title: Effects of anesthetics on hypoglossal nerve discharge and c-Fos expression in brainstem hypoglossal premotor neurons.
abstract: This study examined the effects of anesthesia on the hypoglossal nerve and diaphragm activities and on c-Fos expression in brainstem hypoglossal premotor neurons (pmXII). Experiments were performed in 71 rats by using halothane inhalation, pentobarbital sodium, or mixtures of alpha-chloralose and urethane or ketamine and xylazine. First, various cardiorespiratory parameters were measured in the rats (n = 31) during both awake and anesthetized conditions. The volatile anesthetic halothane, but not the other anesthetics, was always associated with a strong phasic inspiratory activity in the hypoglossal nerve. Second, a double-immunohistochemical study was performed in awake and anesthetized rats (n = 40) to gauge the level of activity of pmXII neurons. Brainstem pmXII neurons were identified after microiontophoresis of the retrograde tracer Fluoro-Gold in the right hypoglossal motor nucleus. Patterns of c-Fos expression at different brainstem levels were compared in five groups of rats (i.e., awake or anesthetized with halothane, pentobarbital, chloralose-urethane, and ketamine-xylazine). Sections were processed for double detection of c-Fos protein and Fluoro-Gold by using the standard ABC method and a two-color peroxidase technique. Anesthesia with halothane induced the strongest c-Fos expression in a restricted pool of pmXII located in the pons at the level of the Kölliker-Fuse nucleus and the intertrigeminal region. The results demonstrated a major effect of halothane in inducing changes in hypoglossal activity and revealed a differential expression of c-Fos protein in pmXII neurons among groups of anesthetized rats. We suggest that halothane mediates changes in respiratory hypoglossal nerve discharge by altering activity of premotor neurons in the Kölliker-Fuse and intertrigeminal region.
authors.affiliation: Laboratoire de Physiologie Neurovégétative, UMR Centre National de la Recherche Scientifique 6153, Institut National de la Recherche Agronomique 1147, Faculté des Sciences et Techniques Saint Jérôme, 13397 Marseille 20, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Roda
authors.forename: Juliette
authors.initials: J
authors.lastname: Pio
authors.forename: Armand-Louis
authors.initials: AL
authors.lastname: Bianchi
authors.forename: Christian
authors.initials: C
authors.lastname: Gestreau
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000344:Afferent Pathways / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D005456:Fluorescent Dyes / Q000494:pharmacology; D006221:Halothane / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D007002:Hypoglossal Nerve / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D009046:Motor Neurons / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D016760:Proto-Oncogene Proteins c-fos / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012143:Respiratory Physiological Phenomena / Q000187:drug effects; D012154:Reticular Formation / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D013266:Stilbamidines / Q000494:pharmacology
chemical_list: C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D000777:Anesthetics; D005456:Fluorescent Dyes; D016760:Proto-Oncogene Proteins c-fos; D013266:Stilbamidines; D006221:Halothane