title: Neuroanatomical and physiological evidence that the retrotrapezoid nucleus/parafacial region regulates expiration in adult rats.
abstract: The rostroventrolateral medulla contains two functional neuronal populations: (1) the parafacial respiratory group (pFRG) neurons and (2) the chemosensitive retrotrapezoid nucleus (RTN) neurons. Using anatomical and physiological techniques, we investigated the role of the RTN/pFRG in CO2-induced active expiration (AE) in urethane-anesthetized rats. Anterograde tracing using biotinylated dextran amine (BDA) revealed dense neuronal projections emanating from the RTN/pFRG to the caudal ventral respiratory group (cVRG), 60% of which contained vesicular glutamate transporter-2. The minority (16%) of the RTN projections to the cVRG emanated from Phox2b positive neurons. Hypercapnia (10% CO2) increased DiaEMG and elicited AbdEMG activity. Bilateral injections of muscimol (2mM) into the RTN/pFRG reduced the activation of DiaEMG (23±4%) and abolished AE-induced by chemoreflex stimulation. Taken together, these results support the presence of direct excitatory projections from RTN/pFRG neurons to cVRG expiratory premotor neurons, playing a role in the generation/modulation of AE.
authors.affiliation: Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo (USP), 05508-000 São Paulo, SP, Brazil.
authors.forename: Josiane N
authors.initials: JN
authors.lastname: Silva
authors.affiliation: Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo (USP), 05508-000 São Paulo, SP, Brazil.
authors.forename: Fabiola M
authors.initials: FM
authors.lastname: Tanabe
authors.affiliation: Department of Physiology and Biophysics, Institute of Biomedical Science, University of São Paulo (USP), 05508-000 São Paulo, SP, Brazil.
authors.forename: Thiago S
authors.initials: TS
authors.lastname: Moreira
authors.affiliation: Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo (USP), 05508-000 São Paulo, SP, Brazil. Electronic address: takakura@icb.usp.br.
authors.forename: Ana C
authors.initials: AC
authors.lastname: Takakura
mesh_terms: D000005:Abdomen / Q000502:physiology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D003964:Diaphragm / Q000187:drug effects / Q000502:physiology; D045853:Exhalation / Q000187:drug effects / Q000502:physiology*; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D018398:Homeodomain Proteins / Q000378:metabolism; D006935:Hypercapnia / Q000473:pathology / Q000503:physiopathology; D001239:Inhalation / Q000187:drug effects / Q000502:physiology; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D009044:Motor Cortex / Q000166:cytology / Q000502:physiology; D009118:Muscimol / Q000494:pharmacology; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D010812:Physical Stimulation; D017208:Rats, Wistar; D012018:Reflex / Q000187:drug effects / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism; D050599:Vesicular Glutamate Transport Protein 2 / Q000378:metabolism
chemical_list: D058785:GABA-A Receptor Agonists; D018398:Homeodomain Proteins; C109220:NBPhox protein; C493475:Slc17a6 protein, rat; D014157:Transcription Factors; D050599:Vesicular Glutamate Transport Protein 2; D009118:Muscimol
keywords: Active expiration; Breathing; Caudal ventral respiratory group; Chemoreflex; Retrotrapezoid nucleus