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László S, Bátai IZ, Berkó S, Csányi E, Dombi Á, Pozsgai G, Bölcskei K, Botz L, Wagner Ö, Pintér E. Development of Capsaicin-Containing Analgesic Silicone-Based Transdermal Patches. Pharmaceuticals (Basel) 2022; 15:ph15101279. [PMID: 36297391 PMCID: PMC9611826 DOI: 10.3390/ph15101279] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 09/29/2022] [Accepted: 10/13/2022] [Indexed: 12/03/2022] Open
Abstract
Transdermal therapeutic systems (TTSs) enable convenient dosing in drug therapy. Modified silicone-polymer-based patches are well-controlled and cost-effective matrix diffusion systems. In the present study, we investigated the substance release properties, skin penetration, and analgesic effect of this type of TTS loaded with low-dose capsaicin. Release properties were measured in Franz diffusion cell and continuous flow-through cell approaches. Capsaicin was detected with HPLC-UV and UV spectrophotometry. Raman spectroscopy was conducted on human skin samples exposed to the TTS. A surgical incision or carrageenan injection was performed on one hind paw of male Wistar rats. TTSs were applied to the epilated dorsal skin. Patches were kept on the animals for 6 h. The thermal hyperalgesia and mechanical pain threshold of the hind paws were detected. Patches exhibited controlled, zero-order kinetic capsaicin release. According to the Raman mapping, capsaicin penetrated into the epidermis and dermis of human skin, where the target receptors are expressed. The thermal pain threshold drop of the operated rat paws was reversed by capsaicin treatment compared to that of animals treated with control patches. It was concluded that our modified silicone-polymer-based capsaicin-containing TTS is suitable for the relief of traumatic and inflammatory pain.
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Affiliation(s)
- Szabolcs László
- Department of Inorganic and Analytical Chemistry, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Műegyetem rkp. 3, H-1111 Budapest, Hungary
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti u. 12, H-7624 Pécs, Hungary
| | - István Z. Bátai
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti u. 12, H-7624 Pécs, Hungary
- Molecular Pharmacology Research Group, Szentágothai Research Centre, University of Pécs, Ifjúság ú. 20, H-7624 Pécs, Hungary
| | - Szilvia Berkó
- Institute of Pharmaceutical Technology and Regulatory Affairs, Faculty of Pharmacy, University of Szeged, Eötvös str. 6, H-6720 Szeged, Hungary
| | - Erzsébet Csányi
- Institute of Pharmaceutical Technology and Regulatory Affairs, Faculty of Pharmacy, University of Szeged, Eötvös str. 6, H-6720 Szeged, Hungary
| | - Ágnes Dombi
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti u. 12, H-7624 Pécs, Hungary
- Molecular Pharmacology Research Group, Szentágothai Research Centre, University of Pécs, Ifjúság ú. 20, H-7624 Pécs, Hungary
| | - Gábor Pozsgai
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti u. 12, H-7624 Pécs, Hungary
- Molecular Pharmacology Research Group, Szentágothai Research Centre, University of Pécs, Ifjúság ú. 20, H-7624 Pécs, Hungary
- Correspondence: ; Tel.: +36-72-536-217
| | - Kata Bölcskei
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti u. 12, H-7624 Pécs, Hungary
- Molecular Pharmacology Research Group, Szentágothai Research Centre, University of Pécs, Ifjúság ú. 20, H-7624 Pécs, Hungary
| | - Lajos Botz
- Department of Pharmaceutics and Central Clinical Pharmacy, Faculty of Pharmacy, University of Pécs, Honvéd u. 3., H-7624 Pécs, Hungary
| | - Ödön Wagner
- Department of Inorganic and Analytical Chemistry, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Műegyetem rkp. 3, H-1111 Budapest, Hungary
| | - Erika Pintér
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Szigeti u. 12, H-7624 Pécs, Hungary
- Molecular Pharmacology Research Group, Szentágothai Research Centre, University of Pécs, Ifjúság ú. 20, H-7624 Pécs, Hungary
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Tayeb BO, Winegarden JA, Alashari RA, Alasmari M, Winegarden J, Boker F, Halawi A, Lapidow A, Bradshaw YS, Carr DB. Scoping Review of Off-Label Topical Analgesia in Palliative, Hospice and Cancer Care: Towards Flexibility in Evidence-Based Medicine. J Pain Res 2021; 14:3003-3009. [PMID: 34588811 PMCID: PMC8473564 DOI: 10.2147/jpr.s263845] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 09/07/2021] [Indexed: 12/01/2022] Open
Abstract
