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Byers MR, Calkins DF. Trigeminal sensory nerve patterns in dentine and their responses to attrition in rat molars. Arch Oral Biol 2021; 129:105197. [PMID: 34146928 DOI: 10.1016/j.archoralbio.2021.105197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 06/03/2021] [Accepted: 06/08/2021] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Our goal was to define trigeminal nerve ending quantities and patterns in rat molar dentine, their responses to attrition (tooth wear), and their associated odontoblasts and connections with pulpal plexuses. DESIGN Trigeminal ganglia were labeled for axonal transport of 3H-proteins to dentinal nerve endings in male rats (3-13 months old). Autoradiography detected radio-labeled dentinal tubules as indicators of nerve ending locations. Quantitative morphometry was done (ANOVA, t-tests), and littermates were compared for attrition and innervation. RESULTS There were six dentinal patterns, only two of which had an associated neural plexus of Raschkow and cell-free zone (Den-1, Den-2). Other nerves entered dentin from bush-like endings near elongated odontoblasts (Den-B), as single fibers (Den-X), as networks in predentine (PdN), or as single fibers in tertiary dentine at cusp tips (Den-S). There were at least 186,600 innervated dentinal tubules within the set of three right maxillary molars of the best-labeled rat, and similar densities were found in other rats. Attrition levels differed among cusps and in littermates (t-test p < 0.02-0.0001), but the matched right/left cusps per rat were similar. Innervations of tertiary and enamel-free dentine (Den-S, Den-X) were preserved in all rats. Den-B and Den-2 coronal patterns were unchanged unless displaced by dentinogenesis. Den-1 losses occurred in older cusps, while Den-2 patterns increased near cervical and intercuspal odontoblasts. CONCLUSIONS The extensive molar dentinal innervation had unique distributions per rat per cusp that depended on region (buccal, middle, palatal) and attrition, but only two of six patterns connected to a plexus of Raschkow.
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Affiliation(s)
- Margaret R Byers
- Department of Anesthesiology and Pain Medicine, Univ. Washington, Seattle, WA, 98195-6540, USA.
| | - Dianne F Calkins
- Department of Anesthesiology and Pain Medicine, Univ. Washington, Seattle, WA, 98195-6540, USA
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Liu Q, He H, Mai L, Yang S, Fan W, Huang F. Peripherally Acting Opioids in Orofacial Pain. Front Neurosci 2021; 15:665445. [PMID: 34017236 PMCID: PMC8129166 DOI: 10.3389/fnins.2021.665445] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/12/2021] [Indexed: 12/12/2022] Open
Abstract
The activation of opioid receptors by exogenous or endogenous opioids can produce significant analgesic effects in peripheral tissues. Numerous researchers have demonstrated the expression of peripheral opioid receptors (PORs) and endogenous opioid peptides (EOPs) in the orofacial region. Growing evidence has shown the involvement of PORs and immune cell-derived EOPs in the modulation of orofacial pain. In this review, we discuss the role of PORs and EOPs in orofacial pain and the possible cellular mechanisms involved. Furthermore, the potential development of therapeutic strategies for orofacial pain is also summarized.
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Affiliation(s)
- Qing Liu
- Department of Pediatric Dentistry, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Hongwen He
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China.,Department of Oral Anatomy and Physiology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Lijia Mai
- Department of Pediatric Dentistry, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Shengyan Yang
- Department of Pediatric Dentistry, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Wenguo Fan
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Fang Huang
- Department of Pediatric Dentistry, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
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Liu Q, Fan W, He H, Huang F. The role of peripheral opioid receptors in orofacial pain. Oral Dis 2020; 27:1106-1114. [PMID: 32437594 DOI: 10.1111/odi.13435] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 05/04/2020] [Accepted: 05/12/2020] [Indexed: 12/20/2022]
Abstract
Opioid receptors are widely distributed in the central and peripheral nervous systems and non-neuronal tissues. Numerous researchers have noted the pivotal role of peripheral opioid receptors (PORs) in analgesia. Accumulating evidence has shown the existence of PORs in the trigeminal nerve system, indicating that PORs may be involved in the modulation of orofacial pain. In this review, we summarise the recent evidence for the role of PORs in orofacial pain and discuss the possible cellular mechanisms.
