Effect of topically applied basic fibroblast growth factor on injured cochlear nerve.
OBJECTIVE
Trauma-induced hearing loss after cerebellopontine angle manipulation has been regarded as having a hopeless natural course once it occurs. To challenge such a pessimistic view, we investigated whether pharmacological interventions with basic fibroblast growth factor (bFGF) could ameliorate trauma-induced cochlear nerve degeneration.


METHODS
The cerebellopontine angle portion of the cochlear nerve of rats was quantitatively compressed, and bFGF was topically administered for 2 weeks with a bFGF-soaked absorbable sponge and an osmotic minipump. The animals were killed 2 weeks after the compression procedure. The effect of bFGF in ameliorating cochlear neuronal death was evaluated from the residual number of spiral ganglion cells.


RESULTS
Cerebellopontine angle cisternal application of bFGF ameliorated cochlear nerve degeneration after the compression. Immunocytochemical studies of FGF receptors indicated that topically administered bFGF was internalized by a receptor-mediated mechanism through FGF receptor-1 and/or FGF receptor-2.


CONCLUSIONS
This report demonstrated that therapeutic application of bFGF was feasible to ameliorate trauma-induced cochlear nerve degeneration. Recent technological advances for deafened ears, such as cochlear implants and auditory brainstem implants, in combination with neurotrophic and/or growth factor therapeutic intervention, would be of great potential benefit for patients with hearing loss.
Sekiya
Tetsuji
T
Department of Neurosurgery, Hirosaki University School of Medicine, Hirosaki, Japan. seky@cc.hirosaki-u.ac.jp
Shimamura
Norihito
N
Yagihashi
Akinori
A
Suzuki
Shigeharu
S
D000818:Animals; D002452:Cell Count; D016923:Cell Death / Q000187:drug effects; D003056:Cochlear Nerve / Q000293:injuries* / Q000473:pathology; D004343:Drug Implants; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D015918:Infusion Pumps, Implantable; D008297:Male; D009409:Nerve Crush; D009410:Nerve Degeneration / Q000473:pathology; D009416:Nerve Regeneration / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013136:Spiral Ganglion / Q000187:drug effects / Q000473:pathology
D004343:Drug Implants; D016222:Fibroblast Growth Factor 2