Production of lysophosphatidic acids by lysophospholipase D in human follicular fluids of in vitro fertilization patients

Lysophosphatidic acids (LPAs) are known to be normal constituents of mammalian serum, and they mimic some biological effects of the serum. We previously reported that lysophospholipase D (LPLD) was involved in the accumulation of LPAs in incubated rat plasma and serum. In this study we detected, by gas-liquid chromatography, various molecular species of LPA in follicular fluids collected from women programmed for in vitro fertilization. When the follicular fluid was incubated at 37 degrees C for 48 h, persistent increases in the amounts of LPAs were observed concomitant with decreases in the amounts of the corresponding lysophosphatidylcholines (LPCs), although the concentrations of saturated LPCs increased in the first 6 h of incubation. These results suggest that human follicular fluid has LPLD activity, and this was confirmed by experiments with follicular fluids mixed with an exogenous radioactive LPC. The LPLD showed preference for unsaturated over saturated LPCs, similar to plasma LPLD, indicating that it originated from the circulation.