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The human nasal response to capsaicin
G Philip1, F M Baroody, D Proud
1Department of Medicine, Johns Hopkins Asthma & Allergy Center, Baltimore, MD 21224-6801.
The Journal of Allergy and Clinical Immunology
|December 1, 1994
Summary
Capsaicin nasal challenges activate airway sensory nerves, causing glandular secretion but not increased vascular permeability. Repeated exposure led to reduced responses, indicating tachyphylaxis.
Area of Science:
- Neuroscience
- Immunology
- Rhinology
Background:
- Airway sensory nerves are crucial in responses to inhaled substances.
- Capsaicin, from hot peppers, selectively activates specific sensory nerves.
Purpose of the Study:
- To investigate the effects of selective airway sensory nerve activation in the human nose using capsaicin.
- To understand the physiological responses, including secretion and vascular permeability, following capsaicin challenge.
Main Methods:
- Eight volunteers (4 normal, 4 with allergic rhinitis) received capsaicin nasal challenges.
- Nasal lavage fluid was analyzed for total protein, albumin, and lactoferrin content.
- Repetitive challenges and unilateral disk challenges were performed to assess tachyphylaxis and localized responses.
Main Results:
- Capsaicin induced burning, rhinorrhea, and lacrimation.
- Total protein and lactoferrin (glandular secretion marker) significantly increased, while albumin (vascular permeability marker) did not.
- Repetitive capsaicin challenges resulted in tachyphylaxis of symptoms and secretions.
- Unilateral capsaicin challenge induced secretion on both ipsilateral and contralateral sides.
Conclusions:
- Capsaicin nasal challenge effectively activates airway sensory nerves in humans.
- The induced nasal secretion is primarily glandular, not vascular.
- A central neuronal response is stimulated, and tachyphylaxis limits repeated activation effects.
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