Dear group members,
In a recent study we found a benificial effect of topical capsaicin in
patients with a non-allergic non-infectious perennial rhinitis.
Suggestions have been made, amongst others by Lacroix, that this
benificial effect is generated through modulation of the anti-dromic
reflex which is presumed to be overactive in NANIPER patients. Capsaicin
treatment should either through toxicity or receptor modulation of the
unmyelinated C-afferent system diminish the anti-dromic reflex. A
beautifull hypothesis.
Fang"s group, Wolf's group, and our group, however, were unable to
gather evidence for an increased neuropeptide concentration in the nasal
mucosa of NANIPER patients. This means we have to evaluate the
hypothesis again.
In a recent publication in Nature by Caterina the capsaicin receptor was
identified as a heat activated ion channel. Moreover capsaicin was shown
to kill cells expressing the heat receptor.
The sensation of airflow is generated by cooling of the turbinates.
(Eccles, 1983). Cold receptors may have been identified (Krause's
corpuscles). A big problem in NANIPER patients is the sensation of
decreased nasal passage.
I would like to suggest the hypothesis that the efficacy of capsaicin in
this group of patients is the result of a decrease of the number of
functional heat receptors. As the number of cold receptors is not
modulated the net effect in the cortex is the sensation of increased
nasal flow. Of course this train of thought requires a balance between
heat and cold receptors. Unfortunately I'm not aware of the existence of
such a mechanism.
I would very much like your comments on this hypothesis.
With kind regards,
Henk Blom, ENT-surgeon.
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