Stimulation of phosphatidic acid and phosphatidylinositol labeling in luteal cells by luteinizing hormone releasing hormone

Luteinizing hormone-releasing hormone (LHRH) causes a rapid and marked increase of 32P]orthophosphate incorporation into phosphatidylinositol (PI) and phosphatidic acid (PA) in rat luteal cells in culture. The neurohormone exerts its stimulatory effect at an ED50 value of approximately 15 nM. Human chorionic gonadotropin (hCG) has no effect alone and does not interfere with the LHRH-induced PA-PI labeling. The rapidity and the specificity of the effect of LHRH suggest that the stimulation of the PA-PI cycle may well serve as a potent transducing mechanism responsible for the direct action of LHRH and its agonists at the ovarian level.