Gonadotropin releasing hormone does not affect steroidogenesis in JEG-3 cells

Gonadotropin releasing hormone (GnRH) affects ovarian and testicular steroidogenesis, is produced by the placenta, and increases chorionic gonadotropin (hCG) production in preterm placenta. It was hypothesized that GnRH might also regulate placental synthesis of progesterone (P) and estradiol (E₂) and the effects were studied of GnRH and the [D-Trp⁶]-LH-RH analog on the production of P, E₂, and hCG by JEG-3 choriocarcinoma cells. Neither GnRH nor [D-Trp⁶]-LH-RH had any effect on the production of P, E₂ or hCG. Our findings are similar to a previous observation which showed GnRH did not increase hCG in term placenta, but differed from preterm placenta in which GnRH increased hCG. This suggests there could be maturational changes in the placental response to GnRH and that JEG-3 cells more closely resemble term placenta. It is our conclusion that although GnRH and the GnRH receptor are found in the placenta, GnRH might have no effect on steroid hormone synthesis near term.