BDNF as otoprotectant in toxin-induced hearing loss

Conclusion: Brain-derived neurotrophic factor (BDNF) can prevent auditory brainstem response (ABR) threshold shift changes caused by Pseudomonas aeruginosa exotoxin A (PaExoA). Objective: Peptides of the neurotrophin family are known to prevent neuronal death during embryonic development by interacting with specific membrane receptors. The purpose of this study was to investigate whether a single dose of BDNF is an effective protectant against toxic effects of PaExoA-induced ABR threshold shifts. Materials and Methods: Eight groups of Sprague-Dawley rats were used. There were five control groups (n = 20) as follows. Group A (n = 4) received NaCl solution; group B (n = 3) received 4 mu g BDNF; group C (n = 4) received 1 mu g/20 mu l PaExoA; group D (n = 4) received 2 mu g/20 mu l PaExoA; groupE (n = 5) received 10 mu g/20 mu l PaExoA injected into the round window niche. Three treatment groups (n = 13) received a single dose of PaExoA and 4 mu g of BDNF simultaneously. Group 1 (n = 3) received 1 mu g/20 mu l PaExoA + 4 mu g of BDNF; group 2 (n = 5) received 2 mu g/20 mu l PaExoA + 4 mg BDNF; group 3 (n = 5) received 10 mu g/20 mu l PaExoA+ 4 mu g BDNF. ABR was used to measure efficacy by analyzing threshold shifts before and after injections. Results: A single dose of BDNF prevented changes in ABR thresholds following exposure to increasing concentrations of PaExoA injected into the middle ear.