Effects of prostaglandin F_2α and nitric oxide on the secretory function of bovine luteal cells

The objective of the present study was to investigate the influence of prostaglandin F_2α (PGF_2α) and nitric oxide (NO) on production of steroids and PGs by culturing bovine luteal cells obtained from ovaries on days 8-12 of the estrous cycle with a nitric oxide (NO) donor (Spermine NONOate), and a NO synthase inhibitor (N^G-nitro-L-arginine methyl ester dihydrochloride: L-NAME). When the cells were exposed for 24 h to PGP_2α (10⁷-10⁵ M), production of progesterone (P₄) increased significantly at all doses used (P<0.05). Moreover, PGP_2α stimulated PGP_2α production (P<0.01), depressed testosterone (T) production (P<0.05), but did not affect synthesis of prostaglandin E₂ (PGE₂). Spermine NONOate decreased P₄ production to 66%, 47% and 34% of the control concentration after treatment with 10^-5 M, 10^-4 M and 10^-3 M, respectively, but did not affect T production, and increased PGF_2α synthesis (P<0.05) and PGP₂ (P<0.01) at all doses used. L-NAMP increased production of P₄ (P<0.01) but did not affect (P>0.05) secretion of T, PGF _2α and PGP₂. Estradiol-17β (E₂) was detectable on the level of sensitivity of assay and was not significantly altered by any treatments. The overall results suggest that PGF _2α and NO produced locally in bovine CL play roles in the regulation of the secretory function of the bovine CL as auto/paracrine factors.