title: Blockade of the dorsomedial hypothalamus and the perifornical area inhibits respiratory responses to arousing and stressful stimuli.
abstract: The dorsomedial hypothalamus (DMH) and the perifornical area (DMH/PeF) is one of the key regions of central autonomic processing. Previous studies have established that this region contains neurons that may be involved in respiratory processing; however, this has never been tested in conscious animals. The aim of our study was to investigate the involvement of the DMH/PeF area in mediating respiratory responses to stressors of various intensities and duration. Adult male Wistar rats (n = 8) received microinjections of GABAA agonist muscimol or saline into the DMH/PeF bilaterally and were subjected to a respiratory recording using whole body plethysmography. Presentation of acoustic stimuli (500-ms white noise) evoked transient responses in respiratory rate, proportional to the stimulus intensity, ranging from +44 ± 27 to +329 ± 31 cycles/min (cpm). Blockade of the DMH/PeF almost completely abolished respiratory rate and tidal volume responses to the 40- to 70-dB stimuli and also significantly attenuated responses to the 80- to 90-dB stimuli. Also, it significantly attenuated respiratory rate during the acclimatization period (novel environment stress). The light stimulus (30-s 2,000 lux) as well as 15-min restraint stress significantly elevated respiratory rate from 95 ± 4.0 to 236 ± 29 cpm and from 117 ± 5.2 to 189 ± 13 cpm, respectively; this response was abolished after the DMH/PeF blockade. We conclude that integrity of the DMH/PeF area is essential for generation of respiratory responses to both stressful and alerting stimuli.
authors.affiliation: School of Biomedical Sciences and Pharmacy, and evgeny.bondarenko@newcastle.edu.au.
authors.forename: Evgeny
authors.initials: E
authors.lastname: Bondarenko
authors.affiliation: School of Biomedical Sciences and Pharmacy, and.
authors.forename: Mirza I
authors.initials: MI
authors.lastname: Beig
authors.affiliation: School of Psychology, University of Newcastle, Australia; and.
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Hodgson
authors.affiliation: Biotechnology Centre, Federal University of Paraiba, Joao Pessoa, Paraiba, Brazil.
authors.forename: Valdir A
authors.initials: VA
authors.lastname: Braga
authors.affiliation: School of Biomedical Sciences and Pharmacy, and.
authors.forename: Eugene
authors.initials: E
authors.lastname: Nalivaiko
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001143:Arousal / Q000187:drug effects / Q000502:physiology*; D001341:Autonomic Nervous System / Q000187:drug effects / Q000503:physiopathology; D004302:Dorsomedial Hypothalamic Nucleus / Q000187:drug effects / Q000503:physiopathology*; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D010775:Photic Stimulation; D051381:Rats; D017208:Rats, Wistar; D056152:Respiratory Rate / Q000187:drug effects / Q000502:physiology*; D013312:Stress, Physiological / Q000187:drug effects / Q000502:physiology*; D013315:Stress, Psychological / Q000503:physiopathology*
chemical_list: D058785:GABA-A Receptor Agonists; D009118:Muscimol
keywords: arousal; dorsomedial hypothalamus; respiratory rate; stress; tidal volume