Rheumatoid arthritis (RA) is a common systemic inflammatory autoimmune disease characterized by synovitis and bone destruction. Its clinical characteristics are mainly joint pain, swelling, stiffness and joint deformity. Due to the poor efficacy of both drug and non-drug therapies, RA can significantly impact patients' quality of life and increase personal and socioeconomic burdens. Studies have found that the Janus kinase (JAK)/signal transduction and activator of transcription (STAT) pathway, as classical intracellular signaling pathway, plays an important role in the occurrence and development of connective tissue diseases by regulating inflammation, immunity, and cell differentiation. This article reviews the research progress on the involvement of JAK/STAT signaling pathway in the mechanism of RA pathological pain, in order to provide some reference for understanding the pathogenesis of RA pathological pain and developing specific drug.
Arthritis, Rheumatoid/metabolism* ; Humans ; Signal Transduction/physiology* ; Janus Kinases/metabolism* ; STAT Transcription Factors/metabolism* ; Pain/etiology* ; Animals

Osteoporosis(OP) is a metabolic bone disorder characterized by reduced bone mass and degenerative bone tissue. Osteoporotic pain(OPP) is its most common clinical symptom, significantly affecting the quality of life of patients. With the limitations of modern medical treatments and the intensification of aging, it is imperative to explore more cost-effective interventions for OPP. This paper, based on databases such as China National Knowledge Infrastructure(CNKI), VIP, Wanfang, BioMed, and Web of Science, uncovered the connection between the pathogenesis of OPP in traditional Chinese medicine(TCM) and modern medical mechanisms and retrospectively summarized the basic and clinical research methods and evidence of TCM prescriptions in the treatment of OP and related pain diseases. Studies have shown that TCM prescriptions, focusing on treatments such as nourishing the kidney, strengthening the spleen, and activating blood circulation to remove blood stasis, can significantly improve pain symptoms, increase bone mineral density(BMD), and adjust bone metabolic indicators such as C-terminal telopeptide of type Ⅰ collagen(CTX), serum bone Gla-protein(S-BGP), and alkaline phosphatase(ALP). The mechanisms of action of TCM prescriptions in treating OP and improving OPP symptoms were related to signaling pathways such as Wnt/β-catenin, nuclear factor kappa-B(NF-κB), mitogen-activated protein kinase(MAPK), phosphatidylinositol 3-kinase(PI3K)/protein kinase B(Akt), and the osteoprotegerin(OPG)/receptor activator of NF-κB(RANK)/receptor activator of NF-κB ligand(RANKL) axis. Further strengthening the accumulation and analysis of clinical data, rigorously designing and conducting randomized controlled trials of TCM treatments for OPP with large sample sizes, standardizing outcome measures in basic and clinical research by using methods such as the core outcome set(COS), and incorporating mass spectrometry and omics approaches to uncover more potential active components and mechanisms may contribute to a deeper exploration of the advantages and essence of TCM prescriptions in the treatment of OPP.
Humans ; Osteoporosis/genetics* ; Drugs, Chinese Herbal/administration & dosage* ; Retrospective Studies ; Bone Density/drug effects* ; Medicine, Chinese Traditional ; Pain/metabolism* ; Animals

