The fatty acid composition of lipids of neuronal and glial nuclear fractions isolated from 15-day-old rabbit cerebral cortex

Abstract

A neuronal nuclear fraction (N1) and a glial nuclear fraction (N2) have been isolated from 15-day-old rabbit cerebral cortex using the Thompson procedure. More than 56% of the homogenate DNA was recovered in the two nuclear fractions, with N1 being the larger by about eightfold. Fractions N1 and N2 had very similar phospholipid distributions, with phosphatidyl-inositol being a larger component than phosphatidylserine. Fatty acid analyses demonstrated that phosphatidylethanolamine and phosphatidylinositol, individually, had similar fatty acid profiles in fractions N1 and N2, and also in nuclear and microsomal fractions derived from homogenates of nerve cell bodies isolated from cerebral cortex of 15-day-old rabbits. In contrast, the nuclear phosphatidylcholines had lower levels of palmitate and higher levels of arachidonate than did microsomal phosphatidylcholines. Molecular species analyses indicated that monoenes (41 mol%), tetraenes (20 mol%), and saturates (13 mol%, composed chiefly of palmitate) were the principal classes of N1 phosphatidylcholines, while the diacyl species of phosphatidylethanolamine of this fraction were characterized by high levels of tetraenes (44 mol%), pentaenes (17 mol%), and hexaenes + polyenes (24 mol%). The neutral glycerides of fraction N1 occurred collectively at a level of 0.05 mol/mol phospholipid. Prominent fatty acids of diacylglycerols included palmitate (31%), oleate (20%), arachidonate (14%), and stéarate (13%). Triacylglycerols showed a similar pattern but with relatively high levels of linoleate (11%), while monoacylglycerols consisted almost entirely of palmitate (33%), stearate (35%), and oleate (24%).