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1.
J Orthop Surg Res ; 18(1): 2, 2023 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-36593515

RESUMO

BACKGROUND: Complex regional pain syndrome (CRPS) is a chronic condition following inciting events such as fractures or surgeries with sensorimotor and autonomic manifestations and poor prognosis. This review aimed to provide conclusive evidence about the sensory phenotype of CRPS based on quantitative sensory testing (QST) to understand the underlying pain mechanisms and guide treatment strategies. DATABASES: Eight databases were searched based on a previously published protocol. Forty studies comparing QST outcomes (thermal, mechanical, vibration, and electric detection thresholds, thermal, mechanical, pressure, and electric pain thresholds, wind-up ratio, mechanical pain sensitivity, allodynia, flare area, area after pinprick hyperalgesia, pleasantness after C-tactile stimulation, and pain ratings) in chronic CRPS (adults and children) versus healthy controls were included. RESULTS: From 37 studies (14 of low quality, 22 of fair quality, and 1 of good quality), adults with CRPS showed: (i) significant loss of thermal, mechanical, and vibration sensations, significant gain of thermal and mechanical pain thresholds, significant elevation of pain ratings, and no difference in wind-up ratio; (ii) significant reduction of pleasantness levels and increased area of pinprick hyperalgesia, in the affected limb. From three fair-quality studies, adolescents and children with CRPS showed loss of cold detection with cold hyperalgesia in the affected limb. There was moderate to substantial overall heterogeneity. CONCLUSION: Diffuse thermal and mechanical hypoesthesia with primary and secondary hyperalgesia, enhanced pain facilitation evidenced by increased area of pinprick hyperalgesia, and elevated pain ratings are dominant in adults with CRPS. Adolescents and children with CRPS showed less severe sensory abnormalities.


Assuntos
Síndromes da Dor Regional Complexa , Hiperalgesia , Humanos , Hiperalgesia/diagnóstico , Hiperalgesia/etiologia , Medição da Dor/métodos , Dor , Síndromes da Dor Regional Complexa/diagnóstico , Limiar da Dor/fisiologia
2.
Neuroreport ; 34(2): 108-115, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36608164

RESUMO

Irritable bowel syndrome (IBS) is characterized by gastrointestinal dysmotility and visceral hyperalgesia, and the impaired brain-gut axis is accepted as a crucial cause for the onset of IBS. The objective of this study is to investigate the effects of the adaptive changes in the central neural system induced by stress on IBS-like syndromes in rats. Long-term water avoidance stress (WAS) was used to prepare IBS animals. The changes in neuronal excitation and GABA expression were shown by immunohistochemistry. The mRNA and protein expressions of neurotransmitters were detected with Quantitative reverse-transcription PCR (qRT-PCR) and Enzyme-linked immunosorbent assay (ELISA). The intestinal transit time, fecal moisture content, and abdominal withdrawal reflex scores of rats were recorded to monitor intestinal motility and visceral hyperalgesia. In the WAS-treated rats with enhanced intestinal motility and visceral hypersensitivity, more GABAergic projections were found in the paraventricular nucleus (PVN) of the hypothalamus, which inhibited the firing rate of neurons and decreased the expression of oxytocin. Exogenous oxytocin improved gut motility and decreased AWR scores. The inhibition of oxytocin by the adaptive GABAergic projection in the PVN might be an important mediator of IBS, which indicates a potential novel therapeutic target.


Assuntos
Síndrome do Intestino Irritável , Ratos , Animais , Síndrome do Intestino Irritável/tratamento farmacológico , Núcleo Hipotalâmico Paraventricular/metabolismo , Ocitocina , Hiperalgesia , Fezes
3.
Pain Pract ; 23(1): 41-62, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36617189

RESUMO

OBJECTIVE: To investigate whether sensitivity to movement-evoked pain (SMEP), central sensitivity symptom burden, and quantitative sensory testing (QST) outcomes differ between healthy controls and people with chronic shoulder pain. METHODS: People with chronic shoulder pain (n = 39) and healthy controls (n = 26) completed validated questionnaires measuring demographic, pain characteristics, psychological factors, social support, sleep quality, central sensitivity inventory (CSI), and physical activity levels. A blinded assessor administered QST measuring pressure pain threshold, temporal summation, conditioned pain modulation, and cold hyperalgesia. All participants performed repeated lifting of weighted canisters and reported severity of pain over successive lifts of the weighted canisters. Between-group differences in the QST, SMEP and CSI scores were investigated. Demographic and psychosocial variables were adjusted in the analyses. RESULTS: Dynamic mechanical allodynia, mechanical temporal summation, movement-evoked pain scores, SMEP index, and CSI scores were significantly (p ≤ 0.05) higher in the chronic shoulder pain group than in healthy controls. A significant proportion of people with chronic shoulder pain presented with pro-nociceptive profiles and experienced higher pain severity, interference, and disability. CONCLUSIONS: People with chronic shoulder pain displayed symptoms and signs of central sensitization. Future research should investigate the predictive role of central sensitization on clinical outcomes in shoulder pain.


