Prostaglandin F_2α regulates the nitric oxide generating system in bovine luteal endothelial cells

The objective of the present study was to elucidate whether luteolytic prostaglandin F_2α (PGF) plays roles in regulating the nitric oxide (NO) generating system in luteal endothelial cells (LECs). Reverse transcriptase PCR, immunoblotting and immunostaining revealed the presence of PGF receptor mRNA (521 bp) and protein (64 kDa) in cultured LECs obtained from the mid-stage corpus luteum. When cultured LECs were exposed to 0.1 μM-10 μM PGF, NO production was significantly stimulated by PGF at 24 h. When LECs were exposed to 1 μM PGF for 2, 6 and 24 h, PGF did not affect the expressions of endothelial NO synthase (eNOS) mRNA and protein. On the other hand, PGF stimulated the expression of inducible NOS (iNOS) mRNA (P<0.05) and protein (P<0.05) at 2 h, but not at 6 and 24 h. By observing the conversion of [³C]L-arginine to [³C]L-citrulline, we found that PGF stimulated NOS activity in cultured LECs at 2 h (P<0.05). The overall findings indicate that bovine LECs are a target for PGF and that PGF stimulates iNOS expression and NOS activity in bovine LECs. Stimulation of the NO generating system and NOS activity by PGF may result in increasing local NO production followed by luteolysis.