TRP: What it means
TRP: Transient Receptor Potential
TRP channel classification
Five Group 1 Subfamilies
- TRPC: “C” for canonical
- TRPV: “V” for vanilloid
- TRPVL: “VL” for vanilloid-like
- TRPM: “M” for melastatin
- TRPS: “S” for soromelastatin
- TRPN: “N” for no mechanoreceptor potential C
- TRPA: “A” for ankyrin
Two Group 2 TRP Subfamilies
- TRPML: “ML” for mucolipin
- TRPP: “P” for polycystic
An eighth subfamily, TRPY
TRPs existing in yeast suggest the origin of TRP channels precedes the appearance of metazoan organisms
TRP channel functions
Play critical roles in sensory physiology, which include contributions vision, taste, olfaction, hearing, touch, thermo-sensation, osmosensation.
- Enable individual cells to sense changes in their local environment.
- Many TRP channels are activated by a variety of different stimuli and function as signal integrators
- In the body, TRP channels are thought to behave like microscopic thermometers and are used in animals to sense hot or colt stimuli.
The Importance of TRP channels
TRP channels have been found in a wide range of multicellular species, including worms, fruit flies, zebrafish, mice, and humans.
Significant for human health since disease is caused by mutations in at least four TRP channels.
TRP channels and nociception
Studying TRP channels in context of pain
TRP channel in Drosophila (fruit flies)
•Drosophila (fruit flies) respond to noxious stimuli and have become a powerful model organism for studying the genetics of nociception (Manev and Dimitrijevic, 2004, Tracey et al., 2003, Xu et al., 2006).
•The TRP channel painless was originally identified as a heat-responsive channel mediating thermal-based nociception in fly larvae (Sokabe et al., 2008, Tracey et al., 2003).
•But we are now beginning to understand that the TRP channel painless may be a polymodal receptor, suggesting that it also plays a role in other mechanisms of nociception (such as chemical, mechanical, & in sensitization)
•The painless mRNA encodes a protein of the transient receptor potential ion channel family. (TRP)
•painless is required for thermal and mechanical nociception (pain sensation), but not for sensing light touch
•painless is expressed in peripheral neurons that extend multiple branched dendrites beneath the larval epidermis, comparable to vertebrate pain receptors.
•An antibody to painless binds to localized dendritic structures is thought to be involved in nociceptive signaling.
Drosophila mutant painless flies cannot sense noxious mechanical and thermal stimuli.
The painless gene is expressed in multi-dendritic and chordotonal sensory neurons and is required for the activation of sensory neurons by noxious heat.
This means that we can easily contrast data collected from flies induced with chronic pain versus painless flies that we objectively know are not experiencing pain.
This helps decrease guessing of the subjective experience of pain, thus increasing validity!
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