title: Active expiration induced by excitation of ventral medulla in adult anesthetized rats.
abstract: Data from perinatal and juvenile rodents support our hypothesis that the preBötzinger complex generates inspiratory rhythm and the retrotrapezoid nucleus-parafacial respiratory group (RTN/pFRG) generates active expiration (AE). Although the role of the RTN/pFRG in adulthood is disputed, we hypothesized that its rhythmogenicity persists but is typically silenced by synaptic inhibition. We show in adult anesthetized rats that local pharmacological disinhibition or optogenetic excitation of the RTN/pFRG can generate AE and transforms previously silent RTN/pFRG neurons into rhythmically active cells whose firing is correlated with late-phase active expiration. Brief excitatory stimuli also reset the respiratory rhythm, indicating strong coupling of AE to inspiration. The AE network location in adult rats overlaps with the perinatal pFRG and appears lateral to the chemosensitive region of adult RTN. We suggest that (1) the RTN/pFRG contains a conditional oscillator that generates AE, and (2) at rest and in anesthesia, synaptic inhibition of RTN/pFRG suppresses AE.
authors.affiliation: Systems Neurobiology Laboratory, Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095-1763, USA.
authors.forename: Silvia
authors.initials: S
authors.lastname: Pagliardini
authors.forename: Wiktor A
authors.initials: WA
authors.lastname: Janczewski
authors.forename: Wenbin
authors.initials: W
authors.lastname: Tan
authors.forename: Clayton T
authors.initials: CT
authors.lastname: Dickson
authors.forename: Karl
authors.initials: K
authors.lastname: Deisseroth
authors.forename: Jack L
authors.initials: JL
authors.lastname: Feldman
mesh_terms: D000818:Animals; D045853:Exhalation / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012125:Respiratory Center / Q000187:drug effects / Q000502:physiology*; D012143:Respiratory Physiological Phenomena