MOLECULAR-SPECIES COMPOSITION OF GLYCEROPHOSPHOLIPIDS IN RAT SCIATIC-NERVE AND ITS ALTERATION IN STREPTOZOTOCIN-INDUCED DIABETES

The molecular species compositon of glycerophospholipid classes in ner ves of normal and experimentally diabetic rats was determined. sn-1,2- Diacylglycerol (DAG) moieties of purified phospholipids were liberated enzymatically and analyzed as the benzoate derivatives by high-perfor mance liquid chromatography. The most abundant molecular species in ph osphatidylinositol (PI) from normal nerve were 18:0/20:4 (54%) and 16: 0/18:1 (17%), whereas in phosphatidylcholine (PC), 16:0/18:1 (52%), 16 :0/16:0 (12%) and 18:0/18:1 (11%) predominated. In phosphatidylethanol amine and ethanolamine plasmalogen, 18:1/18:1, 16:0/18:1 and 18:0/18:1 comprised more than 60% and 75% of the molecular species, respectivel y. Phosphatidylserine was characterized by a high content of 18:0/18:1 (38%) and a relative abundance of the 18:1/20:0, 18:1/22:0 and 18:1/2 4: 0 molecular species, which together accounted for over 30% of the t otal. The molecular species profile of phosphatidic acid did not close ly resemble that of any other phospholipids or DAG. In diabetic nerve, the molecular species composition of all diacylphospholipids showed a significant decline in the content of one or more arachidonoyl-contai ning molecular species. The largest decline occurred in PC and the lea st in PI. Except in PC, 16:0/20:4 was more depressed than 18:0/20:4. I n combination with previous analyses of DAG molecular species which sh owed a similar decline in the content of arachidonoyl-containing molec ular species in nerve from experimentally diabetic rats (Zhu, X. and E ichberg, J. (1990) J. Neurochem. 55, 1087-1090), the results suggest t hat nerve DAG arises largely, but not entirely, from phosphoinositides and that PC could be a significant precursor, especially in diabetic nerve.