Pharmacological characterization of the TRPV1 receptor antagonist JYL1421 (SC0030) in vitro and in vivo in the rat

https://doi.org/10.1016/j.ejphar.2005.05.002Get rights and content

Abstract

The TRPV1 capsaicin receptor is an integrator molecule on primary afferent neurones participating in inflammatory and nociceptive processes. The present paper characterizes the effects of JYL1421 (SC0030), a TRPV1 receptor antagonist, on capsaicin-evoked responses both in vitro and in vivo in the rat. JYL1421 concentration-dependently (0.1–2 μM) inhibited capsaicin-evoked substance P, calcitonin gene-related peptide and somatostatin release from isolated tracheae, while only 2 μM resulted in a significant inhibition of electrically induced neuropeptide release. Capsazepine (0.1–2 μM), as a reference compound, similarly diminished both capsaicin-evoked and electrically evoked peptide release. JYL1421 concentration-dependently decreased capsaicin-induced Ca2+ accumulation in cultured trigeminal ganglion cells, while capsazepine was much less effective. In vivo 2 mg/kg i.p. JYL1421, but not capsazepine, inhibited capsaicin-induced hypothermia, eye wiping movements and reflex hypotension (a component of the pulmonary chemoreflex or Bezold–Jarisch reflex). Based on these data JYL1421 is a more selective and in most models also a more potent TRPV1 receptor antagonist than capsazepine, therefore it may promote the assessment of the (patho)physiological roles of the TRPV1 receptor.

Introduction

Capsaicin (8-methyl-N-vanillyl-6-nonenamide), the pungent principle of hot chilli peppers, is a valuable pharmacological tool for the categorization and characterization of primary afferents. The existence of a capsaicin receptor in the cell membrane of a subgroup of nociceptive sensory neurones was hypothesized 30 years ago (Szolcsányi and Jancsó-Gábor, 1975), then it was cloned and identified in the rat (Caterina et al., 1997), guinea pig (McIntyre et al., 2001) and man (Hayes et al., 2000). This receptor was then called vanilloid receptor 1 (VR1), but now it is referred to as TRPV1 based on its phylogenetic relationship with the larger superfamily of transient receptor potential (TRP) channels (Clapham et al., 2001, Gunthorpe et al., 2002, Montell et al., 2002). This non-selective cation channel composed of 6 transmembrane domains has become a promising target for the development of a new generation of anti-inflammatory and analgesic agents with a target on sensory neurones (Szallasi and Blumberg, 1999, Szolcsanyi, 2002). Activation of the TRPV1 receptor induces Ca2+ entry and consequent release of sensory neuropeptides like calcitonin gene-related peptide (CGRP) and tachykinins (e.g. substance P), which mediate vasodilatation, plasma protein extravasation and immune cell accumulation in the innervated area (Maggi, 1995, Helyes et al., 2003). Furthermore, the released somatostatin exerts systemic anti-inflammatory and analgesic actions (Szolcsanyi et al., 1998a, Szolcsanyi et al., 1998b, Helyes et al., 2000, Helyes et al., 2004).

