Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.147
Filtrar
1.
Sci Rep ; 12(1): 19314, 2022 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-36369249

RESUMO

Whisker pad skin incision in infancy causes the prolongation of mechanical allodynia after re-incision in adulthood. A recent study also proposed the importance of sex differences in pain signaling in the spinal cord. However, the sex difference in re-incision-induced mechanical allodynia in the orofacial region is not fully understood. In the rats that experienced neonatal injury in the whisker pad skin, the mechanical allodynia in the whisker pad was significantly prolonged after re-incision in adulthood compared to sham injury in infancy. No significant sex differences were observed in the duration of mechanical allodynia. The duration of mechanical allodynia in male rats was shortened by intracisternal administration of minocycline. However, minocycline had no effects on the duration of mechanical allodynia in female rats. In contrast, intracisternal administration of pioglitazone markedly suppressed mechanical allodynia in female rats after re-incision. Following re-incision, the number of peroxisome proliferator-activated receptor gamma (PPARgamma)-positive cells were reduced in the trigeminal spinal subnucleus caudalis (Vc) in female rats that experienced neonatal injury. Immunohistochemical analyses revealed that PPARgamma was predominantly expressed in Vc neurons. Pioglitazone increased the number of PPARgamma-positive Vc neurons in female rats whose whisker pad skin was incised in both infancy and adulthood stages. Pioglitazone also upregulated heme oxygenase 1 and downregulated NR1 subunit in the Vc in female rats after re-incision. Together, PPARgamma signaling in Vc neurons is a female-specific pathway for whisker pad skin incision-induced mechanical allodynia.


Assuntos
Hiperalgesia , PPAR gama , Ratos , Feminino , Masculino , Animais , Hiperalgesia/etiologia , Hiperalgesia/metabolismo , Pioglitazona/farmacologia , Minociclina , Ratos Sprague-Dawley
2.
Int J Mol Sci ; 23(21)2022 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-36361909

RESUMO

Inflammatory processes within the peripheral nervous system (PNS) are associated with symptoms of hyperalgesia and allodynia. Pro-inflammatory mediators, such as cytokines or prostaglandins, modulate the excitability of nociceptive neurons, called peripheral sensitization. Here, we aimed to examine if previously reported effects of in vitro stimulation with lipopolysaccharide (LPS) on primary cell cultures of dorsal root ganglia (DRG) reflect changes in a model of LPS-induced systemic inflammation in vivo. Male rats were intraperitoneally injected with LPS (100 µg/kg) or saline. Effects of systemic inflammation on expression of inflammatory mediators, neuronal Ca2+ responses, and activation of inflammatory transcription factors in DRG were assessed. Systemic inflammation was accompanied by an enhanced expression of pro-inflammatory cytokines and cyclooxygenase-2 in lumbar DRG. In DRG primary cultures obtained from LPS-treated rats enhanced neuronal capsaicin-responses were detectable. Moreover, we found an increased activation of inflammatory transcription factors in cultured macrophages and neurons after an in vivo LPS challenge compared to saline controls. Overall, our study emphasizes the role of inflammatory processes in the PNS that may be involved in sickness-behavior-associated hyperalgesia induced by systemic LPS treatment. Moreover, we present DRG primary cultures as tools to study inflammatory processes on a cellular level, not only in vitro but also ex vivo.


Assuntos
Gânglios Espinais , Lipopolissacarídeos , Ratos , Masculino , Animais , Gânglios Espinais/metabolismo , Lipopolissacarídeos/efeitos adversos , Hiperalgesia/induzido quimicamente , Hiperalgesia/metabolismo , Inflamação/induzido quimicamente , Inflamação/metabolismo , Mediadores da Inflamação/metabolismo , Citocinas/metabolismo , Fatores de Transcrição/metabolismo
3.
Immun Inflamm Dis ; 10(11): e721, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36301041

RESUMO

BACKGROUND: Dexamethasone (Dexa) and potassium canrenoate (Cane) modulate nociceptive behavior via glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) by two mechanisms (genomic and nongenomic pathways). This study was designed to investigate the Dexa- or Cane-mediated nongenomic and genomic effects on mechanical nociception and inflammation-induced changes in interleukin-6 (IL-6) mediated signaling pathway in rats. METHODS: Freund's complete adjuvant (FCA) was used to trigger an inflammation of the right hind paw in male Sprague-Dawley rats. First, the mechanical nociceptive behavioral changes were examined following intraplantar administration of GR agonist Dexa and/or MR antagonist Cane in vivo. Subsequently, the protein levels of IL-6, IL-6Rα, JAK2, pJAK2, STAT3, pSTAT3Ser727 , migration inhibitory factor, and cyclooxygenase-2 were assessed by Western blot following intraplantar injection of Dexa or Cane or the combination. Moreover, the molecular docking studies determined the interaction between Dexa, Cane, and IL-6. The competition binding assay was carried out using enzyme-linked immunosorbent assays (ELISA). RESULTS: Administration of Dexa and Cane dose-dependently attenuated FCA-induced inflammatory pain. The sub-additive effect of Dexa/Cane combination was elucidated by isobologram analysis, accompanied by decrease in the spinal levels of IL-6, pJAK2, and pSTAT3Ser727 . The molecular docking study demonstrated that both Dexa and Cane displayed a firm interaction with THR138 binding site of IL-6 via a strong hydrogen bond. ELISA revealed that Dexa has a higher affinity to IL-6 than Cane. CONCLUSIONS: There was no additive or negative effect of Dexa and Cane, and they modulate the IL-6/JAK2/STAT3 signaling pathway through competitive binding with IL-6 and relieves hypersensitivity during inflammatory pain.


