Taurine Enhances Excitability of Mouse Cochlear Neural Stem Cells by Selectively Promoting Differentiation of Glutamatergic Neurons Over GABAergic Neurons

Taurine is a sulfur-containing amino acid present in high concentrations in mammalian tissues, and has been implicated in several processes involving brain development and neurotransmission. However, the role of taurine in inner ear neural development is still largely unknown. Here we report that taurine enhanced the viability and proliferation of in vitro mouse cochlear neural stem cell culture, as well as improved neurite outgrowth. Moreover, prolonged taurine treatment also increased the neural electrical activity by escalating changes of intracellular calcium concentration, the number of spontaneous Ca2+ oscillations in cells, and the frequencies of Ca2+ spikes. Most importantly, we found that this escalated neural excitability by taurine was due to combined effect of increase in the population of excitatory glutamatergic neuron and decrease in inhibitory GABAergic neuron population. This is the first report on the effect of taurine to selectively promote neural stem cell differentiation by altering neuron type commitment. Our study has supported the potential of taurine as treatment against hearing loss caused by neuron degeneration, or even as an agent to improve sensitivity of hearing by increasing overall excitability of auditory nervous system.