Abstract
Osteoarthritis (OA) is one of the most prevalent pain‑inducing and disabling diseases globally. Aging is a primary contributing factor to the progression of OA. Forkhead box protein O4 (FOXO4) is known to be involved in the cell cycle and apoptosis regulation. The aim of the present study was to investigate the association between FOXO4 expression and chondrocyte degeneration in rats. Chondrocytes were assigned to the control (4‑week‑old rats), natural degeneration (16‑week‑old rats) or induced degeneration (IL‑1β‑treated chondrocytes from 4‑week‑old rats) groups. Immunocytochemical analysis with β‑galactosidase staining revealed a greater number of stained cells present in the natural and induced degeneration groups than in the control group. PCR analysis indicated lower mRNA expression levels of collagen type II α1 chain (Col2α) and higher levels of FOXO4, and western blotting revealed reduced Col2α protein expression levels and significantly elevated FOXO4 levels in the natural and induced degeneration groups, compared with those in the control group. The results of the present study revealed that FOXO4 expression was altered in the natural and induced degeneration groups, and further research and exploration are needed to clarify the underlying mechanism.