title: Localization and properties of respiratory neurons in the rostral pons of the newborn rat.
abstract: The distribution and discharge pattern of respiratory neurons in the 'pneumotaxic center' of the rostral pons in the rat has remained unknown. We performed optical recordings and whole-cell patch clamp recordings to clarify respiratory neuron activity in the rostral pons of a brainstem-spinal cord preparation from a newborn rat. Inspiratory nerve activity was recorded in the 4th cervical nerve and used as a trigger signal for optical recordings. Respiratory neuron activity was detected in the limited region of the rostral-lateral pons. The main active region was presumed to be primarily the Kölliker-Fuse nucleus. The location of respiratory neurons was further confirmed by Lucifer Yellow staining after conducting whole-cell recordings. From a membrane potential analysis of the respiratory neurons in the rostral pons, the respiratory neurons were divided into four types: inspiratory neuron (71.9%), pre-inspiratory neuron (5.3%), post-inspiratory neuron (19.3%), and expiratory neuron (3.5%). A noticeable difference between pontine and medullary respiratory neurons was that post-inspiratory neurons were more frequently encountered in the pons. Application of a mu-opioid agonist, [d-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin, transformed the burst pattern of post-inspiratory neurons into that of pre-inspiratory neurons. The electrical stimulation of the sensory root of the trigeminal nerve induced three types of responses in 85% of pontine respiratory neurons: inhibitory postsynaptic potentials (42.7%), excitatory postsynaptic potentials (37.7%) and no response (15.1%). Our findings provide the first evidence in the rat for the presence of respiratory neurons in the rostral pons, with localization in the lateral region approximately overlapping with the Kölliker-Fuse nucleus.
authors.affiliation: Department of Pediatric Dentistry, Showa University School of Dentistry, 2-1-1 Kitasenzoku, Ohta-ku, Tokyo 145-8515, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kobayashi
authors.forename: H
authors.initials: H
authors.lastname: Onimaru
authors.forename: M
authors.initials: M
authors.lastname: Inoue
authors.forename: T
authors.initials: T
authors.lastname: Inoue
authors.forename: R
authors.initials: R
authors.lastname: Sasa
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001931:Brain Mapping; D048429:Cell Size; D003952:Diagnostic Imaging / Q000379:methods; D008564:Membrane Potentials / Q000502:physiology*; D008953:Models, Anatomic; D009474:Neurons / Q000145:classification / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000379:methods; D011149:Pons / Q000166:cytology*; D051381:Rats; D017208:Rats, Wistar; D012119:Respiration; D009435:Synaptic Transmission / Q000502:physiology; D014276:Trigeminal Nerve / Q000502:physiology / Q000528:radiation effects