title: Neurotransmitter localization in the neuroepithelial cells and unipolar neurons of the respiratory tract in the bichir, Polypterus bichir bichir G. ST-HIL.
abstract: Immunohistochemical localisation of neurotransmitters was used to determine the distribution of unipolar neurons and neuroepithelial cells (NECs) in the respiratory tract of the bichir, Polypterus bichir bichir. NECs were commonly encountered in the mucociliated epithelium of the lung. Unipolar neurons were located in the submucosal and muscle layers of the glottis. The results suggest the presence of tyrosine hydroxylase (TH) and nNOS immunoreactivities in NECs. In addition, ACh-E/nNOS and TH/nNOS nerve fibers were also found associated with these cells. Unipolar neuronal cells showed a chemical code including the presence of 5-HT, ACh-E, peptides and P2x2 receptors. The present findings indicate that nitric oxide (NO) is a primitive transmitter of neuroepithelial oxygen-sensitive chemoreceptor cells together with acetylcholine. The coexistence of ACh-E with other substances in the unipolar neurons, but not with NO, may be a property of vagal postganglionic neurons since the emergence of the cranial autonomic pathways in the earliest vertebrates. It would be interesting to know about the provenance of the nerves in contact with NECs, which appear to have a complex innervation pattern.
authors.affiliation: Department of Animal Biology and Marine Ecology, Faculty of Science, Section of Comparative Neurobiology and Biomonitoring, University of Messina, Via Salita Sperone 31, I-98166 Messina, Italy. gzaccone@unime.it
authors.forename: Giacomo
authors.initials: G
authors.lastname: Zaccone
authors.forename: Angela
authors.initials: A
authors.lastname: Mauceri
authors.forename: Maria
authors.initials: M
authors.lastname: Maisano
authors.forename: Alessia
authors.initials: A
authors.lastname: Giannetto
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Parrino
authors.forename: Salvatore
authors.initials: S
authors.lastname: Fasulo
mesh_terms: D000818:Animals; D005399:Fishes; D007150:Immunohistochemistry; D008168:Lung / Q000166:cytology* / Q000294:innervation*; D046569:Neuroepithelial Cells / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000032:analysis* / Q000378:metabolism*
chemical_list: D018377:Neurotransmitter Agents