Cyclooxygenase-2 (Cox-2) is induced in granulosa cells of preovulatory follicles by a PKA pathway; whereas, PGF₂ induction of Cox-2 in large luteal cells appears to be due to PKC/calcium-regulated pathways. However, no study has directly compared the timecourse and regulation of Cox-2 in granulosa and luteal cells from the same species.

Methods: Ovine granulosa cells and large luteal cells were cultured with medium, forskolin, or PDD (activates PKC). Cells and medium were harvested at 1, 4, and 24 h after treatment. Cox-2 mRNA was quantified by competitive RT-PCR. PGF₂ was analyzed by ELISA.

Results: Cox-2 mRNA was induced in granulosa cells by forskolin but not PDD with maximal stimulation at 24 h (Copies/Cell in Mean±SEM are: control=1015±362, forskolin=8075±2502, PDD=1467±294; p<0.001). In contrast, PDD was the more potent inducer in large luteal cells with the most dramatic effect at 4 h (control=1625±416, forskolin=4842±1413, PDD=13264±2798; p<0.001). Similarly, forskolin but not PDD increased media PGF₂ in granulosa cells at 24 h (p<0.05); whereas, PDD but not forskolin increased PGF₂ at 4 h (p=0.06) and 24 h (p<0.05) in large luteal cells. Preliminary functional analysis of the 5’ flanking sequence of the ovine Cox-2 gene indicates potent stimulation of transcription by PDD but not forskolin in large luteal cells.