This study adopted a three-dimensional "effect-dose-mechanism" evaluation system to screen the optimal regimen of Yuxuebi Tablets(YXB) combined with ibuprofen(IBU) for chronic musculoskeletal pain(CMP) intervention and elucidate its pharmacological mechanism, so as to provide a scientific basis for the clinical application of the regimen. The experiments were conducted using 8-week-old ICR mice, which were randomly divided into sham operation(sham) group, model(CFA) group, IBU group, YXB group, stasis paralysis tablets combined with ibuprofen low-dose group(IBU-L-YXB), stasis paralysis combined with ibuprofen high-dose group(IBU-H-YXB), stasis paralysis tablets combined with ibuprofen high-dose with ibuprofen discontinuation on the 10th day of administration(IBU-10-YXB), and stasis paralysis tablets combined with ibuprofen high-dose with ibuprofen halving on the 10th day of administration(IBU-1/2-YXB) group. An animal model was established using the CFA plantar injection method. On D0(the second day post-modeling), the success of model establishment was assessed, followed by continuous drug administration for 18 consecutive days from D1 to D18. During this period, mechanical pain threshold was measured by the Von Frey test; thermal hyperalgesia was detected by the hot plate test, and depression-like behavior was observed by the tail suspension test. After treatment, peripheral blood was collected from all groups for complete blood biochemical analysis, and the injected feet of the sham, CFA, IBU, YXB, IBU-YXB, and IBU-10-YXB groups were subjected to oxylipin metabolomics analysis. Immunofluorescence double staining was further performed to detect the co-expression of key oxylipin metabolic enzymes(COX2, LTA4H, and 5/12/15-LOX) and macrophage marker CD68 in the sham, CFA, IBU, and YXB-L/M/H groups. Subsequently, confirmatory analysis of positive indicators was conducted in the sham, CFA, IBU, YXB, IBU-YXB, and IBU-10-YXB groups. On D6(acute phase), mechanical pain sensitivity data showed that compared with the CFA group, only the three combination groups(IBU-YXB, IBU-10-YXB, and IBU-1/2-YXB) exhibited significantly increased paw withdrawal thresholds. On D17(chronic phase), only the IBU-10-YXB group showed a mechanical pain threshold significantly higher than all other monotherapy and combination groups. On D17, thermal pain data showed that compared with the CFA group, all groups except IBU-1/2-YXB had significantly prolonged paw withdrawal latency. On D18, tail suspension data showed that compared with the CFA group, the YXB, IBU-YXB, and IBU-10-YXB groups had significantly reduced immobility time. In summary, IBU-10-YXB stably improved the core symptoms of acute and chronic inflammatory pain. Complete blood count data showed that compared with the sham group, the CFA group had significantly increased mean platelet volume(MPV), while compared with the CFA group, the IBU-YXB and IBU-10-YXB groups had significantly reduced MPV. Moreover, the platelet distribution width(PDW) of the IBU-10-YXB group was further reduced compared with the CFA group. These data suggest that the IBU-10-YXB combination regimen has superior effects on inflammation and blood circulation improvement compared with other treatment groups. At the mechanistic level, each treatment group differentially regulated pro-inflammatory and pro-resolving oxylipin(SPM). Specifically, compared with the CFA group, the IBU and IBU-YXB groups significantly inhibited the synthesis of the prostaglandin family downstream of COX2, reducing pro-inflammatory oxylipins PGD2 and 6-keto-PGF1α but inhibiting PGE1 and PGE2, which played positive roles in peripheral circulation, vasodilation, and inflammation resolution. Compared with the CFA group, the YXB group tended to inhibit the pro-inflammatory oxylipin LTB4 downstream of LTA4H and increase SPMs such as LXA4. The IBU-10-YXB group bidirectionally regulated pro-inflammatory oxylipins and SPMs. Compared with IBU, IBU-10-YXB significantly inhibited the pro-inflammatory mediator 5-HETE. Meanwhile, IBU-10-YXB broadly upregulated SPMs, as evidenced by significant upregulation of LXA4 compared with the CFA group, significant upregulation of LXA5 compared with the IBU and IBU-YXB groups, significant upregulation of RvD1 compared with the CFA group and all other treatment groups, and significant upregulation of RvD5 compared with the sham group. Immunofluorescence double staining results were as follows: compared with the CFA group, the IBU group specifically inhibited the oxylipin metabolic enzyme COX2. In the YXB group, COX2, LTA4H, and 5/12-LOX were significantly inhibited. Within the optimal analgesic dose range, YXB's inhibitory effects on COX2 and LTA4H were dose-dependent, while its inhibitory effects on 5/12-LOX were inversely dose-dependent. The two combination groups(IBU-YXB and IBU-10-YXB) inhibited COX2 and LTA4H without significantly affecting 5-LOX, while IBU-10-YXB further significantly inhibited 12-LOX. These results suggest that the IBU-10-YXB combination regimen effectively maintains stable inhibition of COX2, LTA4H, and 12-LOX while enhancing 5-LOX expression. This combinatorial strategy effectively suppresses pro-inflammatory oxylipins and promotes SPM biosynthesis, overcoming IBU's analgesic ceiling effect and its blockade of pain resolution pathways while compensating for YXB's inability to effectively intervene in acute pain and inflammation. Therefore, it achieves more stable anti-inflammatory, analgesic, and antidepressant effects.
Animals ; Ibuprofen/administration & dosage* ; Mice ; Mice, Inbred ICR ; Drugs, Chinese Herbal/administration & dosage* ; Male ; Musculoskeletal Pain/immunology* ; Tablets ; Humans ; Chronic Pain/metabolism* ; Drug Therapy, Combination ; Disease Models, Animal

