Post-amputation pain causes great suffering to amputees, but still no effective drugs are available due to its elusive mechanisms. Our previous clinical studies found that surgical removal or radiofrequency treatment of the neuroma at the axotomized nerve stump effectively relieves the phantom pain afflicting patients after amputation. This indicated an essential role of the residual nerve stump in the formation of chronic post-amputation pain (CPAP). However, the molecular mechanism by which the residual nerve stump or neuroma is involved and regulates CPAP is still a mystery. In this study, we found that nociceptors expressed the mechanosensitive ion channel TMEM63A and macrophages infiltrated into the dorsal root ganglion (DRG) neurons worked synergistically to promote CPAP. Histology and qRT-PCR showed that TMEM63A was mainly expressed in mechanical pain-producing non-peptidergic nociceptors in the DRG, and the expression of TMEM63A increased significantly both in the neuroma from amputated patients and the DRG in a mouse model of tibial nerve transfer (TNT). Behavioral tests showed that the mechanical, heat, and cold sensitivity were not affected in the Tmem63a^-/- mice in the naïve state, suggesting the basal pain was not affected. In the inflammatory and post-amputation state, the mechanical allodynia but not the heat hyperalgesia or cold allodynia was significantly decreased in Tmem63a^-/- mice. Further study showed that there was severe neuronal injury and macrophage infiltration in the DRG, tibial nerve, residual stump, and the neuroma-like structure of the TNT mouse model, Consistent with this, expression of the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β all increased dramatically in the DRG. Interestingly, the deletion of Tmem63a significantly reduced the macrophage infiltration in the DRG but not in the tibial nerve stump. Furthermore, the ablation of macrophages significantly reduced both the expression of Tmem63a and the mechanical allodynia in the TNT mouse model, indicating an interaction between nociceptors and macrophages, and that these two factors gang up together to regulate the formation of CPAP. This provides a new insight into the mechanisms underlying CPAP and potential drug targets its treatment.
Animals ; Mice ; Amputation, Surgical ; Chronic Pain/pathology* ; Disease Models, Animal ; Ganglia, Spinal/pathology* ; Hyperalgesia/etiology* ; Ion Channels/metabolism* ; Macrophages ; Neuroma/pathology*

Chronic pain is challenging to treat due to the limited therapeutic options and adverse side-effects of therapies. Astrocytes are the most abundant glial cells in the central nervous system and play important roles in different pathological conditions, including chronic pain. Astrocytes regulate nociceptive synaptic transmission and network function via neuron-glia and glia-glia interactions to exaggerate pain signals under chronic pain conditions. It is also becoming clear that astrocytes play active roles in brain regions important for the emotional and memory-related aspects of chronic pain. Therefore, this review presents our current understanding of the roles of astrocytes in chronic pain, how they regulate nociceptive responses, and their cellular and molecular mechanisms of action.
Humans ; Astrocytes/pathology* ; Chronic Pain/pathology* ; Neuroglia/physiology* ; Neurons/physiology* ; Synaptic Transmission ; Chronic Disease

