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  • Sumatriptan inhibits TRPV1 channels in trigeminal neurons. 22289052

    To understand a possible role for transient potential receptor vanilloid 1 (TRPV1) ion channels in sumatriptan relief of pain mediated by trigeminal nociceptors.TRPV1 channels are expressed in small nociceptive sensory neurons. In dorsal root ganglia, TRPV1-containing nociceptors mediate certain types of inflammatory pain. Neurogenic inflammation of cerebral dura and blood vessels in the trigeminal nociceptive system is thought to be important in migraine pain, but the ion channels important in transducing migraine pain are not known. Sumatriptan is an agent effective in treatment of migraine and cluster headache. We hypothesized that sumatriptan might modulate activity of TRPV1 channels found in the trigeminal nociceptive system.We used immunohistochemistry to detect the presence of TRPV1 channel protein, whole-cell recording in acutely dissociated trigeminal ganglia (TG) to detect functionality of TRPV1 channels, and whole-cell recording in trigeminal nucleus caudalis (TNC) to detect effects on release of neurotransmitters from trigeminal neurons onto second order sensory neurons. Effects specifically on TG neurons that project to cerebral dura were assessed by labeling dural nociceptors with DiI.Immunohistochemistry demonstrated that TRPV1 channels are present in cerebral dura, in trigeminal ganglion, and in the TNC. Capsaicin, a TRPV1 agonist, produced depolarization and repetitive action potential firing in current clamp recordings, and large inward currents in voltage clamp recordings from acutely dissociated TG neurons, demonstrating that TRPV1 channels are functional in trigeminal neurons. Capsaicin increased spontaneous excitatory postsynaptic currents in neurons of layer II in TNC slices, showing that these channels have a physiological effect on central synaptic transmission. Sumatriptan (10 µM), a selective antimigraine drug, inhibited TRPV1-mediated inward currents in TG and capsaicin-elicited spontaneous excitatory postsynaptic currents in TNC slices. The same effects of capsaicin and sumatriptan were found in acutely dissociated DiI-labeled TG neurons innervating cerebral dura.Our results build on previous work indicating that TRPV1 channels in trigeminal nociceptors play a role in craniofacial pain. Our findings that TRPV1 is inhibited by the specific antimigraine drug sumatriptan, and that TRPV1 channels are functional in neurons projecting to cerebral dura suggests a specific role for these channels in migraine or cluster headache.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB377
    Nombre del producto:
    Anti-NeuN Antibody, clone A60
  • Intrathecal injection of TRPV1 shRNA leads to increases in blood pressure in rats. 21518266

    The transient receptor potential vanilloid type 1 (TRPV1) channels have been implicated to play a role in blood pressure regulation. However, contribution of tissue specific TRPV1 to blood pressure regulation is largely unknown. Here, we test the hypothesis that TRPV1 expressed in dorsal root ganglia (DRG) of lower thoracic and upper lumbar segments (T8-L3) of the spinal cord and their central and peripheral terminals constitutes a counter regulatory mechanism preventing the increases in blood pressure.The expression of TRPV1 was knocked down by intrathecal injection of TRPV1 short-hairpin RNA (shRNA) in rats. Systolic blood pressure and mean arterial pressure (MAP) were recorded. The level of TRPV1 and tyrosine hydroxylase (TH) was measured by Western blot.Intrathecal injection of TRPV1 shRNA (6 μg kg(-1) day(-1) ) for 3 days increased systolic blood pressure and MAP when compared to rats that received control shRNA (control shRNA: 112 ± 2 vs. TRPV1 shRNA: 123 ± 2 mmHg). TRPV1 expression was suppressed in T8-L3 segments of dorsal horn and DRG as well as mesenteric arteries of rats given TRPV1 shRNA. Contents of TH, a marker of sympathetic nerves, were increased in mesenteric arteries of rats treated with TRPV1 shRNA. Pretreatment with the α1-adrenoceptor blocker, prazosin (1 mg kg(-1) day(-1) , p.o.), abolished the TRPV1 shRNA-induced pressor effects.Our data show that selective knockdown of TRPV1 expressed in DRG of T8-L3 segments of the spinal cord and their central and peripheral terminals increases blood pressure, suggesting that neuronal TRPV1 in these segments possesses a tonic anti-hypertensive effect possibly via suppression of the sympathetic nerve activity.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB5566
    Nombre del producto:
    Anti-Capsaicin Receptor Antibody, CT
  • Angiotensin II induces membrane trafficking of natively expressed transient receptor potential vanilloid type 4 channels in hypothalamic 4B cells. 25080500

