Steroidogenic effects of luteinizing hormone and prolactin on the rat ovary in vivo

The contribution of the adrenal gland to the total amount of progesterone produced in the female rat

1. The amount of progesterone contained in both adrenal glands of a rat was similar to or larger than the amount of progesterone in the ovaries of the same rat. This was found in unstressed rats, in stressed rats and also in pregnant rats.2. After ether anaesthesia and exsanguination the adrenal progesterone content was increased by 75%; the ovarian progesterone content remained unchanged.3. In contrast, prolonged operative stress resulted in a rise in the ovarian content of progesterone and 20-dihydroprogesterone whereas the adrenal progesterone content of these rats was lower than that of unstressed rats.4. The rate at which progesterone was secreted by the adrenal glands of stressed rats was similar to the ovarian progesterone secretion rate. Rats which were kept under mild stress conditions before the experiment showed higher adrenal progesterone secretion rates.

Endocrine control of adrenal progesterone secretion in the ovariectomized rat

In the ovariectomized rat, the adrenal gland secretes progesterone. Adrenocorticotropin treatment elevates concentrations of this steroid in plasma, and inhibitors of adrenocorticotropin or progesterone biosynthesis lower the concentration. Adrenocorticotropin controls progesterone secretion by the adrenal but not by the ovary. Adrenal progesterone and its mode of control may have important influences on reproductive processes.