Testosterone Deficiency Mitigates the Effects of Cardiac Remodeling After Acute Myocardial Infarction in Mice

Name: Rafaela de Araujo Fernandes Corrêa
Type: MSc dissertation
Publication date: 28/05/2018
Advisor:

Namesort descending Role
Athelson Stefanon Bittencourt Co-advisor *
Aurélia Araújo Fernandes Advisor *

Examining board:

Namesort descending Role
Athelson Stefanon Bittencourt Co advisor *
Aurélia Araújo Fernandes Advisor *
Marco Cesar Cunegundes Guimarães Internal Examiner *
Priscila Rossi de Batista External Examiner *

Summary: Studies show that testosterone is related to worse cardiac dysfunction and remodeling after acute myocardial infarction (MI). In this context, the influence of testosterone deficiency, obtained through castration, on cardiac remodeling two months after MI was evaluated. Four groups of male rats were used: 1) submitted to IM, 2) orchidectomized (OQT), 3) OQT + IM and 4) sham. Weighted, hemodynamic, contractile evaluation of left ventricular (LV) papillary muscles, quantification of interstitial collagen percentage and cross-sectional area of myocytes in the LV, as well as qualitative evaluation of coronary bed morphology and quantitative analysis of vascular density index. As expected, there was an increase in LV end-diastolic pressure, interstitial collagen percentage and heart weight / body weight ratios and lung / body weight ratios in the IM and OQT + MI groups compared to the other groups. Myocyte hypertrophy was lower in the OQT + IM group than in the IM group. In the contractile evaluation of the LV papillary muscles, the developed force (g / g) and the time to peak (TTP) were preserved in the OQT + IM group and impaired in the IM group. After beta-adrenergic stimulation, the contraction force of the IM group was decreased, dF / dt + and dF / dt- were lower in the IM and OQT + IM groups than in the other groups and the activation and relaxation kinetics of the group OQT+MI was better than the IM group. Scanning electron microscopy showed that the IM and OQT + MI groups showed an increase in the vascular density index and were characterized by irregular vessel configurations, with distorted shape, abrupt changes in the direction of the vessels, as well as abrupt changes diameter after bifurcations when compared to Sham and OQT. Considering that the OQT + IM group had a lower cross-sectional area and better contractility parameters of the LV papillary muscles, it was concluded that testosterone deficiency is able to ameliorate adverse cardiac remodeling resulting in improved cardiac function.

Key words: Cardiac remodeling. Acute myocardial infarction. Testosterone deficiency. Cardiac hypertrophy. Cardiac contractility.

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