title: Serotonin regulates rhythmic whisking.
abstract: Many rodents explore their environment by rhythmically palpating objects with their mystacial whiskers. These rhythmic whisker movements ("whisking"; 5-9 Hz) are thought to be regulated by an unknown brainstem central pattern generator (CPG). We tested the hypothesis that serotonin (5-HT) inputs to whisking facial motoneurons (wFMNs) are part of this CPG. In response to exogenous serotonin, wFMNs recorded in vitro fire rhythmically at whisking frequencies, and selective 5-HT2 or 5-HT3 receptor antagonists suppress this rhythmic firing. In vivo, stimulation of brainstem serotonergic raphe nuclei evokes whisker movements. Unilateral infusion of selective 5-HT2 or 5-HT3 receptor antagonists suppresses ipsilateral whisking and substantially alters the frequencies and symmetry of whisker movements. These findings suggest that serotonin is both necessary and sufficient to generate rhythmic whisker movements and that serotonergic premotoneurons are part of a whisking CPG.
authors.affiliation: Department of Anatomy & Neurobiology and The Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Alexis
authors.initials: A
authors.lastname: Hattox
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Asaf
authors.initials: A
authors.lastname: Keller
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001933:Brain Stem / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D004558:Electric Stimulation; D004576:Electromyography / Q000379:methods; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008239:Lysine / Q000031:analogs & derivatives* / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008711:Metergoline / Q000494:pharmacology; D017551:Microdialysis; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology*; D009068:Movement / Q000187:drug effects / Q000502:physiology; D010078:Oxazines / Q000494:pharmacology; D018408:Patch-Clamp Techniques / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000502:physiology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D013223:Statistics as Topic; D014738:Vibrissae / Q000187:drug effects / Q000294:innervation / Q000502:physiology*
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D010078:Oxazines; D012702:Serotonin Antagonists; D008711:Metergoline; D012701:Serotonin; C070671:azasetron; C013411:biocytin; D008239:Lysine