Objective: To analyze the therapeutic effect and safety of pancreatic extracorporeal shock wave lithotripsy(P-ESWL) for patients with chronic pancreatitis complicated by stones of the pancreatic duct and to investigate the influencing factors. Methods: A retrospective analysis was performed on clinical data from 81 patients with chronic pancreatitis complicated by pancreatic duct calculus treated with P-ESWL in the Department of Hepatobiliary Surgery, the First Affiliated Hospital of Xi 'an Jiaotong University from July 2019 to May 2022. There were 55 males(67.9%) and 26 females(32.1%). The age was (47±15)years (range: 17 to 77 years). The maximum diameter(M(IQR)) of the stone was 11.64(7.60) mm, and the CT value of the stone was 869 (571) HU. There were 32 patients (39.5%) with a single pancreatic duct stone and 49 patients(60.5%) with multiple pancreatic duct stones. The effectiveness, remission rate of abdominal pain, and complications of P-ESWL were evaluated. Student's t test, Mann Whitney U test, χ² test, or Fisher's exact test was used to compare the characteristics between the effective and ineffective groups of lithotripsy. The factors influencing the effect of lithotripsy were analyzed by univariate and multivariate logistic regression analysis. Results: Eighty-one patients with chronic pancreatitis were treated with P-ESWL 144 times, with an average of 1.78 (95%CI:1.60 to 1.96) times per person. Among them, 38 patients(46.9%) were treated with endoscopy. There were 64 cases(79.0%) with effective removal of pancreatic duct calculi and 17 cases(21.0%) with ineffective removal. Of the 61 patients with chronic pancreatitis accompanied by abdominal pain, 52 cases(85.2%) had pain relief after lithotripsy. After lithotripsy treatment, 45 patients(55.6%) developed skin ecchymosis, 23 patients(28.4%) had sinus bradycardia, 3 patients(3.7%) had acute pancreatitis, 1 patient(1.2%) had a stone lesion, and 1 patient(1.2%) had a hepatic hematoma. Univariate and multivariate logistic regression analysis showed that the factors affecting the efficacy of lithotripsy included the age of patient(OR=0.92, 95%CI: 0.86 to 0.97), the maximum diameter of the stone(OR=1.12,95%CI:1.02 to 1.24) and the CT value of the stone(OR=1.44, 95%CI: 1.17 to 1.86). Conclusions: P-ESWL is effective in the treatment of patients with chronic pancreatitis complicated by calculi of the main pancreatic duct.Factors affecting the efficacy of lithotripsy include patient's age, maximum stone diameter, and CT value of calculi.
Male ; Female ; Humans ; Retrospective Studies ; Acute Disease ; Treatment Outcome ; Calculi/pathology* ; Lithotripsy ; Pancreatitis, Chronic/pathology* ; Pancreatic Diseases/complications* ; Pancreatic Ducts ; Abdominal Pain/therapy*

We investigated the therapeutic effects of superoxide dismutase (SOD) from thermophilic bacterium HB27 on chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) and its underlying mechanisms. A Sprague-Dawley rat model of CP/CPPS was prepared and then administered saline or Thermus thermophilic (Tt)-SOD intragastrically for 4 weeks. Prostate inflammation and fibrosis were analyzed by hematoxylin and eosin staining, and Masson staining. Alanine transaminase (ALT), aspartate transaminase (AST), serum creatinine (CR), and blood urea nitrogen (BUN) levels were assayed for all animals. Enzyme-linked immunosorbent assays (ELISA) were performed to analyze serum cytokine concentrations and tissue levels of malondialdehyde, nitric oxide, SOD, catalase, and glutathione peroxidase. Reactive oxygen species levels were detected using dichlorofluorescein diacetate. The messenger ribonucleic acid (mRNA) expression of tissue cytokines was analyzed by reverse transcription polymerase chain reaction (RT-PCR), and infiltrating inflammatory cells were examined using immunohistochemistry. Nuclear factor-κB (NF-κB) P65, P38, and inhibitor of nuclear factor-κBα (I-κBα) protein levels were determined using western blot. Tt-SOD significantly improved histopathological changes in CP/CPPS, reduced inflammatory cell infiltration and fibrosis, increased pain threshold, and reduced the prostate index. Tt-SOD treatment showed no significant effect on ALT, AST, CR, or BUN levels. Furthermore, Tt-SOD reduced inflammatory cytokine expression in prostate tissue and increased antioxidant capacity. This anti-inflammatory activity correlated with decreases in the abundance of cluster of differentiation 3 (CD3), cluster of differentiation 45 (CD45), and macrophage inflammatory protein 1α (MIP1α) cells. Tt-SOD alleviated inflammation and oxidative stress by reducing NF-κB P65 and P38 protein levels and increasing I-κBα protein levels. These findings support Tt-SOD as a potential drug for CP/CPPS.
Animals ; Chronic Pain ; Cytokines/metabolism* ; Fibrosis ; Humans ; Inflammation/metabolism* ; Male ; NF-kappa B/metabolism* ; Pelvic Pain/pathology* ; Prostatitis/metabolism* ; Rats ; Rats, Sprague-Dawley ; Superoxide Dismutase ; Syndrome

