Abstract
Aging, which is an independent risk factor for heart disease, alters body fat mass and its function. Epicardial fat plays an important physiological and pathophysiological role on cardiac structure and function. This study investigated if aging altered the abundance of epicardial (EF) and abdominal fat (AF) derived mediators in a sex dependent manner in female and male Fischer 344×Brown Norway hybrid (FBN) rats. EF and AF were obtained from 48 female and male, young (6 months), aged (26/30 months) and very aged (30/36 months) FBN rats. Adipose derived anti-inflammatory and pro-inflammatory mediators were measured using ELISA, adipokine array and real-time qPCR. No dramatic changes in circulating lipids other than a higher triglyceride and high density lipoprotein in aged females and a significantly increased circulating adiponectin (p<0.005) in aged rats were observed. Real time PCR results showed that compared to 6 months old female rats, the aged (26 months) and very aged (30 months) rats had significantly lower levels of EF genes: adiponectin (p<0.005), PPARγ (p<0.01, 0.005), IL-6 (p<0.01) and PAI-1 (p<0.01, 0.01), respectively, but not in AF. In contrast, the male rats exhibited an increase in IL-6 in EF (p<0.005) but a decrease in adiponectin and PPARγ in AF with aging. These changes might be attributed to differences in adipocyte make-up or macrophage infiltration. In conclusion, aging had a more profound impact on EF derived mediators in female rather than male rats, which might help explain the increased risk to cardiovascular disease seen in older women.