    Transient receptor potential vanilloid family type 4 (TRPV4) channels are expressed in central neuroendocrine neurons and have been shown to be polymodal in other systems. We previously reported that in the rodent, a model of dilutional hyponatremia associated with hepatic cirrhosis, TRPV4 expression is increased in lipid rafts from the hypothalamus and that this effect may be angiotensin dependent. In this study, we utilized the immortalized neuroendocrine rat hypothalamic 4B cell line to more directly test the effects of angiotensin II (ANG II) on TRPV4 expression and function. Our results demonstrate the expression of corticotropin-releasing factor (CRF) transcripts, for sex-determining region Y (SRY) (male genotype), arginine vasopressin (AVP), TRPV4, and ANG II type 1a and 1b receptor in 4B cells. After a 1-h incubation in ANG II (100 nM), 4B cells showed increased TRPV4 abundance in the plasma membrane fraction, and this effect was prevented by the ANG II type 1 receptor antagonist losartan (1 μM) and by a Src kinase inhibitor PP2 (10 μM). Ratiometric calcium imaging experiments demonstrated that ANG II incubation potentiated TRPV4 agonist (GSK 1016790A, 20 nM)-induced calcium influx (control 18.4 ± 2.8% n = 5 and ANG II 80.5 ± 2.4% n = 5). This ANG II-induced increase in calcium influx was also blocked by 1 μM losartan and 10 μM PP2 (losartan 26.4 ± 3.8% n = 5 and PP2 19.7 ± 3.9% n = 5). Our data suggests that ANG II can increase TRPV4 channel membrane expression in 4B cells through its action on AT1R involving a Src kinase pathway.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo
  • Capsaicin pre-treatment provides neurovascular protection against neonatal hypoxic-ischemic brain injury in rats. 21725760

    Capsaicin, a transient receptor potential vanilloid 1 (TRPV1) agonist, has recently been shown to provide neuroprotection against brain injury in experimental adult models of cerebral ischemia. Accordingly, in this study, we investigated the way in which capsaicin-mediated TRPV1 modulation could attenuate damage in an experimental hypoxic-ischemic (HI) neonatal brain injury model. The Rice-Vannucci method was used in 10-day-old rat pups by performing unilateral carotid artery ligation followed by 2 h of hypoxia (8% O2 at 37°C). Capsaicin was administered intraperitoneally (0.2 mg/kg or 2.0 mg/kg) at 3 h pre-HI or 1 h post-HI. Post assessment included measurement of infarction volume at 24 and 72 h in addition to an assessment of the vascular dynamics of the middle cerebral artery (MCA) at 6 h post-HI. The results indicated that pre-treatment with capsaicin reduced infarction volume significantly with either low-dose or high-dose treatment. Pre-treatment also improved myogenic tone and decreased apoptotic changes in the distal MCA. We concluded that capsaicin pre-treatment may provide neurovascular protection against neonatal HI.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB377
    Nombre del producto:
    Anti-NeuN Antibody, clone A60
  • Transient receptor potential vanilloid type 1 channel (TRPV1) immunolocalization in the murine enteric nervous system is affected by the targeted C-terminal epitope of th ... 23482327

    The expression of transient receptor potential vanilloid type 1 channel (TRPV1) in the enteric nervous system is still the subject of debate. Although a number of studies have reported that TRPV1 is limited to extrinsic afferent fibers, other studies argue for an intrinsic expression of TRPV1. In the present study, reverse transcriptase PCR was employed to establish the expression of TRPV1 mRNA throughout the gastrointestinal tract. Using two antibodies directed against different epitopes of TRPV1, we were able to show at the protein level that the observed distribution pattern of TRPV1 is dependent on the antibody used in the immunohistochemical staining. A first antibody indeed mainly stained neuronal fibers, whereas a second antibody exclusively stained perikarya of enteric neurons throughout the mouse gastrointestinal tract. We argue that these different distribution patterns are due to the antibodies discriminating between different modulated forms of TRPV1 that influence the recognition of the targeted immunogen and as such distinguish intracellular from plasmalemmal forms of TRPV1. Our study is the first to directly compare these two antibodies within the same species and in identical conditions. Our observations underline that detailed knowledge of the epitope that is recognized by the antibodies employed in immunohistochemical procedures is a prerequisite for correctly interpreting experimental results.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo
  • The role of transient receptor potential vanilloid 1 in mechanical and chemical visceral hyperalgesia following experimental colitis. 17719181

