Increased progesterone secretion and 3 beta-hydroxysteroid dehydrogenase activity in human cumulus cells by pregnenolone is limited to the high steroidogenic active cumuli.
OBJECTIVE
Several reports imply that lower progesterone secretion by cumulus-oocyte complexes (COCs) is associated with lower fertilization in the corresponding oocyte. The possible role of progesterone in oocyte fertilization in humans was studied using two approaches: (a) increasing the total progesterone secretion by culturing more than one COC per dish; and (b) increasing the cumulus cell progesterone secretion by providing pregnenolone as a substrate.


METHODS
Mature COCs were cultured individually or cocultured in groups. Oocyte fertilization and progesterone secretion were tested after 20 hr and 3 days in culture, respectively. The cumuli from individually plated COCs were cultured in the absence of oocyte for an additional 3 days in order to test the effects of pregnenolone on progesterone secretion and the 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activity. A comparable study with pregnenolone was performed on the corresponding granulosa-lutein cells.


RESULTS
Increasing the number of COC to two instead of one led to a significant increase in both fertilization rate and progesterone secretion. The addition of pregnenolone during days 3-6 increased significantly both progesterone secretion and 3 beta-HSD activity. Comparable results were observed in granulosa-lutein cells subjected to pregnenolone treatment. Following the first 3 days culture, cumulus masses were categorized as secreting high or low progesterone levels. Adding pregnenolone had a greater effect on both progesterone secretion and 3 beta-HSD activity in the high-progesterone-secreting cumuli.


CONCLUSIONS
Addition of pregnenolone increased progesterone secretion and 3 beta-HSD more efficiently in the higher-progesterone-secreting cumuli. Coculture of two COCs instead of one led to a higher fertilization rate and greater progesterone secretion.
Bar-Ami
S
S
Department of Obstetrics and Gynecology, Rambam Medical Centre, Haifa, Israel. sgyss@zahav.net.il
Gitay-Goren
H
H
D015096:3-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D002452:Cell Count; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D008297:Male; D008597:Menstrual Cycle; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism; D006080:Ovarian Follicle / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011284:Pregnenolone / Q000494:pharmacology*; D011374:Progesterone / Q000378:metabolism*; D011863:Radioimmunoassay; D013084:Sperm-Ovum Interactions
D011374:Progesterone; D011284:Pregnenolone; D015096:3-Hydroxysteroid Dehydrogenases