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OBJECTIVE: Childhood sensory abnormalities experience has a crucial influence on the structure and function of the adult brain. The underlying mechanism of neurological function induced by childhood sensory abnormalities experience is still unclear. Our study was to investigate whether the GABAergic neurons in the anterior cingulate cortex (ACC) regulate social disorders caused by childhood sensory abnormalities experience. METHODS: We used two mouse models, complete Freund's adjuvant (CFA) injection mice and bilateral whisker trimming (BWT) mice in childhood. We applied immunofluorescence, chemogenetic and optogenetic to study the mechanism of parvalbumin (PV) neurons and somatostatin (SST) neurons in ACC in regulating social disorders induced by sensory abnormalities in childhood. RESULTS: Inflammatory pain in childhood leads to social preference disorders, while BWT in childhood leads to social novelty disorders in adult mice. Inflammatory pain and BWT in childhood caused an increase in the number of PV and SST neurons, respectively, in adult mice ACC. Inhibiting PV neurons in ACC improved social preference disorders in adult mice that experienced inflammatory pain during childhood. Inhibiting SST neurons in ACC improved social novelty disorders in adult mice that experienced BWT in childhood. CONCLUSIONS: Our study reveals that PV and SST neurons of the ACC may play a critical role in regulating social disorders induced by sensory abnormalities in childhood.
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Giro del Cíngulo , Ratones Endogámicos C57BL , Parvalbúminas , Somatostatina , Animales , Ratones , Somatostatina/metabolismo , Masculino , Parvalbúminas/metabolismo , Neuronas GABAérgicas/fisiología , Adyuvante de Freund/toxicidad , Vibrisas/fisiología , Vibrisas/inervación , Neuronas , Trastorno de la Conducta Social/etiología , Ratones TransgénicosRESUMEN
Preclinical assessments of pain have often relied upon behavioral measurements and anesthetized neurophysiological recordings. Current technologies enabling large-scale neural recordings, however, have the potential to unveil quantifiable pain signals in conscious animals for preclinical studies. Although pain processing is distributed across many brain regions, the anterior cingulate cortex (ACC) is of particular interest in isolating these signals given its suggested role in the affective ("unpleasant") component of pain. Here, we explored the utility of the ACC toward preclinical pain research using head-mounted miniaturized microscopes to record calcium transients in freely moving male mice expressing genetically encoded calcium indicator 6f (GCaMP6f) under the Thy1 promoter. We verified the expression of GCaMP6f in excitatory neurons and found no intrinsic behavioral differences in this model. Using a multimodal stimulation paradigm across naive, pain, and analgesic conditions, we found that while ACC population activity roughly scaled with stimulus intensity, single-cell representations were highly flexible. We found only low-magnitude increases in population activity after complete Freund's adjuvant (CFA) and insufficient evidence for the existence of a robust nociceptive ensemble in the ACC. However, we found a temporal sharpening of response durations and generalized increases in pairwise neural correlations in the presence of the mechanistically distinct analgesics gabapentin or ibuprofen after (but not before) CFA-induced inflammatory pain. This increase was not explainable by changes in locomotion alone. Taken together, these results highlight challenges in isolating distinct pain signals among flexible representations in the ACC but suggest a neurophysiological hallmark of analgesia after pain that generalizes to at least two analgesics.
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Giro del Cíngulo , Animales , Ratones , Masculino , Giro del Cíngulo/fisiopatología , Giro del Cíngulo/efectos de los fármacos , Dolor/fisiopatología , Inflamación , Ratones Endogámicos C57BL , Analgesia/métodos , Analgésicos/farmacología , Adyuvante de Freund/toxicidad , Ibuprofeno/farmacologíaRESUMEN
ABSTRACT: Few analgesics identified using preclinical models have successfully translated to clinical use. These translational limitations may be due to the unidimensional nature of behavioral response measures used to assess rodent nociception. Advances in high-speed videography for pain behavior allow for objective quantification of nuanced aspects of evoked paw withdrawal responses. However, whether videography-based assessments of mechanical hypersensitivity outperform traditional measurement reproducibility is unknown. First, we determined whether high-speed videography of paw withdrawal was reproducible across experimenters. Second, we examined whether this method distinguishes behavioral responses exhibited by naive mice and mice with complete Freund's adjuvant (CFA)-induced inflammation. Twelve experimenters stimulated naive C57BL/6 mice with varying mechanical stimuli. Paw withdrawal responses were recorded with high-speed videography and scored offline by one individual. Our group was unable to replicate the original findings produced by high-speed videography analysis. Surprisingly, â¼80% of variation was not accounted for by variables previously reported to distinguish between responses to innocuous and noxious stimuli (paw height, paw velocity, and pain score), or by additional variables (experimenter, time-of-day, and animal), but rather by unidentified factors. Similar high-speed videography assessments were performed in CFA- and vehicle-treated animals, and the cumulative data failed to reveal an effect of CFA injection on withdrawal as measured by high-speed videography. This study does not support using paw height, velocity, or pain score measurements from high-speed recordings to delineate behavioral responses to innocuous and noxious stimuli. Our group encourages the continued use of traditional mechanical withdrawal assessments until additional high-speed withdrawal measures are validated in established pain models.