The TRPV1 channel can be considered a molecular integrator of noxious chemical and thermal stimuli in the peripheral terminals of primary sensory neurones involved in pain sensation (Garcia-Martinez et al., 2002). The classical pharmacological tools to study the role of this receptor are TRPV1 receptor antagonists, but the available compounds mostly show moderate potency, species difference and limited selectivity (Helyes et al., 2003). Of them, recent studies have shown that ruthenium red should be considered a non-selective inhibitor of all TRPV channels (Gunthorpe et al., 2002, Smith et al., 2002) and it also acts on many other ion channels and receptors (Amann and Maggi, 1991). Capsazepine is a relatively weak antagonist, which appears to show species- and modality-specific activity (McIntyre et al., 2001, Shin et al., 2002, Savidge et al., 2001, Savidge et al., 2002, Seabrook et al., 2002, Walker et al., 2003). Furthermore, it also inhibits acetylcholine receptors (Liu and Simon, 1997), voltage-gated Ca2+ channels (Docherty et al., 1997), and hyperpolarisation-activated cyclic nucleotide gated channels (Gill et al., 2004) at similar concentrations at which it acts on TRPV1. Iodo-resiniferatoxin effectively inhibits capsaicin-evoked currents in Xenopus oocytes and nociceptive responses in the rat (Wahl et al., 2001, Seabrook et al., 2002). However, its deiodination to resiniferatoxin after systemic administration cannot be excluded, which raises the possibility of inducing desensitization. BCTC represents highly potent TRPV1 receptor antagonistic activity (Pomonis et al., 2003), but from a pharmaceutical development perspective, it has several possible shortcomings including poor metabolic stability, short half-life, poor aqueous solubility and moderate bioavailability (Tafesse et al., 2004). Therefore, there is still a great need for more potent and selective TRPV1 receptor antagonists to define the role of this receptor in physiological and pathophysiological conditions and reveal its significance as a therapeutic target. Recently, novel TRPV1 receptor antagonists with improved potency and/or selectivity compared to capsazepine have been synthesized. Among these, SB366791, a structurally novel inhibitor of rat and human TRPV1 receptor developed by GlaxoSmithKline (Rami et al., 2004) and AMG 9810, an Amgen compound (Gavva et al., 2005), have been reported to be highly effective.

A successful approach initiated by Uhtaek Oh in Seoul National University resulted in high affinity antagonists of the TRPV1 ion channels. [N-(4-tert-butylbenzyl)-N′-[3-fluoro-4-(methylsulfonylamino)benzyl]-thiourea] called JYL1421 (SC0030; Wang et al., 2002, Kim et al., 2004) antagonizes capsaicin-induced Ca2+ uptake in rat TRPV1-expressing Chinese hamster ovary cells with an IC50 of 9.2 nM, having 60-fold greater potency than capsazepine (Wang et al., 2002).

The aim of the present series of experiments was to investigate the TRPV1 receptor antagonistic effect and selectivity of JYL1421 in vitro and in vivo using various rat models. Its effects were compared to capsazepine as a reference compound.

Section snippets

Animals

Experiments were performed on male Wistar rats (Charles Rivers Hungary Ltd., Budapest, Hungary) weighing 180–220 g, which were kept in the Laboratory Animal Centre of the University of Pécs under standard pathogen free conditions at 24–25 °C and provided with standard chow and water ad libitum.

Drugs and chemicals

JYL1421 (SC0030) was synthesized and kindly donated by Uhtaek Oh at Seoul National University (Korea). Urethan, capsaicin and capsazepine were purchased from Sigma (St. Louis, MO, USA). The solvent of

Effect of JYL1421 and capsazepine on capsaicin-evoked neuropeptide release

Capsaicin (10 6 M) evoked 2-, 13- and 3-fold increase of substance P, CGRP and somatostatin release, respectively (Fig. 1). The outflow of CGRP was the most sensitive to the stimulatory effect of capsaicin and enhanced release was observed even in the poststimulation period. The release of all the three peptides was diminished in the presence of 0.1–2 μM JYL1421 in a concentration-dependent manner. The IC50 values for the inhibition of the release of substance P, CGRP and somatostatin were 331,

Discussion and conclusions

A potential role for the TRPV1 receptor in nociception was evidenced long ago since injection of capsaicin induced nocifensive and hyperalgesic behaviours in rodents and pain in humans (Szolcsanyi, 1977, Simone et al., 1987, Gilchrist et al., 1996). Results obtained in TRPV1 gene-deleted mice suggest that TRPV1 plays pivotal role in the peripheral sensitization of nociceptors in several inflammatory/nociceptive processes and tissue damage (Caterina et al., 2000, Davis et al., 2000). Therefore,

Acknowledgements

This work was sponsored by Hungarian Grants: OTKA T-034911, T-043467, T-037523, F-046635, NRDP 1A/002/2002, ETT-03-543/2003, ETT-03-597/2003, ETT-05-598/2003, ETT-03-326/2003 and the Hungarian Academy of Sciences. Zs. Helyes, E. Pintér and G. Pethő were supported by János Bolyai Research Fellowship, J. Németh by István Széchenyi Research Fellowship.