Purpose Scoping reviews address the nature of the literature per se rather than inferring evidence-based treatment guidelines. Scoping reviews of the published literature are intended to describe the aggregated nature of the evidence surrounding some agent or intervention, in contrast to systematic reviews that seek when possible to guide clinical practice. We conducted a scoping review to identify reports of potential clinical utility of off-label topical analgesics and adjuvants when FDA-approved treatments have proven inadequate. Methods We performed a comprehensive search of three databases (PubMed, Web of Science and Embase) for articles dating from 1947 to the present. Mindful that FDA-approved and WHO-recommended analgesic medications often prove inadequate for individual patients in extremis with palliative, hospice or cancer pain, we used broad, structured inclusion criteria to retrieve articles. Results We retrieved 12,100 articles; after screening, we had 39 reports addressing 19 different topical agents out of the 32 chemical entities. Our scoping review disclosed evidence about agents that might not have met inclusion criteria for clinical practice guidelines. Discussion Although generally considered lower quality evidence, case reports or series present suggestions for diverse topical medications to manage pain in challenging circumstances when high-quality evidence for agents and routes of administration is lacking. Conclusion Patients with the greatest need for evidence to identify and guide lesser-used agents during aggressive pain management are the most difficult to enroll and follow in standardized, controlled and/or blinded clinical trials. This scoping review identifies medications, dosages, and routes of topical agents reported to be effective in these often-challenging circumstances. Until larger and higher quality studies are completed, we must rely on the best available evidence even if of lower quality.
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Affiliation(s)
- Baraa O Tayeb
- Department of Anesthesiology and Critical Care, King Abdulaziz University Faculty of Medicine, Jeddah, Saudi Arabia.,King Abdulaziz University Hospital, Jeddah, Saudi Arabia
| | | | - Rawabi A Alashari
- Department of Pharmacology, King Abdulaziz University, Faculty of Medicine, Jeddah, Saudi Arabia.,Department of Pharmaceutical Science, MCPHS University, Boston, MA, USA
| | - Moudi Alasmari
- College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Jeddah, Saudi Arabia.,King Abdullah International Medical Research Center (KAIMRC), Jeddah, Saudi Arabia
| | | | - Faisal Boker
- Emergency Department, King Abdulaziz Medical City-Ministry of National Guard Health Affairs, Jeddah, Saudi Arabia
| | | | - Amy Lapidow
- Tufts Hirsh Health Sciences Library, Boston, MA, USA
| | - Ylisabyth S Bradshaw
- Department of Public Health and Community Medicine, Tufts University School of Medicine, Boston, MA, USA
| | - Daniel B Carr
- Department of Public Health and Community Medicine, Tufts University School of Medicine, Boston, MA, USA
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Fight fire with fire: Neurobiology of capsaicin-induced analgesia for chronic pain. Pharmacol Ther 2020; 220:107743. [PMID: 33181192 DOI: 10.1016/j.pharmthera.2020.107743] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 11/04/2020] [Indexed: 12/12/2022]
Abstract
Capsaicin, the pungent ingredient in chili peppers, produces intense burning pain in humans. Capsaicin selectively activates the transient receptor potential vanilloid 1 (TRPV1), which is enriched in nociceptive primary afferents, and underpins the mechanism for capsaicin-induced burning pain. Paradoxically, capsaicin has long been used as an analgesic. The development of topical patches and injectable formulations containing capsaicin has led to application in clinical settings to treat chronic pain conditions, such as neuropathic pain and the potential to treat osteoarthritis. More detailed determination of the neurobiological mechanisms of capsaicin-induced analgesia should provide the logical rationale for capsaicin therapy and help to overcome the treatment's limitations, which include individual differences in treatment outcome and procedural discomfort. Low concentrations of capsaicin induce short-term defunctionalization of nociceptor terminals. This phenomenon is reversible within hours and, hence, likely does not account for the clinical benefit. By contrast, high concentrations of capsaicin lead to long-term defunctionalization mediated by the ablation of TRPV1-expressing afferent terminals, resulting in long-lasting analgesia persisting for several months. Recent studies have shown that capsaicin-induced Ca2+/calpain-mediated ablation of axonal terminals is necessary to produce long-lasting analgesia in a mouse model of neuropathic pain. In combination with calpain, axonal mitochondrial dysfunction and microtubule disorganization may also contribute to the longer-term effects of capsaicin. The analgesic effects subside over time in association with the regeneration of the ablated afferent terminals. Further determination of the neurobiological mechanisms of capsaicin-induced analgesia should lead to more efficacious non-opioidergic analgesic options with fewer adverse side effects.