    The transient receptor potential vanilloid 1 receptor (TRPV1) is an important nociceptor involved in neurogenic inflammation. We aimed to examine the role of TRPV1 in experimental colitis and in the development of visceral hypersensitivity to mechanical and chemical stimulation. Male Sprague-Dawley rats received a single dose of trinitrobenzenesulfonic acid (TNBS) in the distal colon. In the preemptive group, rats received the TRPV1 receptor antagonist JYL1421 (10 mumol/kg, i.v.) or vehicle 15 min prior to TNBS followed by daily doses for 7 days. In the post-inflammation group, rats received JYL1421 daily for 7 days starting on day 7 following TNBS. The visceromotor response (VMR) to colorectal distension (CRD), intraluminal capsaicin, capsaicin vehicle (pH 6.7) or acidic saline (pH 5.0) was assessed in all groups and compared with controls and naïve rats. Colon inflammation was evaluated with H&E staining and myeloperoxidase (MPO) activity. TRPV1 immunoreactivity was assessed in the thoraco-lumbar (TL) and lumbo-sacral (LS) dorsal root ganglia (DRG) neurons. In the preemptive vehicle group, TNBS resulted in a significant increase in the VMR to CRD, intraluminal capsaicin and acidic saline compared the JYL1421-treated group (P<0.05). Absence of microscopic colitis and significantly reduced MPO activity was also evident compared with vehicle-treated rats (P<0.05). TRPV1 immunoreactivity in the TL (69.1+/-4.6%) and LS (66.4+/-4.2%) DRG in vehicle-treated rats was increased following TNBS but significantly lower in the preemptive JYL1421-treated group (28.6+/-3.9 and 32.3+/-2.3 respectively, P<0.05). JYL1421 in the post-inflammation group improved microscopic colitis and significantly decreased the VMR to CRD compared with vehicle (P<0.05, >/=30 mm Hg) but had no effect on the VMR to chemical stimulation. TRPV1 immunoreactivity in the TL and LS DRG was no different from vehicle or naïve controls. These results suggest an important role for TRPV1 channel in the development of inflammation and subsequent mechanical and chemical visceral hyperalgesia.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB5566
    Nombre del producto:
    Anti-Capsaicin Receptor Antibody, CT
  • Parvalbumin and TRPV1 receptor expression in dorsal root ganglion neurons after acute peripheral inflammation. 19397388

    Expression of parvalbumin (PV) and transient receptor potential vanilloid (TRPV1) receptors in the lumbar dorsal root ganglion neurons (DRG) was evaluated in control animals and in rats after acute carageenan-induced knee joint inflammation. PV is a calcium binding protein that acts as a calcium buffer, affects intracellular calcium homeostasis and may thus influence signal transduction and synaptic transmission. TRPV1 receptors are viewed as molecular integrators of nociceptive stimuli and modulate spinal cord synaptic transmission beside their function in the peripheral nerve endings. In naive rats, 13 % of the L4 DRG neurons had PV immunopositivity (PV+) and 36 % expressed TRPV1 receptors (TRPV1+). The soma of the PV+ neurons was of medium to large size, while the TRPV1 receptors were expressed in small diameter neurons. The co-localization of the PV and TRPV1 immunoreactivity was minimal (0.2 %). There was no significant change in the PV+ (11 %), TRPV1+ (42 %) and PV+TRPV1+ (0.25 %) expression, or shift in the neuronal size distribution 28 h after the unilateral peripheral inflammation, both when compared to controls and when ipsilateral to contralateral sides were evaluated. Thus under the given experimental conditions, no change in somatic TRPV1 receptors and PV expression in L4 DRG neurons was found.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB5370
    Nombre del producto:
    Anti-Capsaicin Receptor Antibody, CT
  • TRPV1 stimulation triggers apoptotic cell death of rat cortical neurons. 18996081

