title: The midbrain periaqueductal grey has no role in the generation of the respiratory motor pattern, but provides command function for the modulation of respiratory activity.
abstract: It has previously been shown that stimulation of cell-columns in the periaqueductal grey (PAG) triggers site-specific cardiorespiratory effects. These are believed to facilitate changes in behaviour through coordinated changes in autonomic outflow. Here, we investigated whether PAG-evoked respiratory commands can be studied in situ using the decerebrate perfused brainstem preparation. Phrenic, vagus and abdominal iliohypogastric nerves were recorded before and after microinjection of L-glutamate (30-50 nl, 10 mM) or isoguvacine (GABA-receptor agonist, 30-50 nl, 10 mM) into the PAG. L-glutamate microinjection triggered a range of site-specific respiratory modulations (n = 17 preparations). Subsequent microinjection of isoguvacine into the same PAG sites had no effect on the baseline respiratory motor pattern or rhythm. We conclude that while the PAG has no function in respiratory pattern generation, PAG-evoked respiratory modulations can be evoked in situ in the absence of higher brain centres and while homeostatic parameters that may affect respiratory drive are held static.
authors: Florey Institute of Neuroscience and Mental Health, University of Melbourne, Gate 11, Royal Parade, Victoria 3052, Australia.
authors: David G S
authors: DG
authors: Farmer
authors: Florey Institute of Neuroscience and Mental Health, University of Melbourne, Gate 11, Royal Parade, Victoria 3052, Australia.
authors: Tara G
authors: TG
authors: Bautista
authors: Florey Institute of Neuroscience and Mental Health, University of Melbourne, Gate 11, Royal Parade, Victoria 3052, Australia.
authors: Sarah E
authors: SE
authors: Jones
authors: Florey Institute of Neuroscience and Mental Health, University of Melbourne, Gate 11, Royal Parade, Victoria 3052, Australia.
authors: Davor
authors: D
authors: Stanic
authors: Florey Institute of Neuroscience and Mental Health, University of Melbourne, Gate 11, Royal Parade, Victoria 3052, Australia. Electronic address: mathias.dutschmann@florey.edu.au.
authors: Mathias
authors: M
authors: Dutschmann
mesh_terms: D000818:Animals; D001049:Apnea / Q000139:chemically induced / Q000503:physiopathology; D018683:Excitatory Amino Acid Agents / Q000494:pharmacology; D018755:GABA Agonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D007539:Isonicotinic Acids / Q000494:pharmacology; D008636:Mesencephalon / Q000187:drug effects / Q000502:physiology*; D008845:Microinjections; D009068:Movement / Q000187:drug effects / Q000502:physiology; D010487:Periaqueductal Gray / Q000187:drug effects / Q000502:physiology*; D010791:Phrenic Nerve / Q000187:drug effects / Q000502:physiology; D017207:Rats, Sprague-Dawley; D018079:Receptors, GABA / Q000378:metabolism; D012119:Respiration / Q000187:drug effects; D059246:Tachypnea / Q000139:chemically induced / Q000503:physiopathology; D014630:Vagus Nerve / Q000187:drug effects / Q000502:physiology
chemical_list: D018683:Excitatory Amino Acid Agents; D018755:GABA Agonists; D007539:Isonicotinic Acids; D018079:Receptors, GABA; D018698:Glutamic Acid; C015300:isoguvacine
keywords: Brainstem; Breath-hold; Breathing; Midbrain; Respiratory rhythm generation; Tachypnoea