Capsaicin, transient receptor potential (TRP) protein subfamilies and the particular relationship between capsaicin receptors and small primary sensory neurons
- PMID: 16955665
- DOI: 10.1111/j.1447-073X.2006.00141.x
Capsaicin, transient receptor potential (TRP) protein subfamilies and the particular relationship between capsaicin receptors and small primary sensory neurons
Abstract
A number of subfamilies of the capsaicin receptor, collectively called TRP, have been reported since the discovery of vanilloid receptor 1 (VR1). The term 'TRP' is derived from 'transient receptor potential', which means the transient and rapid defect of reaction following long stimulation with light in the photoreceptor cells of mutant Drosophila. The common features of TRP family members are the centrally situated six transmembrane domain, in which an ion channel is located, three to four ankirin repeats at the N-terminus and a TRP domain comprising 25 amino acids at the C-terminus. The TRP family members are present in animals, including invertebrates and vertebrates, and in the cells in various tissues in individual animals. During evolution, the original TRP seems to have acquired a wide variety of functions related to sensing the inner or outer environment (e.g. to sensing light (Drosophila), osmolarity, protons, temperature, ligands and mechanical force). In mammals, the TRPV subfamily is exclusively expressed in small- to medium-sized primary sensory neurons that also co-express some chemical markers (i.e. isolectin B4 (IB4), fluoride-resistant acid phosphatase (FRAP), the P2X3 purinoceptor (a receptor provoked by ATP-induced nociception) and Ret, a glial cell line-derived neurotrophic factor receptor). There is a paradox in that regardless of the marked or complete loss of noxious, small sensory neurons (polymodal nociceptors) in mice treated with capsaicin during the neonatal period, as well as in VR1 (TRPV1)-deficient knock-out mice, the responses to noxious heat are normal. Regarding the paradox in mice treated with capsaicin as neonates, our explanation is that although capsaicin probably reduces the number of a subgroup of small neurons (IB4-, VR1+), the remaining IB4+ (VR1-) neurons can sense noxious heat normally. One working hypothesis is that mice lacking TRPV1/2 can sense noxious heat under normal conditions, presumably via another still unknown pathway, and TRPV1 has been suggested to be involved in noxious heat transduction under pathological conditions, such as inflammation and tissue injury. Further studies will be required to clarify these complexities. Mice treated with capsaicin as neonates would provide a model to investigate the above paradoxes, as would TRPV1-knock-out mice, although different mechanisms may be operating in the two models.
Similar articles
-
Is thermal nociception only sensed by the capsaicin receptor, TRPV1?Anat Sci Int. 2009 Sep;84(3):122-8. doi: 10.1007/s12565-009-0048-8. Epub 2009 Jun 27. Anat Sci Int. 2009. PMID: 19562439 Review.
-
The role of the capsaicin receptor TRPV1 and acid-sensing ion channels (ASICS) in proton sensitivity of subpopulations of primary nociceptive neurons in rats and mice.Neuroscience. 2006 May 12;139(2):699-709. doi: 10.1016/j.neuroscience.2005.12.020. Epub 2006 Mar 3. Neuroscience. 2006. PMID: 16515841
-
Differential effects of TRPV channel block on polymodal activation of rat cutaneous nociceptors in vitro.Exp Brain Res. 2009 Jun;196(1):31-44. doi: 10.1007/s00221-009-1808-3. Epub 2009 Apr 30. Exp Brain Res. 2009. PMID: 19404626 Review.
-
TRPV3 is a temperature-sensitive vanilloid receptor-like protein.Nature. 2002 Jul 11;418(6894):186-90. doi: 10.1038/nature00894. Epub 2002 Jun 23. Nature. 2002. PMID: 12077606
-
Artemin overexpression in skin enhances expression of TRPV1 and TRPA1 in cutaneous sensory neurons and leads to behavioral sensitivity to heat and cold.J Neurosci. 2006 Aug 16;26(33):8578-87. doi: 10.1523/JNEUROSCI.2185-06.2006. J Neurosci. 2006. PMID: 16914684 Free PMC article.
Cited by
-
Lack of potentiating effect of increasing temperature on responses to chemical activators in vagal sensory neurons isolated from TRPV1-null mice.Am J Physiol Lung Cell Mol Physiol. 2008 Nov;295(5):L897-904. doi: 10.1152/ajplung.90385.2008. Epub 2008 Aug 29. Am J Physiol Lung Cell Mol Physiol. 2008. PMID: 18757526 Free PMC article.
-
Comparison of the transport of QX-314 through TRPA1, TRPM8, and TRPV1 channels.J Pain Res. 2013;6:223-30. doi: 10.2147/JPR.S41614. Epub 2013 Mar 16. J Pain Res. 2013. PMID: 23525210 Free PMC article.
-
Dietary Supplementation of Capsaicin Enhances Productive and Reproductive Efficiency of Chinese Crossbred Buffaloes in Low Breeding Season.Animals (Basel). 2022 Dec 28;13(1):118. doi: 10.3390/ani13010118. Animals (Basel). 2022. PMID: 36611727 Free PMC article.
-
Biomimetic proopiomelanocortin suppresses capsaicin-induced sensory irritation in humans.Res Pharm Sci. 2016 Dec;11(6):484-490. doi: 10.4103/1735-5362.194890. Res Pharm Sci. 2016. PMID: 28003842 Free PMC article.
-
Transient Receptor Potential Channels in Microglia: Roles in Physiology and Disease.Neurotox Res. 2016 Oct;30(3):467-78. doi: 10.1007/s12640-016-9632-6. Epub 2016 Jun 3. Neurotox Res. 2016. PMID: 27260222 Review.
Publication types
MeSH terms
Substances
LinkOut - more resources
Full Text Sources
Molecular Biology Databases
Miscellaneous