Assuntos
Ácido Canrenoico , Hiperalgesia , Animais , Masculino , Ratos , Dexametasona/farmacologia , Adjuvante de Freund , Hiperalgesia/tratamento farmacológico , Hiperalgesia/metabolismo , Inflamação/tratamento farmacológico , Inflamação/metabolismo , Interleucina-6/farmacologia , Janus Quinase 2/metabolismo , Simulação de Acoplamento Molecular , Dor , Ratos Sprague-Dawley , Receptores de Glucocorticoides , Transdução de Sinais
4.
Anesth Analg ; 135(6): 1293-1303, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36201356

RESUMO

BACKGROUND: Disk herniation is a primary cause of radicular back pain. The purpose of this study was to evaluate the antiallodynic effective dose in 50% of the sample (ED 50 ) and dorsal root ganglion (DRG) protein modulation of a peripheral direct adenosine monophosphate kinase alpha (AMPKα) activator (O304) in a murine model of lumbar disk puncture. METHODS: Male (n = 28) and female (n = 28) mice (C57BL6/J) were assessed for hind paw withdrawal threshold (PWT) and burrowing. Abdominal surgery was performed on all mice, and 48 received a lumbar disk puncture (27-G needle), with 8 serving as nondisk puncture controls. Assessments were repeated at day 7, and mice were then randomized into 5 groups of equal numbers of males and females: O304 at 100 mg/kg (n = 10), 150 mg/kg (n = 10), 200 mg/kg (n = 10), and 250 mg/kg (n = 10) or drug vehicle (n = 8). Starting on day 7, mice received daily gavages of O304 or vehicle for 7 days. On days 14 and 21 PWT and on day 14 burrowing were assessed. The area under the PWT by time curve (AUC) from day 7 to 21 was determined by trapezoidal integration. DRG protein modulation was evaluated in male (n = 10) and female (n = 10) mice (C57BL6/J). Following disk puncture, mice were randomized to receive O304 200 mg/kg or vehicle for 7 days starting on day 7. On day 14, mice were euthanized; the DRG harvested and immunoblot performed for mammalian target of rapamycin (mTOR), transient receptor potential ankyrin 1 (TRPA1), phosphorylated adenosine monophosphate kinase (p-AMPK), phosphorylated extracellular signal-regulated kinase (p-ERK), phosphorylated eukaryotic translation initiation factor 2 subunit 1 (p-EIF2S1), phosphorylated eukaryotic translation initiation factor 4e (p-EIF4E), and glyceraldehyde 3-phosphate dehydrogenase (GADPH). RESULTS: Disk puncture decreased PWT greater in female mice compared with male mice and decreased burrowing at 7 days. PWTs were increased with increasing doses of O304 from 150 to 250 mg/g on day 14 and sustained through day 21. The ED 50 (95% confidence interval [CI]) for reducing mechanical allodynia was 140 (118-164) mg/kg. Burrowing was not increased at day 14 compared to day 7 by O304 administration. Compared to vehicle-treated animals, O304 increased (95% CI) the p-AMPK/GADPH ratio, difference 0.27 (0.08-0.45; P = . 004) and decreased (95% CI) the ratios of p-TRPA1, p-ERK1/2, pEIF4E, and p-EIF2S1 to GADPH by -0.49 (-0.61 to -0.37; P < . 001), -0.53 (-0.76 to -0.29; P < . 001), -0.27 (-0.42 to 0.11; P = . 001), and -0.21 (-0.32 to -0.08; P = . 003) in the DRG, respectively. CONCLUSIONS: The direct peripheral AMPK activator O304 reduced allodynia in a dose-dependent manner, and immunoblot studies of the DRG showed that O304 increased p-AMPK and decreased TRPA1, p-ERK1/2, as well as translation factors involved in neuroplasticity. Our findings confirm the role of peripheral AMPKα activation in modulating nociceptive pain.


Assuntos
Proteínas Quinases Ativadas por AMP , Gânglios Espinais , Ratos , Camundongos , Masculino , Feminino , Animais , Ratos Sprague-Dawley , Proteínas Quinases Ativadas por AMP/metabolismo , Monofosfato de Adenosina/farmacologia , Modelos Animais de Doenças , Punção Espinal , Analgésicos/uso terapêutico , Hiperalgesia/tratamento farmacológico , Hiperalgesia/metabolismo , Camundongos Endogâmicos C57BL , Mamíferos
5.
J Neuroinflammation ; 19(1): 244, 2022 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-36195881

RESUMO

BACKGROUND: Neuropathic pain is still a challenge for clinical treatment as a result of the comprehensive pathogenesis. Although emerging evidence demonstrates the pivotal role of glial cells in regulating neuropathic pain, the role of Schwann cells and their underlying mechanisms still need to be uncovered. Pannexin 1 (Panx 1), an important membrane channel for the release of ATP and inflammatory cytokines, as well as its activation in central glial cells, contributes to pain development. Here, we hypothesized that Schwann cell Panx 1 participates in the regulation of neuroinflammation and contributes to neuropathic pain. METHODS: A mouse model of chronic constriction injury (CCI) in CD1 adult mice or P0-Cre transgenic mice, and in vitro cultured Schwann cells were used. Intrasciatic injection with Panx 1 blockers or the desired virus was used to knock down the expression of Panx 1. Mechanical and thermal sensitivity was assessed using Von Frey and a hot plate assay. The expression of Panx 1 was measured using qPCR, western blotting, and immunofluorescence. The production of cytokines was monitored through qPCR and enzyme-linked immunosorbent assay (ELISA). Panx1 channel activity was detected by ethidium bromide (EB) uptake. RESULTS: CCI induced persistent neuroinflammatory responses and upregulation of Panx 1 in Schwann cells. Intrasciatic injection of Panx 1 blockers, carbenoxolone (CBX), probenecid, and Panx 1 mimetic peptide (10Panx) effectively reduced mechanical and heat hyperalgesia. Probenecid treatment of CCI-induced mice significantly reduced Panx 1 expression in Schwann cells, but not in dorsal root ganglion (DRG). In addition, Panx 1 knockdown in Schwann cells with Panx 1 shRNA-AAV in P0-Cre mice significantly reduced CCI-induced neuropathic pain. To determine whether Schwann cell Panx 1 participates in the regulation of neuroinflammation and contributes to neuropathic pain, we evaluated its effect in LPS-treated Schwann cells. We found that inhibition of Panx 1 via CBX and Panx 1-siRNA effectively attenuated the production of selective cytokines, as well as its mechanism of action being dependent on both Panx 1 channel activity and its expression. CONCLUSION: In this study, we found that CCI-related neuroinflammation correlates with Panx 1 activation in Schwann cells, indicating that inhibition of Panx 1 channels in Schwann cells reduces neuropathic pain through the suppression of neuroinflammatory responses.