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Affiliation(s)
- Qing Liu
- Department of Pediatric Dentistry, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Wenguo Fan
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Hongwen He
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China.,Department of Oral Anatomy and Physiology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Fang Huang
- Department of Pediatric Dentistry, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
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Nav1.7 via Promotion of ERK in the Trigeminal Ganglion Plays an Important Role in the Induction of Pulpitis Inflammatory Pain. BIOMED RESEARCH INTERNATIONAL 2019; 2019:6973932. [PMID: 31032358 PMCID: PMC6458889 DOI: 10.1155/2019/6973932] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 02/17/2019] [Indexed: 12/19/2022]
Abstract
The trigeminal ganglion (TG) refers to sensory neurons bodies that innervate the spinal cord and peripheral axons that innervate teeth. The tetrodotoxin-sensitive sodium (NA) channels (Nav1.7) play important roles in the pathophysiology of pain. In this study, we investigated the TG expression of Nav1.7 and extracellular signal-regulated kinase (ERK) in a rat model of pulpitis to explore the correlation between these channels and inflammatory pain. Pulpitis was confirmed by hematoxylin-eosin staining. In this study, we demonstrated that the reflex of rats to mechanical stimulation increases after pulp exposure and that the exposed rat molar pulp can upregulate the expression of Nav1.7 and ERK in the rat TG. Three days after rat pulp exposure, the expression levels of the two ion channels in the TG increased. TG target injection of PF04856264, a Nav1.7 inhibitor, dose-dependently increased the mechanical pain threshold and was able to inhibit ERK expression. TG target injection of PD98059, an ERK inhibitor, dose-dependently increased the mechanical pain threshold. These factors simultaneously resulted in the highest production. In this study, with the established link to inflammatory pain, we found that Nav1.7 and ERK both play important roles in the induction of inflammatory pain caused by pulpitis. We also found a correlation between the expression levels of Nav1.7 and ERK and the degree of inflammatory pain. Furthermore, ERK signaling pathways were promoted by the Nav1.7 in TG after pulpitis.
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Role of β-1,3-galactosyltransferase 2 in trigeminal neuronal sensitization induced by peripheral inflammation. Neuroscience 2017; 349:17-26. [DOI: 10.1016/j.neuroscience.2017.02.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 01/16/2017] [Accepted: 02/20/2017] [Indexed: 02/06/2023]
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Dynamic Regulation of Delta-Opioid Receptor in Rat Trigeminal Ganglion Neurons by Lipopolysaccharide-induced Acute Pulpitis. J Endod 2015; 41:2014-20. [DOI: 10.1016/j.joen.2015.09.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 08/31/2015] [Accepted: 09/14/2015] [Indexed: 12/17/2022]
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Uhrich E, Gautam M, Hatton J, Rowland K. Corticotropin releasing factor receptor expression in painful human dental pulp. Arch Oral Biol 2015; 60:1048-53. [PMID: 25924915 DOI: 10.1016/j.archoralbio.2015.03.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 02/03/2015] [Accepted: 03/18/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND Our objective was to correlate the presence of symptoms and dental pulp injury with the amount of a subtype of corticotropin releasing factor receptor (CRF-R) in symptomatic and asymptomatic human teeth. We hypothesized that patients diagnosed with irreversible pulpitis have increased levels of CRF-R. MATERIALS AND METHODS Dental history, diagnosis and radiographs were obtained from treatment records following extractions. Teeth were diagnosed as asymptomatic or symptomatic demonstrated by clinical and radiographic evaluation. Tissue sections from tooth pulp were immunoreacted with antibodies directed against CRF receptor 2 (CRF-R2) and neurofilament protein and examined to correlate CRF-R expression with pulpal diagnosis. RESULTS Our results indicated that symptomatic pulps demonstrated significantly greater expression of CRF-R2. The increased expression was localized on distinct cellular profiles throughout the pulp and was not directly correlated with neurofilament expression. CONCLUSIONS Our findings suggest that the analgesic effects of endogenously produced CRF may be enhanced via upregulation of CRF-R2 expression, and may explain the occurrence of reduced pain symptoms in some patients with irreversible pulpitis. The application of CRF-R agonists may be a feasible strategy in reducing pain associated with irreversible pulpitis.