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Szőke É, Bálint M, Hetényi C, Markovics A, Elekes K, Pozsgai G, Szűts T, Kéri G, Őrfi L, Sándor Z, Szolcsányi J, Pintér E, Helyes Z. Small molecule somatostatin receptor subtype 4 (sst 4) agonists are novel anti-inflammatory and analgesic drug candidates. Neuropharmacology 2020; 178:108198. [PMID: 32739276 DOI: 10.1016/j.neuropharm.2020.108198] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 06/07/2020] [Accepted: 06/10/2020] [Indexed: 12/30/2022]
Abstract
We provided strong proof of concept evidence that somatostatin mediates potent analgesic and anti-inflammatory actions via its receptor subtype 4 (sst4) located both at the periphery and the central nervous system. Therefore, sst4 agonists are promising novel drug candidates for neuropathic pain and neurogenic inflammation, but rational drug design was not possible due to the lack of knowledge about its 3-dimensional structure. We modeled the sst4 receptor structure, described its agonist binding properties, and characterized the binding of our novel small molecule sst4 agonists (4-phenetylamino-7H-pyrrolo[2,3-d]pyrimidine derivatives) using an in silico platform. In addition to the in silico binding data, somatostatin displacement by Compound 1 was demonstrated in the competitive binding assay on sst4-expressing cells. In vivo effects were investigated in rat models of neurogenic inflammation and chronic traumatic neuropathic pain. We defined high- and low-affinity binding pockets of sst4 for our ligands, binding of the highest affinity compounds were similar to that of the reference ligand J-2156. We showed potent G-protein activation with the highest potency of 10 nM EC50 value and highest efficacy of 342%. Oral administration of 100 μg/kg of 5 compounds significantly inhibited acute neurogenic plasma protein extravasation in the paw skin by 40-60%, one candidate abolished and 3 others diminished sciatic nerve-ligation induced neuropathic hyperalgesia by 28-62%. The in silico predictions on sst4-ligands were tested in biological systems. Low oral dose of our novel agonists inhibit neurogenic inflammation and neuropathic pain, which opens promising drug developmental perspectives for these unmet medical need conditions.
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Affiliation(s)
- Éva Szőke
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary; János Szentágothai Research Center & Centre for Neuroscience, University of Pécs, Hungary.
