Year: 2022
Type: preprint
Abstract: The mammalian three-phase respiratory motor pattern of inspiration, post-inspiration and expiration is expressed in spinal and cranial motor nerve activities. This pattern is generated by a hierarchical brainstem-wide pre-motor network. However, the local rhythmogenic circuit of the pre-Bötzinger complex (pre-BötC) was established as the ‘noeud vitale’ necessary and sufficient to initiate inspiration. In present study, we tested the effect of unilateral and bilateral inactivation of the pre-BötC (microinjection of the GABA A receptor agonist isoguvacine 10 mM, 50 nl) on respiratory motor activities in an in situ perfused brainstem preparation of rat. As expected, bilateral inactivation of the pre-BötC triggered cessation of phrenic (PNA), hypoglossal (HNA) and vagal (VNA) nerve activities for 15-20 min. Partial recovery from bilateral isoguvacine injection was characterized by erratic activity in all recorded motor nerves reminiscent to patterns observed after disturbed excitatory-inhibitory balance within the local pre-BötC circuit. Surprisingly, ipsilateral isoguvacine injections into the pre-BötC triggered transient (6-8 min) cessation of inspiratory and post-inspiratory VNA (p<0.001) and suppressed inspiratory HNA by -70 ± 15% (p<0.01), while inspiratory PNA burst frequency increased by 46 ± 30% (p<0.01). Taken together, these observations confirm the role of the pre-BötC as the ‘noeud vitale’ of the mammalian respiratory network in situ and highlight a significant role for the pre-BötC in the expression of vagal post-inspiratory and inspiratory activity.
Language: English
Subfield: Endocrine and Autonomic Systems
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W4220793604