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Dezocine is an opioid with low efficacy at µ-opioid and κ-opioid receptors. It also inhibits the reuptake of norepinephrine and serotonin. Dezocine is an effective analgesic against various clinical painful conditions and is widely used in many Asian countries. Given the unique pharmacology of dezocine, the drug may also have antidepressant-like properties. However, no published preclinical study has explored this possibility. This study examined the potential antidepressant-like activity of dezocine in mice. Male ICR mice were used in the forced swimming test, the tail suspension test, the warm water tail withdrawal test and locomotor activity test to test the effects of dezocine (0.3-3.0 mg/kg). The 5-HT1A receptor antagonist WAY-100635 (1 mg/kg), the µ-opioid receptor antagonist ß-funaltrexamine (2 mg/kg) and the κ-opioid receptor agonist U50488 (1 mg/kg) were also studied in combination with dezocine. Dezocine produced a dose-dependent decrease in the immobility time in the forced swimming test and tail suspension test at doses that did not alter the motoric activity as determined in the locomotion test. WAY-100635 and U50488 but not ß-funaltrexamine pretreatment significantly blocked the effects of dezocine. Dezocine dose-dependently increased the latency in the tail withdrawal test which was blocked by WAY-100635 and ß-funaltrexamine. Combined, these results suggest that dezocine may have antidepressant-like effects. Considering the well-documented analgesic property of dezocine, it may be useful to treat pain and depression comorbidity.
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3,4-Dicloro-N-metil-N-(2-(1-pirrolidinil)-ciclohexil)-bencenacetamida, (trans)-Isómero/farmacología , Conducta Animal/efectos de los fármacos , Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Piperazinas/farmacología , Piridinas/farmacología , Receptores Opioides kappa , Receptores Opioides mu , Tetrahidronaftalenos/farmacología , Analgésicos/farmacología , Animales , Antidepresivos/farmacología , Relación Dosis-Respuesta a Droga , Monitoreo de Drogas/métodos , Quimioterapia Combinada/métodos , Ratones , Naltrexona/análogos & derivados , Naltrexona/farmacología , Receptores Opioides kappa/agonistas , Receptores Opioides kappa/metabolismo , Receptores Opioides mu/agonistas , Receptores Opioides mu/metabolismo , Antagonistas del Receptor de Serotonina 5-HT1/farmacología , Resultado del TratamientoRESUMEN
BACKGROUND: Nerve injury-induced changes in gene expression in the dorsal root ganglion (DRG) contribute to neuropathic pain genesis. Eukaryotic initiation factor 4 gamma 2 (eIF4G2) is a general repressor of cap-dependent mRNA translation. Whether DRG eIF4G2 participates in nerve injury-induced alternations in gene expression and nociceptive hypersensitivity is unknown. METHODS: The expression and distribution of eIF4G2 mRNA and protein in mouse DRG after spinal nerve ligation (SNL) were assessed. Effects of eIF4G2 siRNA microinjected through a glass micropipette into the injured DRG on the SNL-induced DRG mu opioid receptor (MOR) and Kv1.2 downregulation and nociceptive hypersensitivity were examined. In addition, effects of DRG microinjection of adeno-associated virus 5-expressing eIF4G2 (AAV5-eIF4G2) on basal DRG MOR and Kv1.2 expression and nociceptive thresholds were analysed. RESULTS: eIF4G2 protein co-expressed with Kv1.2 and MOR in DRG neurones. Levels of eIF4G2 mRNA (1.7 [0.24] to 2.3 [0.14]-fold of sham, P<0.01) and protein (1.6 [0.14] to 2.5 [0.22]-fold of sham, P<0.01) in injured DRG were time-dependently increased on days 3-14 after SNL. Blocking increased eIF4G2 through microinjection of eIF4G2 siRNA into the injured DRG attenuated SNL-induced downregulation of DRG MOR and Kv1.2 and development and maintenance of nociceptive hypersensitivities. DRG microinjection of AAV5-eIF4G2 reduced DRG MOR and Kv1.2 expression and elicited hypersensitivities to mechanical, heat and cold stimuli in naïve mice. CONCLUSIONS: eIF4G2 contributes to neuropathic pain through participation in downregulation of Kv1.2 and MOR in injured DRG and is a potential target for treatment of this disorder.
