Type 1 vanilloid receptor expression by mammalian inner ear ganglion cells.
The type 1 vanilloid receptor (VR1) is a non-specific cation channel activated by capsaicin, lipoxygenase (LOX) products, heat and acid. This study demonstrates VR1 and 5-LOX expression by inner ear ganglion cells. A PCR product (210 bp) was amplified from both oligo(dT)- and random primer-generated cDNAs of rat spiral ganglion cells using VR1 gene-specific primers constructed from the 3' non-homologous region. This PCR product shared 100% sequence homology to a rat VR1 cDNA (GenBank accession no. AF029310) and a rat vanilloid receptor splice variant mRNA (GenBank accession no. AF158248). Frozen sections of PLP-fixed, decalcified Long-Evans rat temporal bones were stained immunohistochemically for VR1. Neurons and satellite cells in both the vestibular and spiral ganglia were VR1-immunopositive. Neurons and supporting cells in adjacent sections of these ganglia were immunopositive for 5-LOX. These findings raise the hypothesis that activation of VR1 by endogenous ligands may contribute to hypersensitivity of the eighth nerve to hair cell inputs in a variety of pathologic conditions, such as tinnitus, Meniere's disease and migraine. In particular, these data suggest that LOX activation during inflammatory processes or during cyclo-oxygenase inhibition (e.g. by aspirin) is a potential intrinsic source of VR1 activation in inner ear ganglia.
Balaban
Carey D
CD
Department of Otolaryngology, University of Pittsburgh School of Medicine, 203 Lothrop Street, Eye and Ear Institute, Rm 153, Pittsburgh, PA 15213, USA. cbalaban@pitt.edu
Zhou
Jianxun
J
Li
Ha-sheng
HS
D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism; D001483:Base Sequence / Q000235:genetics; D007758:Ear, Inner / Q000294:innervation*; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020318:Rats, Long-Evans; D017207:Rats, Sprague-Dawley; D011955:Receptors, Drug / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013136:Spiral Ganglion / Q000378:metabolism*; D050916:TRPV Cation Channels; D014018:Tissue Distribution; D014725:Vestibular Nerve / Q000378:metabolism*
D012333:RNA, Messenger; D011955:Receptors, Drug; D050916:TRPV Cation Channels; C494484:TRPV1 receptor; D001094:Arachidonate 5-Lipoxygenase