IN-VIVO IMAGING OF CORTICAL MEMBRANE REMODELING IN RATS WITH CHRONIC UNILATERAL ABLATION OF NUCLEUS BASALIS MAGNOCELLULARIS - USE OF RADIOLABELED PALMITIC ACID

Membrane remodeling was imaged in vivo in brains of rats with a 2-week -old right-sided ablation of the nucleus basalis magnocellularis (NBM) . To do this, [9,10-H-3]palmitic acid ([H-3]PAM) was injected intraven ously and regional brain incorporation k of tracer was determined wit h quantitative autoradiography after 20 min circulation. In NBM-lesion ed animals, k was elevated significantly (by up to 17%) in ii ipsilat eral frontal or parietal cortical regions, more so in layer I than in layers TV and V. Unoperated animals showed no right-left difference in k, whereas sham-operated animals showed some unilateral effects of d amage due to the needle track. Circulating [H-3]PAM is incorporated in to sn-l positions of brain phospholipids, mainly phosphatidylcholine, and its rate of turnover is thought to reflect turnover of neuronal an d glial membranes, These results, when related to published evidence o f altered cortical phospholipid metabolism in NBM-lesioned rats, sugge st that images of increased [H-3]PAM incorporation into ipsilateral co rtex reflect increased membrane remodeling involving phospholipids.