Aromatase expression in abdominal omental/visceral and subcutaneous fat depots: a comparison of pregnant and obese women

Objective: To investigate total and promoter expression of aromatase in subcutaneous and omental (visceral) fat and compare this expression in pregnant and obese women.

Design: Cross-sectional study.

Setting: Academic hospital.

Patient(s): Six women undergoing elective cesarean section and three women undergoing bariatric surgery.

Intervention(s): Subcutaneous and omental fat obtained during surgery.

Main outcome measure(s): Total aromatase and promoter expression was measured by polymerase chain reaction and protein levels by Western blotting.

Result(s): Total aromatase expression was significantly higher in omental compared with subcutaneous fat from pregnant women; this pattern was reversed in obese women. Aromatase messenger RNA in omentum was significantly higher in pregnancy than obesity, and this was linked to an up-regulation of promoter II (PII). Promoter 1.4 (P1.4) expression was lower than PII, and there was no difference in P1.4 expression between the two fat depots from pregnant subjects. In obese women both P1.4 and PII were up-regulated in subcutaneous compared with omental depots, with P1.4 expression greater than that of PII. Aromatase protein levels were extremely low in fat depots of pregnant women and undetectable in obese women.

Conclusion(s): There are differences between total aromatase and promoter expression in subcutaneous and omental fat from pregnant compared with obese women. These differences support the evidence that the fat depots are derived from different cell lineages and that the promoter-derived aromatase translation varies according to physiologic/pathophysiologic status.