title: TRPA1 induced in sensory neurons contributes to cold hyperalgesia after inflammation and nerve injury.
abstract: Cold hyperalgesia is a well-documented symptom of inflammatory and neuropathic pain; however, the underlying mechanisms of this enhanced sensitivity to cold are poorly understood. A subset of transient receptor potential (TRP) channels mediates thermosensation and is expressed in sensory tissues, such as nociceptors and skin. Here we report that the pharmacological blockade of TRPA1 in primary sensory neurons reversed cold hyperalgesia caused by inflammation and nerve injury. Inflammation and nerve injury increased TRPA1, but not TRPM8, expression in tyrosine kinase A-expressing dorsal root ganglion (DRG) neurons. Intrathecal administration of anti-nerve growth factor (anti-NGF), p38 MAPK inhibitor, or TRPA1 antisense oligodeoxynucleotide decreased the induction of TRPA1 and suppressed inflammation- and nerve injury-induced cold hyperalgesia. Conversely, intrathecal injection of NGF, but not glial cell line-derived neurotrophic factor, increased TRPA1 in DRG neurons through the p38 MAPK pathway. Together, these results demonstrate that an NGF-induced TRPA1 increase in sensory neurons via p38 activation is necessary for cold hyperalgesia. Thus, blocking TRPA1 in sensory neurons might provide a fruitful strategy for treating cold hyperalgesia caused by inflammation and nerve damage.
authors.affiliation: Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Obata
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Katsura
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Mizushima
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yamanaka
authors.forename: Kimiko
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Yi
authors.initials: Y
authors.lastname: Dai
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Fukuoka
authors.forename: Atsushi
authors.initials: A
authors.lastname: Tokunaga
authors.forename: Makoto
authors.initials: M
authors.lastname: Tominaga
authors.forename: Koichi
authors.initials: K
authors.lastname: Noguchi
mesh_terms: D000818:Animals; D017487:Ankyrins; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D003080:Cold Temperature; D005727:Ganglia, Spinal / Q000166:cytology; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000378:metabolism; D006930:Hyperalgesia; D017403:In Situ Hybridization; D007249:Inflammation; D020935:MAP Kinase Signaling System / Q000502:physiology; D008297:Male; D020932:Nerve Growth Factor / Q000378:metabolism; D009475:Neurons, Afferent / Q000166:cytology / Q000378:metabolism* / Q000473:pathology*; D010147:Pain Measurement; D051381:Rats; D017207:Rats, Sprague-Dawley; D000074025:TRPA1 Cation Channel; D050052:TRPC Cation Channels; D050053:TRPM Cation Channels / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors
chemical_list: D017487:Ankyrins; D015220:Calcium Channels; D051100:Glial Cell Line-Derived Neurotrophic Factor; D000074025:TRPA1 Cation Channel; D050052:TRPC Cation Channels; D050053:TRPM Cation Channels; C480976:Trpa1 protein, rat; C498947:Trpm8 protein, rat; D020932:Nerve Growth Factor; D048051:p38 Mitogen-Activated Protein Kinases