N-ACETYLASPARTATE AS AN ACETYL SOURCE IN THE NERVOUS-SYSTEM

Citation
V. Mehta et Maa. Namboodiri, N-ACETYLASPARTATE AS AN ACETYL SOURCE IN THE NERVOUS-SYSTEM, Molecular brain research, 31(1-2), 1995, pp. 151-157
Citations number
31
Categorie Soggetti
Neurosciences
Journal title
ISSN journal
0169328X
Volume
31
Issue
1-2
Year of publication
1995
Pages
151 - 157
Database
ISI
SICI code
0169-328X(1995)31:1-2<151:NAAASI>2.0.ZU;2-3
Abstract
To understand the role of N-acetylaspartate (NAA) as an acetyl donor, we investigated the metabolism of NAA in brain and liver slice prepara tions. The tissue slices were incubated with [C-14-acetyl]NAA (SA = 3 mu Ci/mu mol) or [C-14]acetate (SA = 3 mu Ci/mu mol) for 2 h. The tiss ue was homogenized and was extracted using chloroform/methanol (2:1). The aqueous phase was initially analyzed using anion exchange HPLC whi le the lipid phase was analyzed using a two-dimensional TLC system. Fu rther resolution of the NAA peak from the anion exchange HPLC was perf ormed using a reverse phase HPLC system. The aqueous phase of both the river and brain samples incubated with [C-14-acetyl]NAA revealed simi lar patterns of three distinct radioactivity peaks corresponding to NA A, acetate and an early eluting unknown molecule. Further resolution o f the NAA peak using reverse phase HPLC indicated that it corresponded to NAA and acetyl CoA. There was significant incorporation of radioac tivity into various lipid components in both the brain and liver sampl es. Patterns similar to that observed with NAA were detected in the ca se of [C-14]acetate in both the brain and liver slice preparations. Th ese results demonstrate that NAA metabolism is not restricted to the n ervous system, although its biosynthesis is. It is clear that acetyl m oiety of NAA is incorporated into lipids and partially hydrolyzed to f ree acetate in both brain and liver preparations. Further, production of acetyl CoA from NAA indicates that the acetyl group of NAA is incor porated into lipids and perhaps other acetylated molecules via the ace tyl CoA route. A working hypothesis on the metabolic role of NAA is pr esented.