Abstract

Objective: The ability to form new adipose cells is important to adipose tissue physiology; however, the mechanisms controlling the recruitment of adipocyte progenitors are poorly understood. A role for locally generated angiotensin II in this process is currently proposed. Given that visceral adipose tissue reportedly expresses higher levels of angiotensinogen compared with other depots and the strong association of augmented visceral fat mass with the adverse consequences of obesity, we studied the role of angiotensin II in regulating adipogenic differentiation in omental fat of obese and non-obese humans. Research Methods and Procedures: The angiotensin II effect on adipose cell formation was evaluated in human omental adipocyte progenitor cells that were stimulated to adipogenic differentiation in vitro. The adipogenic response was measured by the activity of the differentiation marker glycerol-3-phosphate dehydrogenase. Results: Angiotensin II reduced the adipogenic response of adipocyte progenitor cells, and the extent of the decrease correlated directly with the subjects' BMI (p = 0.01, R 2 = 0.30). A 56.3 ± 3.4% and 44.5 ± 2.7% reduction of adipogenesis was found in obese and non-obese donors' cells, respectively (p < 0.01). The effect of angiotensin II was reversed by type 1 angiotensin receptor antagonist losartan. Discussion: A greater anti-adipogenic response to angiotensin II in omental adipose progenitor cells from obese subjects opens a venue to understand the deregulation of visceral fat tissue cellularity that has been associated with severe functional abnormalities of the obese condition. Copyright © 2007 NAASO.