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Affiliation(s)
- Elizabeth Uhrich
- Southern Illinois University, School of Dental Medicine, 2800 College Avenue, Alton, IL 62002, United States
| | - Medha Gautam
- Southern Illinois University, School of Dental Medicine, 2800 College Avenue, Alton, IL 62002, United States
| | - John Hatton
- Center for Advanced Dental Education, Saint Louis University, St. Louis, MO 63103, United States
| | - Kevin Rowland
- Southern Illinois University, School of Dental Medicine, 2800 College Avenue, Alton, IL 62002, United States.
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Rowan MP, Szteyn K, Doyle AP, Gomez R, Henry MA, Jeske NA. β-arrestin-2-biased agonism of delta opioid receptors sensitizes transient receptor potential vanilloid type 1 (TRPV1) in primary sensory neurons. Mol Pain 2014; 10:50. [PMID: 25085415 PMCID: PMC4131480 DOI: 10.1186/1744-8069-10-50] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 07/21/2014] [Indexed: 02/06/2023] Open
Abstract
Despite advances in understanding the signaling mechanisms involved in the development and maintenance of chronic pain, the pharmacologic treatment of chronic pain has seen little advancement. Agonists at the mu opioid receptor (MOPr) continue to be vital in the treatment of many forms of chronic pain, but side-effects limit their clinical utility and range from relatively mild, such as constipation, to major, such as addiction and dependence. Additionally, chronic activation of MOPr results in pain hypersensitivity known as opioid-induced hyperalgesia (OIH), and we have shown recently that recruitment of β-arrestin2 to MOPr, away from transient potential vanilloid eceptor type 1 (TRPV1) in primary sensory neurons contributes to this phenomenon. The delta opioid receptor (DOPr) has become a promising target for the treatment of chronic pain, but little is known about the effects of chronic activation of DOPr on nociceptor sensitivity and OIH. Here we report that chronic activation of DOPr by the DOPr-selective agonist, SNC80, results in the sensitization of TRPV1 and behavioral signs of OIH via β-arrestin2 recruitment to DOPr and away from TRPV1. Conversely, chronic treatment with ARM390, a DOPr-selective agonist that does not recruit β-arrestin2, neither sensitized TRPV1 nor produced OIH. Interestingly, the effect of SNC80 to sensitize TRPV1 is species-dependent, as rats developed OIH but mice did not. Taken together, the reported data identify a novel side-effect of chronic administration of β-arrestin2-biased DOPr agonists and highlight the importance of potential species-specific effects of DOPr agonists.
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Affiliation(s)
| | | | | | | | | | - Nathaniel A Jeske
- Departments of Oral and Maxillofacial Surgery, The University of Texas Health Science Center at San Antonio, MC 7908, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
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Gendron L, Mittal N, Beaudry H, Walwyn W. Recent advances on the δ opioid receptor: from trafficking to function. Br J Pharmacol 2014; 172:403-19. [PMID: 24665909 DOI: 10.1111/bph.12706] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 03/17/2014] [Accepted: 03/18/2014] [Indexed: 01/12/2023] Open
Abstract
UNLABELLED Within the opioid family of receptors, δ (DOPrs) and μ opioid receptors (MOPrs) are typical GPCRs that activate canonical second-messenger signalling cascades to influence diverse cellular functions in neuronal and non-neuronal cell types. These receptors activate well-known pathways to influence ion channel function and pathways such as the map kinase cascade, AC and PI3K. In addition new information regarding opioid receptor-interacting proteins, downstream signalling pathways and resultant functional effects has recently come to light. In this review, we will examine these novel findings focusing on the DOPr and, in doing so, will contrast and compare DOPrs with MOPrs in terms of differences and similarities in function, signalling pathways, distribution and interactions. We will also discuss and clarify issues that have recently surfaced regarding the expression and function of DOPrs in different cell types and analgesia. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.
