Aromatization of steroids in peripheral tissues.

The action of glucocorticoids on aromatase activity in human adipose tissue has been investigated. Oestrogen production was increased in tissue maintained in the presence of dexamethasone and cortisol. Dexamethasone was effective at concentrations as low as 1 nmol/l. In contrast, over the 40 h incubation period, cortisol was only effective at concentrations in excess of 500 nmol/l, although after conditions of prolonged incubation, induction of aromatase activity was measurable using cortisol concentrations as low as 28 nmol/l. There were apparent variations in both basal levels of aromatic activity and in response to glucocorticoids in adipose tissue taken from various sites within the body.