Prostaglandin-synthetase activity in developing toad ovary— I. Detection and properties.

ABSTRACT

Prostaglandin-synthetase activity has been measured in the microsomal fraction of developing toad (Bufo melanostictus) ovary using arachidonic acid as the substrate. Indomethacin (0·74 μΜ) and aspirin (0·35 μΜ) inhibit this activity. The activity is maximum in immature ovary and its level gradually decreases with maturity of the organ till the breeding season arrives, when it rises again. Time course study shows that the activity in vitro becomes steady after 3 min of incubation in all the cases, except the immature ones in which it sharply declines. Soluble supernatant was found to contain some inhibitory factor(s), which is partially inactivated by heating at 100°C for 5 min (~ 43%). Intraperitoneal injection of equine luteinizing hormone stimulates this enzyme activity in the mature ovary during non-breeding season. This suggests that similar to mammalians prostaglandin-synthetase, the toad ovary enzyme is also regulated by luteinizing hormone.