Organ-specific, qualitative changes in the phospholipid composition of rats after chronic administration of the antidepressant drug desipramine.

Rats were chronically treated with daily i.p. injections of 10 mg/kg desipramine for 21 days. A 30% decrease in the number of beta-adrenoceptors was observed in brain. A receptor desensitization of similar extent was noted in submaxillary glands and lung. No change in beta-adrenoceptor number was present in heart. Total phospholipid contents were not altered in these organs after chronic drug treatment. However, organ-specific changes were found in the phospholipid composition of submaxillary glands, lung and liver but not in whole brain and heart. The changes were variable but an increase in phosphatidylinositol and decreases in phosphatidylethanolamine and sphingomyelin were consistent. Possible alterations in the phospholipid composition of the brain might have been masked by the large and stable pool of myelin phospholipids. A casual relationship between changes in the phospholipid composition and beta-adrenoceptor desensitization is discussed.