Assuntos
Dor Crônica , Dor de Ombro , Humanos , Sensibilização do Sistema Nervoso Central , Dor Crônica/diagnóstico , Dor Crônica/psicologia , Estudos Transversais , Hiperalgesia/psicologia , Nociceptividade , Medição da Dor , Limiar da Dor/fisiologia , Estudos de Casos e Controles
4.
Blood ; 141(2): 132-133, 2023 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-36633888
5.
Neurosci Lett ; 796: 137054, 2023 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-36610589

RESUMO

Treatment of chronic orofacial pain remains a major therapeutic challenge despite available medications. Melanocortins have been implicated in pathologic pain. Intrathecal administration of MC4R antagonists has been shown to alleviate neuropathic pain (NP) in male rats. However, intrathecal delivery is very invasive and requires surgeon's intervention. Intra-nasal rout offers a non-invasive drug delivery method that can be self-administered making it very attractive clinically. In this study, we investigated the effects of intra-nasally delivered MC4R antagonist (HS014) on trigeminal neuropathic pain (TNP) in male and female rats. We also measured the MC4R protein levels in the trigeminal ganglia (TG) and infraorbital nerve (ION) of rats. We used ION chronic constriction injury (ION-CCI) to induce TNP in rats. We used von Frey and pinprick assays to measure the development of hypersensitivity in the face following ION-CCI. At 22 days post-ION-CCI, we delivered HS014 intra-nasally to measure its effects on TNP in rats. We used enzyme linked immunosorbent assay to measure MC4R protein levels in the TG and ION. ION-CCI resulted in a significant increase of MC4R protein levels in the ipsilateral TG and ION of male and female rats. Intra-nasal delivered HS014 resulted in a significant reduction of ION-CCI induced hypersensitivity in male and female rats. These results demonstrate that intranasal delivery of MC4R antagonist alleviated TNP in male and female rats and suggest that such treatment could be beneficial therapeutically for individuals with chronic NP.


Assuntos
Neuralgia , Neuralgia do Trigêmeo , Feminino , Ratos , Masculino , Animais , Hiperalgesia/tratamento farmacológico , Receptor Tipo 4 de Melanocortina , Neuralgia do Trigêmeo/tratamento farmacológico , Neuralgia do Trigêmeo/metabolismo , Neuralgia/tratamento farmacológico , Neuralgia/metabolismo , Dor Facial/tratamento farmacológico
6.
J Ethnopharmacol ; 305: 116065, 2023 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-36587876

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Neuropathic pain can be debilitating and drastically affects the quality of life of those patients suffering from this condition. The Chinese herb Notopterygium incisum Ting ex H.T. Chang has long been used to disperse "cold". One under examined clinical feature of neuropathic pain is sensitivity to cold. Patients with neuropathic pain or arthritis usually describe a worsening of symptoms during the winter. AIMS OF THIS STUDY: We proposed to test the hypothesis that Notopterygium incisum has a positive effect on the cold sensitivity found in neuropathic pain. MATERIALS AND METHODS: In this study, we established chronic constriction injury (CCI) and cisplatin induced neuropathic pain mice models. Behavioral experiments and physiological examination methods were employed to investigate the effect of water extract of Notopterygium incisum (WN) on cold pain. RESULTS: We found WN reduced cold pain and allyl isothiocyanate (AITC, Transient Receptor Potential A1 (TRPA1 agonist)) induced pain. WN inhibited AITC induced calcium response in HEK 293 cells transfected with TRPA1 and dorsal root ganglion (DRG) neurons. Moreover, we found that oral administration of WN reduced cold allodynia and mechanical allodynia caused by (CCI) and cisplatin induced neuropathic pain. We also observed that oral administration of WN decreased responses to AITC in DRG neurons as well as expression of TRPA1 in the WN treated neuropathic pain model. CONCLUSIONS: The present study provide evidence that Notopterygium incisum alleviates cold allodynia in CCI and cisplatin induced neuropathic pain mouse models. WN alleviated neuropathic pain induced cold allodynia via directly modulating TRPA1. Our findings identify WN as a promising candidate for treating neuropathic pain that highlights a new mechanism of Notopterygium incisum on 'disperse cold'.


