A review of chemical issues in 1H NMR spectroscopy: N-acetyl-L-aspartate, creatine and choline.

The structure and function of the chemicals contributing to the three main peaks seen with 1H NMR spectroscopy, N-acetyl-L-aspartate (NAA), creatine/phosphocreatine (Cr), and choline-containing compounds (Cho) is reviewed and the changes seen with these compounds in various disease states are briefly outlined. NAA is present within neurons although its biological function is largely unknown. NAA is elevated in several degenerative neurological conditions including amyotrophic lateral sclerosis and canavan disease, and in high concentrations it may behave like a neurotoxin. The creatine peak seen with 1H NMR spectroscopy consists of creatine and phosphocreatine which serve as a reserve for high-energy phosphates in the cytosol of muscle and neurons. They also buffer cellular ATP/ADP. The Cho peak seen with 1H NMR consists of a complex mixture of Cho-containing compounds. Cho is a precursor for the neurotransmitter acetylcholine and for the membrane constituent phosphatidylcholine. Future studies of changes seen in the Cho peak with stroke, degenerative dementia, drug intake, and infectious and neoplastic brain masses will be of great interest.