Rapid activation of esophageal mechanoreceptors alters the pharyngeal phase of swallow: Evidence for inspiratory activity during swallow

Abstract

Swallow is a complex behavior that consists of three coordinated phases: oral, pharyngeal, and esophageal. Esophageal distension (EDist) has been shown to elicit pharyngeal swallow, but the physiologic characteristics of EDist-induced pharyngeal swallow have not been specifically described. We examined the effect of rapid EDist on oropharyngeal swallow, with and without an oral water stimulus, in spontaneously breathing, sodium pentobarbital anesthetized cats (n = 5). Electromyograms (EMGs) of activity of 8 muscles were used to evaluate swallow: mylohyoid (MyHy), geniohyoid (GeHy), thyrohyoid (ThHy), thyropharyngeus (ThPh), thyroarytenoid (ThAr), cricopharyngeus (upper esophageal sphincter: UES), parasternal (PS), and costal diaphragm (Dia). Swallow was defined as quiescence of the UES with overlapping upper airway activity, and it was analyzed across three stimulus conditions: 1) oropharyngeal water infusion only, 2) rapid esophageal distension (EDist) only, and 3) combined stimuli. Results show a significant effect of stimulus condition on swallow EMG amplitude of the mylohyoid, geniohyoid, thyroarytenoid, diaphragm, and UES muscles. Collectively, we found that, compared to rapid cervical esophageal distension alone, the stimulus condition of rapid distension combined with water infusion is correlated with increased laryngeal adductor and diaphragm swallow-related EMG activity (schluckatmung), and post-swallow UES recruitment. We hypothesize that these effects of upper esophageal distension activate the brainstem swallow network, and function to protect the airway through initiation and/or modulation of a pharyngeal swallow response.

Evidence for peripheral and central actions of codeine to dysregulate swallowing in the anesthetized cat

“…This circuit is located in the brainstem, but is subject to significant modulation by suprapontine pathways ( 1 ). Further, swallowing also is modulated by peripheral sensory afferents from the lungs and airway ( 2 , 3 ), chest wall ( 3 ), mouth, pharynx, and esophagus ( 1 , 4 – 6 ) and these afferents travel through the vagus, trigeminal, or hypoglossal nerves.…”

Evidence for peripheral and central actions of codeine to dysregulate deglutition in the anesthetized cat

“…This circuit is located in the brainstem, but is subject to significant modulation by suprapontine pathways (1). Further, swallowing also is modulated by peripheral sensory afferents in the lungs and airway (2,3), chest wall(2), mouth, pharynx, and esophagus (1,(4)(5)(6) and these afferents travel in the vagus, trigeminal, or hypoglossal nerves.…”

Prox2+ and Runx3+ neurons regulate esophageal motility

“…hindbrain vagal motor nuclei and the nucleus of the solitary tract) suffices to generate esophageal peristalsis, or if vagal sensory feedback is also required (Janssens et al, 1976; Jean, 1984; Kronecker H., 1883). Several lines of evidence subsequently demonstrated the importance of peripheral feedback for esophageal function, but the exact vagal subtype that provides this feedback is unknown (Falempin et al, 1986; Frazure et al, 2021; Lang, 2009). Classical studies often relied on blunt dissection of the vagus nerve and therefore affected both sensory and motor vagal fibers.…”