Testosterone Deprivation Impairs Cardiac Systolic Function in Orchiectomized Wistar Rats

Several studies have linked low levels of testosterone with increased symptoms of cardiac disease and cardiovascular mortality; however, the effects of testosterone deficiency on cardiac systolic function and morphology are still not completely elucidated. The present study aims to evaluate the influence of testosterone deprivation on cardiac systolic function and morphology. Male Wistar rats were divided into two groups: Sham operation group (Sham): animals underwent sham operation and Orchiectomized group (Orchiec): animals underwent bilateral orchiectomy. The experimental protocol lasted 60 days after the surgery. All animals were weighted and blood samples collected to serum testosterone analysis, determined by chemiluminescence, on first (before orchiectomy) and on 60th days. One day before euthanasia (on the 59th day) echocardiographic parameters were assessed to evaluate left ventricle (LV) systolic function and morphology. Statistical significant difference was set at≤0.05. Orchiec rats presented reduced LV fractional shortening (p=0.032), increased myocardial performance index (MPI) (p=0.043), prolonged mitral valve closure time (p=0.013) and decreased heart rate (p=0.049) when compared to Sham. No statistically significant difference was found in the ejection fraction (p=0.666) between groups. Besides that, heart weight was lower in Orchiec group (p=0.035) when compared to Sham group. Testosterone deprivation reduced cardiac systolic function, changing contraction and relaxation parameters. Testosterone deficiency also changed heart rate and heart weight. The present study demonstrated for the first time that castrated levels of testosterone could alter parameters such as mitral valve closing time and MPI.