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Adyuvante de Freund , Inflamación , Ratones Endogámicos C57BL , Dimensión del Dolor , Animales , Ratones , Masculino , Dimensión del Dolor/métodos , Adyuvante de Freund/toxicidad , Modelos Animales de Enfermedad , Hiperalgesia/fisiopatología , Grabación en Video/métodos , Reproducibilidad de los Resultados , Estimulación Física/efectos adversos , Conducta Animal/fisiología , Conducta Animal/efectos de los fármacosRESUMEN
BACKGROUND: Inflammatory pain is caused by damaged tissue or noxious stimuli, accompanied by the release of inflammatory mediators that often leads to severe hyperalgesia and allodynia with limited therapy options. Recently, a novel mitochondrial-derived peptide (named MOTS-c) was reported to regulate obesity, metabolic homeostasis and inflammatory response. The aim of this study was to investigate the effects of MOTS-c and its related regulatory mechanisms involved in inflammatory pain. METHODS: Male Kunming mice (8-10 weeks-old) were intraplantar injected with formalin, capsaicin, λ-Carrageenan and complete Freund adjuvant (CFA) to establish acute and chronic inflammatory pain. The effects of MOTS-c on the above inflammatory pain mice and its underlying mechanisms were examined by behavioral tests, quantitative polymerase chain reaction (qPCR), western blotting, enzyme linked immunosorbent assay (ELISA), immunohistochemistry (IHC) and immunofluorescence (IF). RESULTS: Behavioral experiments investigated the potential beneficial effects of MOTS-c on multiple acute and chronic inflammatory pain in mice. The results showed that MOTS-c treatment produced potent anti-allodynic effects in formalin-induced acute inflammatory pain, capsaicin-induced nocifensive behaviors and λ-Carrageenan/CFA-induced chronic inflammatory pain model. Further mechanistic studies revealed that central MOTS-c treatment significantly ameliorated CFA-evoked the release of inflammatory factors and activation of glial cells and neurons in the spinal dorsal horn. Moreover, peripheral MOTS-c treatment reduced CFA-evoked inflammatory responses in the surface structure of hindpaw skin, accompanied by inhibiting excitation of peripheral calcitonin gene-related peptide (CGRP) and P2X3 nociceptive neurons. CONCLUSIONS: The present study indicates that MOTS-c may serve as a promising therapeutic target for inflammatory pain.
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Capsaicina , Dolor Crónico , Ratones , Masculino , Animales , Carragenina/toxicidad , Carragenina/uso terapéutico , Capsaicina/farmacología , Inflamación/tratamiento farmacológico , Inflamación/metabolismo , Hiperalgesia/metabolismo , Dolor Crónico/complicaciones , Adyuvante de Freund/toxicidad , Formaldehído/toxicidad , Formaldehído/uso terapéuticoRESUMEN
Peripheral sensitization is one of the primary mechanisms underlying the pathogenesis of chronic pain. However, candidate molecules involved in peripheral sensitization remain incompletely understood. We have shown that store-operated calcium channels (SOCs) are expressed in the dorsal root ganglion (DRG) neurons. Whether SOCs contribute to peripheral sensitization associated with chronic inflammatory pain is elusive. Here we report that global or conditional deletion of Orai1 attenuates Complete Freund's adjuvant (CFA)-induced pain hypersensitivity in both male and female mice. To further establish the role of Orai1 in inflammatory pain, we performed calcium imaging and patch-clamp recordings in wild-type (WT) and Orai1 knockout (KO) DRG neurons. We found that SOC function was significantly enhanced in WT but not in Orai1 KO DRG neurons from CFA- and carrageenan-injected mice. Interestingly, the Orai1 protein level in L3/4 DRGs was not altered under inflammatory conditions. To understand how Orai1 is modulated under inflammatory pain conditions, prostaglandin E2 (PGE2) was used to sensitize DRG neurons. PGE2-induced increase in neuronal excitability and pain hypersensitivity was significantly reduced in Orai1 KO mice. PGE2-induced potentiation of SOC entry (SOCE) was observed in WT, but not in Orai1 KO DRG neurons. This effect was attenuated by a PGE2 receptor 1 (EP1) antagonist and mimicked by an EP1 agonist. Inhibition of Gq/11, PKC, or ERK abolished PGE2-induced SOCE increase, indicating PGE2-induced SOCE enhancement is mediated by EP1-mediated downstream cascade. These findings demonstrate that Orai1 plays an important role in peripheral sensitization. Our study also provides new insight into molecular mechanisms underlying PGE2-induced modulation of inflammatory pain.Significance Statement Store-operated calcium channel (SOC) Orai1 is expressed and functional in dorsal root ganglion (DRG) neurons. Whether Orai1 contributes to peripheral sensitization is unclear. The present study demonstrates that Orai1-mediated SOC function is enhanced in DRG neurons under inflammatory conditions. Global and conditional deletion of Orai1 attenuates complete Freund's adjuvant (CFA)-induced pain hypersensitivity. We also demonstrate that prostaglandin E2 (PGE2) potentiates SOC function in DRG neurons through EP1-mediated signaling pathway. Importantly, we have found that Orai1 deficiency diminishes PGE2-induced SOC function increase and reduces PGE2-induced increase in neuronal excitability and pain hypersensitivity. These findings suggest that Orai1 plays an important role in peripheral sensitization associated with inflammatory pain. Our study reveals a novel mechanism underlying PGE2/EP1-induced peripheral sensitization. Orai1 may serve as a potential target for pathological pain.
