Table 2.
Molecules that Mediate Mechanosensation and Hypersensitivity
| Molecule | Description | Effects in the colon | Reference(s) |
|---|---|---|---|
| 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) |
| Nav1.8 | Voltage-gated Na+ channel | Knockout mice show reduced response to intracolonic 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 hypersensitivity is reversed by specific P2X1, P2X3, and P2X2/3 antagonists. | (69, 70) |
| PAR | Protease-activated receptors | Luminal application of PAR2-activating peptide causes visceral hypersensitivity. | (71) |
| TRPV1 | TRPb-vanilloid 1 receptor | Knockout mice show reduced mechanosensitivity. | (48) |
| TRPV4 | TRPb-vanilloid 4 receptor | Knockout mice show attenuated mechanosensitivity and reduced response to colorectal distension; a selective agonist increases response to colorectal distension. | (56, 60) |
a
References provided here are representative, not exhaustive.
b
TRP, transient receptor potential.