Assuntos
Carbenoxolona , Neuralgia , Trifosfato de Adenosina/farmacologia , Animais , Carbenoxolona/farmacologia , Carbenoxolona/uso terapêutico , Conexinas/genética , Conexinas/metabolismo , Citocinas/metabolismo , Etídio/metabolismo , Etídio/farmacologia , Etídio/uso terapêutico , Hiperalgesia/metabolismo , Lipopolissacarídeos/farmacologia , Camundongos , Proteínas do Tecido Nervoso/metabolismo , Neuralgia/metabolismo , Probenecid/metabolismo , Probenecid/farmacologia , Probenecid/uso terapêutico , RNA Interferente Pequeno/metabolismo , Células de Schwann
6.
Neurosci Lett ; 790: 136890, 2022 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-36181963

RESUMO

Neuropathic pain is a serious health problem, but optimal drug treatments remain lacking. It has been known that the compound NS5806 is a Kv4.3 activator, which increases Kv4.3-mediated K+ current to reduce neuronal excitability. In this study, we investigated the molecular and cellular mechanisms underlying the analgesic effect of NS5806 in neuropathic pain induced by peripheral nerve injury. Using lumbar (L)5/L6 spinal nerve ligation (SNL) in rats, we found that, without changing the basal nociception, the analgesic effect of NS5806 (220 µg/kg) peaked at 4 h and lasted for 8 h after intraperitoneal injection. Multiple doses of NS5806 reduced not only SNL-upregulated proinflammatory mediators in the DRG and spinal cord on day 1 and day 4 after L5/L6 SNL, but also SNL-evoked expansion of DRG macrophages and spinal microglia on day 4. Furthermore, at 10 min after L5 SNL, NS5806 pretreatment for 4 h suppressed SNL-induced phosphorylated extracellular signal-regulated kinase (pERK) in both Kv4.3+ and Kv4.3- neurons in the dorsal root ganglion (DRG) and superficial spinal dorsal horn, indicating that the action of NS5806 is not restricted to Kv4.3+ neurons. In vitro kinase activity assays revealed that NS5806 weakly inhibited ERK2, MEK1, MEK2, and c-Raf in the ERK pathway. Since NS5806 and the ERK pathway inhibitors have similar antinociceptive characteristics, this study suggests that NS5806 also acts as an ERK pathway inhibitor to attenuate neuropathic pain.


Assuntos
Neuralgia , Traumatismos dos Nervos Periféricos , Ratos , Animais , Hiperalgesia/tratamento farmacológico , Hiperalgesia/metabolismo , Traumatismos dos Nervos Periféricos/complicações , Traumatismos dos Nervos Periféricos/tratamento farmacológico , Ratos Sprague-Dawley , Nervos Espinhais/lesões , Neuralgia/tratamento farmacológico , Neuralgia/metabolismo , Gânglios Espinais/metabolismo , Corno Dorsal da Medula Espinal/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Ligadura , Analgésicos/farmacologia , Analgésicos/uso terapêutico
7.
Int J Mol Sci ; 23(19)2022 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-36232555

RESUMO

Neuropathic pain is well known to occur after damage to the somatosensory system. Aryl hydrocarbon receptor (AhR) has neuroprotective effects when the central nervous system is subjected to internal and external stimulations. However, the exact mechanism by which AhR regulates neuropathic pain is poorly understood. Nerve explant culture and the chronic constrictive nerve injury (CCI) model in wild or AhR-knockout mice were used in this study. In the nerve explant culture, the ovoid number increased in the AhR-/- condition and was decreased by omeprazole (AhR agonist) in a dose-dependent manner. Increased nerve degeneration and the associated inflammation response appeared in the AhR-/- condition, and these changes were attenuated by omeprazole. High expression of AhR in the injured nerve was noted after CCI. Deletion of AhR aggravated nerve damages and this was restored by omeprazole. Deletion of AhR increased NGF expression and reduced axon number in the paw skin, but this was attenuated by omeprazole. A highly expressed inflammation reaction over the dorsal spinal cord, somatosensory cortex, and hippocampus was noted in the AhR-deleted animals. Administration of omeprazole attenuated not only the inflammatory response, but also the amplitude of somatosensory evoked potential. Deletion of AhR further aggravated the neurobehavior compared with the wild type, but such behavior was attenuated by omeprazole. Chronic constrictive nerve injury augmented AhR expression of the injured nerve, and AhR deletion worsened the damage, while AhR agonist omeprazole counteracted such changes. AhR agonists could be potential candidates for neuropathic pain treatment.


