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Recent evidence has shown that bone marrow mesenchymal stem cells (BMSCs) have multiple biological applications and play an important role in improving cognitive dysfunction. However, it is still unclear whether BMSCs play a role in cognitive impairment induced by chronic pain. This study aimed to evaluate the therapeutic effect of BMSCs on neuropathic pain-induced cognitive dysfunction and explore its potential mechanisms. A mouse chronic constriction injury (CCI) model was established, and the new object recognition task and fear conditioning were used to detect cognitive function; the expression of CXCL12/CXCR4 in blood and hippocampus was detected. After intravenous injection of BMSCs, changes in cognitive function and expression of the CXCL12/CXCR4 pathway, dentate gyrus neurogenesis, and excitability of hippocampal neurons were detected. In addition, induction of cognitive impairment in normal mice by CXCL12 recombinant protein was used to clarify whether the CXCL12/CXCR4 pathway mediates the cognitive function improvement effect of BMSCs. Our results found CCI mice showed significant cognitive impairment 21 days after surgery, with significantly increased expression of CXCL12/CXCR4 in blood and hippocampus. Intravenous injection of BMSCs significantly improved cognitive function, inhibited expression of CXCL12/CXCR4 in blood and hippocampus, promoted neurogenesis in dentate gyrus of CCI mice, and increased expression of BDNF and c-Fos in the hippocampus. In addition, BMSCs alleviate cognitive impairment induced by intravenous injection of CXCL12 recombinant protein in mice. In summary, BMSCs improve chronic neuropathic pain-induced cognitive dysfunction through peripheral blood CXCL12/CXCR4, and BMSCs may develop into therapeutic targets for chronic pain induced cognitive impairment. Show less

Neuropathic pain (NP) is a debilitating condition with limited treatment options. The ethanolic extract of Bauhinia brachycarpa Benth (EEBb) has demonstrated antinociceptive effects in NP, but its active components and underlying mechanisms of action remain largely unexplored. Bauhinia brachycarpa Benth (BBB), an ethnic medicine in China, has antinociceptive effect on neuropathic pain (NP). In this study, an effective portion from BBB was screened and its antinociceptive mechanism was investigated. After the preparation of ethanolic extract from BBB (EEBb) and different soluble portion from EEBb (peEEBb, eaEEBb, nbEEBb), the total content of flavonoids and phenolic acids were measured. A partial sciatic nerve ligation (PSNL) model in vivo was applied to evaluate the antinociceptive effect and the influence on microglia function of these samples. The possible acting target of BBB was predicted by network pharmacology. And the mechanism of nbEEBb, the most effective antinociceptive portion, were studied by PSNL model in vivo and ATP-induced activation of BV2 model in vitro. nbEEBb had the strongest ability of alleviating NP as well as the obvious effect on microglia polarization. The action of nbEEBb was positively correlated to the total content of flavonoids or phenolic acids. nbEEBb inhibited the protein and gene expressions of most key components in P2X4-BDNF-TrkB signaling pathway. nbEEBb is the most effective portion from BBB on NP, and its mechanism refers to the inhibition of P2X4-BDNF-TrkB signaling pathway, which involved in neuron-microglia interaction. Show less

Pain is common among adults with heart failure (HF), but pain subtypes and associated biomarkers are understudied. The aims were to: 1) characterize chronic pain severity, neuropathic pain quality, locations, and subtypes; and 2) compare pain severity and levels of biomarkers among pain subtypes. An exploratory aim was to correlate levels of biomarkers with pain severity. This pilot descriptive study included cross-sectional data from 60 adults with HF and chronic pain. Pain was evaluated using the PainDETECT questionnaire. Blood biomarkers included interleukin (IL)-10, IL-18, IL-1β, IL-33, IL-6, IL-8, tumor necrosis factor (TNF)-α, brain-derived neurotrophic factor, leptin, adiponectin, and C-reactive protein. Descriptive statistics, Chi-square test of homogeneity, one-way analysis of variance, and Spearman correlation were used for analyses. The mean age was 70.45 (SD 7.92) years. The sample consisted of 63.3% women and 65.0% White race. Participants primarily reported nociceptive pain only (73.3%) with fewer reporting neuropathic pain only (6.7%) and mixed pain (20.0%). Current and 4-week mean pain severity scores were highest in the mixed pain subtype (p both <.05). No biomarkers were significantly different across the pain subtypes, but lower lL-10 (p=.049), and IL-33 (p=.014), were associated with higher pain severity. In this study, chronic pain and its association with underlying biomarkers were characterized. Future research with a larger sample is needed to understand the unique contributions of biomarkers with targeted pain phenotypes. Show less

This research investigated the potential therapeutic role of α-(phenylselanyl) acetophenone (PSAP) in the comorbidity of chronic pain and depression triggered by partial sciatic nerve ligation (PSNL). Male Swiss mice underwent PSNL surgery, and after a four-week period, they received either PSAP (1-50 mg/kg, administered intragastrically) or imipramine (IMI) (50 mg/kg) 30 min prior to behavioral assessments. Both PSAP and IMI effectively alleviated PSNL-induced hypersensitivity to pain and depressive-like symptoms, as demonstrated in forced swim and allodynia tests. Additionally, PSAP counteracted the elevated levels of lipid peroxidation and reactive oxygen species observed in the cortex and hippocampus following PSNL. These neuroprotective effects appear to be linked to PSAP's anti-inflammatory properties, as it downregulated the expression of pro-inflammatory markers such as NF-κB p65, TNF-α, and IDO mRNA in the affected brain regions. Furthermore, PSAP restored hippocampal BDNF mRNA levels, which had been diminished by nerve injury. Since inflammation is a common pathway in both chronic pain and depression, the findings indicate that PSAP holds promise as a treatment for this comorbid condition. Show less