Assuntos
Hiperalgesia , Neuralgia , Camundongos , Humanos , Animais , Hiperalgesia/tratamento farmacológico , Hiperalgesia/metabolismo , Cisplatino , Células HEK293 , Qualidade de Vida , Canal de Cátion TRPA1/metabolismo , Neuralgia/tratamento farmacológico , Neuralgia/metabolismo , Gânglios Espinais/metabolismo
7.
Neurosci Lett ; 796: 137064, 2023 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-36638955

RESUMO

Neuropathic pain has become a global public problem and health burden. Pharmacological interventions are the primary treatment, but the drug cure rate is low with side effects. There is an urgent need to develop novel treatment approaches. High frequency electrical stimulation (KHES) has been widely applied in clinical analgesia. However, its mechanism is poorly understood. In this study, datasets related to neuropathic pain were obtained from the GEO database. The differentially expressed genes (DEGs) and key genes were analyzed through functional enrichment analysis, showing that most of the pathways involve the inflammation. The MyD88 and NFκB pathways were further studied. KHES significantly alleviated mechanical and thermal allodynia in chronic constriction injury of the sciatic nerve mice. KHES also inhibited the increase in Myd88 and p-NFκB expression. The administration of NFκB pathway activator partly reversed the antinociceptive effects of KHES, and NFκB pathway inhibitor achieved analgesic effects similar to those of KHES. Therefore, KHES might be a novel intervention for the treatment of neuropathic pain.


Assuntos
Hiperalgesia , Neuralgia , Ratos , Camundongos , Animais , Hiperalgesia/tratamento farmacológico , Fator 88 de Diferenciação Mieloide/metabolismo , Ratos Sprague-Dawley , Constrição , Nervo Isquiático/lesões , Neuralgia/metabolismo , NF-kappa B/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo
8.
Cells ; 12(2)2023 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-36672219

RESUMO

Drugs enhancing the availability of noradrenaline are gaining prominence in the therapy of chronic neuropathic pain. However, underlying mechanisms are not well understood, and research has thus far focused on α2-adrenergic receptors and neuronal excitability. Adrenergic receptors are also expressed on glial cells, but their roles toward antinociception are not well deciphered. This study addresses the contribution of ß2-adrenergic receptors (ß2-ARs) to the therapeutic modulation of neuropathic pain in mice. We report that selective activation of ß2-ARs with Formoterol inhibits pro-inflammatory signaling in microglia ex vivo and nerve injury-induced structural remodeling and functional activation of microglia in vivo. Systemic delivery of Formoterol inhibits behaviors related to neuropathic pain, such as mechanical hypersensitivity, cold allodynia as well as the aversive component of pain, and reverses chronically established neuropathic pain. Using conditional gene targeting for microglia-specific deletion of ß2-ARs, we demonstrate that the anti-allodynic effects of Formoterol are primarily mediated by microglia. Although Formoterol also reduces astrogliosis at late stages of neuropathic pain, these functions are unrelated to ß2-AR signaling in microglia. Our results underline the value of developing microglial ß2-AR agonists for relief from neuropathic pain and clarify mechanistic underpinnings.


Assuntos
Microglia , Neuralgia , Camundongos , Animais , Neuralgia/tratamento farmacológico , Hiperalgesia/tratamento farmacológico , Receptores Adrenérgicos , Fumarato de Formoterol/farmacologia , Fumarato de Formoterol/uso terapêutico
9.
Int J Mol Sci ; 24(2)2023 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-36674439

