Docosahexaenoic acid improves long-term potentiation attenuated by phospholipase A2 inhibitor in rat hippocampal slices

1 We investigated the possible involvement of phospholipase A(2) (PLA(2)) and its products in longterm potentiation (LTP) in the CA1 neurotransmission of rat hippocampal slices. 2 Inhibitors of Ca2+-independent PLA(2) (iPLA(2)) prevented the induction of LTP without affecting the maintenance phase of LTP whereas Ca2+-dependent PLA(2) inhibitors were virtually ineffective, which suggests a pivotal role of iPLA(2) in the initiation of LTP. 3 We then investigated the effect of docosahexaenoic acid (DHA) and arachidonic acid (AA) on EEL (bromoenol lactone, an iPLA(2)-inhibitor) -impaired LTP, and found that either DHA or AA abolished the effect of EEL. However, DHA did not restore EEL-attenuated LTP when applied after the tetanus. DHA per se affected neither the induction nor maintenance of LTP. Linoleic acid had no effects, either. 4 These results suggest that DHA is crucial for the induction of LTP and that endogenously released DHA during tetanus is sufficient to trigger the formation of LTP.