The aims of this study were to investigate the association between the level of expression of adipose tissue-derived angiotensinogen secretion (A-AGT-S) and indices of body fat mass, to examine the regulation of A-AGT-S in relation to obesity in humans, and finally to assess the contribution of A-AGT-S to plasma AGT in mouse models of obesity and weight reduction. The amount of A-AGT-S was estimated by multiplying the mRNA level of AGT/g adipose tissue by body fat mass. The human sample included 46 Japanese subjects who were recruited for subcutaneous abdominal adipose tissue biopsies. The authors found that the secretion of adipose tissue-derived AGT was substantially increased in both obese humans and obese mice and it was correlated with plasma AGT levels in mouse models of obesity and weight reduction. For instance, plasma AGT levels were increased by ~20% in the obese mouse, whereas they were decreased by ~12% in mice with weight reduction. Moreover, the AGT mRNA levels in adipose tissue were decreased in both obese humans and mice and increased in mice after weight loss, whereas A-AGT-S showed the opposite trend. The authors explained these results in part by triglyceride accumulation and adipocyte hypertrophy in obese adipose tissue. Thus, these results suggest that adipose tissue-derived AGT could contribute to circulating AGT levels and consequently play a role in obesity-related metabolic diseases.
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