| | - Mónika Bálint
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary; János Szentágothai Research Center & Centre for Neuroscience, University of Pécs, Hungary
| | - Csaba Hetényi
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary; János Szentágothai Research Center & Centre for Neuroscience, University of Pécs, Hungary
| | - Adrienn Markovics
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary; János Szentágothai Research Center & Centre for Neuroscience, University of Pécs, Hungary
| | - Krisztián Elekes
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary; János Szentágothai Research Center & Centre for Neuroscience, University of Pécs, Hungary
| | - Gábor Pozsgai
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary; János Szentágothai Research Center & Centre for Neuroscience, University of Pécs, Hungary
| | | | - György Kéri
- Vichem Chemie Research Ltd, Budapest, Hungary
| | - László Őrfi
- Department of Pharmaceutical Chemistry, Pharmacy Faculty, Semmelweis University, Budapest, Hungary
| | - Zoltán Sándor
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary; János Szentágothai Research Center & Centre for Neuroscience, University of Pécs, Hungary
| | - János Szolcsányi
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary; János Szentágothai Research Center & Centre for Neuroscience, University of Pécs, Hungary
| | - Erika Pintér
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary; János Szentágothai Research Center & Centre for Neuroscience, University of Pécs, Hungary; PharmInVivo Ltd, Pécs, Hungary; Algonist GmbH, Vienna, Austria
| | - Zsuzsanna Helyes
- Department of Pharmacology and Pharmacotherapy, Medical School, University of Pécs, Pécs, Hungary; János Szentágothai Research Center & Centre for Neuroscience, University of Pécs, Hungary; PharmInVivo Ltd, Pécs, Hungary; Algonist GmbH, Vienna, Austria
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Sun L, Cui ZG, Zakki SA, Feng QW, Li ML, Inadera H. Mechanistic study of nonivamide enhancement of hyperthermia-induced apoptosis in U937 cells. Free Radic Biol Med 2018; 120:147-159. [PMID: 29551639 DOI: 10.1016/j.freeradbiomed.2018.03.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 03/07/2018] [Accepted: 03/11/2018] [Indexed: 11/16/2022]
Abstract
Hyperthermia is one therapeutic tool for damaging and killing cancer cells, with minimal injury to normal tissues. However, its cytotoxic effects alone are insufficient for quantitative cancer cell death. To overcome this limitation, several studies have explored non-toxic enhancers for hyperthermia-induced cell death. Capsaicin may be applicable as a therapeutic tool against various types of cancer. In the present study, we employed nonivamide, a less-pungent capsaicin analogue, to investigate its possible enhancing effects on hyperthermia-induced apoptosis; moreover, we analyzed its molecular mechanism. Treatment of U937 cells at 44 °C for 15 min, combined with nonivamide 50 μM, revealed enhancement of apoptosis. Significant increases in reactive oxygen species generation, mitochondrial dysfunction, and cleaved caspase-3 were observed during the combined treatment; these were accompanied by an increase in pro-apoptotic Bcl-2 family proteins and a decrease in anti-apoptotic Bcl-2 proteins. In addition, significant increases in p-JNK and p-p38 were detected, following the combined treatment. In conclusion, nonivamide enhanced hyperthermia-induced apoptosis via a mitochondrial-caspase dependent pathway. The underlying mechanism may include elevation of intracellular reactive oxygen species, mitochondrial dysfunction, and increased activation of JNK and p38.
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Affiliation(s)
- Lu Sun
- Department of Public Health, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Zheng-Guo Cui
- Department of Public Health, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan; Graduate School of Medicine, Henan Polytechnic University, Jiaozuo 454000 China
| | - Shahbaz Ahmad Zakki
- Department of Public Health, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Qian-Wen Feng
- Department of Public Health, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Meng-Ling Li
- Department of Public Health, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Hidekuni Inadera
- Department of Public Health, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
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Octreotide modulates the expression of somatostatin receptor subtypes in inflamed rat jejunum induced by Cryptosporidium parvum. PLoS One 2018. [PMID: 29522573 PMCID: PMC5844672 DOI: 10.1371/journal.pone.0194058] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Somatostatins are proteins that are involved in gastrointestinal function. However, little is known with regard to somatostatin receptor subtype (SSTR) expression changes that occur in the jejunum during low-grade inflammation and during subsequent octreotide treatment. The aim of the present study was to investigate the expression of SSTRs in the jejunums of Cryptosporidium parvum (C. parvum)-infected rats by immunohistochemisty, reverse transcription (RT) PCR and quantitative real-time RT-PCR assays. Five-day-old suckling Sprague-Dawley rats (n = 15 for each group) were orally gavaged with 105 Nouzilly isolate (NoI) oocysts. Rats then received 50 μg/kg/day of octreotide by intraperitoneal injection from day 10 to day 17 post-infection. Animals were sacrificed on days 7 and 14 post-infection for immunohistochemical analysis and on days 14, 35 and 50 for mRNA expression analysis of SSTR subtypes. Histological analysis of jejunum tissues demonstrated infection of C. parvum along the villus brush border on day 7 post-infection and infection clearance by day 14 post-infection. Real-time PCR analysis indicated that in the inflamed jejunum, a significant increase in SSTR1 and SSTR2 expression was observed on day 14 post-infection. Octreotide therapy down-regulated the expression of SSTR2 on day 37 post-infection but significantly increased expression of SSTR1, SSTR2 and SSTR3 on day 50 post-infection. The results indicate that specific SSTRs may regulate the inflammatory pathway in the rat intestinal inflammation model.