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Calcio , Dinoprostona , Animales , Femenino , Masculino , Ratones , Calcio/metabolismo , Canales de Calcio/metabolismo , Dinoprostona/farmacología , Dinoprostona/metabolismo , Adyuvante de Freund/toxicidad , Adyuvante de Freund/metabolismo , Ganglios Espinales/metabolismo , Proteína ORAI1/genética , Proteína ORAI1/metabolismo , DolorRESUMEN
Previous studies have shown that the C-C motif chemokine ligand 2 (CCL2) is widely expressed in the nervous system and involved in regulating the development of chronic pain and related anxiety-like behaviors, but its precise mechanism is still unclear. This paper provides an in-depth examination of the involvement of CCL2-CCR2 signaling in the anterior cingulate cortex (ACC) in intraplantar injection of complete Freund's adjuvant (CFA) leading to inflammatory pain and its concomitant anxiety-like behaviors by modulation of glutamatergic N-methyl-D-aspartate receptor (NMDAR). Our findings suggest that local bilateral injection of CCR2 antagonist in the ACC inhibits CFA-induced inflammatory pain and anxiety-like behavior. Meanwhile, the expression of CCR2 and CCL2 was significantly increased in ACC after 14 days of intraplantar injection of CFA, and CCR2 was mainly expressed in excitatory neurons. Whole-cell patch-clamp recordings showed that the CCR2 inhibitor RS504393 reduced the frequency of miniature excitatory postsynaptic currents (mEPSC) in ACC, and CCL2 was involved in the regulation of NMDAR-induced current in ACC neurons in the pathological state. In addition, local injection of the NR2B inhibitor of NMDAR subunits, Ro 25-6981, attenuated the effects of CCL2-induced hyperalgesia and anxiety-like behavior in the ACC. In summary, CCL2 acts on CCR2 in ACC excitatory neurons and participates in the regulation of CFA-induced pain and related anxiety-like behaviors through upregulation of NR2B. CCR2 in the ACC neuron may be a potential target for the treatment of chronic inflammatory pain and pain-related anxiety.
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Ansiedad , Quimiocina CCL2 , Giro del Cíngulo , Inflamación , N-Metilaspartato , Dolor , Receptores CCR2 , Receptores de N-Metil-D-Aspartato , Transducción de Señal , Animales , Giro del Cíngulo/metabolismo , Giro del Cíngulo/efectos de los fármacos , Inflamación/patología , Inflamación/metabolismo , Masculino , Ansiedad/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Quimiocina CCL2/metabolismo , Receptores CCR2/metabolismo , Receptores CCR2/antagonistas & inhibidores , Dolor/metabolismo , Dolor/patología , Transducción de Señal/efectos de los fármacos , Potenciales Postsinápticos Excitadores/efectos de los fármacos , Adyuvante de Freund/toxicidad , Ratones Endogámicos C57BL , Neuronas/metabolismo , Neuronas/efectos de los fármacos , Conducta Animal , Hiperalgesia/metabolismo , Hiperalgesia/patología , Compuestos de Espiro , BenzoxazinasRESUMEN
Chronic pain can induce not only nociceptive but also depressive emotions. A previous study demonstrated that betaine, a commonly used nutrient supplement, has an anti-nociceptive effect, but whether betaine can alleviate chronic pain-induced depressive emotion is elusive. Our current study found that betaine administration significantly eliminated complete Freund's adjuvant (CFA)-induced pain-related depressive-like behaviour. Mechanistically, betaine treatment inhibited microglia and astrocyte activation. Furthermore, betaine significantly promoted the transition of microglia from the M1 to the M2 phenotype, as well as the transition of astrocytes from the A1 to the A2 phenotype. Additionally, the release of pro-inflammatory factors such as IL-18, IL-1ß and IL-6 and anti-inflammatory factors such as IL-10 in the hippocampus induced by CFA were also reversed by betaine administration. Overall, betaine has therapeutic effects on pain-related depressive-like phenotypes caused by CFA, possibly through altering the polarization of microglia and astrocytes to reduce neuroinflammation.
