EFFECT OF AMINOGLUTETHIMIDE PHOSPHATE ON IN VITRO OESTRADIOL STIMULATED PROGESTERONE SYNTHESIS BY RABBIT CORPORA LUTEA

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Abstract
Slices of rabbit corpora lutea were incubated for 3 and 8 h with estradiol-17.beta. in the presence or absence of aminoglutethimide phosphate (AGP) to identify a possible site(s) of action of estrogen on progesterone synthesis. Estradiol was unable to increase progesterone biosynthesis above controls in luteal tissue exposed to AGP during either incubation period. AGP alone significantly reduced progesterone concentrations and synthesis from [14C]acetate at both time periods while estradiol alone increased progesterone mass at 8 h. Changes in 20.alpha.-OH progesterone typically paralleled those of progesterone at 3 h but no effect of the inhibitor was seen at 8 h. Except for an increase in 14C-incorporation into cholesterol esters in the AGP-treated groups at 3 h concentration or synthesis of sterols from labeled acetate did not respond to treatment. Cholesterol side chain cleavage and cholesterol synthesis apparently are not major in vitro sites of action of estradiol in the rabbit corpus luteum.