Interaction of Brain Synaptic Vesicles Induced by Endogenous Ca 2+ -Dependent Phospholipase A 2

Endogenous phospholipase A2 activity of brain synaptic vesicles was Ca2+ -dependent and was increased by prostaglandin F2 alpha, calmodulin, adenosine 3', 5' -monophosphate, and adenosine triphosphate, whereas the activity was inhibited by prostaglandin E2 in the absence or presence of calmodulin. Light-scattering measurements demonstrated that stimulation of the enzyme's activity correlated with the induction of vesicle-vesicle aggregation. The effects of these compounds on endogenous synaptic vesicle phospholipase A2 activity may imply a common end point of their purported neuromodulatory actions, and indicate that synaptic vesicle phospholipase A2 may play a central role in presynaptic neurotransmission.