Upper Airway and Abdominal Motor Output During Sneezing: Is the In Vivo Decererate Rat an Adequate Model?

Abstract

While numerous studies have focused on identifying and characterizing the neural mechanisms mediating upper airway defense reflexes in the anesthetized or decerebrate adult cat, little is known about these behaviors in in vivo rodent models. The current study was undertaken to investigate whether the in vivo decelerate adult rat might serve as an acceptable model for studying these behaviors. To begin to address this possibility, we examined multiple respiratory motor activities in response to mechanical stimulation of the anterior nasal cavity (sufficient to elicit fictive sneezing) in in vivo decerebrate adult rats. We found that the neural activities observed during nasal stimulation were consistent with those previously reported during fictive sneezing in the adult cat model. We suggest that the in vivo decerebrate rat is an acceptable model for studying the sneezing reflex.

Hyperexcitability and plasticity induced by sustained hypoxia on rectus abdominis motoneurons

“…; Ono et al . ). However, in our in vitro experiments, we verified that addition of ionotropic receptor antagonists (GABA, glutamate and glycine) to the bathing solution did not abolish the activity of most tonically active motoneurons, indicating the contribution of intrinsic properties to the excitability of these cells or the involvement of other neurotransmitters (Bayliss et al .…”

“…Previous studies have demonstrated that expiratory muscles are recruited in some diseases, such as hypertension and heart failure, as well as in hypoxic environments (Giordano, 2005;Bosc et al 2010;Haupt et al 2012), to generate active expiration. However, the cellular mechanisms related to how expiratory motoneurons changes their electrophysiological properties to ensure an effective muscle contraction are relevant not only to diseased states, but also to physiological conditions with respect to avoiding large respiratory variability, such as during coughing, sneezing, speaking (Hoit et al 1988;Ono et al 2010), physical activity (Willett et al 2001) or even in the REM sleep epochs (Andrews & Pagliardini, 2015).…”

“…Few studies have aimed to understand the electrophysiological properties of expiratory motoneurons (de Almeida et al 2010;Ford et al 2014). Although internal intercostal muscles contractions have been demonstrated at rest (Leevers & Road, 1995;de Almeida et al 2010), most studies suggest that their excitability is solely dependent on synaptic transmission (Hoit et al 1988;Ono et al 2010). However, in our in vitro experiments, we verified that addition of ionotropic receptor antagonists (GABA, glutamate and glycine) to the bathing solution did not abolish the activity of most tonically active motoneurons, indicating the contribution of intrinsic properties to the excitability of these cells or the involvement of other neurotransmitters (Bayliss et al 1997;Rekling et al 2000).…”

“…However, expiratory spinal motoneurons have received much less attention, probably because expiration is considered as a passive mechanical process at rest. Evidence indicates that expiratory muscles are only recruited during physiological reflexes, such as a coughing and sneezing (Grelot & Milano, 1991;Ono et al 2010), or during high chemical drive, as observed in physical exercise and after hypoxic episodes (Willett et al 2001;Moraes et al 2013;Moraes et al 2014).…”

“…Evidence indicates that expiratory muscles are only recruited during physiological reflexes, such as a coughing and sneezing (Grelot & Milano, ; Ono et al . ), or during high chemical drive, as observed in physical exercise and after hypoxic episodes (Willett et al . ; Moraes et al .…”