Stimulatory and inhibitory effects of prostaglandins on the gonadotropin-sensitive adenylate cyclase in the monkey corpus luteum

Detailed analysis of the action of prostaglandins (PGs) on the corpus luteum in primate species is very limited. In this study we examined the response of the adenylate cyclase system to PGs in homogenates prepared from the corpus luteum of rhesus monkeys at midluteal phase of the menstrual cycle. The conversion of [α³²P] ATP to [³²P] cyclic AMP (cAMP) was assessed in the absence (control activity; 50 μM GTP) and presence of various concentrations of seven PGs and arachiodonic acid, either alone or in combination with 250 nM hCG. Cyclic AMP production increased up to three-fold in the presence of PGD₂, PGE₂, PGI₂ or PGF_2α; however PGA₂, PGB₂, 13,14-dihydro-15-keto PGE₂ and arachidonic acid alone did not alter cAMP levels. In dose-response studies, adenylate cyclase was 10 and 100-fold more sensitive to PGD₂ (V_max at 1 × 10^-5M) than to PGE₂ or to PGI₂ and PGF_2α, respectively. Activity in the presence of hCG plus either PGD₂, PGE₂, PGI₂ or PGF_2α did not differ from that for hCG (or the PG) alone. In contrast, addition of PGA₂ or arachidonate inhibited (p<0.05) hCG-stimulated cAMP production by 50 and 100 percent. We conclude that the gonadotropin-sensitive adenylate cyclase of the macaque corpus leteum is also modulated by several PGs. These factors may either mimic (e.g., PGD₂, PGE₂, PGI₂) or suppress (PGA₂)_ gonodotropin-stimulated cAMP production and possibly cAMP-mediated events in luteal cells.