The effect of the sympathetic and sensory nervous system on active eustachian tube function in the rat.
CONCLUSIONS
We propose that simultaneous activation of the sensory and sympathetic nervous system may adversely affect eustachian tube function, which may have a role in the genesis of Ménière's disease.


OBJECTIVE
We have determined the distribution of sympathetic and nociceptive sensory axons in the mucosa of the rat eustachian tube and investigated whether sympathetic or nociceptive neurons influence the function of the eustachian tube.


METHODS
We tested whether the ability of a rat to equalize air pressure in the middle ear during evoked swallowing was altered by activation or blockade of the local sympathetic nervous system, or by stimulation of nociceptive neurons with capsaicin.


RESULTS
Sympathetic axons were sparse, but CGRP-immunoreactive, nociceptive axons formed a dense subepithelial plexus beneath the eustachian tube epithelium. Neither the adrenergic blocking drug, bretylium, nor electrical stimulation of the superior cervical ganglion significantly altered eustachian tube function. Capsaicin alone did not affect eustachian tube function but capsaicin applied with an alpha adrenoceptor agonist impaired the function of the eustachian tube. Capsaicin applied to the bulla also increased spontaneous swallowing in anaesthetized rats and this effect was enhanced by addition of an alpha adrenoceptor agonist and by stimulation of the superior cervical ganglion.
Franz
Burkhard
B
Department of Anatomy and Cell Biology, University of Melbourne, Australia.
Anderson
Colin R
CR
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000399:Air Pressure; D000818:Animals; D001369:Axons / Q000473:pathology / Q000502:physiology; D001949:Bretylium Compounds / Q000494:pharmacology; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002211:Capsaicin / Q000494:pharmacology; D003679:Deglutition / Q000502:physiology; D004558:Electric Stimulation; D005064:Eustachian Tube / Q000294:innervation* / Q000503:physiopathology*; D005260:Female; D008297:Male; D008575:Meniere Disease / Q000473:pathology / Q000503:physiopathology*; D009619:Nociceptors / Q000473:pathology / Q000503:physiopathology*; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017783:Superior Cervical Ganglion / Q000473:pathology / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000473:pathology / Q000503:physiopathology*
D000316:Adrenergic alpha-Agonists; D001949:Bretylium Compounds; D010656:Phenylephrine; D015740:Calcitonin Gene-Related Peptide; C045166:bretylium; D002211:Capsaicin