Role of cytosolic phospholipase A 2 in eicosanoid generation by corpora lutea of pseudopregnant rats: effects of its specific inhibitor

Abstract

This study was performed to investigate whether 85 kDa cytosolic phospholipase A 2 (cPLA 2) functions in eicosanoid generation in rat corpora lutea (CL) using its specific inhibitor, arachidonyl trifluoromethyl ketone (ATK). In both immature and adult pseudopregnant rats, PLA 2 activity in the cytosol of CL, measured by the liposome-vesicle assay, increased from day 6 of pseudopregnancy (PSP6) to PSP12. 10 μM ATK potently inhibited all of these activities to 10–20% and the rate of the inhibition by ATK was much higher on PSP12. ATK also reduced arachidonic acid (AA) release from luteal cells of PSP12 prelabelled with 3H-AA. Furthermore, the production of prostaglandin E 2 by cultured luteal cells was mostly suppressed by the drug. These results suggest the augmentation of cPLA 2 activity with the luteal age of pseudopregnant rats and its principal role in eicosanoid generation in CL.