ABNORMAL CONTENT OF N-6 AND N-3 LONG-CHAIN UNSATURATED FATTY-ACIDS INTHE PHOSPHOGLYCERIDES AND CHOLESTEROL ESTERS OF PARAHIPPOCAMPAL CORTEX FROM ALZHEIMERS-DISEASE PATIENTS AND ITS RELATIONSHIP TO ACETYL COA CONTENT

The long-chain fatty acid composition of cholesterol esters, phosphati dylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS ) and phosphatidylinositol (PI) from parahippocampal cortex of Alzheim er's disease (AD) patients and control subjects was examined. In gener al the PC fraction contained less polyunsaturated long-chain fatty aci ds than did PE, PS or PI. Of the n-6 polyunsaturated long-chain fatty acids, PI contained the greatest incorporation of these acids followed by PE. There were significant differences between controls and AD pat ients in total n-6 EFAs. Arachidonic acid (C20:4n-6) was the predomina nt fatty acid of this family found to be present. In AD, PE and PS sho wed a deficit of adrenic acid (C22:4n-6) content and PE also contained less arachidonic acid. In AD subjects, the cholesterol esters contain ed significantly less n-3 polyunsaturated fatty acids with, specifical ly, a reduction in alpha-linolenic acid. Acetyl CoA content of hippoca mpal cortex was greater in AD patients than in control subjects indica ting either an increased extent of oxidative metabolism or a failure t o utilise acetyl CoA for anabolic processes. Abnormal magnitude of oxi dative processes could give rise to the biosynthesis of PE and PS spec ies containing less n-6 polyunsaturated fatty acids than occurs in con trol subjects. (C) 1998 Elsevier Science Ltd. All rights reserved.