This study compared the differences in intestinal absorption characteristics of eleven active components in Rubus multibracteatus(RM) extract(protocatechuic acid, tiliroside, scutellarin, luteoloside, astragalin, epicatechin, catechin, xanthotoxin, p-coumaric acid, caffeic acid, and apigenin-7-O-glucuronide) between normal rats and inflammatory pain model rats using the in-vitro everted intestinal sac model. The RM extract was administered at absorption concentrations of 25.0, 50.0, and 100.0 mg·mL~(-1). The contents of the eleven components in intestinal absorption solution samples were quantified by ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS), and their cumulative absorption(Q) and absorption rate constant(K_a) were calculated to evaluate the absorption characteristics of these components in normal rats and inflammatory pain model rats. The results show that except for catechin, epicatechin, and caffeic acid, the cumulative absorption-time curves of the other eight components(protocatechuic acid, tiliroside, scutellarin, luteoloside, astragalin, xanthotoxin, p-coumaric acid, and apigenin-7-O-glucuronide) exhibit an upward trend without saturation, with correlation coefficients(R~2) all > 0.9, indicating linear absorption. However, the overall absorption of all components is not dose-dependent with increasing concentration, suggesting that their absorption mechanisms are not solely passive diffusion. In both normal and model rats, the jejunum shows the highest absorption for all components except xanthotoxin. The overall absorption of seven components(excluding protocatechuic acid, caffeic acid, apigenin-7-O-glucuronide, and luteoloside) in normal rats is better than that in model rats across all intestinal segments. These findings indicate that the pathological state of inflammatory pain alters the intestinal absorption of RM extract, and its mechanism needs further investigation.
Animals ; Rats ; Intestinal Absorption/drug effects* ; Male ; Rats, Sprague-Dawley ; Drugs, Chinese Herbal/metabolism* ; Disease Models, Animal ; Pain/metabolism* ; Intestines/drug effects* ; Intestinal Mucosa/metabolism*

OBJECTIVE: To investigate the variability of bone metabolism levels among different populations and its association with knee osteoarthritis (KOA) pain. METHODS: A total of 50 people (control group) who participated in physical examination from January 2023 to June 2023 were selected, including 26 males and 24 females, wtih a mean aged of (52.14±9.04) years old ranging 41 to 65 years old. The other 50 patients with knee osteoarthritis(case group) who attended the outpatient clinic of the Orthopedics and Traumatology Department in the same time period, including 19 males and 31 females, with a mean age of (53.60±7.76) years old ranging 40 to 65 years. The two groups of Western Ontario and McMaster Universities Osteoarthritis Index(WOMAC) and bone metabolism markers, such as 25-hydroxy-cholecalciferol[25(OH)D], β-isomerized typeⅠcollagen C-telopeptide breakdown products (β-CTX), total typeⅠprocollagen N-terminal propeptide (t-PINP), osteocalcin (OC), parathormone (PTH) levels were compared. Pearson correlation analysis was used to compare the correlation between two groups of bone metabolism related markers and WOMAC. RESULTS: The WOMAC score of the case group (39.90±2.34) was higher than that of the control group (3.60±0.57), with significant difference (P<0.05). There was no significant difference between the two groups of 25 (OH)D, β-CTX and PTH (P>0.05). The t-PINP and OC of the case group were (62.90±52.40) and (19.88±10.15) ng·ml-1, respectively, and those of the control group were (38.86±10.82) and (14.90±3.62) ng·ml^-1, respectively;the t-PINP and OC of the case group were higher than those of the control group, with significant difference (P<0.05). Pearson correlation analysis showed that t-PINP was positively correlated with WOMAC pain score in the case group (r²=0.045, P<0.01). CONCLUSION Bone metabolism levels in the serum of patients with knee osteoarthritis are different from those of healthy people, and the difference between OC and t-PINP is the most obvious, and the concentration of t-PINP levels is positively correlated with pain symptoms in patients with KOA. However, the specific mechanism of correlation between the bone metabolism levels of patients with KOA and their pain symptoms needs to be further elucidated by basic experimental research as well as by enlarging the samples.
Humans ; Female ; Male ; Middle Aged ; Osteoarthritis, Knee/metabolism* ; Aged ; Adult ; Bone and Bones/metabolism* ; Pain/etiology* ; Biomarkers/metabolism*

