TRPV1 and TRPA1 Mediate Peripheral Nitric Oxide-Induced Nociception in Mice

Takashi Miyamoto,Matt J Petrus,Ardem Patapoutian,Adrienne E Dubin,Louis S Premkumar

doi:10.1371/journal.pone.0007596

Takashi Miyamoto, Matt J Petrus + Show 3 more

Open Access

https://doi.org/10.1371/journal.pone.0007596

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Abstract

Nitric oxide (NO) can induce acute pain in humans and plays an important role in pain sensitization caused by inflammation and injury in animal models. There is evidence that NO acts both in the central nervous system via a cyclic GMP pathway and in the periphery on sensory neurons through unknown mechanisms. It has recently been suggested that TRPV1 and TRPA1, two polymodal ion channels that sense noxious stimuli impinging on peripheral nociceptors, are activated by NO in heterologous systems. Here, we investigate the relevance of this activation. We demonstrate that NO donors directly activate TRPV1 and TRPA1 in isolated inside-out patch recordings. Cultured primary sensory neurons display both TRPV1- and TRPA1-dependent responses to NO donors. BH4, an essential co-factor for NO production, causes activation of a subset of DRG neurons as assayed by calcium imaging, and this activation is at least partly dependent on nitric oxide synthase activity. We show that BH4-induced calcium influx is ablated in DRG neurons from TRPA1/TRPV1 double knockout mice, suggesting that production of endogenous levels of NO can activate these ion channels. In behavioral assays, peripheral NO-induced nociception is compromised when TRPV1 and TRPA1 are both ablated. These results provide genetic evidence that the peripheral nociceptive action of NO is mediated by both TRPV1 and TRPA1.

Highlights

Nitric oxide (NO) is a gaseous signaling molecule generated from arginine and oxygen by nitric oxide synthases (NOS) [1]
We sought to determine if NO activates cultured dorsal root ganglia (DRG) neurons using compounds that spontaneously release NO
Completely blocked the NO donor-induced increase in calcium levels when applied before application of SNAP (Fig. 1C, and Table 1). These results suggest that NO released from SNAP activates a subset of DRG neurons through ruthenium red (RR)-sensitive ion channel(s)

Summary

Introduction

Nitric oxide (NO) is a gaseous signaling molecule generated from arginine and oxygen by nitric oxide synthases (NOS) [1]. NO signaling is carried out by at least two separate pathways. NO stimulates soluble guanylyl cyclase (sGC) to increase cyclic guanosine monophosphate (cGMP), which in turn modulates a variety of downstream signaling targets [4]. NO covalently and reversibly forms adducts with free thiols of cysteine residues within proteins and directly modifies protein function [5]. Functional significance of this S-nitrosylation has not been as well established as the NO-cGMP pathway, accumulating evidence suggests that it is a widespread mechanism of NO action [5,6]

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