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Amygdala mediates respiratory responses to sudden arousing stimuli and to restraint stress in rats.

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AJP Regulatory Integrative and Comparative Physiology

Published online on

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 GABA-A 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 and in tidal volume 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 (70-90dB). 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 the expression of respiratory responses to stressful or alerting stimuli in rats.