Intravenous injection of [1-14C]arachidonate to examine regional brain lipid metabolism in unanesthetized rats
Article first published online: 11 OCT 2004
Copyright © 1989 Alan R. Liss, Inc.
Journal of Neuroscience Research
Volume 24, Issue 3, pages 413–423, November 1989
How to Cite
DeGeorge, J. J., Noronha, J. G., Bell, J., Robinson, P. and Rapoport, S. I. (1989), Intravenous injection of [1-14C]arachidonate to examine regional brain lipid metabolism in unanesthetized rats. J. Neurosci. Res., 24: 413–423. doi: 10.1002/jnr.490240311
- Issue published online: 11 OCT 2004
- Article first published online: 11 OCT 2004
- Manuscript Accepted: 14 JUN 1989
- Manuscript Revised: 2 JUN 1989
- Manuscript Received: 10 MAR 1989
- fatty acid;
- brain metabolism;
We examined the metabolic disposition and brain distribution of an unsaturated fatty acid, [1-14C]arachidonate, between 5 and 240 min following its intravenous bolus injection in unanesthetized adult rats. Injected [1-14C]arachidonate was cleared rapidly from plasma, with less than 10% remaining by 2 min. Total brain radioactivity, 0.2% of the injected dose, was near maximal by 5 min, reached a peak by 15 min, then slowly declined. Radioactivity in brain lipids constituted greater than 82% of the total brain radioactivity at all times. Radioactivity in aqueoussoluble metabolites was greatest at 5 min (13% of total) and declined to 5% by 240 min. Protein pelletassociated radioactivity gradually rose to a peak of 7% by 120 min. Within the lipid fraction, more than 92% of radioactivity was in glycerolipids, with greater than 81% in phospholipids. Radioactivity in inositol phosphoglyceride was maximal at 5 min (47% of phospholipid radioactivity); and declined to 34% by 20 min, whereas radioactivity in choline phosphoglyceride peaked at 15 min (41% of phospholipid radioactivity) and was constant thereafter. In contrast, radioactivity in ethanolamine phosphoglycerides increased from 7 to 17% during the course of the experiment. Quantitative autoradiography of brain sections indicated incorporation of [1-14C]arachidonate into gray-matter regions was 1.5- to threefold that into white-matter regions. The data were analyzed in terms of a model for brain fatty acid uptake from plasma. Estimates of unidirectional transfer constants, k, for [1-14]arachidonate from plasma to brain regions with an intact blood-brain barrier ranged from 0.0005 to 0.0015 ml · sec−1 · g−1 and were correlated with those for [9,10-3H]palmitate. The results indicate that brain phospholipid metabolism in awake animals can be examined regionally and quantitatively using intravenous injection of [1-14C]arachidonate combined with quantitative autoradiography and biochemical analysis.