Inhibition of phospholipase A2 activity reduces membrane fluidity in rat hippocampus

Summary. 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 100µM 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 Alzheimers disease.