Abstract
Male Wistar rats aged 6–26 months were obtained from the colony of The Gerontology Research Center of the National Institute on Aging, and pathological profiles were assessed. One hundred animals were sacrificed at 6, 12, 18, 21, 24, and 26 months and used for cross-sectional determinations; also, 150 animals were followed longitudinally and sacrificed when clinical signs of moribundity appeared. Renal disease contributed the most common pathology observed in both studies (found in over 70% of the animals examined), with neoplasms a secondary problem (pituitary tumors were by far the most prevalent, with adenomas present in ≈ 20% of the animals). This analysis represents the first complete pathological characterization of this commonly used rat model for aging research, and offers an opportunity for comparison with other rat strains.