Faculty Collaboration Database

Retrograde labeling reveals extensive distribution of genioglossal motoneurons possessing 5-HT2A receptors throughout the hypoglossal nucleus of adult dogs. Brain Res 2007 Feb 09;1132(1):110-9

Date

12/26/2006

Pubmed ID

17188659

DOI

10.1016/j.brainres.2006.10.099

Scopus ID

2-s2.0-33846193319 (requires institutional sign-in at Scopus site)   9 Citations

Abstract

Inspiratory hypoglossal motoneurons (IHMNs) innervate the muscles of the tongue and play an important role in maintaining upper airway patency. However, this may be reduced during sleep and by sedatives, potent analgesics, and volatile anesthetics. The genioglossal (GG) muscle is the main protruder and depressor muscle of the tongue and contributes to upper airway patency during inspiration. In vitro data suggest that serotonin (5-hydroxytryptamine, 5-HT), via the 5-HT(2A) receptor (5-HT(2A)R) subtype, plays a key role in controlling the excitability of IHMNs. The distribution of GG motoneurons (GGMNs) within the hypoglossal (XII) nucleus has not been studied in the adult dog. Further, it is uncertain whether the 5-HT(2A)R is located on GGMNs in the adult dog. We therefore used the cholera toxin B (CTB) subunit as a retrograde tracer to map the location of GGMNs in combination with immunofluorescent labeling to determine the presence and colocalization of 5-HT(2A)R within the XII nucleus in adult mongrel dogs. Injection of CTB into the GG muscle resulted in retrogradely labeled cells in a compact column throughout the XII nucleus, extending from 0.75 mm caudal to 3.45 mm rostral to the obex. Fluorescence immunohistochemistry revealed extensive 5-HT(2A)R labeling on CTB-labeled GGMNs. Identification of the 5-HT(2A)R on GGMNs in the XII nucleus of the adult dog supports in vitro data and suggests a physiological role for this receptor subtype in controlling the excitability of GGMNs, which contribute to the maintenance of upper airway patency.

Author List

Brandes IF, Zuperku EJ, Dean C, Hopp FA, Jakovcevic D, Stuth EA

Author

Eckehard A. Stuth MD Professor in the Anesthesiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Brain Mapping
Canidae
Cell Count
Cholera Toxin
Dogs
Hypoglossal Nerve
Immunohistochemistry
Medulla Oblongata
Motor Neurons
Receptor, Serotonin, 5-HT2A
Respiration
Serotonin
Species Specificity
Synaptic Transmission
Tongue