Aromatase activity and concentrations of cortisol, progesterone and testosterone in breast and abdominal adipose tissue.

Aromatase activity and concentrations of cortisol, progesterone and testosterone were measured in samples of breast and abdominal adipose tissue obtained from both pre- and postmenopausal subjects. Enzyme activity was determined by the incorporation of tritium from [1 beta-3H]androstenedione into water and found to be in close agreement to that measured when tritium labelled oestrone (E1) and oestradiol (E2) were isolated. No significant difference in enzyme activity was noted between breast and abdominal adipose tissue. Increased aromatase activity was not observed in adipose tissue taken from a subject with endometrial cancer. Cortisol concentrations were found to be significantly higher (P less than 0.05) in abdominal as compared to breast tissue. Without attaining statistical significance progesterone concentrations were higher in abdominal as compared to breast adipose tissue. Aromatase activity was not related to either cortisol or testosterone tissue concentration, but an inverse relationship between progesterone concentration and aromatase activity was observed (r = 0.542, P less than 0.02). On the basis of results obtained a hypothesis for the increased conversion of androgen to oestrogen as seen after the menopause has been proposed.