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Factor 4G Eucariótico de Iniciación/genética , Ganglios Espinales/metabolismo , Regulación de la Expresión Génica , Canal de Potasio Kv.1.2/genética , Neuralgia/genética , Receptores Opioides mu/genética , Animales , Células Cultivadas , Modelos Animales de Enfermedad , Regulación hacia Abajo , Masculino , Ratones , Neuralgia/metabolismo , Neuronas/metabolismo , Dimensión del DolorRESUMEN
Toll like receptor 7 (TLR7) is expressed in neurons of the dorsal root ganglion (DRG), but whether it contributes to neuropathic pain is elusive. We found that peripheral nerve injury caused by ligation of the fourth lumbar (L4) spinal nerve (SNL) or chronic constriction injury of sciatic nerve led to a significant increase in the expression of TLR7 at mRNA and protein levels in mouse injured DRG. Blocking this increase through microinjection of the adeno-associated virus (AAV) 5 expressing TLR7 shRNA into the ipsilateral L4 DRG alleviated the SNL-induced mechanical, thermal and cold pain hypersensitivities in both male and female mice. This microinjection also attenuated the SNL-induced increases in the levels of phosphorylated extracellular signal-regulated kinase ½ (p-ERK1/2) and glial fibrillary acidic protein (GFAP) in L4 dorsal horn on the ipsilateral side during both development and maintenance periods. Conversely, mimicking this increase through microinjection of AAV5 expressing full-length TLR7 into unilateral L3/4 DRGs led to elevations in the amounts of p-ERK1/2 and GFAP in the dorsal horn, augmented responses to mechanical, thermal and cold stimuli, and induced the spontaneous pain on the ipsilateral side in the absence of SNL. Mechanistically, the increased TLR7 activated the NF-κB signaling pathway through promoting the translocation of p65 into the nucleus and phosphorylation of p65 in the nucleus from the injured DRG neurons. Our findings suggest that DRG TLR7 contributes to neuropathic pain by activating NF-κB in primary sensory neurons. TLR7 may be a potential target for therapeutic treatment of this disorder.
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Neuralgia , Células Receptoras Sensoriales , Receptor Toll-Like 7 , Animales , Femenino , Ganglios Espinales , Hiperalgesia , Masculino , Glicoproteínas de Membrana , Ratones , FN-kappa BRESUMEN
Chronic pain is a significant public health problem with a lack of safe and effective analgesics. The imidazoline I2 receptor (I2 R) is a promising analgesic target, but the neuroanatomical structures involved in mediating I2 R-associated behaviors are unknown. I2 Rs are enriched in the arcuate nucleus, dorsal raphe (DR), interpeduncular nucleus, lateral mammillary body, medial habenula, nucleus accumbens (NAc) and paraventricular nucleus; thus, this study investigated the antinociceptive and hypothermic effects of microinjections of the I2 R agonist 2-(2-benzofuranyl)-2-imidazoline hydrochloride (2-BFI). In rats, intra-DR microinjections produced antinociception in complete Freund's adjuvant- and chronic constriction injury-induced pain models. Intra-NAc microinjections produced antinociception and increased noxious stimulus-associated side time in a place escape/avoidance paradigm. Intra-NAc pretreatment with the I2 R antagonist idazoxan but not the D1 receptor antagonist SCH23390 or the D2 receptor antagonist raclopride attenuated intra-NAc 2-BFI-induced antinociception. Intra-NAc idazoxan did not attenuate systemically administered 2-BFI-induced antinociception. Microinjections into the other regions did not produce antinociception, and in none of the regions produced hypothermia. These data suggest that I2 R activation in some but not all I2 R-enriched brain regions is sufficient to produce antinociception and supports the theory that different I2 R-associated effects are mediated via distinct receptor populations, which may in turn be distributed differentially throughout the CNS.