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Affiliation(s)
- Louis Gendron
- Département de physiologie et biophysique, Institut de pharmacologie de Sherbrooke, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada
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Moustafa MA. Nebulized lidocaine alone or combined with fentanyl as a premedication to general anesthesia in spontaneously breathing pediatric patients undergoing rigid bronchoscopy. Paediatr Anaesth 2013. [PMID: 23190026 DOI: 10.1111/pan.12081] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Pediatric bronchoscopy is an intensely stimulating procedure that requires a deep level of anesthesia to prevent hemodynamic overstimulation and straining. Topical anesthesia of the airway may be a beneficial component of the anesthetic technique to achieve adequate depth without residual sedation. Experimental evidence suggests that in addition to its central effects, locally applied opioids elicit potent analgesic effects. METHODS Forty-five patients aged 1-6 years scheduled for rigid bronchoscopy for foreign body removal were selected and subjected preoperatively to a nebulizer setting according to its components patients were divided into three groups. Group A: Nebulized solution contains 4 mg·kg(-1) lidocaine 1%. Group B: Nebulized solution contains 4 mg·kg(-1) lidocaine 1% plus 2 μg·kg(-1) fentanyl. Group C: Nebulized solution contains 0.9% normal saline. Anesthesia was induced with 8% sevoflurane in 100% oxygen and maintained with continuous infusion of propofol 200 μg·kg(-1). Increments of 500 μg·kg(-1) propofol were given to the patient in case of straining or coughing. Patients were followed for the hemodynamics, the intraoperative difficulties, postoperative sedation score, time to full wakefulness and the postoperative complications. RESULTS The hemodynamic parameters were much more stable in the fentanyl group relative to the other two groups. Also, the incidence of intraoperative difficulties was less significantly evident among patients in the fentanyl group (As regards cough P(1) = 0.003, P(2) = 0.0001, As regards the need to manual ventilation P(1) = 0.037, P(2) = 0.001, As regards Propofol increments P(1) = 0.001, P(2) = 0.001 where P(1) refers to the fentanyl group relative to the lidocaine group, and P(2) refers to fentanyl group relative to the placebo group). The postoperative sedation score was significantly higher, and the time to full wakefulness was significantly prolonged among patients in the fentanyl group relative to the other groups (P = 0.0001). CONCLUSION It is concluded that preoperative nebulized fentanyl reduces the hemodynamic response to bronchoscopy and decreases the intraoperative coughing in response to surgical manipulation without significant side effects except prolonged time to full wakefulness of patients.
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Affiliation(s)
- Moustafa A Moustafa
- Anesthesia and Surgical Intensive Care, Faculty of medicine, Alexandria university, Alexandria, Egypt.
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Feng Y, He X, Yang Y, Chao D, Lazarus LH, Xia Y. Current research on opioid receptor function. Curr Drug Targets 2012; 13:230-46. [PMID: 22204322 DOI: 10.2174/138945012799201612] [Citation(s) in RCA: 197] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 08/09/2011] [Accepted: 08/12/2011] [Indexed: 12/11/2022]
Abstract
The use of opioid analgesics has a long history in clinical settings, although the comprehensive action of opioid receptors is still less understood. Nonetheless, recent studies have generated fresh insights into opioid receptor-mediated functions and their underlying mechanisms. Three major opioid receptors (μ-opioid receptor, MOR; δ-opioid receptor, DOR; and κ-opioid receptor, KOR) have been cloned in many species. Each opioid receptor is functionally sub-classified into several pharmacological subtypes, although, specific gene corresponding each of these receptor subtypes is still unidentified as only a single gene has been isolated for each opioid receptor. In addition to pain modulation and addiction, opioid receptors are widely involved in various physiological and pathophysiological activities, including the regulation of membrane ionic homeostasis, cell proliferation, emotional response, epileptic seizures, immune function, feeding, obesity, respiratory and cardiovascular control as well as some neurodegenerative disorders. In some species, they play an essential role in hibernation. One of the most exciting findings of the past decade is the opioid-receptor, especially DOR, mediated neuroprotection and cardioprotection. The upregulation of DOR expression and DOR activation increase the neuronal tolerance to hypoxic/ischemic stress. The DOR signal triggers (depending on stress duration and severity) different mechanisms at multiple levels to preserve neuronal survival, including the stabilization of homeostasis and increased pro-survival signaling (e.g., PKC-ERK-Bcl 2) and antioxidative capacity. In the heart, PKC and KATP channels are involved in the opioid receptor-mediated cardioprotection. The DOR-mediated neuroprotection and cardioprotection have the potential to significantly alter the clinical pharmacology in terms of prevention and treatment of life-threatening conditions like stroke and myocardial infarction. The main purpose of this article is to review the recent work done on opioids and their receptor functions. It shall provide an informative reference for better understanding the opioid system and further elucidation of the opioid receptor function from a physiological and pharmacological point of view.
