Topographical localization of lipofuscin pigment in the brain of the aged fat-tailed dwarf lemur (Cheirogaleus medius) and grey lesser mouse lemur (Microcebus murinus): Comparison to iron localization

The present study was undertaken to explore the distribution of lipofuscin in the brain of cheirogaleids by autofluorescence and compare it to other s tudies of iron distribution. Aged dwarf(Cheirogaleus medius) and mouse (Mic rocebus murinus) lemurs provide a reliable model for the study of normal an d pathological cerebral aging. Accumulation of lipofuscin, an age pigment d erived by lipid peroxidation, constitutes the most reliable cytological cha nge correlated with neuronal aging. Brain sections of four aged (8-15 year old) and 3 young (2-3 year old) animals were examined. Lipofuscin accumulat ion was observed in the aged animals but not in the young ones. Affected re gions include the hippocampus (granular and pyramidal cells), where no iron accumulation was observed, the olfactory nucleus and the olfactory bulb (m itral cells), the basal forebrain, the hypothalamus, the cerebellum (Purkin je cells), the neocortex (essentially in the pyramidal cells), and the brai nstem. Even though iron is known to catalyse lipid oxidation, our data indi cate that iron deposits and lipofuscin accumulation are not coincident. Dif ferent biochemical and morphological cellular compartments might be involve d in iron and lipofuscin deposition. The nonuniform distribution of lipofus cin indicates that brain structures are not equally sensitive to the factor s causing lipofuscin accumulation. The small size, the rapid maturity, and the relatively short life expectancy of the cheirogaleids make them a good model system in which to investigate the mechanisms of lipofuscinogenesis i n primates. (C) 1999 Wiley-Liss, Inc.