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Encéfalo/efectos de los fármacos , Imidazoles/farmacología , Núcleo Accumbens/efectos de los fármacos , Receptores de Dopamina D1/efectos de los fármacos , Analgésicos/farmacología , Animales , Benzofuranos/farmacología , Femenino , Imidazolinas/farmacología , Masculino , Dimensión del Dolor/métodos , Ratas Sprague-DawleyRESUMEN
Chronic pain remains a challenging clinical reality, yet currently available analgesics are insufficient to meet clinical needs. Increasing attention has been paid to bioactive compounds from natural plants, which may be efficacious against pain. This study examined the antinociceptive effects of isosakuranetin, a plant-derived transient receptor potential melastatin 3 blocker, in a rat model of peripheral neuropathy. Adult male Sprague-Dawley rats were first allowed to go through the chronic constriction injury surgery to develop neuropathic pain. They were then treated with isosakuranetin (1.5, 3, or 6 mg/kg) intraperitoneally and the effects on mechanical, thermal, and cold hyperalgesia were assessed using the von Frey filament test, Hargreaves' plantar test, and cold plate test, respectively. Isosakuranetin dose-dependently alleviated mechanical, thermal, and cold hyperalgesia and the antinociceptive potency was similar across the assays. In the rotarod test, isosakuranetin did not significantly affect motor performance within the doses tested, confirming the antinociceptive specificity. In summary, these findings suggest that isosakuranetin may be useful in treating neuropathic pain and deserves further investigation.
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Analgésicos/uso terapéutico , Flavonoides/uso terapéutico , Hiperalgesia/tratamiento farmacológico , Neuralgia/tratamiento farmacológico , Animales , Frío , Modelos Animales de Enfermedad , Calor , Masculino , Estimulación Física , Ratas Sprague-Dawley , Prueba de Desempeño de Rotación con Aceleración Constante , Canales Catiónicos TRPM/antagonistas & inhibidoresRESUMEN
The imidazoline I2 receptor is an emerging drug target for analgesics. This study extended previous studies by examining the antinociceptive effects of three I2 receptor agonists (2-BFI, BU224, and CR4056) in the formalin test. The receptor mechanisms and anatomical mediation of I2 receptor agonist-induced antinociception were also examined. Formalin-induced flinching responses (2%, 50 µl) were quantified after treatment with I2 receptor agonists alone or in combination with the I2 receptor antagonist idazoxan. Anatomical mediation was studied by locally administering 2-BFI into the plantar surface or into the right lateral ventricle through cannulae (intracerebroventricular). The locomotor activity was also examined after central (intracerebroventricular) administration of 2-BFI. 2-BFI (1-10 mg/kg, intraperitoneal) and BU224 (1-10 mg/kg, intraperitoneal) attenuated the spontaneous flinching response observed during 10 min (phase 1) and 20-60 min (phase 2) following formalin treatment, whereas CR4056 (1-32 mg/kg, intraperitoneal) decreased only phase 2 flinching response. The I2 receptor antagonist idazoxan attenuated the antinociceptive effects of 2-BFI and BU224 during phase 1, but not phase 2. Peripheral administration of 2-BFI (1-10 mg/kg, intraplantar) to the hind paw of rats had no antinociceptive effect. In contrast, centrally delivered 2-BFI (10-100 µg, intracerebroventricular) dose-dependently attenuated phase 1 and phase 2 flinching at doses that did not reduce the locomotor activity. Together, these data revealed the differential antinociceptive effects of I2 receptor agonists and the differential antagonism profiles by idazoxan, suggesting the involvement of different I2 receptor subtypes in reducing different phases of formalin-induced pain-like behaviors. In addition, the results also suggest the central mediation of I2 receptor agonist-induced antinociceptive actions.