Assuntos
Lesões por Esmagamento , Neuralgia , Fármacos Neuroprotetores , Traumatismos do Sistema Nervoso , Animais , Constrição , Constrição Patológica , Modelos Animais de Doenças , Hiperalgesia/metabolismo , Inflamação/genética , Camundongos , Camundongos Knockout , Fator de Crescimento Neural , Neuralgia/etiologia , Neuralgia/genética , Omeprazol , Receptores de Hidrocarboneto Arílico/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Nervo Isquiático/metabolismo
8.
Pain Physician ; 25(7): E1137-E1151, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36288601

RESUMO

BACKGROUND: In neuropathic pain following peripheral nerve injury, microglia are rapidly activated and accumulated in the spinal cord. Physical exercise can alleviate neuropathic pain. However, the exact mechanism underlying this analgesic effect is not fully understood. OBJECTIVES: We aimed to investigate the molecular mechanisms by which exercise alleviates neuropathic pain in relation to brain-derived neurotrophic factor (BDNF), microglia polarization, and autophagy. STUDY DESIGN: A randomized controlled animal study divided into 2 stages. The first stage comprised 4 groups each with 6 mice, and the second stage comprised 6 groups, 3 with 18 mice and 3 with 12 mice. SETTING: Department of Anesthesiology, Lanzhou University Second Hospital, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University. METHODS: Von Frey filaments, Western blotting, immunofluorescence, and transmission electron microscopy analyses were conducted to detect relevant markers. RESULTS: After peripheral nerve injury, exercise training downregulated BDNF expression and reversed microglial activation, as indicated by the increased expression of the M2 marker CD206 and decreased expression of the M1 marker CD86 in the spinal dorsal horn of mice. Autophagy flux was enhanced after exercise training, as suggested by the increased expression of the autophagy markers LC3-II/LC3-I and Beclin1 and decreased expression of the autophagy adaptor protein p62. Furthermore, autophagy inhibition by 3-methyladenine aggravated M1 polarization and hyperalgesia, whereas autophagy induced by rapamycin promoted M2 polarization and reduced hyperalgesia. Intrathecal injection of BDNF significantly upregulated BDNF expression, inhibited autophagy, triggered M1 polarization of spinal microglia, and aggravated hyperalgesia. Furthermore, BDNF regulated autophagy through the AKT/mTOR pathway, thereby participating in exercise training-mediated polarization of microglia after nerve injury. LIMITATIONS: The effect of exercise on autophagy and pain cannot be assessed in an in vitro model. The influence of intrathecal injection of BDNF on the metabolic changes in other neuronal cells and the subsequent effects on pain should be investigated. Further studies on how exercise training modulates microglial autophagy to alleviate neuropathic pain are needed. CONCLUSIONS: Exercise training promoted the recovery of sciatic nerve injury in mice, possibly by regulating microglial polarization through BDNF/AKT/mTOR signaling-mediated autophagy flux. We confirmed the efficacy of exercise training in alleviating neuropathic pain and suggest a new therapeutic target for neuropathic pain.


Assuntos
Neuralgia , Traumatismos dos Nervos Periféricos , Ratos , Camundongos , Animais , Microglia/metabolismo , Fator Neurotrófico Derivado do Encéfalo , Hiperalgesia/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas Proto-Oncogênicas c-akt/farmacologia , Traumatismos dos Nervos Periféricos/metabolismo , Proteína Beclina-1/metabolismo , Proteína Beclina-1/farmacologia , Ratos Sprague-Dawley , Neuralgia/tratamento farmacológico , Serina-Treonina Quinases TOR/metabolismo , Serina-Treonina Quinases TOR/farmacologia , Serina-Treonina Quinases TOR/uso terapêutico , Autofagia , Corno Dorsal da Medula Espinal/metabolismo , Sirolimo/metabolismo , Sirolimo/farmacologia , Sirolimo/uso terapêutico , Analgésicos/uso terapêutico
9.
Elife ; 112022 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-36264609

RESUMO

Functionally distinct subtypes/clusters of dorsal root ganglion (DRG) neurons may play different roles in nerve regeneration and pain. However, details about their transcriptomic changes under neuropathic pain conditions remain unclear. Chronic constriction injury (CCI) of the sciatic nerve represents a well-established model of neuropathic pain, and we conducted single-cell RNA-sequencing (scRNA-seq) to characterize subtype-specific perturbations of transcriptomes in lumbar DRG neurons on day 7 post-CCI. By using PirtEGFPf mice that selectively express an enhanced green fluorescent protein in DRG neurons, we established a highly efficient purification process to enrich neurons for scRNA-seq. We observed the emergence of four prominent CCI-induced clusters and a loss of marker genes in injured neurons. Importantly, a portion of injured neurons from several clusters were spared from injury-induced identity loss, suggesting subtype-specific transcriptomic changes in injured neurons. Moreover, uninjured neurons, which are necessary for mediating the evoked pain, also demonstrated cell-type-specific transcriptomic perturbations in these clusters, but not in others. Notably, male and female mice showed differential transcriptomic changes in multiple neuronal clusters after CCI, suggesting transcriptomic sexual dimorphism in DRG neurons after nerve injury. Using Fgf3 as a proof-of-principle, RNAscope study provided further evidence of increased Fgf3 in injured neurons after CCI, supporting scRNA-seq analysis, and calcium imaging study unraveled a functional role of Fgf3 in neuronal excitability. These findings may contribute to the identification of new target genes and the development of DRG neuron cell-type-specific therapies for optimizing neuropathic pain treatment and nerve regeneration.


