Vanilloid receptor homologue, VRL1, is expressed by both A- and C-fiber sensory neurons.
The capsaicin receptor (VR1) homologue, VRL1, is thought to be responsible for transducing high-threshold heat responses in Adelta-fiber neurons. In the present study, the expression of VRL1 by A- or C-fiber sensory neurons in rats was investigated by using a VRL1 and 200 kDa neurofilament (NF200, an A-fiber marker) double immunohistochemical staining method. Approximately 46% of VRL-positive neurons were NF200 positive. Though double-labeled neurons tended to be medium to large, many VRL1 single-labeled neurons were large. Dense VRL1 immunoreactivity was also found in laminae I and II of the spinal dorsal horn, where nociceptive Adelta- and C-fibers normally terminate. These results suggest that both C-fiber and Adelta-fiber primary sensory neurons express VRL1, and VRL1 may play an important role in nociception.
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Department of Pharmacology, Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow CM20 2QR, UK.
D000818:Animals; D002211:Capsaicin / Q000378:metabolism; D002452:Cell Count; D048429:Cell Size / Q000502:physiology; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism*; D006930:Hyperalgesia / Q000378:metabolism* / Q000503:physiopathology; D009412:Nerve Fibers / Q000378:metabolism* / Q000648:ultrastructure; D009413:Nerve Fibers, Myelinated / Q000378:metabolism* / Q000648:ultrastructure; D016900:Neurofilament Proteins / Q000378:metabolism; D009475:Neurons, Afferent / Q000166:cytology / Q000378:metabolism*; D009619:Nociceptors / Q000378:metabolism* / Q000648:ultrastructure; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D011955:Receptors, Drug / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology; D050916:TRPV Cation Channels
D005456:Fluorescent Dyes; D016900:Neurofilament Proteins; D011955:Receptors, Drug; D050916:TRPV Cation Channels; C494484:TRPV1 receptor; D002211:Capsaicin