SCIENCE SIGNALING

Hearing Essentials About Glutamate Transporters

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Science  08 Feb 2008:
Vol. 319, Issue 5864, pp. 701
DOI: 10.1126/science.319.5864.701c

Although three vesicular glutamate transporters (VGLUTs) have been identified, only two are found in identified glutamatergic neurons. In contrast, VGLUT3 is expressed in several populations of neurons that release other classical neurotransmitters, including inhibitory GABAergic interneurons in the hippocampus and cortex. Seal et al. found that mice lacking VGLUT3 were profoundly deaf: They failed to show a startle response to loud noises and did not exhibit auditory evoked potentials. Electrophysiological analysis revealed a defect in signaling from the inner hair cells (IHCs) of the cochlea to the auditory nerve, and morphological analysis showed abnormalities of IHC synapses. Immunofluorescence revealed that VGLUT3 was present in synaptic regions of the IHCs of wild-type mice. Whereas the conductances in the IHCs of the mice lacking VGLUT3 resembled those in wild-type mice, electrophysiological analysis indicated that these neurons failed to release glutamate. The authors conclude that VGLUT3 is essential for hearing and plays an important role in the regulation of cortical excitability. — EMA

Neuron 57, 263 (2008).

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