Inhibition of Cumulus Cell Progesterone Secretion by Low Molecular Weight Fractions of Porcine Follicular Fluid Which Also Inhibit Oocyte Maturation*
- 1 February 1980
- journal article
- research article
- Published by The Endocrine Society in Endocrinology
- Vol. 106 (2) , 584-591
- https://doi.org/10.1210/endo-106-2-584
Abstract
To examine the inhibitory effect of an oocyte maturation inhibitor (OMI) on progesterone secretion from cumulus cells, cumulus-enclosed oocytes were harvested from medium- sized (3–5 mm) porcine follicles and cultured for 2 days in the presence and absence of various fractions of porcine follicular fluid. Two fractions eluted from a Sephadex G–25 column had OMI activity and, in addition, significantly inhibited progesterone secretion from cumulus cells in a dose-dependent manner. The inhibitory effect upon progesterone secretion as well as upon oocyte maturation was reversed after removal of the inhibitory agent from the culture medium and subsequent culture under control conditions. A crude low molecular fraction (< 10,000 daltons) of porcine follicular fluid also brought about a significant inhibition of oocyte maturation as well as cumulus cell progesterone secretion. The addition of FSH and LH overcame the inhibitory influence of the low molecular weight fraction of follicular fluid upon progesterone secretion of the cumulus cells. The addition of aminoglutethimide, a steroidogenesis inhibitor, to cultured cumulus-enclosed oocytes inhibited progesterone secretion but failed to inhibit oocyte maturation, indicating that inhibition of progesterone secretion per se is not responsible for the inhibition of oocyte maturation. These studies indicate that partially purified OMI fractions, in addition to keeping the oocyte in the immature dictyate state, also inhibit cumulus cell outgrowth and progesterone secretion. These actions may reflect a generalized action to keep the cumulus-oocyte complex in an immature state. (Endocrinology106: 584, 1980)Keywords
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