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Pethő G, Bölcskei K, Füredi R, Botz B, Bagoly T, Pintér E, Szolcsányi J. Evidence for a novel, neurohumoral antinociceptive mechanism mediated by peripheral capsaicin-sensitive nociceptors in conscious rats. Neuropeptides 2017; 62:1-10. [PMID: 28291541 DOI: 10.1016/j.npep.2017.02.079] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 12/16/2016] [Accepted: 02/07/2017] [Indexed: 11/20/2022]
Abstract
Stimulation of capsaicin-sensitive peripheral sensory nerve terminals induces remote anti-inflammatory effects throughout the body of anesthetized rats and guinea-pigs mediated by somatostatin. As somatostatin has also antinociceptive effects, the study aimed at investigating whether similar remote antinociceptive effects can be demonstrated in awake animals. In conscious rats, nociceptive nerve endings of the right hind paw decentralized by cutting the sciatic and saphenous nerves 18h before were chemically stimulated, and drop of the noxious heat threshold (heat hyperalgesia) induced by prior (18h before) plantar incision was measured on the contralateral, left hind paw using an increasing-temperature water bath. 18h after nerve transection, mustard oil-evoked plasma extravasation was not significantly reduced in the right hind paw as tested by in vivo fluorescence imaging. Applying agonist of either transient receptor potential vanilloid 1 (TRPV1) or transient receptor potential ankyrin 1 (TRPA1) receptor (capsaicin or mustard oil, respectively) to the nerve-transected paw inhibited the plantar incision-induced drop of the noxious heat threshold on the contralateral paw. The onset of these remote antihyperalgesic effects was 10-20min. A similar contralateral inhibitory effect of capsaicin or mustard oil treatment was observed on neuropathic mechanical hyperalgesia evoked by partial sciatic nerve injury 2days before nerve transection and measured by a Randall-Selitto apparatus. The remote thermal antihyperalgesic effect was prevented by chronic (5days) denervation or local capsaicin desensitization of the stimulated paw; reduced by intraperitoneally applied antagonist of somatostatin (cyclosomatostatin) or opioid receptors (naloxone). The response was mimicked by intraperitoneally applied somatostatin and associated with a 72±27% increase in plasma somatostatin-like immunoreactivity that was absent after chronic (5days) denervation. In conclusion, chemical activation of decentralized peripheral capsaicin-sensitive nociceptors evokes remote antihyperalgesic responses initiated outside the central nervous system and mediated by somatostatin and endogenous opioids.
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Affiliation(s)
- Gábor Pethő
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Szigeti út 12, H-7624 Pécs, Hungary.
