Brain phospholipases A2:: a perspective on the history

The phospholipases A(2) (PLA(2)) belong to a large family of enzymes involved in the generation of several second messengers that play an important role in signal transduction processes associated with normal brain function. The phospholipase A(2) family includes secretory phospholipase A(2), cytosolic phospholipase A(2), calcium-independent phospholipase A(2), plasmalogen-selective phospholipase A(2) and many other enzymes with phospholipase A(2) activity that have not been classified. Few attempts have been made purify and characterize the multiple forms of PLA(2) and none have been fully characterized and cloned from brain tissue. A tight regulation of phospholipase A(2) isozymes is necessary for maintaining physiological levels of free fatty acids including arachidonic acid and its metabolites in the various types of neural cells. Under normal conditions, phospholipase A(2) isozymes may be involved in neurotransmitter release, long-term potentiation, growth and differentiation, and membrane repair. Under pathological conditions, high levels of lipid metabolites generated by phospholipase A(2) are involved in neuroinflammation, oxidative stress, and neural cell injury. (C) 2004 Elsevier Ltd. All rights reserved.