Rat pituitaries were pretreated with indomethacin (8 μm), PGE2, PGF2α, or iloprost (500 nm) for 4 h and further incubated with the drugs with or without GnRH (100 nm) for 3 h (Indomethacin + GnRH) and 4 h (PG + GnRH). The medium was collected and LH (A and C) and FSH (B and D) were determined by RIA. Note that indomethacin enhanced GnRH-stimulated LH, but not FSH release, whereas PGF2α, but not PGE2 or iloprost, inhibited GnRH-stimulated LH, but not FSH release. One-way ANOVA determined that **, P < 0.01 and *, P < 0.05 were significantly different between treatment groups.