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Dolor Crónico , Microglía , Ratones , Animales , Betaína/efectos adversos , Astrocitos , Adyuvante de Freund/toxicidad , Inflamación/genéticaRESUMEN
Increasing evidence suggests that alternative splicing plays a critical role in pain, but its underlying mechanism remains elusive. Herein, we employed complete Freund's adjuvant (CFA) to induce inflammatory pain in mice. A combination of genomics research techniques, lentivirus-based genetic manipulations, behavioral tests, and molecular biological technologies confirmed that splicing factor Cwc22 mRNA and CWC22 protein were elevated in the spinal dorsal horn at 3 days after CFA injection. Knockdown of spinal CWC22 by lentivirus transfection (lenti-shCwc22) reversed CFA-induced thermal hyperalgesia and mechanical allodynia, whereas upregulation of spinal CWC22 (lenti-Cwc22) in naïve mice precipitated pain. Comprehensive transcriptome and genome analysis identified the secreted phosphoprotein 1 (Spp1) as a potential gene of CWC22-mediated alternative splicing, however, only Spp1 splicing variant 4 (Spp1 V4) was involved in thermal and mechanical nociceptive regulation. In conclusion, our findings demonstrate that spinal CWC22 regulates Spp1 V4 to participate in CFA-induced inflammatory pain. Blocking CWC22 or CWC22-mediated alternative splicing may provide a novel therapeutic target for the treatment of persistent inflammatory pain.
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Empalme Alternativo , Nocicepción , Animales , Ratones , Adyuvante de Freund/toxicidad , Hiperalgesia/metabolismo , Inflamación/metabolismo , Osteopontina/metabolismo , Dolor/tratamiento farmacológico , Médula Espinal/metabolismoRESUMEN
Fentanyl is a potent analgesic with a rapid onset and short half-life that make it a useful treatment for pain and a lethal drug of abuse. The present study used voluntary home cage wheel running to assess the effect of hindpaw inflammation, fentanyl administration, and spontaneous fentanyl withdrawal. Fentanyl (0.32 or 1.0 mg/kg/day) or placebo osmotic pumps were implanted subcutaneously and rats received an intraplantar injection of Complete Freund's Adjuvant (CFA) or saline. Rats with hindpaw inflammation caused by CFA administration were less active than rats injected with saline into the hindpaw. The antinociceptive effect of 0.32 mg/kg/day of fentanyl was evident as a recovery of wheel running in these rats. Administration of 1 mg/kg/day of fentanyl almost completely inhibited wheel running during the first day in rats with and without hindpaw inflammation. Wheel running increased each subsequent day until the pumps were surgically removed after day 3. Withdrawal from 0.32 or 1 mg/kg/day of fentanyl caused a decrease in wheel running that lasted 2 days in rats without hindpaw inflammation. In contrast, withdrawal was only evident following termination of 1 mg/kg/day of fentanyl in rats with hindpaw inflammation. This decrease in running seemed to persist beyond the 3 days of assessment. These data demonstrate that fentanyl can either depress or restore activity depending on the dose and pain condition. Moreover, termination of 3 days of continuous fentanyl administration resulted in a dose and time dependent decrease in wheel running consistent with opioid withdrawal.
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Fentanilo , Actividad Motora , Animales , Ratas , Fentanilo/administración & dosificación , Adyuvante de Freund/toxicidad , Inflamación/complicaciones , Dolor/tratamiento farmacológicoRESUMEN
INTRODUCTION: Inflammatory pain is a significant global clinical challenge that involves both unpleasant sensory and emotional experiences. The treatment of pain is imminent, and we are committed to seeking new analgesics for pain relief. Transcrocetin meglumine salt (TCMS), a saffron metabolite derived from the crocin apocarotenoids, has exhibited the ability to cross the blood-brain barrier and exert neuroprotective effects. In this study, we aimed to investigate whether TCMS could ameliorate complete Freund's adjuvant (CFA)-induced inflammatory pain in mice and elucidate its underlying mechanisms. METHODS: Here, we established an inflammatory pain model in mice by injecting CFA into the left hind paw. Three days later, we administered intraperitoneal injections of TCMS (10 mg/kg) or saline to the animals. We examined mechanical allodynia, thermal hypersensitivity, and anxiety behavior. Furthermore, the activation of glial cells and proinflammatory cytokines in the spinal cord were detected. RESULTS: Our results showed that TCMS significantly reversed the mechanical allodynia and thermal hypersensitivity in the CFA-injected mice. Furthermore, TCMS administration effectively inhibited the activation of microglia and astrocytes in the spinal cord induced by CFA. Additionally, TCMS suppressed the production and release of spinal proinflammatory cytokines, including TNF-α, IL-1ß, and IL-6, in CFA-injected mice. CONCLUSION: Taken together, our findings demonstrate that TCMS holds promise as an innovative analgesic due to its ability to ameliorate inflammatory reactions.
