Distinct types of lipofuscin pigment in the hippocampus and cerebellum of aged cheirogaleid primates.

The formation of autofluorescent lipopigment or lipofuscin is a highly consistent and reliable cytological change that correlates with cellular aging in postmitotic cells. One causal factor of lipofuscinogenesis involves free radical-induced lipid peroxidation. In mammals, dentate gyrus neurons and Purkinje cells are usually affected widely. In this study, we investigated the ultrastructure of lipofuscin deposits in large neurons of the dentate gyrus and in Purkinje cells of aged fat-tailed dwarf lemurs (Cheirogaleus medius Geoffroy, 1812) with electron and confocal microscopy and compared it with previous observations in other species. Cheirogaleid primates such as mouse and dwarf lemurs are archaic primates that provide interesting nonhuman models of aging. Our study revealed region-specific as well as species-specific characteristics of lipofuscin ultrastructure. This suggests differences in cellular metabolism and/or in organelles involved in lipofuscin production in cerebellar Purkinje cells and in hippocampal dentate gyrus neurons.