Dorsolateral PAG mediates respiratory arousal in rats (1178.3)

Abstract

Our aim was to determine whether dorsolateral PAG (dl‐PAG) mediates respiratory responses to novel environment, sudden stimuli and restraint stress. Guide cannulas were implanted bilaterally in 6 adult male Wistar rats. On different days, either saline of GABAA agonist muscimol (100 pg/200 nl) were microinjected into the dl‐PAG, and respiratory signal was recorded using whole‐body plethysmography during adaptation period (30 min), following presentation of acoustic stimuli (500‐ms white noise at 70, 80 and 90 dB), and during restraint. Placing animal in the plethysmograph elicited exploratory behaviour, including vigorous sniffing; blockade of the dl‐PAG substantially attenuated these changes. Acoustic stimuli elicited short‐latency tachypneic responses; administration of muscimol did not affect their amplitude but increased latency of responses to 80‐ and 90‐dB stimuli. Restraint stress provoked sustained increase in the dominant respiratory rate associated with the fraction of time spent at high (>250 cpm) respiratory frequency; blockade of dl‐PAG attenuated the later effect. We conclude that the integrity of the dl‐PAG is essential for mediating respiratory changes associated with active coping.Grant Funding Source: Supported by Capes PVE 088/2012 and CNPq