TYROSINE HYDROXYLASE-IMMUNOREACTIVE CELLS IN THE NODOSE GANGLION FOR THE CANINE LARYNX

SEVERAL substances have been reported as candidates for the neurotrans mitter in the laryngeal afferent system. In the present study we demon strated that catecholamine is also a candidate neurotransmitter in the canine laryngeal afferent system using tyrosine hydroxylase (TH) immu nochemistry in combination with retrograde labelling with cholera toxi n B in subunit-conjugated gold (CTBG). A few cells in the nodose gangl ion labelled by application of CTBG to the internal branch of the supe rior laryngeal nerve were also TH-immunoreactive. These cells were als o labelled following application of CTBG to the nucleus of the solitar y tract. These results indicate that some of the TH-IR cells in the no dose ganglion could be primary afferent neurones for the canine larynx .