Luteinization of bovine granulosa cells and corpus luteum formation associated with loss of androgen-aromatizing ability

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Abstract
The relative aromatizing ability of bovine luteinizing granulosa cells and dispersed luteal cells in tissue culture was studied. Luteinization of granulosa cells, as indicated by steadily increasing progesterone production (from 50-300 ng/105 cells per day over 4-5 days), was accompanied by a dramatic reduction in their capacity to aromatize exogenous androgen; estradiol-17.beta. production falling from 200 to < 10 ng/105 cells per day over 4-5 days. Luteal cells also had only a very limited capacity to aromatize exogenous androgen, maximum estradiol-17.beta. production being < 600 pg per 105 cells/day. The loss in aromatizing capacity of granulosa cells during luteinization was also reflected in the relative endogenous steroid content of non-luteinized granulosa cells and luteal tissue, the former containing high levels of estradiol-17.beta., .ltoreq. 28 ng/mg protein, while the latter, although containing substantial amounts of testosterone, .ltoreq. 5.7 ng/g tissue, contained very little estradiol-17.beta., .ltoreq. 0.35 ng/g tissue. Luteinization of bovine granulosa cells and subsequent corpus luteum formation is associated with a loss in androgen aromatase activity.