The relationship between the production and the anti-gonadotrophic action of prostaglandin F2α in luteal cells from the marmoset monkey (Callithrix jacchus) in the early and mid-luteal phase

To address the potential luteolytic role for prostaglandin F2α (PGF2α) in the corpus luteum of the common marmoset monkey (Callithrix jacchus), the ability of marmoset luteal cells, maintained in monolayer culture, to produce PGF2α was determined in vitro in the presence and absence of human chorionic gonadotrophin (hCG) and other established pharmacological modulators of PGF2α synthesis. We also assessed the effects of the PGF2α analogue, cloprostenol, on progesterone output from luteal cells isolated in the early luteal phase versus the mid-luteal phase (days 3 and 14 post ovulation, respectively). Cloprostenol had no effect on progesterone output from luteal cells isolated on day 3 of the luteal phase, whereas it significantly inhibited both basal and hCG-stimulated progesterone synthesis by day 14 luteal cells during the culture period 48-72 h (P < 0.001). Intra-luteal PGF2α concentrations were 5-fold higher in luteal cells isolated in the early luteal phase than in mid-luteal phase cells (16.5 ± 3.5 versus 3.5 ± 0.6 pmol/105 cells). While PGF2α production was unaffected by hCG in vitro, it was decreased by indomethacin (1000 ng/ml) (P < 0.05) and stimulated by the calcium ionophore A23187 (10 μmol/l) (P < 0.05) in luteal cells from both stages of the luteal phase. Phospholipase A2 did not influence PGF2α production by day 3 luteal cells whereas at 10 IU/ml, it significantly stimulated PGF2α production by day 14 luteal cells (P < 0.05). Hence, the timing of luteolysis in the common marmoset monkey appears to involve changes in both the luteal cell response to and production of PGF2α.