ABSTRACT
BACKGROUND AND OBJECTIVES: Ginkgo biloba extract (GBE) enhances cell survival in various organs. GBE protects nerve cells in the central nervous system and is clinically applied in Parkinson's and Alzheimer's disease. GBE can protect ototoxicity caused by cisplantin and gentamycin through rescue of hair cells in Organ of Corti and is accepted as one of the therapeutic agents for sudden deafness and tinnitus. The experimental study on GBE for the inner ear is confined to the hair cells, not to the spiral ganglion neurons (SGNs) which is the stimulated part by the electrode of cochlear implant. The aim of this study is to elucidate the effect of GBE on the survival of SGNs after hair cell loss in rats. MATERIALS AND METHOD: Ten Sprague-Dawley rats aged 50 days (P50) were deafened with kanamycin sulfate. GBE (EGb 761) was injected into the right cochlea and artificial perilymph was injected into the left side. The number and size of SGNs were compared after immunohistochemical statin in both groups. The expression of pJun, which is well-known as a proapoptotic transcription factor in the cochlea, was also compared. RESULTS: The number of SGNs was significantly larger in the GBE group than the control. The expression of pJun activity was significantly decreased in GBE group than the control. The size of SGNs in both groups was similar. CONCLUSION: These results suggest that GBE can protect SGNs death by inhibiting the pJun-C-jun N-terminal kinase pathway. GBE might be a potential drug for the patients with total deafness before or after cochlear implantation surgery for better hearing results.