Inhibition of phospholipase A2 activity reduces membrane fluidity in rat hippocampus.

Phospholipase A2 (PLA2) is a family of key enzymes in membrane phospholipid metabolism. In rats, the inhibition of PLA2 activity in the hippocampus was found to impair memory formation. Because memory function is largely dependent on the fluidity of brain membranes, we performed the present study to investigate the effects of in vivo PLA2 inhibition (with PACOCF3) on the fluidity of hippocampal membranes from rats trained in a learning task. Hippocampal tissue from rats injected with 100 microM PACOCF3 showed reduced membrane fluidity as compared to vehicle (p < 0.01), and the reduction of membrane fluidity was highly correlated with PLA2 inhibition (r = .76, p < 0.03). This finding is of interest because reduction of brain membrane fluidity impairs memory formation and both decreased PLA2 activity and reduced membrane fluidity have been reported in the brain from patients with Alzheimer's disease.