RESUMO

Cocaine- and amphetamine-regulated transcript (CART) peptides are involved in several physiological and pathological processes, but their mechanism of action is unrevealed due to the lack of identified receptor(s). We provided evidence for the antihyperalgesic effect of CART(55-102) by inhibiting dipeptidyl-peptidase 4 (DPP4) in astrocytes and consequently reducing neuroinflammation in the rat spinal dorsal horn in a carrageenan-evoked inflammation model. Both naturally occurring CART(55-102) and CART(62-102) peptides are present in the spinal cord. CART(55-102) is not involved in acute nociception but regulates spinal pain transmission during peripheral inflammation. While the full-length peptide with a globular motif contributes to hyperalgesia, its N-terminal inhibits this process. Although the anti-hyperalgesic effects of CART(55-102), CART(55-76), and CART(62-76) are blocked by opioid receptor antagonists in our inflammatory models, but not in neuropathic Seltzer model, none of them bind to any opioid or G-protein coupled receptors. DPP4 interacts with Toll-like receptor 4 (TLR4) signalling in spinal astrocytes and enhances the TLR4-induced expression of interleukin-6 and tumour necrosis factor alpha contributing to inflammatory pain. Depending on the state of inflammation, CART(55-102) is processed in the spinal cord, resulting in the generation of biologically active isoleucine-proline-isoleucine (IPI) tripeptide, which inhibits DPP4, leading to significantly decreased glia-derived cytokine production and hyperalgesia.


Assuntos
Hiperalgesia , Receptor 4 Toll-Like , Ratos , Animais , Hiperalgesia/metabolismo , Dipeptidil Peptidase 4 , Isoleucina , Nociceptividade , Dor/metabolismo , Fragmentos de Peptídeos/farmacologia , Medula Espinal/metabolismo , Inflamação/metabolismo
10.
BMC Anesthesiol ; 23(1): 22, 2023 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-36639747

RESUMO

PURPOSE: The simultaneous use of drugs with different mechanisms of analgesic action is a strategy for achieving effective pain control while minimizing dose-related side effects. Choline was described to potentiate the analgesic action of parecoxib sodium at small doses in several inflammatory pain models. However, these findings are still very limited, and more associated data are required to confirm the effectiveness of the combined choline and parecoxib sodium therapy against inflammatory pain. METHODS: Adult rats were randomly divided into 9 groups (N = 6/group). The sham surgery group received an intraperitoneal (i.p.) injection of saline. Rats with chronic constriction injury (CCI) of the sciatic nerve received saline, choline (cho, 6, 12 and 24 mg/kg), parecoxib sodium (pare, 3, 6, and 12 mg/kg), or a combination of choline 6 mg/kg and parecoxib sodium 3 mg/kg. Mechanical and heat pain thresholds were measured at 30 min after drug treatment at Days 3, 5, 7, 10, and 14 after CCI. Another 30 rats were divided into 5 groups (N = 6/group): the sham, CCI + saline, CCI + cho-6 mg/kg, CCI + pare-3 mg/kg, and CCI + cho-6 mg/kg + pare-3 mg/kg groups. After repeated drug treatment for 7 days, five rats were randomly selected from each group, and the lumbar dorsal root ganglia (DRGs) (L4-6) were harvested for western blot analysis. RESULTS: Choline significantly attenuated mechanical and heat hypersensitivity in CCI rats at 12 and 24 mg/kg doses (P < 0.05) but was not effective at the 6 mg/kg dose. Parecoxib sodium exerted significant pain inhibitory effects at the 6 and 12 mg/kg doses (P < 0.05) but not at the 3 mg/kg dose. Combining a low dose of choline (6 mg/kg) and parecoxib sodium (3 mg/kg) produced significant pain inhibition in CCI rats and reduced the expression of high mobility group protein 1 (HMGB1) and nuclear factor-kappa Bp65 (NF-κBp65) in L4-6 DRGs. CONCLUSION: 1. In a rat model of chronic neuropathic pain (CCI), at a certain dose, choline or parecoxib sodium can alleviate mechanical pain and thermal hyperalgesia caused by CCI. 2. The combination of choline and parecoxib sodium in nonanalgesic doses can effectively relieve neuropathic pain, and its mechanism may be related to the inhibition of the high mobility group protein 1 (HMGB1)/Toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NF-κB) pathway.