    Transient receptor potential vanilloid 1 (TRPV1) functions as a polymodal nociceptor and is activated by several vanilloids, including capsaicin, protons and heat. Although TRPV1 channels are widely distributed in the brain, their roles remain unclear. Here, we investigated the roles of TRPV1 in cytotoxic processes using TRPV1-expressing cultured rat cortical neurons. Capsaicin induced severe neuronal death with apoptotic features, which was completely inhibited by the TRPV1 antagonist capsazepine and was dependent on extracellular Ca(2+) influx. Interestingly, nifedipine, a specific L-type Ca(2+) channel blocker, attenuated capsaicin cytotoxicity, even when applied 2-4 h after the capsaicin. ERK inhibitor PD98059 and several antioxidants, but not the JNK and p38 inhibitors, attenuated capsaicin cytotoxicity. Together, these data indicate that TRPV1 activation triggers apoptotic cell death of rat cortical cultures via L-type Ca(2+) channel opening, Ca(2+) influx, ERK phosphorylation, and reactive oxygen species production.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB5889
    Nombre del producto:
    Anti-Capsaicin Receptor Antibody, NT
  • Ultrastructural analysis of the synaptic connectivity of TRPV1-expressing primary afferent terminals in the rat trigeminal caudal nucleus. 20878780

    Trigeminal primary afferents that express the transient receptor potential vanilloid 1 (TRPV1) are important for the transmission of orofacial nociception. However, little is known about how the TRPV1-mediated nociceptive information is processed at the first relay nucleus in the central nervous system (CNS). To address this issue, we studied the synaptic connectivity of TRPV1-positive (+) terminals in the rat trigeminal caudal nucleus (Vc) by using electron microscopic immunohistochemistry and analysis of serial thin sections. Whereas the large majority of TRPV1+ terminals made synaptic contacts of an asymmetric type with one or two postsynaptic dendrites, a considerable fraction also participated in complex glomerular synaptic arrangements. A few TRPV1+ terminals received axoaxonic contacts from synaptic endings that contained pleomorphic synaptic vesicles and were immunolabeled for glutamic acid decarboxylase, the synthesizing enzyme for the inhibitory neurotransmitter γ-aminobutyric acid (GABA). We classified the TRPV1+ terminals into an S-type, containing less than five dense-core vesicles (DCVs), and a DCV-type, containing five or more DCVs. The number of postsynaptic dendrites was similar between the two types of terminals; however, whereas axoaxonic contacts were frequent on the S-type, the DCV-type did not receive axoaxonic contacts. In the sensory root of the trigeminal ganglion, TRPV1+ axons were mostly unmyelinated, and a small fraction was small myelinated. These results suggest that the TRPV1-mediated nociceptive information from the orofacial region is processed in a specific manner by two distinct types of synaptic arrangements in the Vc, and that the central input of a few TRPV1+ afferents is presynaptically modulated via a GABA-mediated mechanism.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB1511
  • Group II metabotropic glutamate receptor activation on peripheral nociceptors modulates TRPV1 function. 19026992

    Transient receptor potential vanilloid 1 (TRPV1) receptors are critical to nociceptive processing. Understanding how these receptors are modulated gives insight to potential therapies for pain. We demonstrate using double labeling immunohistochemistry that Group II metabotropic glutamate receptors (mGluRs) are co-expressed with TRPV1 on rat dorsal root ganglion (DRG) cells. In behavioral studies, intraplantar 0.1 microM APDC, a group II agonist, significantly attenuates capsaicin-induced nociceptive behaviors through a local effect. The APDC-induced inhibition of capsaicin responses is blocked by 1 microM LY341495, a group II antagonist. At the single fiber level, nociceptor responses to capsaicin are significantly decreased following exposure to APDC and this effect is blocked by LY341495. Finally, activation of peripheral group II mGluRs inhibits forskolin-induced thermal hyperalgesia and nociceptor heat sensitization, suggesting group II receptors are negatively coupled to the cAMP/PKA pathway. The data indicate that group II mGluRs and TRPV1 receptors are co-expressed on peripheral nociceptors and activation of mGluRs can inhibit painful sensory transmission following TRPV1 activation. The data are consistent with group II and TRPV1 receptors being linked intracellularly by the cAMP/PKA pathway. Peripheral group II mGluRs are important targets for drug discovery in controlling TRPV1-induced nociception.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB1553
    Nombre del producto:
    Anti-Metabotropic Glutamate Receptor 2/3 Antibody