Effect of neuroleptics on phospholipase A2 activity in the brain of rats.

The effect of neuroleptics on phospholipase A2 (PLA2) activity in rat brain plasma membranes was studied. Chlorpromazine (10 mg/kg), fluphenazine (5 mg/kg), thioridazine (5 mg/kg), trifluoperazine (5 mg/kg), haloperidol (2 mg/kg), and sulpiride (100 mg/kg) were administered to rats intraperitoneally as a single dose or long-term treatment (4 weeks). The PLA2 activity was determined 24, 48, and 72 h after the last injection of a drug. The enzyme activity was decreased after a single or 4-week administration of chlorpromazine, trifluoperazine, haloperidol, and sulpiride. Fluphenazine and thioridazine caused an increase of PLA2 activity in rat brain both after a single dose and long-term administration. For the first time it was shown that neuroleptics cannot only inhibit but also increase, PLA2 activity. Elucidation of this fact requires further studies.