Assuntos
Colina , Isoxazóis , Neuralgia , Animais , Ratos , Analgésicos/farmacologia , Analgésicos/uso terapêutico , Constrição , Proteína HMGB1 , Hiperalgesia/tratamento farmacológico , Hiperalgesia/metabolismo , Neuralgia/tratamento farmacológico , Neuralgia/etiologia , Ratos Sprague-Dawley , Nervo Isquiático , Colina/farmacologia , Isoxazóis/farmacologia
11.
Molecules ; 28(2)2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36677929

RESUMO

Arthroplasty is an orthopedic surgical procedure that replaces a dysfunctional joint by an orthopedic prosthesis, thereby restoring joint function. Upon the use of the joint prosthesis, a wearing process begins, which releases components such as titanium dioxide (TiO2) that trigger an immune response in the periprosthetic tissue, leading to arthritis, arthroplasty failure, and the need for revision. Flavonoids belong to a class of natural polyphenolic compounds that possess antioxidant and anti-inflammatory activities. Hesperidin methyl chalcone's (HMC) analgesic, anti-inflammatory, and antioxidant effects have been investigated in some models, but its activity against the arthritis caused by prosthesis-wearing molecules, such as TiO2, has not been investigated. Mice were treated with HMC (100 mg/kg, intraperitoneally (i.p.)) 24 h after intra-articular injection of 3 mg/joint of TiO2, which was used to induce chronic arthritis. HMC inhibited mechanical hyperalgesia, thermal hyperalgesia, joint edema, leukocyte recruitment, and oxidative stress in the knee joint (alterations in gp91phox, GSH, superoxide anion, and lipid peroxidation) and in recruited leukocytes (total reactive oxygen species and GSH); reduced patellar proteoglycan degradation; and decreased pro-inflammatory cytokine production. HMC also reduced the activation of nociceptor-sensory TRPV1+ and TRPA1+ neurons. These effects occurred without renal, hepatic, or gastric damage. Thus, HMC reduces arthritis triggered by TiO2, a component released upon wearing of prosthesis.


Assuntos
Artrite , Chalconas , Hesperidina , Camundongos , Animais , Nociceptores/metabolismo , Chalconas/uso terapêutico , Inflamação/tratamento farmacológico , Inflamação/metabolismo , Artrite/tratamento farmacológico , Estresse Oxidativo , Antioxidantes/farmacologia , Anti-Inflamatórios/farmacologia , Hiperalgesia/tratamento farmacológico , Citocinas/metabolismo
12.
J Neurosci Methods ; 386: 109783, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36610617

RESUMO

Pharmacological assays based on the measurement of nociceptive responses in laboratory animals are a fundamental tool to assess analgesic strategies. During our experience with this type of experiments, we have been repeatedly challenged by different concerns related to their interpretation or relevance. Although these subjects are frequently discussed in our lab, they do not usually find a place in research articles with original data, in which the focus on results seems mandatory. In the present manuscript we try to discuss as central issues some of these aspects that often cross transversally our research. We have gathered them in five topics inspired by the results obtained in our laboratory. The two initial sections are devoted to the influence of the behavioral method used to assess nociception on the results achieved, as well as to the possibility that data may be more easily accepted when obtained with standard methods than with alternative ones. The third topic is related to the difficulties encountered when working with a molecule that may evoke dual effects, acting as pronociceptive or antinociceptive depending on the dose. The fourth point deals with the situation in which a particular hyperalgesic reaction is related to several molecules but the single inhibition of only one of them can completely prevent it. Finally, the last issue is addressed to comment the impact in the progress of pain research of experiments performed in animal models of pathological settings.


Assuntos
Hiperalgesia , Dor , Animais , Medição da Dor , Analgésicos/farmacologia
13.
Sci Adv ; 9(4): eade7002, 2023 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-36706180

RESUMO

Microglia are important mediators of neuroinflammation, which underlies neuropathic pain. However, the molecular checkpoints controlling microglial reactivity are not well-understood. Here, we investigated the role of Orai1 channels for microglia-mediated neuroinflammation following nerve injury and find that deletion of Orai1 in microglia attenuates Ca2+ signaling and the production of inflammatory cytokines by proalgesic agonists. Conditional deletion of Orai1 attenuated microglial proliferation in the dorsal horn, spinal cytokine levels, and potentiation of excitatory neurotransmission following peripheral nerve injury. These cellular effects were accompanied by mitigation of pain hyperalgesia in microglial Orai1 knockout mice. A small-molecule Orai1 inhibitor, CM4620, similarly mitigated allodynia in male mice. Unexpectedly, these protective effects were not seen in female mice, revealing sexual dimorphism in Orai1 regulation of microglial reactivity and hyperalgesia. Together, these findings indicate that Orai1 channels are key regulators of the sexually dimorphic role of microglia for the neuroinflammation that underlies neuropathic pain.