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a complex disease that is often accompanied by mental health disorders. However, the potential mechanisms underlying the heterogeneous clinical presentation of CP/CPPS remain uncertain. This study analyzed widely targeted metabolomic data of expressed prostatic secretions (EPS) and plasma to reveal the underlying pathological mechanisms of CP/CPPS. A total of 24 CP/CPPS patients from The Second Nanning People's Hospital (Nanning, China), and 35 asymptomatic control individuals from First Affiliated Hospital of Guangxi Medical University (Nanning, China) were enrolled. The indicators related to CP/CPPS and psychiatric symptoms were recorded. Differential analysis, coexpression network analysis, and correlation analysis were performed to identify metabolites that were specifically altered in patients and associated with various phenotypes of CP/CPPS. The crucial links between EPS and plasma were further investigated. The metabolomic data of EPS from CP/CPPS patients were significantly different from those from control individuals. Pathway analysis revealed dysregulation of amino acid metabolism, lipid metabolism, and the citrate cycle in EPS. The tryptophan metabolic pathway was found to be the most significantly altered pathway associated with distinct CP/CPPS phenotypes. Moreover, the dysregulation of tryptophan and tyrosine metabolism and elevation of oxidative stress-related metabolites in plasma were found to effectively elucidate the development of depression in CP/CPPS. Overall, metabolomic alterations in the EPS and plasma of patients were primarily associated with oxidative damage, energy metabolism abnormalities, neurological impairment, and immune dysregulation. These alterations may be associated with chronic pain, voiding symptoms, reduced fertility, and depression in CP/CPPS. This study provides a local-global perspective for understanding the pathological mechanisms of CP/CPPS and offers potential diagnostic and therapeutic targets.
Humans ; Male ; Prostatitis/blood* ; Adult ; Pelvic Pain/blood* ; Metabolomics ; Prostate/metabolism* ; Middle Aged ; Chronic Pain/blood* ; Metabolome ; Case-Control Studies ; Tryptophan/blood* ; Depression/blood* ; Oxidative Stress/physiology* ; Chronic Disease ; Lipid Metabolism/physiology*

Exercise-induced analgesia (EIA) refers to the elevation of pain thresholds and reduction in sensitivity to noxious stimuli achieved through exercise training. As a non-pharmacological treatment strategy, exercise therapy has demonstrated positive effects on both acute and chronic pain. Increasing evidence indicates that modulation of glial cell activity is an important mechanism underlying analgesia. Spinal glial cells contribute to the development and maintenance of pathological pain by promoting pain signal transmission through inflammatory responses and synaptic remodeling. Exercise can differentially regulate microglia and astrocyte activity, inhibiting multiple inflammatory signaling pathways, such as P2X4/P2X7 purinergic receptors, brain-derived neurotrophic factor (BDNF)/phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR), interleukin (IL)-6/Janus kinase (JAK) 2/signal transducer and activator of transcription 3 (STAT3), p38-mitogen-activated protein kinases (MAPK), and Toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB), thereby reducing the release of pro-inflammatory cytokines, decreasing inflammatory and nociceptive hypersensitivity, and alleviating pathological pain. This review also summarized the effects of different exercise intensities, durations, and frequencies on glial cell responses in order to provide a theoretical foundation for optimizing exercise-based interventions for pathological pain conditions.
Humans ; Microglia/metabolism* ; Astrocytes/metabolism* ; Exercise/physiology* ; Signal Transduction ; Analgesia/methods* ; Spinal Cord/cytology* ; Exercise Therapy ; Pain Management/methods* ; Animals ; Brain-Derived Neurotrophic Factor/metabolism*