Central sensitization is essential in maintaining chronic pain induced by chronic pancreatitis (CP), but cortical modulation of painful CP remains elusive. Here, we examined the role of the anterior cingulate cortex (ACC) in the pathogenesis of abdominal hyperalgesia in a rat model of CP induced by intraductal administration of trinitrobenzene sulfonic acid (TNBS). TNBS treatment resulted in long-term abdominal hyperalgesia and anxiety in rats. Morphological data indicated that painful CP induced a significant increase in FOS-expressing neurons in the nucleus tractus solitarii (NTS) and ACC, and some FOS-expressing neurons in the NTS projected to the ACC. In addition, a larger portion of ascending fibers from the NTS innervated pyramidal neurons, the neural subpopulation primarily expressing FOS under the condition of painful CP, rather than GABAergic neurons within the ACC. CP rats showed increased expression of vesicular glutamate transporter 1, and increased membrane trafficking and phosphorylation of the N-methyl-D-aspartate receptor (NMDAR) subunit NR2B and the α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) subunit GluR1 within the ACC. Microinjection of NMDAR and AMPAR antagonists into the ACC to block excitatory synaptic transmission significantly attenuated abdominal hyperalgesia in CP rats, which was similar to the analgesic effect of endomorphins injected into the ACC. Specifically inhibiting the excitability of ACC pyramidal cells via chemogenetics reduced both hyperalgesia and comorbid anxiety, whereas activating these neurons via optogenetics failed to aggravate hyperalgesia and anxiety in CP rats. Taken together, these findings provide neurocircuit, biochemical, and behavioral evidence for involvement of the ACC in hyperalgesia and anxiety in CP rats, as well as novel insights into the cortical modulation of painful CP, and highlights the ACC as a potential target for neuromodulatory interventions in the treatment of painful CP.
Animals ; Anxiety/etiology* ; Chronic Pain/etiology* ; GABAergic Neurons ; Gyrus Cinguli/metabolism* ; Hyperalgesia/metabolism* ; Pancreatitis, Chronic/pathology* ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate/metabolism* ; Trinitrobenzenesulfonic Acid/toxicity*

BACKGROUND: One of the most frequent problems caused by diabetes is the so called painful diabetic neuropathy. This condition can be treated through numerous types of therapy. The purpose of this study was to analyze, as a meta-analysis, different treatments used to alleviate painful diabetic neuropathy, with the aim of generating results that help making decisions when applying such treatments to tackle this pathology. METHODS: A search was conducted in the main databases for Health Sciences, such as PUBMED, Web of Science (WOS), and IME biomedicina (Spanish Medical Reports in Biomedicine), to gather randomized controlled trials about treatments used for painful diabetic neuropathy. The analyzed studies were required to meet the inclusion criteria selected, especially those results related to pain intensity. RESULTS: Nine randomized controlled trials were chosen. The meta-analysis shows significant positive effects for those treatments based on tapentadol [g: −1.333, 95% CI (−1.594; −1.072), P < 0.05], duloxetine [g: −1.622, 95 % CI (−1.650; −1.594), P < 0.05], pregabalin [g: −0.607, 95% CI (−0.980; −0.325), P < 0.05], and clonidine [g: −0.242, 95 % CI (−0.543; −0.058), P < 0.05]. CONCLUSIONS: This meta-analysis indicates the effectiveness of the treatments based on duloxetine, gabapentin and pregabalin, as well as other drugs, such as tapentadol and topic clonidine, whose use is better prescribed in more specific situations. The results provided can help increase the knowledge about the treatment of painful diabetic neuropathy and also in the making of clinical practice guidelines for healthcare professionals.
Chronic Pain ; Clonidine ; Delivery of Health Care ; Diabetes Complications ; Diabetic Neuropathies ; Duloxetine Hydrochloride ; Pain Management ; Pathology ; Pregabalin

The application of arthroscopy is becoming increasingly widespread due to the development of surgical instruments and techniques. Subtalar pathology can cause chronic pain in the hindfoot, but it is often misdiagnosed as a lesion of the adjacent ankle joint, which can lead to delayed diagnosis and treatment. Subtalar arthroscopy and posterior endoscopy are good methods to confirm and treat the posterior pathology of the subtalar joint and posterior ankle joint.
Ankle Joint ; Arthroscopy* ; Chronic Pain ; Delayed Diagnosis ; Endoscopy* ; Pathology ; Subtalar Joint ; Surgical Instruments

