REGULATION OF PROSTAGLANDIN-F2-ALPHA RECEPTOR MESSENGER-RNA IN HUMAN GRANULOSA-LUTEAL CELLS BY HUMAN CHORIONIC-GONADOTROPIN AND PROSTAGLANDIN-F2-ALPHA

This study examined the effects of prostaglandin F-2 alpha (PGF(2 alph a)) and human chorionic gonadotropin (hCG) on the levels of PGF(2 alph a)-receptor (PGF(2 alpha)-R) mRNA and steroidogenesis, in the human gr anulosa luteal cell (hGLC). Human GLCs collected from patients undergo ing in vitro fertilization, were cultured for 24 h, after which cells were exposed to culture media containing either vehicle, hCG (1 IU/mL) , or hCG plus PGF(2 alpha) (10-(11)-10(-6) M)I for a further 24 h. Fol lowing the treatment period, media were collected and stored (-20 degr ees C) until assayed for progesterone and 1 7 beta-estradiol (estradio l). Immediately following the treatment period, cells were extracted f or total RNA. Transcripts for PGF(2 alpha)-R were detected by PCR with two different sets of oligonucleotide primers based on the published human and rat PGF(2 alpha)-R sequences. PCR products were confirmed to be those of PGF(2 alpha)-R by size and by Southern blot hybridization with an internal oligo nucleotide probe. All experiments were perform ed a minimum of three times, on cells from a minimum of three separate patients. Prostaglandin F-2 alpha-R mRNA was significantly downregula ted, whereas progesterone and estradiol production were significantly stimulated by hCG. Conversely, both low (10(-11) M) and high concentra tions (10(-6) M) of PGF(2 alpha) restored PGF(2 alpha)-R m RNA levels to those of the controls, whereas steroidogenesis was significantly in hibited by these conditions. At a concentration of 10(-9) M PGF(2 alph a)-R mRNA was barely detectable. Progesterone and estradiol production were inversely related to PGF(2 alpha)-R levels, since hCG-stimulated progesterone and estradiol production were completely restored in the presence of 10(-9) M PGF(2 alpha). Messenger RNA levels for the house keeping gene p-actin were unaltered by the above treatments. In conclu sion, in the human granulosa luteal cell, PGF(2)alpha-R mRNA levels ar e inversely related to hCG-stimulated steroidogenesis (which was bipha sic in nature). Moreover, in the presence of hCG, PGF(2 alpha) downreg ulates its receptor mRNA, thus providing a potential form of negative feedback on its own actions, which may be important in rescuing the co rpus luteum from PGF(2 alpha)-mediated luteolysis should pregnancy occ ur.