Chronic visceral pain is a persistent and debilitating condition arising from dysfunction or sensitization of the visceral organs and their associated nervous pathways. Increasing evidence suggests that imbalances in central nervous system function play an essential role in the progression of visceral pain, but the exact mechanisms underlying the neural circuitry and molecular targets remain largely unexplored. In the present study, the ventral tegmental area (VTA) was shown to mediate visceral pain in mice. Visceral pain stimulation increased c-Fos expression and Ca²⁺ activity of glutamatergic VTA neurons, and optogenetic modulation of glutamatergic VTA neurons altered visceral pain. In particular, the upregulation of NMDA receptor 2A (NR2A) subunits within the VTA resulted in visceral pain in mice. Administration of a selective NR2A inhibitor decreased the number of visceral pain-induced c-Fos positive neurons and attenuated visceral pain. Pharmacology combined with chemogenetics further demonstrated that glutamatergic VTA neurons regulated visceral pain behaviors based on NR2A. In summary, our findings demonstrated that the upregulation of NR2A in glutamatergic VTA neurons plays a critical role in visceral pain. These insights provide a foundation for further comprehension of the neural circuits and molecular targets involved in chronic visceral pain and may pave the way for targeted therapies in chronic visceral pain.
Animals ; Male ; Visceral Pain/metabolism* ; Up-Regulation/physiology* ; Ventral Tegmental Area/metabolism* ; Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors* ; Neurons/drug effects* ; Mice, Inbred C57BL ; Mice ; Proto-Oncogene Proteins c-fos/metabolism* ; Chronic Pain/metabolism* ; Glutamic Acid/metabolism*

Empathy is crucial for communication and survival for individuals. Whether empathy in pain contagion shows sex differences and its underlying mechanisms remain unclear. Here, we report that pain contagion can occur in stranger female rats, but not in stranger males. Blocking oxytocin receptors in the anterior cingulate cortex (ACC) suppressed pain contagion in female strangers, while oxytocin administration induced pain contagion in male strangers. In vitro, corticosterone reduces neuronal activation by oxytocin. During male stranger interactions, higher corticosterone decreased oxytocin receptor-positive neuronal activity in the ACC, suppressing pain contagion. These findings highlight the role of oxytocin in pain contagion and suggest that sex differences in empathy may be determined by the balance of oxytocin and corticosterone in the ACC. This study suggests an approach for the treatment of certain mental disorders associated with abnormal empathy, such as autism and depression.
Animals ; Oxytocin/pharmacology* ; Gyrus Cinguli/drug effects* ; Male ; Female ; Corticosterone/pharmacology* ; Empathy/drug effects* ; Sex Characteristics ; Receptors, Oxytocin/antagonists & inhibitors* ; Pain/psychology* ; Rats ; Rats, Sprague-Dawley ; Neurons/metabolism*

Chronic pain, frequently comorbid with neuropsychiatric disorders, significantly impairs patients' quality of life and functional capacity. Accumulating evidence implicates the chemokine CCL2 and its receptor CCR2 as key players in chronic pain pathogenesis. This review examines the regulatory mechanisms of the CCL2/CCR2 axis in chronic pain processing at three hierarchical levels: (1) Peripheral Sensitization: CCL2/CCR2 modulates TRPV1, Nav1.8, and HCN2 channels to increase neuronal excitability and CGRP signaling and calcium-dependent exocytosis in peripheral nociceptors to transmit pain. (2) Spinal Cord Central Sensitization: CCL2/CCR2 contributes to NMDAR-dependent plasticity, glial activation, GABAergic disinhibition, and opioid receptor desensitization. (3) Supraspinal Central Networks: CCL2/CCR2 signaling axis mediates the comorbidity mechanisms of pain with anxiety and cognitive impairment within brain regions, including the ACC, CeA, NAc, and hippocampus, and it also increases pain sensitization through the descending facilitation system. Current CCL2/CCR2-targeted therapeutic strategies and their development status are discussed, highlighting novel avenues for chronic pain management.
Humans ; Chronic Pain/physiopathology* ; Animals ; Neuroglia/metabolism* ; Chemokine CCL2/metabolism* ; Receptors, CCR2/metabolism*