title: Amygdala mediates respiratory responses to sudden arousing stimuli and to restraint stress in rats.
abstract: Both human and animal studies have demonstrated that respiratory parameters change in response to presentation of alerting stimuli, as well as during stress, yet central neuronal pathways that mediate such responses remain unknown. The aim of our study was to investigate the involvement of the amygdala 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 amygdala bilaterally and were subjected to a respiratory recording using whole body plethysmography. Presentation of acoustic stimuli (500-ms white noise, 40-90 dB) caused transient responses in respiratory rate that were proportional to the stimulus intensity, ranging from +13 ± 9 cpm to +276 ± 67 cpm for 40- and 90-dB stimuli, respectively. Inhibition of the amygdala significantly suppressed respiratory rate responses to the high-intensity stimuli (70-90 dB). Submitting rats to the restraint stress significantly elevated the mean respiratory rate (+72 ± 8 cpm) and the dominant respiratory rate (+51 ± 12 cpm), as well as the fraction of high-frequency respiratory rate (+10 ± 3%). Inhibition of the amygdala by muscimol significantly suppressed these responses. We conclude that the amygdala is one of the key structures that are essential for expression of respiratory responses to stressful or alerting stimuli in rats.
authors.affiliation: School of Biomedical Sciences, Faculty of Health, University of Newcastle, New South Wales, Australia; and Laboratory of Neuroimmunology, School of Psychology, Faculty of Science and Information Technology, University of Newcastle, New South Wales, Australia evgeny.bondarenko@newcastle.edu.au.
authors.forename: Evgeny
authors.initials: E
authors.lastname: Bondarenko
authors.affiliation: Laboratory of Neuroimmunology, School of Psychology, Faculty of Science and Information Technology, University of Newcastle, New South Wales, Australia.
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Hodgson
authors.affiliation: School of Biomedical Sciences, Faculty of Health, University of Newcastle, New South Wales, Australia; and.
authors.forename: Eugene
authors.initials: E
authors.lastname: Nalivaiko
mesh_terms: D000679:Amygdala / Q000502:physiology*; D000818:Animals; D001143:Arousal / Q000187:drug effects / Q000502:physiology*; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D008297:Male; D023421:Models, Animal; D009118:Muscimol / Q000494:pharmacology; D009622:Noise / Q000009:adverse effects; D051381:Rats; D017208:Rats, Wistar; D012119:Respiration / Q000187:drug effects; D012149:Restraint, Physical / Q000502:physiology*; D013312:Stress, Physiological / Q000502:physiology*; D013990:Tidal Volume / Q000187:drug effects / Q000502:physiology
chemical_list: D058785:GABA-A Receptor Agonists; D009118:Muscimol
keywords: amygdala; arousal; respiratory rate; stress; tidal volume