Differential alteration of phospholipase A2 activities in brain of patients with schizophrenia

We recently reported that the activity of a calcium-independent subtype of phospholipase A(2) is increased in blood of patients with schizophrenia. The present investigation examined whether similar changes take place in brain of patients with this disorder, and for comparison, in patients with bipolar disorder. The activity of two classes of PLA(2), calcium-stimulated and independent, were assayed in autopsied temporal, prefrontal and occipital cortices, putamen, hippocampus and thalamus of 10 patients with schizophrenia, 8 patients with bipolar disorder and 12 matched control subjects. Calcium-independent PLA(2) activity was increased by 45% in the temporal cortex of patients with schizophrenia as compared with the controls but was not significantly altered in other brain areas. In contrast, calcium-stimulated PLA(2) activity was decreased by 27-42% in the temporal and prefrontal cortices and putamen, with no significant alterations in other brain regions. Brain PLA(2) activity was normal in patients with bipolar disorder. Calcium-stimulated PLA(2) activity was normal in cortex, cerebellum and striatum of rats treated acutely or chronically with haloperidol, whereas calcium-independent PLA(2) activity was decreased in striatum of chronically treated animals, indicating that altered PLA(2) activity in patients with schizophrenia is unlikely to be a direct effect of medication. Studies of the cellular role played by PLA(2) suggest that decreased calcium-stimulated PLA(2) activity, as also occurs in striatum of chronic human cocaine users, may be due, in part, to increased dopaminergic activity in the disorder, whereas increased calcium-independent PLA(2) activity may be related to abnormal fatty acid metabolism and oxidative stress in schizophrenia. (C) 1999 Elsevier Science B.V. All rights reserved.