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Benzofuranos/farmacología , Imidazoles/farmacología , Receptores de Imidazolina/agonistas , Quinazolinas/farmacología , Analgésicos/farmacología , Animales , Conducta Animal/efectos de los fármacos , Benzofuranos/administración & dosificación , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Imidazoles/administración & dosificación , Inyecciones Intraperitoneales , Inyecciones Intraventriculares , Locomoción/efectos de los fármacos , Masculino , Dolor/tratamiento farmacológico , Dimensión del Dolor , Quinazolinas/administración & dosificación , Ratas , Ratas Sprague-Dawley , Factores de TiempoRESUMEN
Lung cancer is the leading cause of cancer-related death worldwide. Transforming growth factor-ß receptor II (TGF-ßRII) plays an important role in the regulation of proliferation and progression in cancer. Statins have been documented to exhibit anticancer and cancer chemopreventive properties. However, the effects and mechanisms of simvastatin on the development of lung cancer are still unclear. In the present study, quiescent A549 cells were treated in vitro with fetal bovine serum (FBS) in the presence or absence of simvastatin. MTT, Western blot, and real-time qPCR were used to detect cell viability, activation of ERK, and expression of TGF-ßRII at the protein and RNA level. Our results demonstrated that simvastatin inhibited activation of ERK, downregulated expression of TGF-ßRII, and suppressed A549 cell proliferation. Furthermore, the effects of simvastatin can be reversed by farnesyl pyrophosphate (FPP). Therefore, these results suggest that simvastatin may inhibit A549 cell proliferation and downregulate TGF-ßRII expression by inhibiting activation of ERK. Our findings may advance the current understanding of the effects of simvastatin on cancer progression and contribute to the study of cancer treatment.
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Quinasas MAP Reguladas por Señal Extracelular/biosíntesis , Neoplasias Pulmonares/tratamiento farmacológico , Proteínas Serina-Treonina Quinasas/biosíntesis , Receptores de Factores de Crecimiento Transformadores beta/biosíntesis , Simvastatina/administración & dosificación , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Quinasas MAP Reguladas por Señal Extracelular/genética , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patología , Fosfatos de Poliisoprenilo/administración & dosificación , Proteínas Serina-Treonina Quinasas/genética , Receptor Tipo II de Factor de Crecimiento Transformador beta , Receptores de Factores de Crecimiento Transformadores beta/genética , Sesquiterpenos/administración & dosificaciónAsunto(s)
Receptores ErbB/genética , Ganglios Espinales/metabolismo , Síndromes de Compresión Nerviosa/genética , Neuralgia/genética , Regulación hacia Arriba/genética , Animales , Modelos Animales de Enfermedad , Receptores ErbB/metabolismo , Ganglios Espinales/efectos de los fármacos , Gefitinib/farmacología , Vértebras Lumbares/efectos de los fármacos , Vértebras Lumbares/patología , Masculino , Síndromes de Compresión Nerviosa/complicaciones , Neuralgia/complicaciones , Neuralgia/patología , Inhibidores de Proteínas Quinasas/farmacología , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN Interferente Pequeño/metabolismo , Ratas Sprague-Dawley , Transducción de Señal/efectos de los fármacos , Serina-Treonina Quinasas TOR/metabolismo , Regulación hacia Arriba/efectos de los fármacosRESUMEN
Objective: We utilized bibliometric and data visualization techniques to discern the primary research domains and emerging frontiers in the field of adult hippocampal neurogenesis (AHN). Methods: We systematically searched the Web of Science database for AHN-related articles published between 2004 and 2023. The retrieved articles were filtered based on publication types (articles and reviews) and language (English). We employed CiteSpace, VOSviewer, and the online bibliometric platform (bibliometric.com) to visualize and analyze the collected data. Results: In total, 1,590 AHN-related publications were discovered, exhibiting a steady increase in yearly publications over time. The United States emerged as the leading contributor in AHN research in terms of both publication quantity and national influence. Among all research institutions in the field of AHN, the University of California System exhibited the highest impact. Kempermann, Gerd was the most active author. The publications of the top three active authors primarily focused on the functions of AHN, and reversing hippocampal damage and cognitive impairment by improving AHN. An analysis of reference co-citation clustering revealed 8 distinct research clusters, and the notable ones included "adult hippocampal neurogenesis," "neurogenesis," "hippocampus," "dentate gyrus," "neural stem cell," and "depression." Additionally, a burst keyword detection indicated that 'anxiety' is a current research hotspot in the field of AHN. Conclusion: This in-depth bibliographic assessment of AHN offers a deeper insight into the present research hotspots in the field. The association between AHN and cognitive diseases, such as Alzheimer's disease (AD) and anxiety, has emerged as a prominent research hotspot.