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Citocinas , Hiperalgesia , Ratones , Animales , Citocinas/metabolismo , Hiperalgesia/inducido químicamente , Hiperalgesia/tratamiento farmacológico , Adyuvante de Freund/toxicidad , Meglumina/efectos adversos , Dolor/tratamiento farmacológico , Neuroglía/metabolismo , Inflamación/inducido químicamente , Inflamación/tratamiento farmacológico , Inflamación/metabolismo , Médula EspinalRESUMEN
Orofacial pain (OFP) is a clinically very common and the most troubling condition; however, there is few effective way to relieve OFP. Rab11a, a small molecule guanosine triphosphate enzyme, is one of the Rab member family playing a vital role in intracellular endocytosis and the pain process. Therefore, we investigated the hub genes of rat OFP model induced by Complete Freund's Adjuvant (CFA) via re-analyzing microarray data (GSE111160). We found that Rab11a acted as a key hub gene in the process of OFP. During the validation of Rab11a, the OFP model was established by peripheral injection of CFA, which decreased the head withdrawal threshold (HWT) and head withdrawal lantency (HWL). Rab11a was observed in NeuN of Sp5C instead of GFAP/IBA-1, and double-IF of Rab11a and Fos positive cells were increased on the 7th day after CFA modeling statistically. Rab11a protein expression in TG and Sp5C of CFA group was also significantly increased. Interestingly, injection of Rab11a-targeted short hairpin RNA (Rab11a-shRNA) into Sp5C could reverse the decrease in HWT and HWL and reduce the expression level of Rab11a. Electrophysiological recording further demonstrated that the activity of Sp5C neuron was improved in CFA group, while Rab11a-shRNA considerably decreased the enhancement of Sp5C neuronal activity. Finally, we detected the expression level of p-PI3K, p-AKT, and p-mTOR in Sp5C of rats after injecting the Rab11a-shRNA virus. To our surprise, CFA upregulated the phosphorylation of PI3K, AKT and mTOR in Sp5C, and Rab11a-shRNA downregulated these molecules' expression. Our data suggest that CFA activates the PI3K/AKT signaling pathway through up-regulating Rab11a expression, which can induce OFP hyperalgesia development furtherly. Targeting Rab11a may be a novel treatment strategy for OFP.
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Fosfatidilinositol 3-Quinasas , Proteínas Proto-Oncogénicas c-akt , Animales , Ratas , Dolor Facial/inducido químicamente , Adyuvante de Freund/toxicidad , Hiperalgesia/metabolismo , Inflamación/inducido químicamente , Inflamación/metabolismo , Ratas Sprague-Dawley , Serina-Treonina Quinasas TORRESUMEN
AIMS: Lysine-specific demethylase 6B (KDM6B) serves as a key mediator of gene transcription. It regulates expression of proinflammatory cytokines and chemokines in variety of diseases. Herein, the role and the underlying mechanisms of KDM6B in inflammatory pain were studied. METHODS: The inflammatory pain was conducted by intraplantar injection of complete Freund's adjuvant (CFA) in rats. Immunofluorescence, Western blotting, qRT-PCR, and chromatin immunoprecipitation (ChIP)-PCR were performed to investigate the underlying mechanisms. RESULTS: CFA injection led to upregulation of KDM6B and decrease in the level of H3K27me3 in the dorsal root ganglia (DRG) and spinal dorsal horn. The mechanical allodynia and thermal hyperalgesia following CFA were alleviated by the treatment of intrathecal injection of GSK-J4, and by microinjection of AAV-EGFP-KDM6B shRNA in the sciatic nerve or in lumbar 5 dorsal horn. The increased production of tumor necrosis factor-α (TNF-α) following CFA in the DRGs and dorsal horn was inhibited by these treatments. ChIP-PCR showed that CFA-induced increased binding of nuclear factor κB with TNF-α promoter was repressed by the treatment of microinjection of AAV-EGFP-KDM6B shRNA. CONCLUSIONS: These results suggest that upregulated KDM6B via facilitating TNF-α expression in the DRG and spinal dorsal horn aggravates inflammatory pain.
