Glial cell line-derived neurotrophic factor. Potential for otoprotection

Area of Science:

• Neuroscience
• Ototoxicity Research
• Inner Ear Biology

Background:

• Sensorineural hearing loss stems from cochlear hair cell and auditory neuron degeneration.
• Neurotrophic factors like BDNF and NT-3 support auditory neuron survival.
• Ototoxic drugs such as cisplatin and neomycin induce significant cell death in the cochlea.

Purpose of the Study:

• To investigate the protective effects of Glial cell line-derived neurotrophic factor (GDNF) against ototoxicity.
• To evaluate GDNF's efficacy in preserving hair cells and auditory neurons in vitro and in vivo.
• To assess GDNF's potential therapeutic application for preventing drug-induced hearing loss.

Main Methods:

• Cultured rat cochlear explants and dissociated cells were treated with ototoxic drugs (cisplatin, neomycin) with or without GDNF.
• Immunostaining (phalloidin-FITC) identified surviving hair cells in explant cultures.
• Animal models (guinea pigs) received GDNF via inner or middle ear delivery before systemic ototoxin exposure (cisplatin, kanamycin/ethacrinic acid).

Main Results:

• GDNF significantly increased hair cell survival by approximately 2-fold in cultures treated with cisplatin or neomycin.
• GDNF treatment improved auditory neuron survival by approximately 5-fold in cisplatin-exposed cochlear cultures.
• In vivo studies showed that GDNF-treated ears had about twice the number of surviving hair cells compared to control ears.

Conclusions:

• Glial cell line-derived neurotrophic factor (GDNF) demonstrates significant neuroprotective effects against ototoxic agents.
• GDNF treatment can preserve both hair cells and auditory neurons, offering a potential therapeutic strategy for ototoxicity.
• The expression of the GDNF receptor (ret) in the inner ear supports its role in mediating these protective effects.