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OBJECTIVE: To evaluate the effect of transcutaneous electrical acupoint stimulation (TEAS) for alleviating postoperative cough in lung cancer patients undergoing video-assisted thoracoscopic surgery. METHODS: A total of 110 patients with lung cancer undergoing video-assisted thoracoscopic surgery were randomly divided into a TEAS group (55 cases, 2 cases dropped out) and a sham-TEAS group (55 cases, 4 cases dropped out). In the TEAS group, TEAS was delivered 30 min before anesthesia and on day 1 to day 4 after operation separately, with disperse-dense wave, in frequence of 2 Hz/100 Hz. The acupoints included Feishu (BL 13), Pishu (BL 20), Shenshu (BL 23), Hegu (LI 4), Lieque (LU 7) and Taixi (KI 3) on the both sides. In the sham-TEAS group, at the same time points and same acupoints as the TEAS group, the electrode pads were attached to the acupoints, but without electric stimulation. The interventions were given 30 min each time, once daily in the two groups. The incidence of cough and the scores of visual analogue scale (VAS) for cough on the first day (T1), the third day (T2), the fifth day (T3), 1 month (T4) and 3 months (T5) after operation, as well as the scores of the Leicester cough questionnaire (LCQ) on T4 and T5 were compared between the two groups; the contents of serum C-reactive protein (CRP), interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) were detected before surgery (T0) and at T1, T2 and T3. The first flatus time, the first defecation time, the first ambulation time, the postoperative hospital day and the incidence of postoperative nausea and vomiting were compared between the two groups. RESULTS: Compared with the sham-TEAS group, the cough incidence at T3 and cough VAS scores at T1 to T5 were lower in the TEAS group (P<0.05, P<0.01), and the LCQ scores at T4 and T5 were higher (P<0.05). The serum contents of CRP, IL-6 and TNF-αat T1 to T3 in the TEAS group were lower than those of the sham-TEAS group (P<0.01). The first flatus time, the first defecation time and the first ambulation time were earlier (P<0.05, P<0.01); and the postoperative hospital day was shorter (P<0.05) and the incidence of postoperative nausea and vomiting was lower (P<0.05) in the TEAS group when compared with those of the sham-TEAS group. CONCLUSION: TEAS relieves cough in lung cancer patients undergoing video-assisted thoracoscopic surgery, improves quality of life and promotes the early postoperative recovery.
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Puntos de Acupuntura , Tos , Neoplasias Pulmonares , Complicaciones Posoperatorias , Cirugía Torácica Asistida por Video , Estimulación Eléctrica Transcutánea del Nervio , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Proteína C-Reactiva/metabolismo , Tos/etiología , Tos/terapia , Interleucina-6/sangre , Neoplasias Pulmonares/cirugía , Complicaciones Posoperatorias/terapia , Complicaciones Posoperatorias/etiología , Factor de Necrosis Tumoral alfa/sangreRESUMEN
BACKGROUND: There is growing evidence of a strong correlation between pain sensitivity and cognitive function under both physiological and pathological conditions. However, the detailed mechanisms remain largely unknown. In the current study, we sought to explore candidate genes and common molecular mechanisms underlying pain sensitivity and cognitive function with a transcriptome-wide association study using recombinant inbred mice from the BXD family. METHODS: The pain sensitivity determined by Hargreaves' paw withdrawal test and cognition-related phenotypes were systematically analyzed in 60 strains of BXD mice and correlated with hippocampus transcriptomes, followed by quantitative trait locus (QTL) mapping and systems genetics analysis. RESULTS: The pain sensitivity showed significant variability across the BXD strains and co-varies with cognitive traits. Pain sensitivity correlated hippocampual genes showed a significant involvement in cognition-related pathways, including glutamatergic synapse, and PI3K-Akt signaling pathway. Moreover, QTL mapping identified a genomic region on chromosome 4, potentially regulating the variation of pain sensitivity. Integrative analysis of expression QTL mapping, correlation analysis, and Bayesian network modeling identified Ring finger protein 20 (Rnf20) as the best candidate. Further pathway analysis indicated that Rnf20 may regulate the expression of pain sensitivity and cognitive function through the PI3K-Akt signaling pathway, particularly through interactions with genes Ppp2r2b, Ppp2r5c, Col9a3, Met, Rps6, Tnc, and Kras. CONCLUSIONS: Our study demonstrated that pain sensitivity is associated with genetic background and Rnf20-mediated PI3K-Akt signaling may involve in the regulation of pain sensitivity and cognitive functions.