Recent studies have shown that the chemokine receptor CXCR3 and its ligand CXCL10 in the dorsal root ganglion mediate itch in experimental allergic contact dermatitis (ACD). CXCR3 in the spinal cord also contributes to the maintenance of neuropathic pain. However, whether spinal CXCR3 is involved in acute or chronic itch remains unclear. Here, we report that Cxcr3 mice showed normal scratching in acute itch models but reduced scratching in chronic itch models of dry skin and ACD. In contrast, both formalin-induced acute pain and complete Freund's adjuvant-induced chronic inflammatory pain were reduced in Cxcr3 mice. In addition, the expression of CXCR3 and CXCL10 was increased in the spinal cord in the dry skin model induced by acetone and diethyl ether followed by water (AEW). Intrathecal injection of a CXCR3 antagonist alleviated AEW-induced itch. Furthermore, touch-elicited itch (alloknesis) after compound 48/80 or AEW treatment was suppressed in Cxcr3 mice. Finally, AEW-induced astrocyte activation was inhibited in Cxcr3 mice. Taken together, these data suggest that spinal CXCR3 mediates chronic itch and alloknesis, and targeting CXCR3 may provide effective treatment for chronic pruritus.
Acetamides ; therapeutic use ; Animals ; Chemokine CXCL10 ; metabolism ; Chloroquine ; toxicity ; Chronic Disease ; Cyclopropanes ; adverse effects ; Dehydration ; complications ; Dinitrofluorobenzene ; adverse effects ; Disease Models, Animal ; Formaldehyde ; toxicity ; Freund's Adjuvant ; toxicity ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Motor Activity ; drug effects ; Pain ; chemically induced ; Pruritus ; chemically induced ; pathology ; Pyrimidines ; therapeutic use ; Receptors, CXCR3 ; antagonists & inhibitors ; genetics ; metabolism ; Skin ; pathology ; Spinal Cord ; drug effects ; metabolism ; pathology ; Time Factors ; p-Methoxy-N-methylphenethylamine ; toxicity

Chronic pain and itch are a pathological operation of the somatosensory system at the levels of primary sensory neurons, spinal cord and brain. Pain and itch are clearly distinct sensations, and recent studies have revealed the separate neuronal pathways that are involved in each sensation. However, the mechanisms by which these sensations turn into a pathological chronic state are poorly understood. A proposed mechanism underlying chronic pain and itch involves abnormal excitability in dorsal horn neurons in the spinal cord. Furthermore, an increasing body of evidence from models of chronic pain and itch has indicated that synaptic hyperexcitability in the spinal dorsal horn might not be a consequence simply of changes in neurons, but rather of multiple alterations in glial cells. Thus, understanding the key roles of glial cells may provide us with exciting insights into the mechanisms of chronicity of pain and itch, and lead to new targets for treating chronic pain and itch.
Animals ; Chronic Pain ; pathology ; Humans ; Neuralgia ; metabolism ; Pruritus ; pathology ; Sensory Receptor Cells ; physiology ; Spinal Cord ; pathology

BACKGROUND: Persistent pain after total knee arthroplasty (TKA) is dissatisfying to the patient and frustrating to the surgeon. The purpose of this study is to evaluate the aseptic causes and clinical course of intractable pain following TKA. METHODS: Of the total 2,534 cases of primary TKA reviewed, 178 cases were classified as having aseptic persistent pain that was not resolved within 1 year after surgery. Except for the cases with periprosthetic fracture (56 knees), 122 cases of aseptic painful TKA were divided into two groups: intra-articular group (83 knees) and extra-articular group (39 knees). RESULTS: In the intra-articular group, the main reasons for pain were aseptic loosening (n = 40), polyethylene wear (n = 16), instability (n = 10), recurrent hemarthrosis (n = 5), patellar maltracking (n = 4), tendon ruptures (n = 4), and stiffness (n = 2). In the extraarticular group, 10 knees (25.6%) were found to have nerve entrapment in the spine, 6 knees (15.4%) were found to have hip osteoarthritis or femoral head avascular necrosis. The reasons for persistent knee pain in the remaining 23 knees (59.0%) still remain elusive. CONCLUSIONS: Persistent pain after TKA originated from pathology of extra-articular origin in a considerable number of cases in this study. Therefore, it is important to perform thorough preoperative evaluations to reduce pain resulting from extra-articular causes. Furthermore, meticulous surgical procedures and optimal alignment are required to reduce pain of intra-articular origin related to implant wear, instability, and patellar maltracking.
Arthroplasty, Replacement, Knee* ; Chronic Pain ; Head ; Hemarthrosis ; Humans ; Knee ; Necrosis ; Nerve Compression Syndromes ; Osteoarthritis, Hip ; Pain, Intractable ; Pathology ; Periprosthetic Fractures ; Polyethylene ; Rupture ; Spine ; Tendons