Acta Oto-laryngologica · Jan 17, 2017

Involvement of p53 and Bcl-2 in sensory cell degeneration in aging rat cochleae

By Xu Y, Yang WP, Hu BH et al.

CONCLUSION: p53 and Bcl-2 (B-cell lymphoma 2) are involved in the process of sensory cell degeneration in aging cochleae. OBJECTIVE: To determine molecular players in age-related hair cell degeneration, this study examined the changes in p53 and Bcl-2 expression at different stages of apoptotic and necrotic death of hair cells in aging rat cochleae. METHODS: Young (3-4 months) and aging (23-24 months) Fisher 344/NHsd rats were used. The thresholds of the auditory brainstem response (ABR) were measured to determine the auditory function. Immunolabeling was performed to determine the expression of p53 and Bcl-2 proteins in the sensory epithelium. Propidium iodide staining was performed to determine the morphologic changes in hair cell nuclei. RESULTS: Aging rats exhibited a significant elevation in ABR thresholds at all tested frequencies (p < 0.001). The p53 and Bcl-2 immunoreactivity was increased in aging hair cells showing the early signs of apoptotic changes in their nuclei. The Bcl-2 expression increase was also observed in hair cells displaying early signs of necrosis. As the hair cell degenerative process advanced, p53 and Bcl-2 immunoreactivity became reduced or absent. In the areas where no detectable nuclear staining was present, p53 and Bcl-2 immunoreactivity was absent.

doi.org/10.1080/00016489.2016.1274425PubMed 28093932Mechanisms