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Fosfatidilinositol 3-Quinasas , Proteínas Proto-Oncogénicas c-akt , Ratones , Animales , Ratones Endogámicos C57BL , Teorema de Bayes , Umbral del Dolor , CogniciónRESUMEN
Metformin is a hypoglycemic drug widely used in the treatment of type 2 diabetes. It has been proven to have analgesic and neuroprotective effects. Metformin can reverse pain in rodents, such as diabetic neuropathic pain, neuropathic pain caused by chemotherapy drugs, inflammatory pain and pain caused by surgical incision. In clinical use, however, metformin is associated with reduced plasma vitamin B12 levels, which can further neuropathy. In rodent diabetes models, metformin plays a neuroprotective and analgesic role by activating adenosine monophosphate-activated protein kinase, clearing methylgloxal, reducing insulin resistance, and neuroinflammation. This paper also summarized the neurological adverse reactions of metformin in diabetic patients. In addition, whether metformin has sexual dimorphism needs further study.
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Diabetes Mellitus Tipo 2 , Neuropatías Diabéticas , Metformina , Fármacos Neuroprotectores , Adenosina Monofosfato/metabolismo , Diabetes Mellitus Tipo 2/complicaciones , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Neuropatías Diabéticas/tratamiento farmacológico , Neuropatías Diabéticas/etiología , Humanos , Hipoglucemiantes/uso terapéutico , Metformina/uso terapéutico , Fármacos Neuroprotectores/uso terapéutico , Dolor , Proteínas Quinasas/metabolismo , Vitamina B 12RESUMEN
AIMS: Paclitaxel-induced downregulation of two-pore domain K+ channel 1.1 (K2p1.1) caused by increasing DNA methylation within its gene promoter in the dorsal root ganglion (DRG) contributes to neuropathic pain. Given that ten-eleven translocation methylcytosine dioxygenase 1 (TET1) promotes DNA demethylation and gene transcription, the present study investigated whether DRG overexpression of TET1 produces an antinociceptive effect on the paclitaxel-induced nociceptive hypersensitivity. MAIN METHODS: TET1 was overexpressed in the DRG through unilateral microinjection of the herpes simplex virus expressing full-length Tet1 mRNA into the fourth and fifth lumbar DRGs of male rats. Behavioral tests were carried out to examine the effect of this overexpression on the paclitaxel-induced nociceptive hypersensitivity. Western blot analysis, chromatin immunoprecipitation assay and 5-hydroxymethylcytosine detection assay were performed to assess the levels of TET1/K2p1.1, 5-methylcytosine and 5-hydroxymethylcytosine, respectively. KEY FINDINGS: DRG overexpression of TET1 mitigated the paclitaxel-induced mechanical allodynia, heat hyperalgesia and cold hyperalgesia on the ipsilateral side during the development and maintenance periods. Locomotor function or basal (acute) responses to mechanical, heat or cold stimuli were not affected. Mechanistically, DRG overexpression of TET1 rescued the expression of K2p1.1 by blocking the paclitaxel-induced increase in the level of 5-methylcytosine and correspondingly reversing the paclitaxel-induced decreases in the amount of 5-hydroxymethylcytosine within the K2p1.1 promoter region in the microinjected DRGs of male rats. SIGNIFICANCE: Our findings suggest that DRG overexpression of TET1 alleviated chemotherapy-induced neuropathic pain likely through rescuing DRG K2p1.1 expression. Our findings may provide a potential avenue for the management of this disorder.
