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 intravenously and regional brain incorporation k* of tracer was determined with quantitative autoradiography after 20 min circulation. In NBM-lesioned animals, k* was elevated significantly (by up to 17%) in ii ipsilateral 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 damage due to the needle track. Circulating [H-3]PAM is incorporated into sn-l positions of brain phospholipids, mainly phosphatidylcholine, and its rate of turnover is thought to reflect turnover of neuronal and glial membranes, These results, when related to published evidence of altered cortical phospholipid metabolism in NBM-lesioned rats, suggest that images of increased [H-3]PAM incorporation into ipsilateral cortex reflect increased membrane remodeling involving phospholipids.
