Ultrastructural and quantitative study of atypical age-related bodies in the hamster brain

Atypical bodies (ABs), related to aging, are described in the central nervous system of normal aged hamsters. Our study used ultrastructural microscopy and quantitative stereology analysis to study these structures in the hypothalamus and brain stem of 3, 6, 12, 18, 24 and 30 month-old hamsters. We found that these complex bodies have an oval or a round profile with a core of fibrillar or tubular structures rounded by a cytoplasmic crown. We frequently observed accumulations of organelles displaying evidence of degeneration. We found that these structures did not appear until 12 months and their frequency increased with age from 12 to 30 months. Their size can range from 3 to 10 microns, although the median size is 6.5 +/- 0.49 microns in diameter. There is a significant correlation between the quantity of these ABs and the animal's age. Their appearance in both hamster and human normal aging can provide an appropriate animal model to yield more information about the normal aging process. This knowledge of the normal aging process in hamsters may also give new insights into which processes in the human brain occur with normal aging and which ones may be exacerbated as in Alzheimer's disease.