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Dioxigenasas , Neuralgia , Animales , Dioxigenasas/genética , Dioxigenasas/metabolismo , Ganglios Espinales , Hiperalgesia/inducido químicamente , Hiperalgesia/metabolismo , Masculino , Neuralgia/inducido químicamente , Neuralgia/metabolismo , Paclitaxel/farmacología , Canales de Potasio/genética , Canales de Potasio/metabolismo , Ratas , Células Receptoras Sensoriales/metabolismoRESUMEN
In the present study, the ability of baicalin to relieve neuropathic pain due to spinal nerve ligation in rats was explored, and the relationship between baicalin and α2-adrenoceptors (α2-AR) was determined. The neuropathic pain model was established by ligating the L5-L6 spinal nerves in Sprague-Dawley rats. Several α2-AR antagonists were injected into the intramedullary sheath to evaluate the role of baicalin in neuropathic pain. The antagonists included nonselective α2-AR antagonist idazoxan, α2a-AR antagonist BRL 44408, α2b-AR antagonist ARC 239 and α2c-AR antagonist JP 1302. The rats were divided into an untreated control group, saline group, baicalin group and baicalin + α2-AR antagonist groups. Paw withdrawal threshold (PWT) was tested to assess the level of pain felt by the rats. The levels of α2-AR mRNA were tested by reverse transcription-quantitative PCR. Inflammatory factors, including tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-17 and IL-1ß, were analyzed by ELISA. The histopathological changes were assessed by hematoxylin and eosin staining. Flow cytometry was used to examine the percentage of CD4+ peripheral blood mononuclear cells (PBMCs). Compared with the saline group, the PWT value increased after treating with baicalin. However, intrathecal injection of α2-AR antagonist reversed the antinociceptive effects of baicalin. Compared with the saline group, the expression of α2a-AR and α2c-AR mRNA was upregulated significantly in the baicalin group (P<0.05). Levels of α2-AR mRNA were also decreased in the baicalin + idazoxan group compared with the baicalin group (P<0.05). The levels of TNF-α, IL-6, IL-17 and IL-1ß were raised after treatment with baicalin. In addition, baicalin treatment ameliorated the histological damage in the spinal cord. The percentage of CD4+ PBMCs was increased in the saline group compared with the control group (P<0.05). Compared with the baicalin group, the percentage of CD4+ PBMCs was raised after treatment with the α2-AR antagonists. In conclusion, intrathecal injection of baicalin produced an antiallodynic effect in a spinal nerve ligation-induced neuropathic pain model. The mechanism may be related to the regulation of a2-AR expression.
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Peripheral nerve injury-induced changes in gene transcription and translation in the dorsal root ganglion (DRG) play a critical role in the development and maintenance of neuropathic pain. Long noncoding RNAs (lncRNAs) regulate gene expression. Here, we report that peripheral nerve injury caused by ligation of the fourth spinal nerve (SNL) led to a time-dependent increase in the expression in H19, an lncRNA, in the injured DRG. Microinjection of a specific H19 siRNA, but not negative control scrambled siRNA, into the injured DRG 4 days before SNL alleviated mechanical allodynia and thermal hyperalgesia on days 3 and 5 post-SNL. Additionally, DRG microinjection of the H19 siRNA on day 7 after SNL reduced mechanical allodynia and thermal hyperalgesia on days 10 and 12 post-SNL. DRG microinjection of neither siRNA affected locomotor activity and acute basal responses to mechanical and thermal stimuli. Our findings suggest that H19 participates in the peripheral mechanism underlying the development and maintenance of neuropathic pain. H19 may be a potential target for treatment of this disorder.
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[This corrects the article DOI: 10.3389/fnmol.2017.00350.].
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Thalamic pain, a type of central poststroke pain, frequently occurs following ischemia/hemorrhage in the thalamus. Current treatment of this disorder is often ineffective, at least in part due to largely unknown mechanisms that underlie thalamic pain genesis. Here, we report that hemorrhage caused by microinjection of type IV collagenase or autologous whole blood into unilateral ventral posterior lateral nucleus and ventral posterior medial nucleus of the thalamus increased the expression of Fgr, a member of the Src family nonreceptor tyrosine kinases, at both mRNA and protein levels in thalamic microglia. Pharmacological inhibition or genetic knockdown of thalamic Fgr attenuated the hemorrhage-induced thalamic injury on the ipsilateral side and the development and maintenance of mechanical, heat, and cold pain hypersensitivities on the contralateral side. Mechanistically, the increased Fgr participated in hemorrhage-induced microglial activation and subsequent production of TNF-α likely through activation of both NF-κB and ERK1/2 pathways in thalamic microglia. Our findings suggest that Fgr is a key player in thalamic pain and a potential target for the therapeutic management of this disorder.
