Sex-specific vagal and spinal modulation of swallow and its coordination with breathing

Abstract

Swallow-breathing coordination is influenced by changes in lung volume, which is modulated by feedback from both vagal and spinal sensory afferents. The purpose of this study was to manipulate feedback from these afferents, with and without a simultaneous mechanical challenge (chest compression), in order to assess the influence of each sensory pathway on swallow in rats. We hypothesized that manipulation of afferent feedback would shift the occurrence of swallow toward the inspiratory phase of breathing. Afferent feedback was perturbed by lidocaine nebulization, extra-thoracic vagotomy, or lidocaine administration to the pleural space in sodium pentobarbital anesthetized rats (N = 43). These different afferent perturbations were performed both in control conditions (no chest compression), and with chest compression. Manipulating pulmonary stretch receptor-mediated volume feedback in male animals decreased swallow occurrence. Female rats appear to rely more on spinal afferent feedback, as swallow occurrence shifted to late expiration with chest compression and vagotomy or lidocaine injections. Results suggest that sex-specific mechanisms modulate swallow-breathing coordination, and that vagal feedback is inhibitory to swallow-related muscles, while spinal feedback from pleural afferents has excitatory effects. This study supports the theory that a balance of vagal and spinal afferent feedback is necessary to maintain an optimal swallow pattern and swallow-breathing coordination.

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

“…This strength of these correlations contrast with our previous publications [ 13 , 17 , 38 , 54 ]. This is most likely due to the reductions in swallow amplitude and duration with the esophageal distension stimuli, which increased variability of the dataset, thus revealing these relationships.…”

“…Table 2 is a matrix showing all Pearson Product Moment Correlations for EMG amplitude and duration measures. Due to the relatively small amplitude and short duration of the swallows induced by esophageal distension, there were stronger correlations between EMG amplitude and duration than those reported in our previous publications [ 13 , 17 , 38 , 54 ].…”

Postinspiratory complex acts as a gating mechanism regulating swallow-breathing coordination and other laryngeal behaviors

“…Swallow has been thought of as an "all or nothing" response as early as 1883 (Meltzer, 1883). Whether modulating spinal or vagal feedback (Huff A, 2020b), central drive for swallow/breathing (Huff, Karlen-Amarante, Pitts, & Ramirez, 2022) or lesions in swallow related areas of the brainstem (Car, 1979;Robert W Doty, Richmond, & Storey, 1967;Wang & Bieger, 1991) swallow either occurred or did not. Swallows are thought to be a fixed action pattern, with duration of stimulation having no effect on behavior duration (Fig.…”

Sex-specific vagal and spinal modulation of breathing with chest compression

“…Experiments were performed on 48 anesthetized spontaneously breathing Sprague Dawley (SD) retired breeder rats [24 male (0.49 ± 0.04kg) and 19 female (0.39 ± 0.08kg) Envigo, Indianapolis, IN], of which only 43 completed the protocol. Ages ranged from 8-9 months, which were shared with a complementary paper to this study [46]. We recognize that retired breeders are older than the general adult rat, however studies investigating breathing and aging use SD rats with an average age of 13 months [47].…”