Assuntos
Neuralgia , RNA Citoplasmático Pequeno , Ratos , Camundongos , Masculino , Feminino , Animais , Gânglios Espinais/metabolismo , Transcriptoma , Análise de Célula Única , Cálcio/metabolismo , Ratos Sprague-Dawley , Neuralgia/metabolismo , Neurônios/metabolismo , Hiperalgesia/metabolismo , Proteínas de Transporte/metabolismo , Proteínas de Membrana/metabolismo
10.
Cells ; 11(19)2022 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-36231054

RESUMO

Calcitonin-gene-related peptide (CGRP) plays a key role in migraine pathophysiology and more specifically in the mechanisms underlying peripheral and central sensitization. Here, we explored the interaction of CGRP with other pain mediators relevant for neuronal sensitization in an animal model of chronic migraine. Male Sprague-Dawley rats were exposed to nitroglycerin (NTG, 5 mg/kg, i.p.) or vehicle co-administered with the CGRP receptor antagonist olcegepant (2 mg/kg i.p.), or its vehicle, every other day over a 9-day period. Twenty-four hours after the last injection of NTG (or vehicle), behavioral test and ex vivo analysis were performed. Olcegepant attenuated NTG-induced trigeminal hyperalgesia in the second phase of the orofacial formalin test. Interestingly, it also reduced gene expression and protein levels of CGRP, pro-inflammatory cytokines, inflammatory-associated miRNAs (miR-155-5p, miR-382-5p, and miR-34a-5p), and transient receptor potential ankyrin channels in the medulla-pons area, cervical spinal cord, and trigeminal ganglia. Similarly, olcegepant reduced the NTG-induced increase in CGRP and inflammatory cytokines in serum. The findings show that the activation of the CGRP pathway in a migraine animal model was associated to the persistent activation of inflammatory pathways, which was paralleled by a condition of hyperalgesia. These molecular events are relevant for informing us about the mechanisms underlying chronic migraine.


Assuntos
MicroRNAs , Transtornos de Enxaqueca , Animais , Anquirinas , Calcitonina , Peptídeo Relacionado com Gene de Calcitonina/genética , Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Antagonistas do Receptor do Peptídeo Relacionado ao Gene de Calcitonina , Citocinas , Modelos Animais de Doenças , Hiperalgesia/metabolismo , Masculino , Transtornos de Enxaqueca/induzido quimicamente , Transtornos de Enxaqueca/tratamento farmacológico , Transtornos de Enxaqueca/genética , Nitroglicerina , Ratos , Ratos Sprague-Dawley , Receptores de Peptídeo Relacionado com o Gene de Calcitonina
11.
J Neuroinflammation ; 19(1): 264, 2022 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-36309729

RESUMO

BACKGROUND: People with spinal cord injury (SCI) frequently develop neuropathic pain (NP) that worsens disability and diminishes rehabilitation efficacy. Chronic NP is presently incurable due to poor understanding of underlying mechanisms. We hypothesized that multilocus neuroinflammation (NIF) might be a driver of SCI NP, and tested it by investigating whether NP coexisted with central NIF, neurotransmission (NTM), neuromodulation (NML) and neuroplasticity (NPL) changes post-SCI. METHODS: Female Sprague-Dawley rats (230-250 g) with T10 compression or laminectomy were evaluated for physical conditions, coordinated hindlimb functions, neurological reflexes, and mechanical/thermal sensitivity thresholds at 1 day post-injury (p.i.) and weekly thereafter. Eight weeks p.i., central nervous system tissues were histochemically and immunohistochemically characterized for parameters/markers of histopathology and NIF/NTM/NML/NPL. Also analyzed was the correlative relationship between levels of selected biomarkers and thermosensitivity thresholds via statistical linear regression. RESULTS: SCI impaired sensorimotor functions, altered reflexes, and produced spontaneous pain signs and hypersensitivity to evoked nociceptive, mechanical, and thermal inputs. Only injured spinal cords exhibited neural lesion, microglia/astrocyte activation, and abnormal expression of proinflammatory cytokines, as well as NIF/NTM/NML/NPL markers. Brains of SCI animals displayed similar pathophysiological signs in the gracile and parabrachial nuclei (GrN and PBN: sensory relay), raphe magnus nucleus and periaqueduct gray (RMN and PAG: pain modulation), basolateral amygdala (BLA: emotional-affective dimension of pain), and hippocampus (HPC: memory/mood/neurogenesis). SCI augmented sensory NTM/NPL (GrN and PBN); increased GAD67 (PAG) level; reduced serotonin (RMN) and fear-off neuronal NTR2 (BLA) expressions; and perturbed neurogenesis (HPC). CONCLUSION: T10 compression caused chronic hyperalgesia that coexisted with NIF/NTM/NML/NPL responses at multilevel neuroaxis centers. The data have provided multidimensional biomarkers as new mechanistic leads to profile SCI NP for therapeutic/therapy development.


Assuntos
Neuralgia , Traumatismos da Medula Espinal , Ratos , Animais , Feminino , Hiperalgesia/metabolismo , Ratos Sprague-Dawley , Neuralgia/metabolismo , Traumatismos da Medula Espinal/patologia , Inflamação/complicações , Biomarcadores
12.
Cells ; 11(19)2022 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-36231048

RESUMO

Physical activity-based rehabilitative interventions represent the main treatment concept for people suffering from spinal cord injury (SCI). The role such interventions play in the relief of neuropathic pain (NP) states is emerging, along with underlying mechanisms resulting in SCI-induced NP (SCI-NP). Animal models have been used to investigate the benefits of activity-based interventions (ABI), such as treadmill training, wheel running, walking, swimming, and bipedal standing. These activity-based paradigms have been shown to modulate inflammatory-related alterations as well as induce functional and structural changes in the spinal cord gray matter circuitry correlated with pain behaviors. Thus far, the research available provides an incomplete picture of the cellular and molecular pathways involved in this beneficial effect. Continued research is essential for understanding how such interventions benefit SCI patients suffering from NP and allow the development of individualized rehabilitative therapies. This article reviews preclinical studies on this specific topic, goes over mechanisms involved in SCI-NP in relation to ABI, and then discusses the effectiveness of different activity-based paradigms as they relate to different forms, intensity, initiation times, and duration of ABI. This article also summarizes the mechanisms of respective interventions to ameliorate NP after SCI and provides suggestions for future research directions.