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Affiliation(s)
- Yuan Feng
- Yale University School of Medicine, New Haven, CT, USA
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Abstract
OBJECTIVES Corneal damage causes severe pain. This study investigated whether peripheral opioid receptors are present in the human cornea and assessed the efficacy of topical fentanyl in patients with corneal erosion. METHODS Immunohistochemical staining experiments were performed to examine the presence of both mu and delta-receptors on peripheral nerve fibers within human corneal tissue. In a randomized, double-blind clinical trial dexpanthenol (n=20) or dexpanthenol plus 10 microg fentanyl (n=20) were topically applied every 4 hours to the eye of patients with a surgical intervention of corneal damage and subjective pain intensity was determined by a numerical rating scale. RESULTS Immunohistochemical staining identified peripheral nerve fibers in human cornea expressing both mu and delta-opioid receptors. In patients with corneal damage the ophthalmic intervention in local anesthesia decreased the subjective pain intensity significantly. At 4-hour intervals after the ophthalmic intervention, moderate pain intensity levels were not altered by the application of dexpanthenol with or without fentanyl. At 24 hours pain intensity dropped significantly, most likely owing to a natural decrease in pain, because the erosion was almost healed. DISCUSSION Both mu and delta-receptors are localized on nerve fibers within the cornea, which are accessible for topical opioid treatment. However, our formulation and dose of topical fentanyl in combination with dexpanthenol did not show any benefit in relieving pain from corneal erosion. Future studies are planned to determine the optimal protocol and dose of topical opioid treatment.
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Abstract
OBJECTIVE In this review, we explain our current understanding of the molecular basis for pain relief by capsaicin and other transient receptor potential vanilloid subfamily, member 1 (TRPV1) agonists. We summarize disease-related changes in TRPV1 expression and its implications for therapy and potential adverse effects. Last, we provide an overview of the current clinical uses of topical and injectable TRPV1 agonist preparations in both oncologic and nononcologic populations. METHOD Search of MEDLINE and other databases. RESULTS The capsaicin receptor TRPV1 is a polymodal nociceptor exhibiting a dynamic threshold of activation that could be lowered under inflammatory conditions. Consistent with this model, TRPV1 knock-out mice are devoid of post-inflammatory thermal hyperalgesia. TRPV1 desensitization of primary sensory neurons is a powerful approach to relieve symptoms of nociceptive behavior in animal models of chronic pain. However, over-the-counter capsaicin creams have shown moderate to poor analgesic efficacy. This is in part related to low dose, poor skin absorption, and compliance factors. Recently developed site-specific capsaicin therapy with high-dose patches and injectable preparations seem to be safe and reportedly provide long-lasting analgesia with rapid onset. CONCLUSIONS We argue that TRPV1 agonists and antagonists are not mutually exclusive but rather complimentary pharmacologic approaches for pain relief and we predict a "revival" for capsaicin and other TRPV1 agonists in the clinical management of pain associated with inflammation, metabolic imbalances (eg, diabetes), infections (HIV), and cancer, despite the current focus of the pharmaceutical industry on TRPV1 antagonists.
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Localized increases in corticotropin-releasing factor receptors in pulp after dental injury. J Endod 2007; 33:1319-24. [PMID: 17963955 DOI: 10.1016/j.joen.2007.08.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Revised: 08/03/2007] [Accepted: 08/04/2007] [Indexed: 11/22/2022]
Abstract
Corticotropin-releasing factor (CRF) binds to membrane-bound CRF receptors (CRF-Rs). Among the actions mediated by activated CRF-Rs is beta-endorphin (END) release from immune cells, increasing peripheral antinociception. For assessment of inflammatory regulation of CRF-R expression, rats underwent pulp exposure of left, first mandibular molars and recovered for 6 days. Control pulpal tissue consisted of contralateral, uninjured molars and left, first mandibular molars of uninjured animals. Pulp tissue specimens were incubated with antibodies directed against CRF-R (both isoforms), neurofilament, CD45, and END. We observed (1) increases in pulp CRF-R immunoreactivity after injury, (2) increased CRF-R immunoreactivity expressed in 3 distinct zones in relation to the injury, and (3) increased CD45 and END immunoreactivity in regions surrounding the pulpal abscess. CRF-Rs might provide an additional target for novel analgesics to treat pulpal pain.