Assuntos
Microglia , Neuralgia , Camundongos , Masculino , Feminino , Animais , Microglia/metabolismo , Hiperalgesia/genética , Doenças Neuroinflamatórias , Neuralgia/genética , Camundongos Knockout , Citocinas/metabolismo , Medula Espinal , Proteína ORAI1/genética
14.
J Vis Exp ; (191)2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-36688541

RESUMO

The tibial neuroma transposition (TNT) is a rat model in which allodynia at the neuroma site (tibial nerve) can be independently evaluated from allodynia at the plantar surface of the hind paw innervated by the intact sural nerve. This TNT model is suitable to test therapies for neuroma pain, such as the potential superiority of certain surgical therapies that are already used in the clinic, or to evaluate new drugs and their effect on both pain modalities in the same animal. In this model, a distal lesion (neurotmesis) is made in the tibial nerve, and the proximal nerve end is transposed and fixed subcutaneously and pretibially to enable assessments of the neuroma site with a 15 g Von Frey monofilament. To assess allodynia over the sural nerve, Von Frey monofilaments can be used via the up-down method on the plantar lateral region of the hind paw. After cutting the tibial nerve, mechanical hypersensitivity develops at the neuroma site within 1 week after surgery and persists at least until 12 weeks after surgery. Allodynia at the sural innervated plantar surface develops within 3 weeks after surgery compared to the contralateral limb. At 12 weeks, a neuroma forms on the proximal end of the severed tibial nerve, indicated by dispersion and swirling of axons. For the TNT model surgery, multiple critical (micro)surgical steps need to be followed, and some surgery practice under terminal anesthesia is advised. Compared to other neuropathic pain models, such as the spared nerve injury model, allodynia over the neuroma site can be independently tested from sural nerve hypersensitivity in the TNT model. However, the neuroma site can be tested only in rats, not in mice. The tips and directions provided in this protocol can help research groups working on pain successfully implement the TNT model in their facility.


Assuntos
Neuralgia , Neuroma , Ratos , Camundongos , Animais , Hiperalgesia/tratamento farmacológico , Modelos Animais de Doenças , Nervo Tibial/cirurgia , Neuroma/etiologia , Neuroma/cirurgia
15.
In Vivo ; 37(1): 132-142, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36593019

RESUMO

BACKGROUND/AIM: The ectopic pain associated with inferior alveolar nerve (IAN) injury has been reported to involve macrophage expression in the trigeminal ganglion (TG). However, the effect of age-related changes on this abnormal pain conditions are still unknown. This study sought to clarify the involvement of age-related changes in macrophage expression and phenotypic conversion in the TG and how these changes enhance ectopic mechanical allodynia after IAN transection (IANX). MATERIALS AND METHODS: We used senescence-accelerated mouse (SAM)-prone 8 (SAMP8) and SAM-resistance 1 (SAMR1) mice, which are commonly used to study ageing-related changes. Mechanical stimulation was applied to the whisker pad skin under light anaesthesia; the mechanical head withdrawal threshold (MHWT) was measured for 21 d post-IANX. We subsequently counted the numbers of Iba1 (macrophage marker)-immunoreactive (IR) cells, Iba1/CD11c (M1-like inflammatory macrophage marker)-co-IR cells, and Iba1/CD206 (M2-like anti-inflammatory macrophage marker)-co-IR cells in the TG innervating the whisker pad skin. After continuous intra-TG administration of liposomal clodronate Clophosome®-A (LCCA) to IANX-treated SAMP8-mice, the MHWT values of the whisker pad skin were examined. RESULTS: Five days post-IANX, the MHWT had significantly decreased in SAMP8 mice compared to SAMR1-mice. Iba1-IR and Iba1/CD11c-co-IR cell counts were significantly increased in SAMP8 mice compared to SAMR1 mice 5 d post-IANX. LCCA administration significantly restored MHWT compared to control-LCCA administration. CONCLUSION: Ectopic mechanical allodynia of whisker pad skin after IANX is exacerbated by ageing, which involves increases in M1-like inflammatory macrophages in the TG.


