Liver Pigment, Liver Histidase, and Renal Lysozyme Changes in Relation to Age in Normal and Irradiated Syrian Hamsters

The life spans, the soluble/insoluble collagen ratios in skin, and disease patterns in relation to age of normal and irradiated Syrian hamsters of the Bezanson strain were recently reported from this laboratory (1). The study revealed that this strain of hamster is relatively short-lived, with a mean survival time for normal animals of 22 months, and that mean survival time could be reduced to 14 months by 425 R of total-body irradiation. A decline of soluble/insoluble collagen ratios in skin of normal and irradiated animals appeared to be a reliable biochemical indicator of chronologic age. The decline was not significantly influenced by irradiation. The present study extends these prior experiments and was designed to investigate other possible biochemical parameters of aging in this animal population. Stored frozen organs from animals used in the earlier experiment plus tissues from additional, normal, young and old Bezanson hamsters were analyzed for quantity of ethanol-extractable and ethanol-nonextractable liver "age" pigment, specific activity of liver histidase, and specific activity of renal lysozyme. Age dependence has been shown in previous studies to occur for one variety of age pigment (lipofuscin) (2), for liver histidase (3), and for renal lysozyme (G. M. Troup and R. L. Walford, unpublished observations, 1966) in other animals.