Changes in Histological Features, Apoptosis and Necroptosis, and Inflammatory Status in the Livers and Kidneys of Young and Adult Rats

Abstract

Objective: Aging entails a gradual rise in low-grade inflammation affected by cellular degeneration and death. Inflammaging refers to the chronic, low-grade inflammation that occurs alongside the aging process. This study attempts to evaluate the hepatic and renal histological changes, apoptosis and necroptosis rates, and inflammaging status of 6-week-old and 10-month-old rats. Materials and Methods: This study uses 12 male rats separated into two groups: Young Group (6-week-old rats; n = 6), and Adult Group (10-month-old rats; n = 6). Animals were sacrificed under anesthesia. The rats\" livers and kidneys were removed, and each organ tissue was divided into two parts: one for the microscopic examination (H&E and TUNEL immunohistochemistry) and the other for biochemical determination (tumor necrosis factor-alpha [TNF-α], nuclear factor-kappa beta [NF-κB], interleukin1-Beta [IL-1β], IL6, receptor-interacting serine/threonine protein kinase [RIP], and RIP3). Results: The histological features of the livers and kidneys of the 6-week-old rats were consistent with healthy mammalian organ features, while some histological changes were detected in sections of the 10-month-old rats. The apoptosis rate indicated by TUNEL immunohistochemistry was seen to have increased in the 10-month-old rats, while the necroptosis rate indicated by RIP3 Western-blotting analysis was conversely determined to have decreased. Significant increases in TNF-α and NF-κB levels were consistent with the increased apoptosis rate in the 10-month-old rats compared to the 6-week-old rats. Conclusion: One of the striking results of this study is that the degenerative changes related to aging began to be seen even in 10-month-old rats. The researchers used healthy rats of this age as control subjects as well as to create experimental models.