SENSORY NERVE FIBERS,NOCICEPTORS

[Guest guest]

2010 The American Thoracic Society

Sensory Detection and Responses to Toxic Gases

Abstract

The inhalation of reactive gases and vapors can lead to severe damage of the

airways and lung, compromising the function of the respiratory system. Exposures

to oxidizing, electrophilic, acidic, or basic gases frequently occur in

occupational and ambient environments. Corrosive gases and vapors such as

chlorine, phosgene, and chloropicrin were used as warfare agents and in

terrorist acts. Chemical airway exposures are detected by the olfactory,

gustatory, and nociceptive sensory systems that initiate protective

physiological and behavioral responses. This review focuses on the role of

airway nociceptive sensory neurons in chemical sensing and discusses the recent

discovery of neuronal receptors for reactive chemicals. Using physiological,

imaging, and genetic approaches, Transient Receptor Potential (TRP) ion channels

in sensory neurons were shown to respond to a wide range of noxious chemical

stimuli, initiating pain, respiratory depression, cough, glandular secretions,

and other protective responses. TRPA1, a TRP ion channel expressed in

chemosensory C-fibers, is activated by almost all oxidizing and electrophilic

chemicals, including chlorine, acrolein, tear gas agents, and methyl isocyanate,

the highly noxious chemical released in the Bhopal disaster. Chemicals likely

activate TRPA1 through covalent protein modification. Animal studies using TRPA1

antagonists or TRPA1-deficient mice confirmed the role of TRPA1 in chemically

induced respiratory reflexes, pain, and inflammation in vivo. New research shows

that sensory neurons are not merely passive sensors of chemical exposures.

Sensory channels such as TRPA1 are essential for maintenance of airway

inflammation in asthma and may contribute to the progression of airway injury

following high-level chemical exposures

http://pats.atsjournals.org/cgi/content/abstract/7/4/269

Cough: The Emerging Role of the TRPA1 Channel

http://www.springerlink.com/content/9m1376162j781153/

Occupational, Environmental, and Irritant-Induced Cough

http://www.oto.theclinics.com/article/S0030-6665(09)00211-4/abstract

Olfactory bulb volume in the clinical assessment of olfactory dysfunction

http://www.ncbi.nlm.nih.gov/pubmed/19382487