Analysis of phospholipid molecular species in brain by P-31 NMR spectroscopy

Techniques are described for the P-31 NMR analysis of glycerophospholipid ( PL) headgroup and molecular species in brain. The P-31 NMR spectrum of PLs from human temporal cortex, solubilized in aqueous Na cholate, typically sh owed 3 major resonances, assigned to phosphatidylcholine (PC) molecular spe cies containing 0, 1, or 2 fully saturated acyl chains. Less species resolu tion was obtained for the other PL headgroups under these conditions. Alkyl acyl- and alkenylacyl-PC were readily discerned using the CHCl3-CH3OH-H2O s olvent method. The chain-length, temperature, and species dependences of th e P-31 NMR chemical shifts were explored in model PLs, Assignments of signa ls from phosphatidylethanolamine (PE) subclasses were confirmed in the sodi um-cholate system by lipase-mediated selective hydrolysis of bovine-brain P E, The utility of P-31 NMR to monitor enzymatic PL oxidation was further de monstrated. Possible changes in PL composition with postmortem interval (PM I) in rat brain were examined. No significant changes were seen in PL headg roup or PC species composition with PMI at up to 18 hours. Where comparable , the Na-cholate-solubilization and solvent methods gave similar quantitati ve results for headgroup analysis on the same samples. The present work dem onstrates the feasibility and utility of the dual system for analysis of PL s in brain. Magn Reson Med 44: 215-223, 2000. (C) 2000 Wiley-Liss, Inc.