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PK Chakraborty1 *, MM Cisar1 , MF Nelson1
Dept. of Ob-Gyn, Uniformed Services University of the Health Sciences, Bethesda, MD 1
Because of their central role in follicular development, maturation of the ovum, and development of the subsequent corpus luteum, the characterization of granulosa cell function and differentiation is of interest to reproductive biologists. Our objective was to evaluate progesterone (P4) production by all transretinoic acid (RA, 10 M) alone or in combination with ovine FSH (oFSH, .05 g/ml) in the presence of 22-R hydroxycholesterol (22-R, 1 g/ml) as a substrate by transformed rat granulosa cells (DC-3) in culture over a period of 96h. Cells (~50,000/well) were cultured in Iscove's Modified Dulbecco's Medium (2% fetal bovine serum) in wells in a total volume of 3 ml. Culture medium was collected once every 24h following addition of RA and/or oFSH for up to 96h. Experiments were conducted in triplicate and medium was quantitated for P4 by RIA. In the presence of substrate alone all treatments produced significant amounts of P4 daily, compared to respective controls. Daily production of P4 with 22-R alone ranged between .023 to .046 ng/ml. Addition of oFSH did not affect this secretion rate and P4 ranged between .025 and .045 ng/ml. However, addition of RA alone increased P4 production to .21 ng/ml (24h), .89 ng/ml (48h), .71 ng/ml (72h), and declined thereafter to .13 ng/ml (96h). Addition of oFSH in combination with RA gave similar responses during the same time perods, .23 ng/ml (24h), .96 ng/ml (48h), .76 ng/ml (72h) and .31 ng/ml (96h), respectively.
Our results indicate that RA is a potent stimulator of P4 production by DC-3 cells and can induce responses that are up to 20 fold greater than 22-R alone or in combination with oFSH. These data indicate that RA may regulate granulosa cell steroidogenesis by a mechanism different from gonadotropin-induced steroidogenesis.
This abstract is being presented on Monday, August 2 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.