Physical exercise is widely recognized for reducing neuropathic pain. However, the interaction between the immune and opioidergic systems in supraspinal structures is still not fully understood. To evaluate the impact of opioid receptor blockade on the effects of low-intensity exercise on the sensory, cognitive, and emotional aspects of neuropathic pain after sciatic nerve injury. Male Swiss mice (2 months old) were submitted to sciatic nerve crush and divided into sedentary or exercised groups. The exercised groups performed treadmill running for two weeks, with or without naloxone pre-treatment to block opioid receptors. Sensory responses were assessed using the von Frey test, while cognitive and emotional-like behaviors were evaluated through the Mechanical Conflict-Avoidance System (MCAS) and open field test, respectively. Cytokine levels (IL-4, IL-10) and brain-derived neurotrophic factor (BDNF) were quantified in the brainstem and prefrontal cortex by ELISA. Exercise reduced mechanical hypersensitivity and improved performance in cognitive and exploratory tasks. These effects were prevented by naloxone administration. Exercise also increased IL-4, IL-10, and BDNF levels in supraspinal regions, while naloxone reversed these changes, indicating the involvement of μ-opioid receptors in exercise-induced immunomodulation. Low-intensity exercise promotes analgesia and neuroimmune regulation in neuropathic pain through supraspinal μ-opioid receptor activation. The blockade of these receptors abolishes the beneficial effects of exercise, reinforcing the interaction between opioidergic and immune systems in pain modulation. Show less

There has been less explanation for whether lumbar disc injury, particularly through puncture and nucleus pulposus (NP) aspiration, can influence chronic low back pain (LBP). We aim to investigate whether intradiscal injury modifies spine structure and contributes to behavioral alteration and peripheral neuronal hyperexcitability in a rat model. Male Sprague-Dawley rats (n = 50) were subjected to lumbar disc (L4/5 and L5/6) puncture with nucleus pulposus aspiration (PUNCT) or sham surgery. Nociceptive processing was investigated through behavioral tests [dynamic weight bearing (DWB) and hindpaw withdrawal threshold], electrophysiological recordings of mechanosensitive single afferent nerves (MSAN), and calcium imaging of DiI-labeled dorsal root ganglion (DRG) neurons in response to capsaicin. Expression levels of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in the disc and subchondral bone were quantified, and bone structure was assessed using ex vivo micro-computed tomography (µCT). The PUNCT group displayed significant behavioral changes, including increased forelimb dependency in DWB and decreased hindpaw withdrawal thresholds. Electrophysiological data indicated MSAN hyperexcitability with a reduced threshold to intradiscal pressure, and calcium imaging revealed heightened capsaicin (1 μM)-induced calcium influx in DiI-labeled DRG neurons from the PUNCT group. NGF and BDNF expression significantly increased in both the disc and subchondral bone of the PUNCT group. µCT analysis revealed hypertrophic bone volume, diminished trabecular bone quality, and localized bone erosion in the PUNCT group. Intradiscal injury caused by puncture and NP aspiration induces spinal structural remodeling and peripheral neuronal sensitization, contributing to chronic LBP. Show less

This study aimed to investigate the therapeutic effects of minocycline on neuropathic pain by examining its regulatory influence on hippocampal proinflammatory cytokines and brain-derived neurotrophic factor (BDNF) levels, given the established involvement of neuroinflammation and BDNF dysregulation in the pathogenesis of neuropathic pain and associated neurological dysfunctions. This study used a rat model of neuropathic pain induced by L5 spinal nerve transection (L5-SNT). Forty-eight male Sprague-Dawley rats were divided into four groups: naive, sham-operated, model + saline, and model + minocycline. Minocycline was administered intraperitoneally at 40 mg/kg daily. Mechanical allodynia was assessed using the von Frey test, while real-time reverse transcription and ELISA were employed to quantify hippocampal expression of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), IL-1β, and BDNF at various time points postsurgery. L5-SNT induced significant mechanical allodynia in the model + saline group, which was significantly attenuated by minocycline treatment in the model + minocycline group on days 3, 7, and 11 postsurgery (P < 0.05). Minocycline significantly reduced TNF-α, IL-6, and BDNF levels in the hippocampus, particularly on day 7 post-SNT (P < 0.05); however, minocycline did not significantly affect IL-1β levels. These findings suggest that minocycline's analgesic effects may be mediated through the downregulation of key proinflammatory cytokines and BDNF in the hippocampus. Minocycline administration significantly mitigates mechanical allodynia and modulates hippocampal neuroinflammatory markers in a rat model of neuropathic pain. These results highlight minocycline's potential as a therapeutic option for neuropathic pain, particularly in targeting neuroinflammation within the hippocampus. Show less