Arachidonic acid metabolism in human granulosa cells: evidence for cyclooxygenase and lipoxygenase activity in vitro.

In view of the studies demonstrating the involvement of eicosanoids (prostaglandins and hydroxyperoxides, including leukotrienes) in ovulation in several mammalian species, we have examined the activity of the two enzyme systems, lipoxygenase and cyclooxygenase in human granulosa cells obtained from women undergoing in-vitro fertilization--embryo transfer. The activity of cyclooxygenase was assessed by radioimmunoassay of prostaglandin E and of 6-keto-prostaglandin F1 alpha, the conversion product of prostacyclin, accumulated in the culture medium of granulosa cells. Lipoxygenase activity was detected by the conversion of [14C]arachidonic acid into its products (hydroxyperoxides and leukotrienes) separated by reversed phase high-performance liquid chromatography. The results confirmed the activity of cyclooxygenase in human granulosa cells, production in vitro of prostaglandin E and prostacyclin and demonstrated the presence of active lipoxygenase enzymes. These results support the possible involvement of eicosanoids in ovulation of the human.