divided into two groups: Sham operation group (n=7): animals that underwent sham operation and Orchiectomized group (Orchiec) (n=4): animals that underwent bilateral orchiectomy. Total testosterone levels were determined by chemiluminescence assay. Cardiac morphology and function were analyzed 59 days after the beginning of the experiment. For image acquisition two-dimensional (2-D) and M-mode images were obtained and analyzed from the parasternal long and short axis as well as from crosssectional views of basal (at the tip of the mitral valve leaflets), medium (at the papillary muscle level) and apical (distal to papillary muscle, before the final curve cavity) planes. The cardiac morphology was evaluated by the left ventricle, analyzing walls, area and diameter both in the systole and in the diastole. While cardiac function was evaluated from the following variables: shortening fraction, ejection fraction and cardiac output. At the Doppler, the closing time, mitral valve acceleration time and aortic valve deceleration acceleration time were analyzed.
Results: Orchiectomized rats had a shorter fraction of shortening than control, while mitral valve closure time was increased in this group. The myocardial performace index was impaired. In addition, there was brachycardia in the orchiectomized group. The values of cardiac output and diastolic output are not different between the groups. The heart weitgh in the orchiectomized rats was lower than control, however no other significant differences were found in cardiac morphology. A positive statistically significant correlation between total testosterone levels and left ventricle fractional shortening was also observed.
Conclusions: Deprivation of testosterone acts by decreasing the contractile function if the heart, therefore it decreases the heart rate. The relation between the cardiac morphology with testosterone was not found.
testosterone deprivation; cardiac contractile function; echocardiography
Universidade Federal de Ciências da Saúde de Porto Alegre - Rio Grande do Sul - Brasil
Rachel Pinto Dornelles Dutra, Gabriela Almeida Motta, Ernani Luis Rhoden, Claudia Ramos Rhoden, Angela Maria Vicente Tavares, Alexandre Luz de Castro, Graziele Halmenschlager