TOPOGRAPHICAL LOCALIZATION OF IRON IN BRAINS OF THE AGED FAT-TAILED DWARF LEMUR (CHEIROGALEUS-MEDIUS) AND GRAY LESSER MOUSE LEMUR (MICROCEBUS-MURINUS)

Iron deposits in the human brain are characteristic of normal aging bu t have also been implicated in various neurodegenerative diseases. Amo ng nonhuman primates, strepsirhines are of particular interest because hemosiderosis has been consistently observed in captive aged animals. In particular, the cheirogaleids, because of their small size, rapid maturity, fecundity, and relatively short life expectancy, are a usefu l model system for the study of normal and pathological cerebral aging . This study was therefore undertaken to explore iron localization in the brain of aged cheirogaleids (mouse and dwarflemurs) with histochem istry and magnetic resonance microscopy. Results obtained with both te chniques were comparable. There was no difference between old animals in the two species. The young animals (3 years old) showed no iron dep osits. In the old animals (8-15 years old), iron pigments were mainly localized in the globus pallidus, the substantia nigra, the neocortica l and cerebellar white matter, and anterior forebrain structures, incl uding the nucleus basalis of Meynert. This distribution agrees with pr evious findings in monkeys and humans. In addition, we observed iron i n the thalamus of these aged nonhuman primates. Microscopic NMR images clearly reveal many features seen with the histochemical procedure, a nd magnetic resonance microscopy is a powerful method for visualizing age-related changes in brain iron. (C) 1998 Wiley-Liss, Inc.