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Ganglios Espinales , Histonas , Asta Dorsal de la Médula Espinal , Factor de Necrosis Tumoral alfa , Animales , Ratas , Desmetilación , Adyuvante de Freund/toxicidad , Ganglios Espinales/metabolismo , Histonas/metabolismo , Hiperalgesia/metabolismo , Lisina/metabolismo , Dolor/metabolismo , Dimensión del Dolor , Ratas Sprague-Dawley , ARN Interferente Pequeño/metabolismo , Asta Dorsal de la Médula Espinal/metabolismo , Factor de Necrosis Tumoral alfa/metabolismo , Regulación hacia ArribaRESUMEN
Chronic pain, along with comorbid psychiatric disorders, is a common problem worldwide. A growing number of studies have focused on non-opioid-based medicines, and billions of funds have been put into digging new analgesic mechanisms. Peripheral inflammation is one of the critical causes of chronic pain, and drugs with anti-inflammatory effects usually alleviate pain hypersensitivity. Sophoridine (SRI), one of the most abundant alkaloids in Chinese herbs, has been proved to exert antitumor, antivirus and anti-inflammation effects. Here, we evaluated the analgesic effect of SRI in an inflammatory pain mouse model induced by complete Freund's adjuvant (CFA) injection. SRI treatment significantly decreased pro-inflammatory factors release after LPS stimuli in microglia. Three days of SRI treatment relieved CFA-induced mechanical hypersensitivity and anxiety-like behavior, and recovered abnormal neuroplasticity in the anterior cingulate cortex of mice. Therefore, SRI may be a candidate compound for the treatment of chronic inflammatory pain and may serve as a structural basis for the development of new drugs.
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Dolor Crónico , Hiperalgesia , Ratones , Animales , Hiperalgesia/complicaciones , Hiperalgesia/tratamiento farmacológico , Hiperalgesia/inducido químicamente , Adyuvante de Freund/toxicidad , Matrinas , Dolor Crónico/tratamiento farmacológico , Analgésicos/farmacología , Analgésicos/uso terapéutico , Ansiedad/complicaciones , Ansiedad/tratamiento farmacológicoRESUMEN
The origin of chronic pain is linked to inflammation, characterized by increased levels of proinflammatory cytokines in local tissues and systemic circulation. Transforming growth factor beta-activated kinase 1 (TAK1) is a key regulator of proinflammatory cytokine signaling that has been well characterized in the context of cancer and autoimmune disorders, yet its role in chronic pain is less clear. Here, we evaluated the ability of our TAK1 small-molecule inhibitor, takinib, to attenuate pain and inflammation in preclinical models of inflammatory, neuropathic, and primary pain. Inflammatory, neuropathic, and primary pain was modeled using intraplantar complete Freund's adjuvant (CFA), chronic constriction injury (CCI), and systemic delivery of the catechol-O-methyltransferase (COMT) inhibitor OR486, respectively. Behavioral responses evoked by mechanical and thermal stimuli were evaluated in separate groups of mice receiving takinib or vehicle prior to pain induction (baseline) and over 12 days following CFA injection, 4 weeks following CCI surgery, and 6 hours following OR486 delivery. Hindpaw edema was also measured prior to and 3 days following CFA injection. Upon termination of behavioral experiments, dorsal root ganglia (DRG) were collected to measure cytokines. We also evaluated the ability of takinib to modulate nociceptor activity via in vitro calcium imaging of neurons isolated from the DRG of Gcamp3 mice. In all 3 models, TAK1 inhibition significantly reduced hypersensitivity to mechanical and thermal stimuli and expression of proinflammatory cytokines in DRG. Furthermore, TAK1 inhibition significantly reduced the activity of tumor necrosis factor (TNF)-primed/capsaicin-evoked DRG nociceptive neurons. Overall, our results support the therapeutic potential of TAK1 as a novel drug target for the treatment of chronic pain syndromes with different etiologies. PERSPECTIVE: This article reports the therapeutic potential of TAK1 inhibitors for the treatment of chronic pain. This new treatment has the potential to provide a greater therapeutic offering to physicians and patients suffering from chronic pain as well as reduce the dependency on opioid-based pain treatments.
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Dolor Crónico , Animales , Ratones , Catecol O-Metiltransferasa , Dolor Crónico/complicaciones , Citocinas/metabolismo , Modelos Animales de Enfermedad , Adyuvante de Freund/toxicidad , Ganglios Espinales/metabolismo , Hiperalgesia/metabolismo , Inflamación/complicaciones , Ratas Sprague-Dawley , RatasRESUMEN
BACKGROUND: Inflammation often leads to the occurrence of chronic pain, and many miRNAs have been shown to play a key role in the development of inflammatory pain. However, whether miR-26a-5p relieves pain induced by inflammation and its possible mechanism are still unclear. METHODS: The complete Freund's adjuvant (CFA)-induced inflammatory pain mouse model was employed. Intrathecal or subcutaneous injection of miR-26a-5p agomir was performed after modeling to study its antinociceptive effect and the comparison of different administration methods. Bioinformatics analysis of miRNAs was performed to study the downstream mechanisms of miR-26a-5p. HE staining, RT-qPCR, Western blotting, and immunofluorescence were used for further validation. RESULTS: A single intrathecal and subcutaneous injection of miR-26a-5p both reversed mechanical hypersensitivity and thermal latency in the left hind paw of mice with CFA-induced inflammatory pain. HE staining and immunofluorescence studies found that both administrations of miR-26a-5p alleviated inflammation in the periphery and spinal cord. Bioinformatics analysis and dual-luciferase reporter gene analysis identified Wnt5a as a direct downstream target gene of miR-26a-5p. Wnt5a was mainly expressed in neurons and microglia in the spinal cord of mice with inflammatory pain. Intrathecal injection of miR-26a-5p could significantly reduce the expression level of Wnt5a and inhibit the downstream molecules of noncanonical Wnt signaling Camk2/NFAT, inhibiting the release of spinal cord inflammatory factors and alleviating the activation of microglia. In addition, miR-26a-5p could also inhibit lipopolysaccharide (LPS)-stimulated BV2 cell inflammation in vitro through a noncanonical Wnt signaling pathway. CONCLUSIONS: miR-26a-5p is a promising therapy for CFA-induced inflammatory pain. Both intrathecal and subcutaneous injections provide relief for inflammatory pain. miR-26a-5p regulated noncanonical Wnt signaling to be involved in analgesia partly through antineuroinflammation, suggesting a pain-alleviating effect via noncanonical Wnt signaling pathway in the CFA-induced inflammatory pain model in vivo.