References (60)

  • C.A. Maggi

    Tachykinins and calcitonin gene-related peptide (CGRP) as co-transmitters released from peripheral endings of sensory nerves

    Prog. Neurobiol.

    (1995)
  • C. Montell et al.

    A unified nomenclature for the superfamily of TRP cation channels

    Mol. Cell

    (2002)
  • G. Pethő et al.

    Effects of TRPV1 receptor antagonists on stimulated iCGRP release from isolated skin of rats and TRPV1 mutant mice

    Pain

    (2004)
  • H.K. Rami et al.

    Discovery of small molecule antagonists of TRPV1

    Bioorg. Med. Chem. Lett.

    (2004)
  • J.C. Roberts et al.

    [3H]Resiniferatoxin autoradiography in the CNS of wild-type and TRPV1 null mice defines TRPV1 (VR-1) protein distribution

    Brain Res.

    (2004)
  • J. Savidge et al.

    Cloning and functional characterization of the guinea pig vanilloid receptor 1

    Neuropharmacology

    (2002)
  • J.R. Savidge et al.

    Comparison of intracellular calcium signals evoked by heat and capsaicin in cultured rat dorsal root ganglion neurons and in a cell line expressing the rat vanilloid receptor VR1

    Neuroscience

    (2001)
  • D.A. Simone et al.

    Hyperalgesia to heat after intradermal injection of capsaicin

    Brain Res.

    (1987)
  • L. Tafesse et al.

    Synthesis and evaluation of pyridazinylpiperazines as vanilloid receptor 1 antagonists

    Bioorg. Med. Chem. Lett.

    (2004)
  • H.P. Teng et al.

    Capsazepine elevates intracellular Ca2+ in human osteosarcoma cells, questioning its selectivity as a vanilloid receptor antagonist

    Life Sci.

    (2004)
  • M. Zimmermann

    Ethical guidelines for investigations of experimental pain in conscious animals

    Pain

    (1983)
  • R. Amann et al.

    The non-peptide NK1 receptor antagonist SR140333 produces long-lasting inhibition of neurogenic inflammation, but does not influence acute chemo- or thermonociception in rats

    Naunyn-Schmiedeberg's Arch. Pharmacol.

    (1995)
  • S. Bevan et al.

    Capsazepine: a competitive antagonist of the sensory neurone excitant capsaicin

    Br. J. Pharmacol.

    (1992)
  • M.J. Caterina et al.

    The capsaicin receptor: a heat-activated ion channel in the pain pathway

    Nature

    (1997)
  • M.J. Caterina et al.

    Impaired nociception and pain sensation in mice lacking the capsaicin receptor

    Science

    (2000)
  • D.E. Clapham et al.

    The TRP ion channel family

    Nat. Rev., Neurosci.

    (2001)
  • J.C.G. Coleridge et al.

    Afferent vagal C fibre innervation of the lungs and airways and its functional significance

    Rev. Physiol., Biochem. Pharmacol.

    (1984)
  • J.B. Davis et al.

    Vanilloid receptor-1 is essential for inflammatory thermal hyperalgesia

    Nature

    (2000)
  • R.J. Docherty et al.

    Capsazepine block of voltage-activated calcium channels in adult rat dorsal root ganglion neurones in culture

    Br. J. Pharmacol.

    (1997)
  • C. Garcia-Martinez et al.

    Attenuation of thermal nociception and hyperalgesia by VR1 blockers

    Proc. Natl. Acad. Sci. U. S. A.

    (2002)
  • Cited by (0)

    1

    Zs. Helyes and B. Jakab contributed equally to the present work. Likewise, J. Németh and J. Szolcsányi also made equal contributions.

    View full text