Capsaicin sensory responses

The primary counterirritant in group D is capsaicin, a natural substance found in red chili peppers and responsible for the hot, spicy characteristic when used in foods.32,33,48 Capsaicin stimulates the release of substance P from local sensory nerve fibers, depleting substance P stores over time. A period of reduced sensitivity to painful stimuli follows, and transmission of pain impulses to the central nervous system is reduced.42... 

The stimulation of C fibers by capsaicin causes a subset of sensory airway neurons to release several neuropeptides, which include tachykinin, substance P and neurokinin A. In addition to capsaicin, other endogenous mediators including histamine, prostaglandins and bradykinins can also result in their release. These neuropeptides are responsible for neurogenic inflammation, which is characterized by vasodilation, mucus secretion, plasma protein extravasation, increased expression of the adhesion molecules and bronchoconstriction. 

Lundblad, L., Lundberg, J.M. (1984). Capsaicin sensitive sensory neurons mediate the response to nasal irritation induced by the vapor phase of cigarette smoke. Toxicology. 33 1-7. 

Bowden, J.J., Baluk, P., Lefevre, P.M. etal. (1994). Sensory denervation by neonatal capsaicin pretreatment increases the chronic inflammatory response to Mycoplasma pulmonis infection in the rat respiratory tract. Am. J. Respir. Crit. Cate Med. 149, A333 (Abstract). 

Ellis, J.L. and Undem, B.J. (1991). Role of peptidoleukotrienes in capsaicin-sensitive sensory fibre-mediated responses in guinea-pig airways. J. Physiol. Lond. 436, 469-484. 

Eopshire, J.C. and Nicol, G.D. (1997). Activation and recovery of the PGE2-mediated sensitisation of the capsaicin response in rat sensory neurons. J. Neurophysiol., 78 3152-3164. 

Geppetti P, Del Bianco E, Patacchini R, et al. (1991) Low pH-induced release of calcitonin gene-related peptide from capsaicin-sensitive sensory nerves mechanism of action and biological response. Neuroscience 41 295-301... 

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