TRH regulation of tracheal tension through vagal preganglionic motoneurons.
TRH-immunoreactive nerve terminals innervate the ambiguous nucleus in the rabbit. Vagal preganglionic motoneurons that innervate the trachea, were revealed by HRP histochemistry in the rostral part of the ambiguous nucleus and the dorsal motor nucleus of the vagus. HRP histochemistry plus TRH immunocytochemistry revealed that TRH-immunoreactive axon terminals synapsed on ambiguous nucleus neurons retrogradely labeled by HRP injection into tracheal smooth muscle and the superior laryngeal nerve. Microinjection of 50 ng TRH into the rostral ambiguous nucleus caused slight dilation followed by constriction, which was inhibited by atropine and vagotomy. Results show that central TRH-containing neurons regulate tracheal tension through synapses on vagal preganglionic motoneurons that innervate tracheal smooth muscle.
D000818:Animals; D001370:Axonal Transport; D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D006735:Horseradish Peroxidase; D007150:Immunohistochemistry; D008526:Medulla Oblongata / Q000187:drug effects / Q000502:physiology*; D008845:Microinjections; D008854:Microscopy, Electron; D016253:Microscopy, Immunoelectron; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000294:innervation*; D009411:Nerve Endings / Q000502:physiology / Q000648:ultrastructure; D011817:Rabbits; D013569:Synapses / Q000502:physiology / Q000648:ultrastructure; D013973:Thyrotropin-Releasing Hormone / Q000032:analysis / Q000494:pharmacology / Q000502:physiology*; D014132:Trachea / Q000294:innervation*; D014630:Vagus Nerve / Q000187:drug effects / Q000502:physiology*; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins
D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins; D013973:Thyrotropin-Releasing Hormone; D006735:Horseradish Peroxidase