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Ionotropic glutamate receptors mediate excitatory drive to caudal medullary expiratory neurons in the rabbit.
Brain Res. 2005 Sep 21; 1056(2):145-57.BR

Abstract

Most of the neurons of the caudal ventral respiratory group (cVRG) are bulbospinal expiratory neurons that receive their main excitatory drive from more rostral, but not yet defined regions. This study was devoted to investigate the functional role of ionotropic excitatory amino acid (EAA) receptors in the excitatory drive transmission to cVRG expiratory neurons during eupnoeic breathing and some respiratory reflexes including cough induced by mechanical stimulation of the tracheobronchial tree. The experiments were performed on spontaneously breathing rabbits under pentobarbitone anesthesia making use of microinjections (30--50 nl) of EAA receptor antagonists into the cVRG. Phrenic nerve and abdominal muscle activities were recorded. Bilateral microinjections of 50 mM kynurenic acid (KYN), a broad-spectrum EAA antagonist, and 10 mM 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a non-NMDA antagonist, or 5 mM 6-nitro-7-sulphamoylbenzo(f)quinoxaline-2,3-dione (NBQX), a more specific non-NMDA antagonist, completely suppressed spontaneous rhythmic abdominal activity and reflex expiratory responses either to tracheal occlusion at end-inspiration (Breuer-Hering inflation reflex) or to expiratory threshold loading (5 cm H(2)O); they also suppressed both the inspiratory and expiratory components of the cough reflex. Spontaneous rhythmic abdominal activity and the reflex respiratory responses were strongly reduced, but not completely abolished by microinjections of 10 mM d(-)-2-amino-5-phosphonopentanoic acid (D-AP5), an NMDA antagonist. The results provide evidence that the excitatory drive to cVRG bulbospinal expiratory neurons during eupnoeic breathing and the investigated respiratory reflexes is mediated by EAA receptors. They also support the view that neurons located in the cVRG are not merely elements of the expiratory output system.

Authors+Show Affiliations

Dipartimento di Scienze Fisiologiche, Università degli Studi di Firenze, Viale G.B. Morgagni 63, I-50134 Firenze, Italy. fulva.bongianni@unifi.itNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16122708

Citation

Bongianni, Fulvia, et al. "Ionotropic Glutamate Receptors Mediate Excitatory Drive to Caudal Medullary Expiratory Neurons in the Rabbit." Brain Research, vol. 1056, no. 2, 2005, pp. 145-57.
Bongianni F, Mutolo D, Nardone F, et al. Ionotropic glutamate receptors mediate excitatory drive to caudal medullary expiratory neurons in the rabbit. Brain Res. 2005;1056(2):145-57.
Bongianni, F., Mutolo, D., Nardone, F., & Pantaleo, T. (2005). Ionotropic glutamate receptors mediate excitatory drive to caudal medullary expiratory neurons in the rabbit. Brain Research, 1056(2), 145-57.
Bongianni F, et al. Ionotropic Glutamate Receptors Mediate Excitatory Drive to Caudal Medullary Expiratory Neurons in the Rabbit. Brain Res. 2005 Sep 21;1056(2):145-57. PubMed PMID: 16122708.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Ionotropic glutamate receptors mediate excitatory drive to caudal medullary expiratory neurons in the rabbit. AU - Bongianni,Fulvia, AU - Mutolo,Donatella, AU - Nardone,Furio, AU - Pantaleo,Tito, PY - 2005/05/04/received PY - 2005/07/13/revised PY - 2005/07/13/accepted PY - 2005/8/27/pubmed PY - 2005/12/13/medline PY - 2005/8/27/entrez SP - 145 EP - 57 JF - Brain research JO - Brain Res VL - 1056 IS - 2 N2 - Most of the neurons of the caudal ventral respiratory group (cVRG) are bulbospinal expiratory neurons that receive their main excitatory drive from more rostral, but not yet defined regions. This study was devoted to investigate the functional role of ionotropic excitatory amino acid (EAA) receptors in the excitatory drive transmission to cVRG expiratory neurons during eupnoeic breathing and some respiratory reflexes including cough induced by mechanical stimulation of the tracheobronchial tree. The experiments were performed on spontaneously breathing rabbits under pentobarbitone anesthesia making use of microinjections (30--50 nl) of EAA receptor antagonists into the cVRG. Phrenic nerve and abdominal muscle activities were recorded. Bilateral microinjections of 50 mM kynurenic acid (KYN), a broad-spectrum EAA antagonist, and 10 mM 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a non-NMDA antagonist, or 5 mM 6-nitro-7-sulphamoylbenzo(f)quinoxaline-2,3-dione (NBQX), a more specific non-NMDA antagonist, completely suppressed spontaneous rhythmic abdominal activity and reflex expiratory responses either to tracheal occlusion at end-inspiration (Breuer-Hering inflation reflex) or to expiratory threshold loading (5 cm H(2)O); they also suppressed both the inspiratory and expiratory components of the cough reflex. Spontaneous rhythmic abdominal activity and the reflex respiratory responses were strongly reduced, but not completely abolished by microinjections of 10 mM d(-)-2-amino-5-phosphonopentanoic acid (D-AP5), an NMDA antagonist. The results provide evidence that the excitatory drive to cVRG bulbospinal expiratory neurons during eupnoeic breathing and the investigated respiratory reflexes is mediated by EAA receptors. They also support the view that neurons located in the cVRG are not merely elements of the expiratory output system. SN - 0006-8993 UR - https://www.unboundmedicine.com/medline/citation/16122708/Ionotropic_glutamate_receptors_mediate_excitatory_drive_to_caudal_medullary_expiratory_neurons_in_the_rabbit_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0006-8993(05)01063-2 DB - PRIME DP - Unbound Medicine ER -