Assuntos
Neuralgia , Traumatismos da Medula Espinal , Animais , Substância Cinzenta , Hiperalgesia/metabolismo , Atividade Motora , Neuralgia/metabolismo , Traumatismos da Medula Espinal/complicações , Traumatismos da Medula Espinal/metabolismo , Traumatismos da Medula Espinal/terapia
13.
Magnes Res ; 35(1): 1-10, 2022 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-36214549

RESUMO

In the present study, we investigated whether magnesium sulphate activates the L-arginine/NO/cGMP pathway and elicits peripheral antinociception. The male Swiss mice paw pressure test was performed with hyperalgesia induced by intraplantar injection of prostaglandin E2. All drugs were administered locally into the right hind paw of animals. Magnesium sulphate (20, 40, 80 and 160 µg/paw) induced an antinociceptive effect. The dose of 80 µg/paw elicited a local antinociceptive effect that was antagonized by the non-selective NOS inhibitor, L-NOArg, and by the selective neuronal NOS inhibitor, L-NPA. The inhibitors, L-NIO and L-NIL, selectively inhibited endothelial and inducible NOS, respectively, but were ineffective regarding peripheral magnesium sulphate injection. The soluble guanylyl cyclase inhibitor, ODQ, blocked the action of magnesium sulphate, and the cGMP-phosphodiesterase inhibitor, zaprinast, enhanced the antinociceptive effects of intermediate dose of magnesium sulphate. Our results suggest that magnesium sulphate stimulates the NO/cGMP pathway via neuronal NO synthase to induce peripheral antinociceptive effects.


Assuntos
Dinoprostona , Sulfato de Magnésio , Analgésicos/farmacologia , Animais , Arginina/metabolismo , GMP Cíclico/metabolismo , Dinoprostona/efeitos adversos , Hiperalgesia/induzido quimicamente , Hiperalgesia/tratamento farmacológico , Hiperalgesia/metabolismo , Sulfato de Magnésio/farmacologia , Masculino , Camundongos , Óxido Nítrico , Nitroarginina , Inibidores de Fosfodiesterase/farmacologia , Guanilil Ciclase Solúvel/antagonistas & inibidores
14.
Bull Exp Biol Med ; 173(5): 594-601, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36214984

RESUMO

We studied the interaction between glucocorticoid receptor (GR) and HCN4 channels in the rat model of spared nerve injury (SNI) in Sprague-Dawley rats (n=124). The animals were randomly divided into 6 groups: sham-operated (SO; n=24), SNI (reference group; n=20), and 4 experimental SNI groups intrathecally treated with dexamethasone (DEX; GR agonist; n=20), RU38486 (GR antagonist; n=20), ZD7288 (HCN channels blocker; n=20), and ZD7288+DEX (n=20). The paw mechanical withdrawal threshold (PWT) was measured one day before surgery (SO group) and on days 1, 3, 7, 14, and 21 after surgery. Behavioral results showed that mechanical hyperalgesia appeared on day 1 after SNI, while PWT decreased gradually with time. The expression of GR and HCN4 channels in L4-L6 dorsal horn of the spinal cord was detected by Western blotting and immunohistochemistry. In the reference group, SNI significantly increased GR expression up to day 14 after surgery in comparison with the SO group. The expression of GR showed a tendency to increase in the DEX group (with the maximum expression on days 14 and 21), significantly increased in the RU38486 group (maximum on day 7). In the ZD7288 group, GR expression was lower than in the SNI group and did not change throughout the experiment, suggesting that ZD7288 could block the expression of GR. In the DEX group, the expression of HCN4 channels was significantly higher on day 1 after SNI, but there were no differences in this parameter between the RU38486 and ZD7288 groups. In the ZD7288+DEX group, the expression of HCN4 channels significantly increased on days 14 and 21 after SNI. Thus, GR and HCN4 have the same linkage in the formation of central sensitization after SNI, but antagonists have no significant effect on the improvement of pain behavior.


Assuntos
Neuralgia , Traumatismos dos Nervos Periféricos , Animais , Dexametasona/farmacologia , Hiperalgesia/tratamento farmacológico , Hiperalgesia/metabolismo , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/genética , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/metabolismo , Mifepristona/farmacologia , Neuralgia/tratamento farmacológico , Traumatismos dos Nervos Periféricos/complicações , Traumatismos dos Nervos Periféricos/tratamento farmacológico , Traumatismos dos Nervos Periféricos/metabolismo , Canais de Potássio/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismo , Medula Espinal/metabolismo , Corno Dorsal da Medula Espinal/metabolismo
15.
Int J Mol Sci ; 23(20)2022 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-36292950

RESUMO

Tropomyosin receptor kinase A (TrkA/NTRK1) is a high-affinity receptor for nerve growth factor (NGF), a potent pain mediator. NGF/TrkA signaling elevates synovial sensory neuronal distributions in the joints and causes osteoarthritis (OA) pain. We investigated the mechanisms of pain transmission as to whether peripheral sensory neurons are linked to the cellular plasticity in the dorsal root ganglia (DRG) and are critical for OA hyperalgesia. Sensory neuron-specific deletion of TrkA was achieved by tamoxifen injection in 4-week-old TrkAfl/fl;NaV1.8CreERT2 (Ntrk1 fl/fl;Scn10aCreERT2) mice. OA was induced by partial medial meniscectomy (PMM) in 12-week-old mice, and OA-pain-related behavior was analyzed for 12 weeks followed by comprehensive histopathological examinations. OA-associated joint pain was markedly improved without cartilage protection in sensory-neuron-specific conditional TrkA knock-out (cKO) mice. Alleviated hyperalgesia was associated with suppression of the NGF/TrkA pathway and reduced angiogenesis in fibroblast-like synovial cells. Elevated pain transmitters in the DRG of OA-induced mice were significantly diminished in sensory-neuron-specific TrkA cKO and global TrkA cKO mice. Spinal glial activity and brain-derived neurotropic factor (BDNF) were significantly increased in OA-induced mice but were substantially eliminated by sensory-neuron-specific deletion. Our results suggest that augmentation of NGF/TrkA signaling in the joint synovium and the peripheral sensory neurons facilitate pro-nociception and centralized pain sensitization.


