Vagal afferent C-fiber neuropeptide release machinery

Vagal afferent C-fibers are unmyelinated sensory neurons that innervate the respiratory tract, playing a pivotal role in detecting noxious stimuli and initiating protective reflexes (Mazzone & Undem, 2016). The neuropeptide release machinery in these fibers consists of a complex array of proteins, including SNARE complexes (SNAP-25, syntaxin, VAMP) and voltage-gated calcium channels, which mediate the exocytosis of proinflammatory neuropeptides like Substance P and Calcitonin Gene-Related Peptide (CGRP) (Lee & Yu, 2014). Upon activation by chemical or mechanical irritants, these fibers trigger neurogenic inflammation, characterized by vasodilation, protein extravasation, and bronchoconstriction (Barnes, 2001). This machinery is a significant therapeutic target for respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), and chronic refractory cough (Undem & Taylor-Clark, 2014). Pharmacological intervention often involves inhibiting the release process using botulinum toxins, which cleave SNARE proteins, or modulating the upstream ion channels like TRPV1, TRPA1, and P2X3 that drive the calcium influx necessary for vesicle fusion (Pelleg et al., 2019). Additionally, gabapentinoids target the alpha2delta subunit of calcium channels to dampen the excitability and subsequent peptide release from these afferents (Dussor et al., 2013).

Other names

Airway C-fiber neuroeffector mechanismVagal sensory nerve exocytosis complexBronchopulmonary C-fiber release apparatusNeurogenic inflammatory machinery

Inhibition of neuropeptide exocytosis via cleavage of SNARE proteins or by modulating the activity of ion channels (TRPV1, TRPA1, P2X3, and voltage-gated calcium channels) that regulate intracellular calcium concentrations required for vesicle fusion.