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Accidente Cerebrovascular Hemorrágico/genética , Hiperalgesia/genética , Neuralgia/genética , Dimensión del Dolor/métodos , Proteínas Proto-Oncogénicas/genética , Familia-src Quinasas/genética , Animales , Colagenasas/toxicidad , Modelos Animales de Enfermedad , Accidente Cerebrovascular Hemorrágico/inducido químicamente , Accidente Cerebrovascular Hemorrágico/patología , Humanos , Hiperalgesia/inducido químicamente , Hiperalgesia/patología , Sistema de Señalización de MAP Quinasas/genética , Ratones , Ratones Noqueados , FN-kappa B/genética , Neuralgia/inducido químicamente , Neuralgia/patología , Tálamo/efectos de los fármacos , Tálamo/metabolismo , Tálamo/patologíaRESUMEN
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMEN
Peripheral nerve injury downregulates the expression of the µ-opioid receptor (MOR) and voltage-gated potassium channel subunit Kv1.2 by increasing their DNA methylation in the dorsal root ganglion (DRG). Ten-eleven translocation methylcytosine dioxygenase 1 (TET1) causes DNA demethylation. Given that DRG MOR and Kv1.2 downregulation contribute to neuropathic pain genesis, this study investigated the effect of DRG TET1 overexpression on neuropathic pain. Overexpression of TET1 in the DRG through microinjection of herpes simplex virus expressing full-length TET1 mRNA into the injured rat DRG significantly alleviated the fifth lumbar spinal nerve ligation (SNL)-induced pain hypersensitivities during the development and maintenance periods, without altering acute pain or locomotor function. This microinjection also restored morphine analgesia and attenuated morphine analgesic tolerance development after SNL. Mechanistically, TET1 microinjection rescued the expression of MOR and Kv1.2 by reducing the level of 5-methylcytosine and increasing the level of 5-hydroxymethylcytosine in the promoter and 5' untranslated regions of the Oprml1 gene (encoding MOR) and in the promoter region of the Kcna2 gene (encoding Kv1.2) in the DRG ipsilateral to SNL. These findings suggest that DRG TET1 overexpression mitigated neuropathic pain likely through rescue of MOR and Kv1.2 expression in the ipsilateral DRG. Virus-mediated DRG delivery of TET1 may open a new avenue for neuropathic pain management.
Asunto(s)
Dioxigenasas/metabolismo , Canal de Potasio Kv.1.2/metabolismo , Neuralgia/terapia , Receptores Opioides mu/metabolismo , Células Receptoras Sensoriales/metabolismo , Animales , Dioxigenasas/genética , Ganglios Espinales/metabolismo , Canal de Potasio Kv.1.2/genética , Masculino , Neuralgia/genética , Neuralgia/metabolismo , Ratas , Ratas Sprague-Dawley , Receptores Opioides mu/genética , Resultado del TratamientoRESUMEN
Interleukin-17 (IL-17) is considered to play an important role in the pathogenesis of a number of inflammatory conditions. Previous studies demonstrated that intranasal injections of IL-17 resulted in pulmonary inflammation and lung damage, we therefore hypothesize that dexmedetomidine, a potent α2 adrenergic receptor agonist that shows anti-inflammation effects in several animal models of inflammation, would attenuate IL-17 induced lung injury. We examined the lung damage using a histological approach, and assessed the number of lung-infiltrating neutrophils in the bronchoalveolar lavage fluid. We then compared the production of selected cytokines by measuring their serum concentration after various treatments. Finally, we evaluated the expression of selected inflammatory genes and activation of NF-κB in the lung epithelial cells, using real-time PCR and western blot assay, respectively. In every aspect of pulmonary inflammation investigated, dexmedetomidine significantly and dose-dependently attenuated the inflammatory effects of IL-17. Our results not only give a comprehensive description of the protective action of dexmedetomidine on IL-17 induced acute lung injury, but also provide insights to the underlying cellular and molecular mechanisms.