THE RESPIRATORY RESPONSE OF TRPV1 KNOCKOUT MICE TO TRIGEMINAL IRRITANTS

The trigeminal nerve is composed of polymodal neurons which innervate the nasal cavity, nasopharynx, oral cavity and cornea. Trigeminal nociceptive fibers are stimulated by a wide variety of chemical irritants. However, the mechanism of stimulation is known for only a few compounds. TRPV1 channels, for example, are activated by capsaicin. The present study was designed to address this question. Classic experiments have established that exposure to upper respiratory tract irritants results in a systematic alteration in the normal mammalian exhalation pattern which results in a decrease in respiration rate. This patterned respiration rate depression has been used as an indicator of sensory irritation, the “Alaire Test.” In the present study, an air dilution olfactometer was used to administer volatile compounds to unanesthetized mice which were restrained in a double chamber plethysmograph. Respiration rate depression for female wild type (C57Bl/6J) mice was compared to female Trpv1 knockout mice for a variety of compounds in an attempt to determine if TRPV1 is responsible for the detection of the irritants. Trpv1 knockout mice did not appear to show respiratory rate depression when exposed to cyclohexanone, a known TRPV1 agonist. Amyl acetate, eugenol and nicotine caused a significant respiratory rate depression in wild type and Trpv1 -/- mice. It appears that cyclohexanone is primarily detected via TRPV1, while the detection of amyl acetate, eugenol and nicotine are mediated by other receptors. Eugenol and nicotine are most likely being detected by TRPA1 or TRPV3 and nAChR, respectively.

Grantor dc:publisher

Wake Forest University

Year dc:date.issued

2008

Author dc:creator

• Saunders, CJ

• Animal physiology

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10339/14853

OAI identifier oai:identifier

oai:wakespace.lib.wfu.edu:10339/14853