Article
Depletion of Adiponectin in Pericardial-Fat Tissue: A Potential Role for Cardiac MMP-Regulation
Depletion von Adiponektin im Perikardialen Fettgewebe: Potentielle Funktionen für die Kardiale MMP-Regulation
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Published: | August 10, 2005 |
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Visceral fat-accummulation has been associated with an increased cardiovascular risk including the development of heart failure. However, functional differences between distinct visceral fat depots (e.g. pericardial fat, epididymal fat) are unknown. The adipose-specific protein adiponectin has been demonstrated to exert direct effects on cardiovascular cells. In the present study we investigated the expression of adiponectin protein in pericardial vs. epididymal adipose tissue in obese Zucker rats. In rat cardiac fibroblast we studied the regulation of matrix metalloproteinase (MMP)-9 by adiponectin.
Male Obese zucker rats (n=6) were killed at 11 weeks of age (mean body weight: 415+/-9.2g, mean adiponecin serum level: 6.3+/-0.6µg/ml), and epididymal and pericardial fat depots were removed for protein isolation. Adiponectin protein expression was reduced by 52.2+/-12.4% (p<0.01) in the pericardial fat depots compared to epididymal fat depots, as assessed by western immunoblotting. To identify a function of locally produced adiponectin, we investigated the regulation of MMP-9 expression in primary rat cardiac fibroblasts. Cardiac fibroblasts were stimulated with angiotensin II (AngII 100nmol/L) +/- adiponectin (5µg/ml) and MMP-9 protein expression (88 and 92kDa) was measured after 24h. AngII stimulated MMP-9 expression by 2.2+/-0.2-fold (p<0.05 vs. vehicle-treated cells). AngII-induced MMP-9 expression was potently blocked by 51+/-15.5% (p<0.05 vs. AngII alone) in the presence of adiponectin.
The present study identifies a distinct endocrine function of pericardial fat tissue compared to other visceral fat depots. Depletion of adiponectin expression in pericardial fat tissue may play an important role in the regulation of cardiac MMP expression, which may affect cardiac remodelling during obesity.