Inside Information: The Unique Features of Visceral Sensation

Table 2.

Molecules that Mediate Mechanosensation and Hypersensitivity

Molecule	Description	Effects in the colon	Reference(s)
^a References provided here are representative, not exhaustive. ^b TRP, transient receptor potential.
5-HT₃	Serotonin receptor	Antagonists attenuate glycerol-induced visceral nociception and prevent restraint stress induced colonic hypersensitivity.	(66, 67)
ASIC3	Acid-sensing ion channel	Knockout mice show reduced mechanosensitivity.	(48, 62)
Na_v1.8	Voltage-gated Na⁺ channel	Knockout mice show reduced response to intra-colonic capsaicin or intracolonic mustard oil.	(68)
P2X	Purinergic P2X receptors	ATP is released from the colonic mucosa by colorectal distension, and pelvic nerve afferents are activated by α,β-methyleneATP; visceral hyper- sensitivity is reversed by specific P2X₁, P2X₃, and antagonists. P2X_2/3	(69, 70)
PAR	Protease-activated receptors	Luminal application of PAR₂-activating peptide causes visceral hypersensitivity.	(71)
TRPV1	TRP^b-vanilloid 1 receptor	Knockout mice show reduced mechanosensitivity.	(48)
TRPV4	TRP^b-vanilloid 4 receptor	Knockout mice show attenuated mechanosensitivity and reduced response to colorectal distension; a selective agonist increases response to colorectal distension.	(56, 60)