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Hiperalgesia , MicroARNs , Ratones , Animales , Hiperalgesia/tratamiento farmacológico , Hiperalgesia/metabolismo , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina , Adyuvante de Freund/toxicidad , Dolor/tratamiento farmacológico , Dolor/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Inflamación/inducido químicamente , Inflamación/genéticaRESUMEN
Osteoarthritis (OA) is a common osteoarthropathy with chronic inflammatory pain as the core symptom in middle-aged and elderly people. LncRNA MEG3 (Maternally expressed gene 3) is involved in the development of OA via regulation of angiogenesis, which causes the activation and overexpression of transient receptor potential vanilloid type-1 (TRPV1). In this study, we investigated the mechanism of MEG3-TRPV1 signaling in chronic inflammatory pain (CIP) of rat model. Chronic inflammatory pain was modeled using subcutaneous microinjection of complete Freund's adjuvant (CFA) into the left hind paw of rats. We showed that TRPV1 mRNA and protein were significantly increased, while MEG3 mRNA was significantly decreased, in the DRG and SDH of CFA-induced rats. In addition, intrathecal injection of MEG3-overexpressing lentivirus significantly downregulated TRPV1 expression and alleviated chronic inflammatory pain in CFA-induced rats. Treatment with a TRPV1 antagonist also significantly relieved chronic inflammatory pain in CFA-induced rats. In general, our results reveal that MEG3 alleviates chronic inflammatory pain by downregulating TRPV1 expression. These findings may provide new therapeutic targets in the treatment of patients with OA.
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Dolor Crónico , ARN Largo no Codificante , Animales , Ratas , Dolor Crónico/complicaciones , Dolor Crónico/genética , Adyuvante de Freund/toxicidad , Hiperalgesia/tratamiento farmacológico , Inflamación/complicaciones , Inflamación/inducido químicamente , ARN Largo no Codificante/genética , ARN Mensajero/genética , Canales Catiónicos TRPV/genética , Canales Catiónicos TRPV/metabolismoRESUMEN
DNA hydroxylation catalyzed by Tet dioxygenases occurs abundantly in neurons in mammals. However, effects of ten-eleven translocation methylcytosine dioxygenase 1 (TET1) expression and hydroxymethylation status on neuron injury remain unclear. This study was designed to explore the effects of TET1 and TET2 expression in the inflammatory pain of rats induced by complete Freund's adjuvant (CFA). Mechanical paw withdrawal threshold (PWT) and thermal withdrawal latency (TWL) were detected to assess pain behavior. The expression of TET1 and TET2 were measured in the dorsal root ganglion (DRG) with western blotting analysis. Immunofluorescence staining is employed to detect the expression and co-location of TRPV1 with TET1. Intrathecal administration of Bobcat339 was used to inhibit TET1 function in dorsal root ganglion. The paw withdrawal threshold and thermal withdrawal latency of rats were significantly reduced after CFA Injection. Western blot results showed that the expression of TET1 was significantly increased at 3 days after CFA injection, but TET2 had no statistical difference. Immunofluorescence results showed that TET1 was co-localized with TRPV1. Intrathecal administration of Bobcat339 improved mechanical and thermal pain threshold in CFA rats. Our findings highlight the role of TET1 in chronic inflammatory pain model. The expression of TET1 was increased in CFA rats, and suppression of TET1 will ameliorate inflammatory pain.
