Progesterone and insulin resistance. III. Time-course study of progesterone action on differentially labelled 14C-glucose utilization by adipose tissue and isolated adipocytes of the female rat.

Progesterone action on glucose metabolism was evaluated on parametrial fat pads and on isolated adipocytes using glucose labelled on C1, C2 and C6, (1) The steroid decreased the pentose cycle, but had no effect on the krebs cycle as judged by the C5/C1 ratio. (2) The radiorespirometric method, in combination with appropriately labelled glucose, demonstrated a rapid in vitro effect of progesterone on oxidation of (1-14C)-glucose. This finding suggest that progesterone acts on the glucose metabolism of the adipose tissue by a non-classical mechanism of steroid hormone action.