CHRONIC LITHIUM TREATMENT DECREASES BRAIN PHOSPHOLIPASE A(2) ACTIVITY

Chronic lithium administration decreases the turnover of arachidonic a cid (AA) in several brain phospholipids. This suggests that lithium ma y attenuate phospholipase A(2) (PLA(2)) activity in brain. We now repo rt effects of chronic lithium treatment on PLA(2) activity in postnucl ear supernatant from rat brain: Enzyme activity was determined by two assay methods, radiometric and fluorometric, and measured the release of the fatty acid on the second acyl position (sn2) from choline and e thanolamine phospholipids. PLA(2) activity in brain postnuclear supern atant from rats chronically treated with lithium in the diet was signi ficantly decreased (20-50%) when compared with controls. In vehicle or lithium-treated rats, PLA(2) activity was not significantly augmented or attenuated by the addition of calcium chelators, divalent cations or LiCl supplementation (1.0 mM) to postnuclear supernatant. These res ults suggest that a major therapeutic effect of lithium is to attenuat e brain PLA(2) activity involved in signal transduction.