TRPV1 blockade in vivo elicited hyperthermia in multiple species, from rodents to humans, suggesting that TRPV1 is involved in body temperature maintenance.[3] Recently, AMG 517, a highly selective TRPV1 antagonist was dropped out of clinical trials due to the undesirable magnitude of hyperthermia.[4] A second molecule, SB-705498 was also evaluated in the clinic but its effect on body temperature was not reported.[5]
The role of TRPV1 in the regulation of body temperature has emerged in last few years. Based on a number of TRPV1 selective antagonists causing an increase in body temperature (hyperthermia), it was proposed that TRPV1 is tonically active in vivo and regulates body temperature.[3] In a recent report, it was found that tonically active TRPV1 channels are present in the viscera and keep an ongoing suppressive effect on body temperature.[9]
Central nervous system
TRPV1 is also expressed at high levels in the central nervous system and has been proposed as a target for treatment of not only pain but also for other conditions such as anxiety.[10] Furthermore TRPV1 appears to mediate long term depression (LTD) in the hippocampus.[11] LTD has been linked to a decrease in the ability to make new memories, unlike its opposite long term potentiation (LTP), which aids in memory formation. A dynamic pattern of LTD and LTP occuring at many synapses provides a code for memory formation. Long-term depression and subsequent prunning of dampened down synapses is important in memory formation. In rat brain slices, activation of TRV1 with heat or capsaicin induced LTD while capsazepine blocked capsaicin's ability to induce LTD.[11] Hence there may be therapeutic potential in antagonizing TRPV1 in the central nervous system, perhaps as a treatment for epilepsy (TRPV1 is already a target in the peripheral nervous system for pain relief).
^ Cui M, Honore P, Zhong C, Gauvin D, Mikusa J, Hernandez G, Chandran P, Gomtsyan A, Brown B, Bayburt EK, Marsh K, Bianchi B, McDonald H, Niforatos W, Neelands TR, Moreland RB, Decker MW, Lee CH, Sullivan JP, Faltynek CR (2006). "TRPV1 receptors in the CNS play a key role in broad-spectrum analgesia of TRPV1 antagonists". J. Neurosci.26 (37): 9385–93. doi:10.1523/JNEUROSCI.1246-06.2006. PMID 16971522.
^ Huang SM, Bisogno T, Trevisani M, Al-Hayani A, De Petrocellis L, Fezza F, Tognetto M, Petros TJ, Krey JF, Chu CJ, Miller JD, Davies SN, Geppetti P, Walker JM, Di Marzo V (2002). "An endogenous capsaicin-like substance with high potency at recombinant and native vanilloid VR1 receptors". Proc. Natl. Acad. Sci. U.S.A.99 (12): 8400–5. doi:10.1073/pnas.122196999. PMID 12060783.
^ ab Gavva NR, Bannon AW, Surapaneni S, Hovland DN Jr, Lehto SG, Gore A, Juan T, Deng H, Han B, Klionsky L, Kuang R, Le A, Tamir R, Wang J, Youngblood B, Zhu D, Norman MH, Magal E, Treanor JJ, Louis JC (March 2007). "The vanilloid receptor TRPV1 is tonically activated in vivo and involved in body temperature regulation". J. Neurosci.27 (13): 3366–74. doi:10.1523/JNEUROSCI.4833-06.2007. PMID 17392452.
^ Gavva NR, Treanor JJ, Garami A, Fang L, Surapaneni S, Akrami A, Alvarez F, Bak A, Darling M, Gore A, Jang GR, Kesslak JP, Ni L, Norman MH, Palluconi G, Rose MJ, Salfi M, Tan E, Romanovsky AA, Banfield C, Davar G (May 2008). "Pharmacological blockade of the vanilloid receptor TRPV1 elicits marked hyperthermia in humans". Pain136 (1-2): 202–10. doi:10.1016/j.pain.2008.01.024. PMID 18337008.
^ Chizh BA, O'Donnell MB, Napolitano A, Wang J, Brooke AC, Aylott MC, Bullman JN, Gray EJ, Lai RY, Williams PM, Appleby JM (November 2007). "The effects of the TRPV1 antagonist SB-705498 on TRPV1 receptor-mediated activity and inflammatory hyperalgesia in humans". Pain132 (1-2): 132–41. doi:10.1016/j.pain.2007.06.006. PMID 17659837.
^ Jhaveri MD, Elmes SJ, Kendall DA, Chapman V (2005). "Inhibition of peripheral vanilloid TRPV1 receptors reduces noxious heat-evoked responses of dorsal horn neurons in naïve, carrageenan-inflamed and neuropathic rats". Eur. J. Neurosci.22 (2): 361–70. doi:10.1111/j.1460-9568.2005.04227.x. PMID 16045489.
Heiner I, Eisfeld J, Lückhoff A (2004). "Role and regulation of TRP channels in neutrophil granulocytes.". Cell Calcium33 (5-6): 533–40. PMID 12765698.
Geppetti P, Trevisani M (2004). "Activation and sensitisation of the vanilloid receptor: role in gastrointestinal inflammation and function.". Br. J. Pharmacol.141 (8): 1313–20. doi:10.1038/sj.bjp.0705768. PMID 15051629.
Clapham DE, Julius D, Montell C, Schultz G (2006). "International Union of Pharmacology. XLIX. Nomenclature and structure-function relationships of transient receptor potential channels.". Pharmacol. Rev.57 (4): 427–50. doi:10.1124/pr.57.4.6. PMID 16382100.
Szallasi A, Cruz F, Geppetti P (2007). "TRPV1: a therapeutic target for novel analgesic drugs?". Trends in molecular medicine12 (11): 545–54. doi:10.1016/j.molmed.2006.09.001. PMID 16996800.
Liddle RA (2007). "The role of Transient Receptor Potential Vanilloid 1 (TRPV1) channels in pancreatitis.". Biochim. Biophys. Acta1772 (8): 869–78. doi:10.1016/j.bbadis.2007.02.012. PMID 17428642.