Assuntos
Fator de Crescimento Neural , Osteoartrite , Camundongos , Animais , Fator de Crescimento Neural/genética , Fator de Crescimento Neural/metabolismo , Receptor trkA/genética , Receptor trkA/metabolismo , Tropomiosina/metabolismo , Hiperalgesia/metabolismo , Fator Neurotrófico Derivado do Encéfalo/genética , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Células Receptoras Sensoriais/metabolismo , Dor/metabolismo , Gânglios Espinais/metabolismo , Osteoartrite/metabolismo , Tamoxifeno/metabolismo
16.
Sci Rep ; 12(1): 14840, 2022 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-36050326

RESUMO

Understanding the interactions between diet, obesity, and diabetes is important to tease out mechanisms in painful pathology. Western diet is rich in fats, producing high amounts of circulating bioactive metabolites. However, no research has assessed how a high-fat diet (HFD) alone may sensitize an individual to non-painful stimuli in the absence of obesity or diabetic pathology. To investigate this, we tested the ability of a HFD to stimulate diet-induced hyperalgesic priming, or diet sensitization in male and female mice. Our results revealed that 8 weeks of HFD did not alter baseline pain sensitivity, but both male and female HFD-fed animals exhibited robust mechanical allodynia when exposed to a subthreshold dose of intraplantar Prostaglandin E2 (PGE2) compared to mice on chow diet. Furthermore, calcium imaging in isolated primary sensory neurons of both sexes revealed HFD induced an increased percentage of capsaicin-responsive neurons compared to their chow counterparts. Immunohistochemistry (IHC) showed a HFD-induced upregulation of ATF3, a neuronal marker of injury, in lumbar dorsal root ganglia (DRG). This suggests that a HFD induces allodynia in the absence of a pre-existing condition or injury via dietary components. With this new understanding of how a HFD can contribute to the onset of pain, we can understand the dissociation behind the comorbidities associated with obesity and diabetes to develop pharmacological interventions to treat them more efficiently.


Assuntos
Diabetes Mellitus , Dieta Hiperlipídica , Animais , Diabetes Mellitus/metabolismo , Dieta Hiperlipídica/efeitos adversos , Feminino , Gânglios Espinais/metabolismo , Hiperalgesia/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Obesidade/metabolismo , Dor/metabolismo
17.
Neurosci Lett ; 789: 136864, 2022 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-36063980

RESUMO

Chronic pain remains a disabling disease with limited therapeutic options. Pyramidal neurons in the prefrontal cortex (PFC) express excitatory Gq-coupled 5-HT2A receptors (5-HT2AR) and their effector system, the inhibitory Kv7 ion channel. While recent publications show these cells innervate brainstem regions important for regulating pain, the cellular mechanisms underlying the transition to chronic pain are not well understood. The present study examined whether local blockade of 5-HT2AR or enhanced Kv7 ion channel activity in the PFC would attenuate mechanical allodynia associated with spared nerve injury (SNI) in rats. Following SNI, we show that inhibition of PFC 5-HT2ARs with M100907 or opening of PFC Kv7 channels with retigabine reduced mechanical allodynia. Parallel proteomic and RNAScope experiments evaluated 5-HT2AR/Kv7 channel protein and mRNA. Our results support the role of 5-HT2ARs and Kv7 channels in the PFC in the maintenance of chronic pain.


Assuntos
Dor Crônica , Neuralgia , Animais , Dor Crônica/tratamento farmacológico , Dor Crônica/metabolismo , Hiperalgesia/metabolismo , Neuralgia/tratamento farmacológico , Neuralgia/metabolismo , Córtex Pré-Frontal/metabolismo , Proteômica , RNA Mensageiro/metabolismo , Ratos , Serotonina/metabolismo
18.
Neuropharmacology ; 219: 109253, 2022 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-36108796

RESUMO

High-frequency stimulation (HFS) of the sciatic nerve leads to long-term potentiation (LTP) at C-fiber synapse and long-lasting pain hypersensitivity. The underlying mechanisms, however, are still unclear. In the present study, we investigated the involvement of astrocytes derived l-lactate in the spinal dorsal horn subsequent to glucocorticoid (GC) secretion into the plasma in this process using Sprague-Dawley rats and Aldh1L1-CreERT2 mice of either sex. We found that HFS increased l-lactate and monocarboxylate transporters 1/2 (MCT1/2) in the spinal dorsal horn. Inhibition of glycogenolysis or blocking lactate transport prevented the induction of spinal LTP following HFS. Furthermore, Chemogenetical inhibition of dorsal horn astrocytes, which were activated by HFS, prevented spinal LTP, alleviated the mechanical allodynia and the decreased the level l-lactate and GFAP expression in the dorsal horn following HFS. In contrast, Chemogenetics activation of dorsal horn astrocytes in naïve rats induced spinal LTP as well as mechanical allodynia, and increased GFAP expression and l-lactate. Application of l-lactate directly to the spinal cord of naïve rats induced spinal LTP, mechanical allodynia, and increased spinal expression of p-ERK. Importantly, HFS increased GC in the plasma and glucocorticoid receptor (GR) expression in spinal astrocytes, adrenalectomy or knocking down of GR in astrocytes by using Cre-Loxp system blocked the mechanical allodynia, prevented the spinal LTP and the enhancement of lactate after HFS. These results show that lactate released from spinal astrocytes following glucocorticoid release into the plasma enhance synaptic transmission at the C-fiber synapse and underlie pain chronicity.


