Apelin‑13 reduces high glucose‑induced mitochondrial dysfunction in cochlear hair cells by inhibiting endoplasmic reticulum stress.

The complex manifestation of diabetic hearing loss and the relative inaccessibility of the inner ear contribute to the lack of research. The present study aimed to reveal the role of Apelin-13, a critical regulator of lipid metabolism, in diabetes-induced hearing loss. Cochlear hair cells treated with high glucose (HG) were adopted as an research model, and the impacts of Apelin-13 on cellular oxidative stress, apoptosis, mitochondrial dysfunction and endoplasmic reticulum (ER) stress were determined. In addition, cells were treated with the ER stress agonist tunicamycin to further explore its potential role in the regulatory effects of Apelin-13. Apelin-13 inhibited oxidative stress and apoptosis in the HG-induced cells. Additionally, Apelin-13 elevated mitochondrial membrane potential and ATP production, whereas it reduced mitochondrial reactive oxygen species levels. The levels of ER stress-related proteins exhibited a downward trend in response to Apelin-13. By contrast, tunicamycin reversed the effects of Apelin-13 on the aforementioned aspects, suggesting the role of ER stress in the regulatory effects of Apelin-13. In conclusion, the present study elucidated the protective role of Apelin-13 in ameliorating HG-induced mitochondrial functional impairment in cochlear hair cells by inhibiting ER stress.