Nitro-oleic acid desensitizes TRPA1 and TRPV1 agonist responses in adult rat DRG neurons

Xiulin Zhang, Kevin B. Koronowski, Lu Li, Bruce A. Freeman, Stephen Woodcock, William C. de Groat

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Nitro-oleic acid (OA-NO2), an electrophilic fatty acid nitroalkene byproduct of redox reactions, activates transient receptor potential ion channels (TRPA1 and TRPV1) in primary sensory neurons. To test the possibility that signaling actions of OA-NO2 might modulate TRP channels, we examined: (1) interactions between OA-NO2 and other agonists for TRPA1 (allyl-isothiocyanate, AITC) and TRPV1 (capsaicin) in rat dissociated dorsal root ganglion cells using Ca2+ imaging and patch clamp techniques and (2) interactions between these agents on sensory nerves in the rat hindpaw. Ca2+ imaging revealed that brief application (15-30s) of each of the three agonists induced homologous desensitization. Heterologous desensitization also occurred when one agonist was applied prior to another agonist. OA-NO2 was more effective in desensitizing the response to AITC than the response to capsaicin. Prolonged exposure to OA-NO2 (20min) had a similar desensitizing effect on AITC or capsaicin. Homologous and heterologous desensitizations were also demonstrated with patch clamp recording. Deltamethrin, a phosphatase inhibitor, reduced the capsaicin or AITC induced desensitization of OA-NO2 but did not suppress the OA-NO2 induced desensitization of AITC or capsaicin, indicating that heterologous desensitization induced by either capsaicin or AITC occurs by a different mechanism than the desensitization produced by OA-NO2. Subcutaneous injection of OA-NO2 (2.5mM, 35μl) into a rat hindpaw induced delayed and prolonged nociceptive behavior. Homologous desensitization occurred with AITC and capsaicin when applied at 15minute intervals, but did not occur with OA-NO2 when applied at a 30min interval. Pretreatment with OA-NO2 reduced AITC-evoked nociceptive behaviors but did not alter capsaicin responses. These results raise the possibility that OA-NO2 might be useful clinically to reduce neurogenic inflammation and certain types of painful sensations by desensitizing TRPA1 expressing nociceptive afferents.

Original languageEnglish (US)
Pages (from-to)12-21
Number of pages10
JournalExperimental Neurology
Volume251
DOIs
StatePublished - Jan 2014
Externally publishedYes

Keywords

  • Desensitization
  • Nitro-oleic acid
  • Nociception
  • Primary sensory neuron
  • TRP channels

ASJC Scopus subject areas

  • Neurology
  • Developmental Neuroscience

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