Assuntos
Hiperalgesia , Traumatismos do Nervo Trigêmeo , Ratos , Camundongos , Animais , Ratos Sprague-Dawley , Hiperalgesia/complicações , Hiperalgesia/metabolismo , Gânglio Trigeminal/metabolismo , Traumatismos do Nervo Trigêmeo/complicações , Traumatismos do Nervo Trigêmeo/metabolismo , Dor Facial/complicações , Dor Facial/metabolismo , Nervo Mandibular/metabolismo , Macrófagos/metabolismo
16.
PLoS One ; 18(1): e0280579, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36649306

RESUMO

A frequently used paradigm to quantify endogenous pain modulation is offset analgesia, which is defined as a disproportionate large reduction in pain following a small decrease in a heat stimulus. The aim of this study was to determine whether suggestion influences the magnitude of offset analgesia in healthy participants. A total of 97 participants were randomized into three groups (hypoalgesic group, hyperalgesic group, control group). All participants received four heat stimuli (two constant trials and two offset trials) to the ventral, non-dominant forearm while they were asked to rate their perceived pain using a computerized visual analogue scale. In addition, electrodermal activity was measured during each heat stimulus. Participants in both intervention groups were given a visual and verbal suggestion about the expected pain response in an hypoalgesic and hyperalgesic manner. The control group received no suggestion. In all groups, significant offset analgesia was provoked, indicated by reduced pain ratings (p < 0.001) and enhanced electrodermal activity level (p < 0.01). A significant group difference in the magnitude of offset analgesia was found between the three groups (F[2,94] = 4.81, p < 0.05). Participants in the hyperalgesic group perceived significantly more pain than the hypoalgesic group (p = 0.031) and the control group (p < 0.05). However, the electrodermal activity data did not replicate this trend (p > 0.05). The results of this study indicate that suggestion can be effective to reduce but not increase endogenous pain modulation quantified by offset analgesia in healthy participants.


Assuntos
Analgesia , Dor , Humanos , Dor/psicologia , Analgesia/métodos , Manejo da Dor/métodos , Hiperalgesia , Medição da Dor , Hipestesia
17.
Pain ; 164(2): e121, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36638312
18.
Sci Rep ; 13(1): 489, 2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36627362

RESUMO

Posterior hypothalamus (PH), an important part of the descending pain processing pathway, has been found to be activated in trigeminal autonomic cephalalgias. However, there are very few studies conducted and information regarding its implications in trigeminal neuropathic pain (TNP). Therefore, we aimed to ascertain whether optogenetic inhibition of PH could affect the outcomes of a chronic constriction injury in the infraorbital nerve (CCI-ION) rat model. Animals were divided into the TNP animal, sham, and naive-control groups. CCI-ION surgery was performed to mimic TNP symptoms, and the optogenetic or null virus was injected into the ipsilateral PH. In vivo single-unit extracellular recordings were obtained from both the ipsilateral ventrolateral periaqueductal gray (vlPAG) and contralateral ventral posteromedial (VPM) thalamus in stimulation "OFF" and "ON" conditions. Alterations in behavioral responses during the stimulation-OFF and stimulation-ON states were examined. We observed that optogenetic inhibition of the PH considerably improved behavioral responses in TNP animals. We found increased and decreased firing activity in the vlPAG and VPM thalamus, respectively, during optogenetic inhibition of the PH. Inhibiting PH attenuates trigeminal pain signal transmission by modulating the vlPAG and trigeminal nucleus caudalis, thereby providing evidence of the therapeutic potential of PH in TNP management.


Assuntos
Neuralgia , Neuralgia do Trigêmeo , Ratos , Animais , Ratos Sprague-Dawley , Optogenética , Neuralgia/terapia , Neuralgia/metabolismo , Hipotálamo Posterior/metabolismo , Hiperalgesia/metabolismo
19.
Brain Res ; 1798: 148154, 2023 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-36335995

RESUMO

Painmanagement after oral surgeries is essential to enhance recovery, reduce negative outcomes and improve the experience of the patient. Naltrexone (NTX) is a non-selective opioid receptor antagonist that has been shown to modulate neuro-inflammation when employed in low to ultra-low doses. In addition, ultra-low dose naltrexone (ULDN) has been shown to potentiate opioids' analgesia and to have opioid-sparing effects. Herein it was investigated the effect of ULDN in a model of postoperative orofacial pain in rats, and it was tested the hypothesis that blockade of TLR4-signalling pathway contributes to its antinociceptive effect. Systemic NTX reduced heat hyperalgesia in female rats and heat and mechanical hyperalgesia in male rats after incision surgery. Combined treatment with NTX and morphine, both at ineffective doses, resulted in a significant reduction of heat hyperalgesia in male rats. NTX injection at the incision site failed to change heat hyperalgesia, but injection at the trigeminal ganglion (TG) or subnucleus caudalis (Sp5C) caused a significant reduction in heat hyperalgesia. At these sites, blockade of TLR4 impeded NTX effect. Lipopolysaccharide (LPS) injection in the intraoral mucosa resulted in facial heat hyperalgesia an increase in IL-1ß levels in the TG, which were reduced by systemic NTX. Stimulation of macrophages with LPS resulted in increase of nitric oxide, IL-1ß and CXCL-2 levels which were reduced by NTX. Altogether, these results provide evidence for an antinociceptive effect of ULDN in postoperative orofacial pain and suggest that blockade of TLR4 and downstream signaling pathway contribute to its effect.