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Dolor Crónico , Dioxigenasas , Animales , Ratas , Dolor Crónico/complicaciones , Dioxigenasas/metabolismo , Adyuvante de Freund/toxicidad , Ganglios Espinales , Umbral del DolorRESUMEN
We studied the effects of inflammatory pain on working memory and correlated the pain effects with changes in dendritic spine density and glutamate signaling in the medial prefrontal cortex (mPFC) of male and female mice. Injection of Complete Freund's Adjuvant (CFA) into the hind paw modeled inflammatory pain. The CFA equally decreased the mechanical thresholds in both sexes. The density of dendritic spines, as a marker for neuronal input, increased on the dendrites of both, pyramidal cells and interneurons in males but only on the dendrites of interneurons in CFA injected females. Next, we injected virus with glutamate sensor (pAAV5.hSyn.iGluSnFr) into the mPFC and used fiber photometry to record glutamate signaling during Y-maze spontaneous alternations test, which is a test for working memory in rodents. The detected fluorescent signal was higher during correct alternations when compared to incorrect alternations in both sexes. The CFA injection did not change the pattern of glutamate fluorescence during the test but the female mice made fewer incorrect alternations than their male counterparts. Furthermore, while the CFA injection decreased the expression of the glutamate transporter VGlut1 on the soma of mPFC neurons in both sexes, the decrease was sex dependent. We concluded that inflammatory pain, which increases sensory input into the mPFC neurons, may impair working memory by altering the glutamate signaling. The glutamate deficit that develops as a result of the pain is more pronounced in male mice in comparison to female mice.
Asunto(s)
Memoria a Corto Plazo , Dolor , Ratones , Masculino , Femenino , Animales , Adyuvante de Freund/toxicidad , Dolor/metabolismo , Trastornos de la Memoria/etiología , Sistema de Transporte de Aminoácidos X-AG , Ácido Glutámico , Inflamación/inducido químicamente , Inflamación/metabolismoRESUMEN
Chronic pain increases the risk of developing anxiety, with limbic areas being likely neurological substrates. Despite high clinical relevance, little is known about the precise behavioral, hormonal, and brain neuroplastic correlates of anxiety in the context of persistent pain. Previous studies have shown that decreased nociceptive thresholds in chronic pain models are paralleled by anxiety-like behavior in rats, but there are conflicting ideas regarding its effects on the stress response and circulating corticosterone levels. Even less is known about the molecular mechanisms through which the brain encodes pain-related anxiety. This study examines how persistent inflammatory pain in a rat model would impact anxiety-like behaviors and corticosterone release, and whether these changes would be reflected in levels of global DNA methylation in brain areas involved in stress regulation. Complete Freund's adjuvant (CFA) or saline was administered in the right hindpaw of adult male Wistar rats. Behavioral testing included the measurement of nociceptive thresholds (digital anesthesiometer), motor function (open field test), and anxiety-like behaviors (elevated plus maze and the dark-light box test). Corticosterone was measured via radioimmunoassay. Global DNA methylation (enzyme immunoassay) as well as DNMT3a levels (western blotting) were quantified in the amygdala, prefrontal cortex, and ventral hippocampus. CFA administration resulted in persistent reduction in nociceptive threshold in the absence of locomotor abnormalities. Increased anxiety-like behaviors were observed in the elevated plus maze and were accompanied by increased blood corticosterone levels 10 days after pain induction. Global DNA methylation was decreased in the amygdala, with no changes in DNMT3a abundance in any of the regions examined. Persistent inflammatory pain promotes anxiety -like behaviors, HPA axis activation, and epigenetic regulation through DNA methylation in the amygdala. These findings describe a molecular mechanism that links pain and stress in a well-characterized rodent model.
Asunto(s)
Dolor Crónico , Corticosterona , Amígdala del Cerebelo , Animales , Ansiedad/complicaciones , Ansiedad/genética , Metilación de ADN/genética , Epigénesis Genética , Adyuvante de Freund/toxicidad , Sistema Hipotálamo-Hipofisario , Masculino , Sistema Hipófiso-Suprarrenal , Ratas , Ratas WistarRESUMEN
α2 adrenergic agonists are widely used in clinical anesthesia and ICU sedation owing to their effective sedative and analgesic effects. Lumbago and leg pain is the most common clinical pain disease. Studies have reported that lumbago and leg pain is associated with dysregulation of paravertebral muscles, especially psoas major muscles. In the present study, a unilateral lower extremity chronic inflammation and pain model was established by subcutaneous administration of low-dose complete Fredrin's adjuvant (CFA) into the posterior paw of rats. α2 adrenalin receptor agonist was then injected into the psoas major muscle. Behavioral tests were conducted for 21 days. Psoas major muscle tissue was harvested for evaluation of biochemical indexes related to pain. The effect of α2 adrenergic receptor agonist injected into psoas major muscle on chronic inflammatory pain of lower extremities in rats was explored. The results showed that injection of α2 adrenergic receptor agonist into the psoas major muscle relieved CFA-induced mechanical hyperalgesia. Administration of α2 adrenergic receptor antagonist yohimbine reversed the analgesic effect of α2 adrenergic receptor agonists. Administration of dexmedetomidine into psoas major muscle downregulated the levels of norepinephrine, interleukin-6 and tumor necrosis factor-α in tissues. The findings of the present study show that administration of α2 adrenoceptor agonists into the psoas major muscle relieves chronic inflammatory pain induced by CFA. Local injection of dexmedetomidine also exerted anti-inflammatory and anti-sympathetic effect by activating α2-adrenoceptor in the psoas major muscle.