Assuntos
Hiperalgesia , Potenciação de Longa Duração , Animais , Astrócitos/metabolismo , Glucocorticoides/metabolismo , Glucocorticoides/farmacologia , Hiperalgesia/metabolismo , Ácido Láctico/metabolismo , Potenciação de Longa Duração/fisiologia , Camundongos , Dor/metabolismo , Células do Corno Posterior , Ratos , Ratos Sprague-Dawley , Receptores de Glucocorticoides/metabolismo , Medula Espinal/fisiologia , Corno Dorsal da Medula Espinal
19.
J Neurosci ; 42(42): 7862-7874, 2022 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-36096670

RESUMO

Peripheral neuropathic pain induced by the chemotherapeutic cisplatin can persist for months to years after treatment. Histone deacetylase 6 (HDAC6) inhibitors have therapeutic potential for cisplatin-induced neuropathic pain since they persistently reverse mechanical hypersensitivity and spontaneous pain in rodent models. Here, we investigated the mechanisms underlying reversal of mechanical hypersensitivity in male and female mice by a 2 week treatment with an HDAC6 inhibitor, administered 3 d after the last dose of cisplatin. Mechanical hypersensitivity in animals of both sexes treated with the HDAC6 inhibitor was temporarily reinstated by a single injection of the neutral opioid receptor antagonist 6ß-naltrexol or the peripherally restricted opioid receptor antagonist naloxone methiodide. These results suggest that tonic peripheral opioid ligand-receptor signaling mediates reversal of cisplatin-induced mechanical hypersensitivity after treatment with an HDAC6 inhibitor. Pointing to a specific role for δ opioid receptors (DORs), Oprd1 expression was decreased in DRG neurons following cisplatin administration, but normalized after treatment with an HDAC6 inhibitor. Mechanical hypersensitivity was temporarily reinstated in both sexes by a single injection of the DOR antagonist naltrindole. Consistently, HDAC6 inhibition failed to reverse cisplatin-induced hypersensitivity when DORs were genetically deleted from advillin+ neurons. Mechanical hypersensitivity was also temporarily reinstated in both sexes by a single injection of a neutralizing antibody against the DOR ligand met-enkephalin. In conclusion, we reveal that treatment with an HDAC6 inhibitor induces tonic enkephalin-DOR signaling in peripheral sensory neurons to suppress mechanical hypersensitivity.SIGNIFICANCE STATEMENT Over one-fourth of cancer survivors suffer from intractable painful chemotherapy-induced peripheral neuropathy (CIPN), which can last for months to years after treatment ends. HDAC6 inhibition is a novel strategy to reverse CIPN without negatively interfering with tumor growth, but the mechanisms responsible for persistent reversal are not well understood. We built on evidence that the endogenous opioid system contributes to the spontaneous, apparent resolution of pain caused by nerve damage or inflammation, referred to as latent sensitization. We show that blocking the δ opioid receptor or its ligand enkephalin unmasks CIPN in mice treated with an HDAC6 inhibitor (latent sensitization). Our work provides insight into the mechanisms by which treatment with an HDAC6 inhibitor apparently reverses CIPN.


Assuntos
Antineoplásicos , Neuralgia , Camundongos , Masculino , Feminino , Animais , Desacetilase 6 de Histona/metabolismo , Cisplatino/toxicidade , Receptores Opioides delta , Hiperalgesia/induzido quimicamente , Hiperalgesia/tratamento farmacológico , Hiperalgesia/metabolismo , Antagonistas de Entorpecentes/farmacologia , Ligantes , Analgésicos Opioides/efeitos adversos , Camundongos Endogâmicos C57BL , Neuralgia/induzido quimicamente , Neuralgia/tratamento farmacológico , Neuralgia/metabolismo , Inibidores de Histona Desacetilases , Niacinamida , Antineoplásicos/toxicidade , Encefalina Metionina , Encefalinas , Anticorpos Neutralizantes
20.
Int Immunopharmacol ; 112: 109219, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36084541

RESUMO

Neuropathic pain caused by nerve injury presents with severe spontaneous pain and a range of comorbidities, including deficits in higher executive functioning, none of which are adequately treated with current analgesics. Interleukin-6 (IL-6), a proinflammatory cytokine, is critically involved in the development and maintenance of central sensitization. However, the roles of IL-6 in neuropathic pain and related comorbidities have yet to be fully clarified. The present study examined the effect of MR16-1, an anti-IL-6 receptor antibody and inhibits IL-6 activity, on allodynia and cognitive impairment in mice with neuropathic pain following partial sciatic nerve ligation (PSNL). Significant upregulation of IL-6 expression was observed in the hippocampus in PSNL mice. Intranasal administration of MR16-1 significantly improved cognitive impairment but not allodynia in PSNL mice. Intranasal MR16-1 blocked PSNL-induced degenerative effects on hippocampal neurons. Intraperitoneal administration of MR16-1 suppressed allodynia but not cognitive impairment of PSNL mice. The findings suggest that cognitive impairment associated with neuropathic pain is mediated through changes in hippocampus induced by IL-6. These data also suggest that IL-6 mediated peripheral inflammation underlies allodynia, and IL-6 mediated inflammation in the central nervous system underlies cognitive impairment associated with neuropathic pain, and further suggest the therapeutic potential of blocking IL-6 functioning by blocking its receptor.


Assuntos
Neuralgia , Camundongos , Animais , Neuralgia/metabolismo , Hiperalgesia/tratamento farmacológico , Hiperalgesia/metabolismo , Nervo Isquiático/lesões , Analgésicos/uso terapêutico , Ligadura , Citocinas/metabolismo , Inflamação/tratamento farmacológico
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...