Assuntos
Hiperalgesia , Naltrexona , Masculino , Feminino , Ratos , Animais , Naltrexona/farmacologia , Hiperalgesia/tratamento farmacológico , Hiperalgesia/metabolismo , Receptor 4 Toll-Like/metabolismo , Lipopolissacarídeos/uso terapêutico , Analgésicos Opioides/uso terapêutico , Dor Facial/tratamento farmacológico , Dor Pós-Operatória/tratamento farmacológico
20.
Exp Neurol ; 359: 114232, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36179876

RESUMO

Chemotherapy-induced neuropathic pain is a serious clinical problem and one of the major side effects in cancer treatment. The endocannabinoid system (ECS) plays a crucial role in regulating pain neurotransmission, and changes in the expression of different components of the ECS have been reported in experimental models of persistent pain. In addition, sex differences have been observed in ECS regulation and function. The aim of our study was to evaluate whether administration of oxaliplatin, a neurotoxic antineoplastic agent, induced changes in the expression of ECS components in peripheral and central stations of the pain pathway, and if those changes exhibited sexual dimorphism. Adult male and female rats were injected with oxaliplatin or saline, and mechanical and cold hypersensitivity and allodynia were evaluated using Von Frey and Choi Tests. The mRNA levels corresponding to cannabinoid receptors (CB1, CB2), cannabinoid-related receptors (GPR55, 5HT1A, TRPV1) and to the main enzymes involved in the synthesis (DAGL, DAGL, NAPE-PLD) and degradation (MGL, FAAH) of endocannabinoids were assessed in lumbar dorsal root ganglia (DRGs) and spinal cord by using real time RT-PCR. In addition, the levels of the main endocannabinoids, 2-arachidonoylglycerol (2-AG) and anandamide (AEA), were evaluated using commercial ELISA kits. Oxaliplatin administration induced the development of mechanical and cold hypersensitivity and allodynia in male and female animals. Oxaliplatin also induced early and robust changes in the expression of several components of the ECS in DRGs. A marked upregulation of CB1, CB2, 5HT1A and TRPV1 was detected in both sexes. Interestingly, while DAGL mRNA levels remained unchanged, DAGL was downregulated in male and upregulated in female rats. Finally, MGL and NAPE-PLD showed increased levels only in male animals, while FAAH resulted upregulated in both sexes. In parallel, reduced 2-AG and AEA levels were detected in DRGs from male or female rats, respectively. In the lumbar spinal cord, only TRPV1 mRNA levels were found to be upregulated in both sexes. Our results reveal previously unreported changes in the expression of cannabinoid receptors, ligands and enzymes occurring mainly in the peripheral nervous system and displaying certain sexual dimorphism. These changes may contribute to the physiopathology of oxaliplatin-induced neuropathic pain in male and female rats. A better understanding of these dynamic changes will facilitate the development of mechanism- and sex-specific approaches to optimize the use of cannabinoid-based medicines for the treatment of chemotherapy-induced pain.


Assuntos
Antineoplásicos , Canabinoides , Neuralgia , Feminino , Masculino , Ratos , Animais , Endocanabinoides/metabolismo , Endocanabinoides/uso terapêutico , Caracteres Sexuais , Hiperalgesia/metabolismo , Oxaliplatina/toxicidade , Canais de Cátion TRPV/metabolismo , Neuralgia/metabolismo , Receptores de Canabinoides/metabolismo , Antineoplásicos/toxicidade , Antineoplásicos/uso terapêutico , RNA Mensageiro , Modelos Teóricos , Receptor CB1 de Canabinoide/genética , Receptor CB1 de Canabinoide/metabolismo , Receptor CB1 de Canabinoide/uso terapêutico , Receptor CB2 de Canabinoide/genética , Receptor CB2 de Canabinoide/metabolismo
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