Neurotrophic effects of taurine on spiral ganglion neurons in vitro

Taurine is an ubiquitary expressed aminosulfonic acid known to play an important role in the development and maintenance of the nervous system. It is distributed in the inner ear, contributing toward the protection of hair cells against aminoglycoside-induced or bilirubin-induced ototoxicity. Thus, the question arises whether taurine also has an influence on the cellular integrity of the auditory neurons. To test this hypothesis, isolated cells of the spiral ganglion were cocultured with taurine or the neurotrophic factors brain derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) as controls. The analysis included cellular survival rate and neurite outgrowth. With application of taurine, the survival of glial cells and neurons was stimulated in a similar pattern, whereas BDNF and NT-3 only effected neuronal survival. Furthermore, administration of taurine resulted in enhanced neurite outgrowth comparable with the effect of the neurotrophic factors. These new insights on the neuromodulatory effects of taurine on auditory neurons suggest the use of this aminosulfonic acid to reduce the degeneration of auditory neurons in sensorineural hearing loss. Consecutively, a new therapeutical approach for the therapy of hearing impairment could be discussed.