Localization of vesicular glutamate transporters in the peripheral vestibular system of rat

Abstract

Objective To examine the vesicular glutamate transporters (VGluTs: VGluT1-VGluT3) in the peripheral vestibular system. Methods The vestibular structures, including Scarpa's ganglion (vestibular ganglion, VG), maculae of utricle and saccule, and ampullary cristae, from normal Sprague-Dawley rats were processed immunohistochemically for VGluTs, by avidin-biotinylated peroxidase complex method, with 3-3'-diaminobenzidine (DAB) as chromogen. Results (1) VGluT1 was localized to partial neurons of VG and to the putative primary afferent fibers innervating vestibular end-organs. (2) Intense VGluT3 immunoreactivity was detected in large number of sensory epithelia cells, and weak labeling of VGluT3-positive afferent fibers was in the maculae and ampullary cristae. (3) No or very weak VGluT2 immunoreactivity was observed in the VG and acoustic maculae. Conclusion These results provide the morphological support that glutamate exists in the peripheral vestibular system, and it may play an important role in the centripetal vestibular transmission.

Modalities of GABA and Glutamate Neurotransmission in the Vertebrate Inner Ear Vestibule

“…In that respect, recent results in the rat vestibular periphery, V Glu T 1 immunoreactivity was found in primary afferent fibers innervating hair cells whereas V Glu T 2 was not found at all, contrasting the results of V Glu T 3 which was found in a large number of hair cells [56].…”

Vesicular Glutamate Transporter 3 Is Required for Synaptic Transmission in Zebrafish Hair Cells

“…EPSCs in afferent boutons are mediated by AMPA receptors (Glowatzki and Fuchs, 2002), supporting cells abutting the afferent synapse express the glutamateaspartate transporter (GLAST) (Furness et al, 2002), and phosphate-activated glutaminase (a glutamate synthetic enzyme) has been detected in the mitochondria of hair cells in the mammalian cochlea (Takumi et al, 1999). It was reported previously that vesicular glutamate transporter 3 (VGLUT3) immunoreactivity is present in the sensory epithelial cells and afferent fibers of the peripheral vestibular system in rats (Wang et al, 2007). Furthermore, mRNA for VGLUT1 has been isolated from cochlear hair cells, and at least one group has reported VGLUT1 protein at the guinea pig afferent synapse (Furness and Lawton, 2003).…”

The c.824C>A and c.616dupA mutations in the SLC17a8 gene are associated with auditory neuropathy and lead to defective expression of VGluT3

“…The SLC17a8 gene was first cloned and named in 2002 [19] and located in the autosomal region 12q23.1, with a total length of 80 Kb. The protein encoded by the SLC17a8 gene is vesicular glutamate transporter 3 (VGluT3), which is located on the vesicular membrane in the cytoplasm [12,13]. The VGluT3 protein can specifically load glutamate in the cytoplasm of hair cells into synaptic vesicles [18].…”

“…Previous studies on the SLC17a8 gene and its coding protein VGluT3 focused on the distribution of expression products [13,14] and SLC17a8 gene knockout animal models, but few studies have explored human SLC17a8 gene-induced deafness mutations. Only one pathogenic mutation and two suspected mutations have been identified in the SLC17a8 gene.…”