An overview of the sensory receptors regulating cough

Abstract

The cough reflex represents a primary defensive mechanism for airway protection in a variety of mammalian species. However, excessive and inappropriate coughing can emerge as a primary presenting symptom of many airway diseases. Cough disorders are characterized by a reduction in the threshold for reflex initiation and, as a consequence, the occurrence of cough in response to stimuli that are normally innocuous in nature. The current therapeutic strategies for the treatment of cough disorders are only moderately effective. This undoubtedly relates in part to limitations in our understanding of the neural components comprising the cough reflex pathway. The aim of this review is to provide an overview of current concepts relating to the sensory innervation to the mammalian airways, focusing particularly on the sensory receptors that regulate cough. In addition, the review will highlight particular areas and issues relating to cough neurobiology that are creating controversy in the field.

Measuring voluntary and reflexive cough strength in healthy individuals

“…It is believed that RARs are directly activated by the low pH of citric acid resulting in mechanical distortion of the nerve ending (Kollarik & Undem, 2002;Mazzone, 2005). Indirect activation of RARs also occurs via the bronchoconstriction effects of citric acid (Mazzone, 2005). It is still unclear which of these three receptors, individually or collectively, are responsible for the elicitation of the RC and precisely how they work together to regulate it (Canning, 2006;Haji et al, 2013).…”

“…RARs have only been found to respond to one tussigenic agent, citric acid (Pecova, Javorkova, Kudlicka, & Tatar, 2007). It is believed that RARs are directly activated by the low pH of citric acid resulting in mechanical distortion of the nerve ending (Kollarik & Undem, 2002;Mazzone, 2005). Indirect activation of RARs also occurs via the bronchoconstriction effects of citric acid (Mazzone, 2005).…”

“…Citric acid is known to be a powerful tussigenic agent that stimulates both chemosensors and mechanosensors by acting on both C-fibres and RARs (Mazzone, 2005;Pecova et al, 2007).…”

Characterization and biological activity of Solidago canadensis complex

“…Aqueous extracts of polysaccharides are widely used in therapy for irritated gastrointestinal mucus membranes [36]. There is an increased evidence for bioadhesive effects of polysaccharides to epithelial tissue [37].…”

Peak Morphology and Scalp Topography of the Pharyngeal Sensory-Evoked Potential

“…Sensory deficits in the UA are implicated in disorders of swallowing and cough (1-4), and in obstructive sleep apnea (5-7). Sensory receptors in the UA serve as “triggers” for the airway protective mechanisms of swallowing and coughing, and may act in a feedback loop responsible for maintaining airway patency during sleep (8-10). As such, it is important to understand the sensory components of the UA, both generally and within specific anatomic regions.…”