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FRISTAD INGE, BLETSA ATHANASIA, BYERS MARGARET. Inflammatory nerve responses in the dental pulp. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1601-1546.2010.00247.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Szallasi A, Cortright DN, Blum CA, Eid SR. The vanilloid receptor TRPV1: 10 years from channel cloning to antagonist proof-of-concept. Nat Rev Drug Discov 2007; 6:357-72. [PMID: 17464295 DOI: 10.1038/nrd2280] [Citation(s) in RCA: 625] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The clinical use of TRPV1 (transient receptor potential vanilloid subfamily, member 1; also known as VR1) antagonists is based on the concept that endogenous agonists acting on TRPV1 might provide a major contribution to certain pain conditions. Indeed, a number of small-molecule TRPV1 antagonists are already undergoing Phase I/II clinical trials for the indications of chronic inflammatory pain and migraine. Moreover, animal models suggest a therapeutic value for TRPV1 antagonists in the treatment of other types of pain, including pain from cancer. We argue that TRPV1 antagonists alone or in conjunction with other analgesics will improve the quality of life of people with migraine, chronic intractable pain secondary to cancer, AIDS or diabetes. Moreover, emerging data indicate that TRPV1 antagonists could also be useful in treating disorders other than pain, such as urinary urge incontinence, chronic cough and irritable bowel syndrome. The lack of effective drugs for treating many of these conditions highlights the need for further investigation into the therapeutic potential of TRPV1 antagonists.
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Affiliation(s)
- Arpad Szallasi
- Department of Pathology, Monmouth Medical Center, Long Branch, New Jersey 07740, USA.
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Abstract
In this article, we review the key basic mechanisms associated with this phenomena and more recently identified mechanisms that are current areas of interest. Although many of these pain mechanisms apply throughout the body, we attempt to describe these mechanisms in the context of trigeminal pain.
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Affiliation(s)
- Michael A Henry
- Department of Endodontics, University of Texas Health Science Center at San Antonio School of Dentistry, Mail Code 7892, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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Rattan V, Arora S, Grover VK. Assessment of the effectiveness of peripheral administration of fentanyl with lidocaine in inflamed dentoalveolar tissues. Int J Oral Maxillofac Surg 2007; 36:128-31. [PMID: 17101259 DOI: 10.1016/j.ijom.2006.09.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2006] [Revised: 09/02/2006] [Accepted: 09/18/2006] [Indexed: 11/16/2022]
Abstract
Peripheral action of opioids for pain control, for which local inflammation has been shown to be crucial, is being increasingly used in clinical practice. The aim of this study was to evaluate the hypothesis that addition of fentanyl to lidocaine, when injected into inflamed dentoalveolar tissues, can improve the quality of analgesia during surgery. Seventy-one patients reporting with pain and tenderness in the maxillary tooth were assigned into the experimental (LAF) or control (LA) group in a prospective, randomized double-blind trial. The LAF group (n = 36) was injected submucosally with a mixture of 40 microg of fentanyl (0.8 ml) and 2% lidocaine hydrochloride with 1:200000 adrenaline (2 ml). In the LA group (n = 35) 0.9% of saline (0.8 ml) was added instead of fentanyl. The pain scores were recorded before injecting, 5 min after injection, and immediately after surgery using a visual analogue scale. The mean pain scores were not significantly different at all time intervals. Twelve patients in the LAF group (2.75+/-0.72 ml) and ten patients in the LA (2.90+/-0.70 ml) group required additional local anaesthetic to achieve pain control. In conclusion, there was no improvement in quality of intraoperative analgesia on addition of fentanyl to lidocaine in inflamed dentoalveolar tissues.
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Affiliation(s)
- V Rattan
- Unit of Oral and Maxillofacial Surgery, Oral Health Sciences Centre, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
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