| | - Kata Bölcskei
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Szigeti út 12, H-7624 Pécs, Hungary; Molecular Pharmacology Research Team, János Szentágothai Research Centre, University of Pécs, Ifjúság útja 20, H-7624 Pécs, Hungary
| | - Réka Füredi
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Szigeti út 12, H-7624 Pécs, Hungary
| | - Bálint Botz
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Szigeti út 12, H-7624 Pécs, Hungary; Molecular Pharmacology Research Team, János Szentágothai Research Centre, University of Pécs, Ifjúság útja 20, H-7624 Pécs, Hungary
| | - Teréz Bagoly
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Szigeti út 12, H-7624 Pécs, Hungary
| | - Erika Pintér
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Szigeti út 12, H-7624 Pécs, Hungary
| | - János Szolcsányi
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Szigeti út 12, H-7624 Pécs, Hungary
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Analgesic effect of dimethyl trisulfide in mice is mediated by TRPA1 and sst 4 receptors. Nitric Oxide 2017; 65:10-21. [PMID: 28137611 DOI: 10.1016/j.niox.2017.01.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 01/25/2017] [Accepted: 01/25/2017] [Indexed: 12/16/2022]
Abstract
TRPA1 receptors are calcium-permeable ligand-gated channels expressed in primary sensory neurons and involved in inflammation and pain. Activation of these neurons might have analgesic effect. Suggested mechanism of analgesic effect mediated by TRPA1 activation is the release of somatostatin (SOM) and its action on sst4 receptors. In the present study analgesic effect of TRPA1 activation on primary sensory neurons by organic trisulfide compound dimethyl trisulfide (DMTS) presumably leading to SOM release was investigated. Opening of TRPA1 by DMTS in CHO cells was examined by patch-clamp and fluorescent Ca2+ detection. Ca2+ influx upon DMTS administration in trigeminal ganglion (TRG) neurons of TRPA1 receptor wild-type (WT) and knockout (KO) mice was detected by ratiometric Ca2+ imaging. SOM release from sensory nerves of murine skin was assessed by radioimmunoassay. Analgesic effect of DMTS in mild heat injury-induced mechanical hyperalgesia was examined by dynamic plantar aesthesiometry. Regulatory role of DMTS on deep body temperature (Tb) was measured by thermocouple thermometry with respirometry and by telemetric thermometry. DMTS produced TRPA1-mediated currents and elevated [Ca2+]i in CHO cells. Similar data were obtained in TRG neurons. DMTS released SOM from murine sensory neurons TRPA1-dependently. DMTS exerted analgesic effect mediated by TRPA1 and sst4 receptors. DMTS-evoked hypothermia and hypokinesis were attenuated in freely-moving TRPA1 KO animals. Our study has presented original evidence regarding analgesic action of DMTS which might be due to TRPA1-mediated SOM release from sensory neurons and activation of sst4 receptors. DMTS could be a novel analgesic drug candidate.
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Feasibility of Topical Applications of Natural High-Concentration Capsaicinoid Solutions in Patients with Peripheral Neuropathic Pain: A Retrospective Analysis. Pain Res Manag 2016; 2016:9703036. [PMID: 28115879 PMCID: PMC5223041 DOI: 10.1155/2016/9703036] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 11/23/2016] [Accepted: 12/08/2016] [Indexed: 11/17/2022]
Abstract
Background. Capsaicin, one of several capsaicinoid compounds, is a potent TRPV1 agonist. Topical application at high concentration (high concentration, >1%) induces a reversible disappearance of epidermal free nerve endings and is used to treat peripheral neuropathic pain (PNP). While the benefit of low-concentration capsaicin remains controversial, the 8%-capsaicin patch (Qutenza®, 2010, Astellas, Netherlands) has shown its effectiveness. This patch is, however, costly and natural high-concentration capsaicinoid solutions may represent a cheaper alternative to pure capsaicin. Methods. In this retrospective study, 149 patients were screened, 132 were included with a diagnosis of neuropathic pain, and eighty-four were retained in the final analyses (median age: 57.5 years [IQR25–75: 44.7–67.1], male/female: 30/54) with PNP who were treated with topical applications of natural high-concentration capsaicinoid solutions (total number of applications: 137). Indications were postsurgical PNP (85.7%) and nonsurgical PNP (14.3%) (posttraumatic, HIV-related, postherpetic, and radicular PNP). Objectives. To assess the feasibility of topical applications of natural high-concentration capsaicinoid solutions for the treatment of PNP. Results. The median treated area was 250 cm2 [IQR25–75: 144–531]. The median amount of capsaicinoids was 55.1 mg [IQR25–75: 28.7–76.5] per plaster and the median concentration was 172.3 μg/cm2 [IQR25–75: 127.6–255.2]. Most patients had local adverse effects on the day of treatment, such as mild to moderate burning pain and erythema. 13.6–19.4% of the patients experienced severe pain or erythema. Following treatment, 62.5% of patients reported a lower pain intensity or a smaller pain surface, and 35% reported a sustained pain relief lasting for at least 4 weeks. Conclusion. Analgesic topical treatment with natural high-concentration capsaicinoid is feasible and may represent a low cost alternative to alleviate PNP in clinical practice.
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