Volume 115, Nº 1, July 2020
DOI: https://doi.org/10.36660/abc.20180143
ORIGINAL ARTICLE
Decreased Collagen Type I is Associated with Increased Metalloproteinase-2 Activity and Protein Expression of Leptin in the Myocardium of Obese Rats
Danielle Cristina Tomaz da Silva-Bertani
Danielle Fernandes Vileigas
Gustavo Augusto Ferreira Mota
Sérgio Luiz Borges de Souza
Loreta Casquel De Tomasi
Dijon Henrique Salomé de Campos
Adriana Fernandes de Deus
Paula Paccielli Freire
Carlos Augusto Barnabe Alves
Carlos Roberto Padovani
Antonio Carlos Cicogna
Figure 2 – Representative western blots and quantification of myocardial collagen type I, TIMP-1, TIMP-2, and leptin from control and obese rats (n = 6 per group).Western blot bands were normalized to β-actin. Data are presented as mean ± SD. Student’s t-test. *: p < 0.05.
Abstract
Background: Obesity is a risk factor for medical complications, including the cardiovascular system. There is limited information on collagen in the heart in obesity. Our previous study showed decreased protein levels of myocardial collagen type I in obese rats fed a high-fat diet for 34 weeks. However, the mechanisms responsible for low levels are not fully elucidated.
Objective: The purpose of this study was to test the hypothesis that the reduction in collagen type I is associated with increased metalloproteinase-2 (MMP-2) activity, which is linked to elevated leptin in the myocardium of obese rats.
Methods: Thirty-day-old male Wistar rats were randomized into two groups, control (standard diet) and obese (high-fat diet), and fed for 34 weeks. The general animal characteristics and metabolic and endocrine profiles were evaluated. Myocardial protein expressions of collagen I, leptin, tissue inhibitors of metalloproteinases (TIMP), and MMP-2 activity were assessed. Pearson correlation was employed to determine the associations between variables. The level of significance was 5%.
Results: The obese animals had increased adiposity index compared to control. Comorbidities such as glucose intolerance, hyperinsulinemia, insulin resistance, hyperleptinemia, and hypertension were observed in obese rats. Obesity reduced collagen I, TIMP-1, and TIMP-2, and it increased leptin and MMP-2 in the myocardium. There was a negative correlation between collagen I and MMP-2 and a positive correlation between leptin and MMP-2.
Conclusion: The hypothesis was confirmed; the reduction in collagen type I is associated with increased MMP-2 activity and leptin expression in the myocardium of obese rats. (Arq Bras Cardiol. 2020; 115(1):61-70)
Keywords: Cardiovascular Diseases/physiopathology; Obesity; Collagen Type 1; Rats; Leptin; Adiposity; Tissue Inhibitor of Metalloproteinases; Metaloproteinase-2.
