Patients suffering from nerve injury often experience exacerbated pain responses and complain of memory deficits. The dorsal hippocampus (dHPC), a well-defined region responsible for learning and memory, displays maladaptive plasticity upon injury, which is assumed to underlie pain hypersensitivity and cognitive deficits. However, much attention has thus far been paid to intracellular mechanisms of plasticity rather than extracellular alterations that might trigger and facilitate intracellular changes. Emerging evidence has shown that nerve injury alters the microarchitecture of the extracellular matrix (ECM) and decreases ECM rigidity in the dHPC. Despite this, it remains elusive which element of the ECM in the dHPC is affected and how it contributes to neuropathic pain and comorbid cognitive deficits. Laminin, a key element of the ECM, consists of α-, β-, and γ-chains and has been implicated in several pathophysiological processes. Here, we showed that peripheral nerve injury downregulates laminin β1 (LAMB1) in the dHPC. Silencing of hippocampal LAMB1 exacerbates pain sensitivity and induces cognitive dysfunction. Further mechanistic analysis revealed that loss of hippocampal LAMB1 causes dysregulated Src/NR2A signaling cascades via interaction with integrin β1, leading to decreased Ca²⁺ levels in pyramidal neurons, which in turn orchestrates structural and functional plasticity and eventually results in exaggerated pain responses and cognitive deficits. In this study, we shed new light on the functional capability of hippocampal ECM LAMB1 in the modulation of neuropathic pain and comorbid cognitive deficits, and reveal a mechanism that conveys extracellular alterations to intracellular plasticity. Moreover, we identified hippocampal LAMB1/integrin β1 signaling as a potential therapeutic target for the treatment of neuropathic pain and related memory loss.
Animals ; Laminin/genetics* ; Hippocampus/metabolism* ; Neuralgia/metabolism* ; Cognitive Dysfunction/etiology* ; Male ; Peripheral Nerve Injuries/metabolism* ; Extracellular Matrix/metabolism* ; Integrin beta1/metabolism* ; Pyramidal Cells/metabolism* ; Signal Transduction

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*

Objective:To evaluate the role and molecular mechanism of laminin β1(LAMB1)in cortical neurons in regulation of glutamate receptors.Methods:Recombinant lentivirus(LV-shLamb1)-mediated knockdown of LAMB1 expression in mouse primary cortical neurons was performed,followed by immunofluorescence staining and Western blot to detect changes in F-actin,glutamate receptor subtypes(AMPA receptors GluR1/GluR2,NMDA receptors NR1/NR2A),and ERK-related protein expression in cortical neurons.Results:LV-shLamb1 significantly inhibited LAMB1 expression in mouse cortical neurons.Concurrently,LV-shLamb1 markedly increased F-actin polymerization,as well as the expression of AMPA receptor subunits GluR1 and GluR2,and NMDA receptor subunits NR1 and NR2A.Further,Western blot detection showed that the phosphorylation level of ERK was significantly increased after LV-shLamb1 infec-tion.Conclusion:LAMB1 is expressed in cortical neurons.Suppression of LAMB1 expression in mouse cortical neu-rons activates the ERK pathway,which in turn promotes the polymerization of the cytoskeletal protein F-actin and the expression of glutamate receptors.This suggests that LAMB1 may regulate F-actin homeostasis and glutamate receptor levels through the ERK pathway,thereby playing a potentially important role in neuronal function.

Objective:To observe the therapeutic effects of electroacupuncture(EA)stimulation on chronic pain and associated negative emotions,and to investigate the activity changes of glutamatergic neurons in the primary motor cortex(M1)following EA stimulation.Methods:Male C57BL/6J mice were randomly divided into four groups:sham surgery(Sham),pure electroacupuncture stimulation(EA),nerve injury(SNI)and electroacupuncture treatment of nerve injury(SNI+EA).Thirty days after the SNI model establishment,EA stimulation was administered bilaterally to the Zusanli(ST36)acupoints in mice.von Frey filaments and Hargreaves heat sensitivity testing were used to detect mechanical and thermal hyperalgesia.The elevated plus maze test was conducted to assess the impact on anxiety-like behaviors in mice.Dual immunofluorescence staining was employed to observe changes in c-Fos expression in M1 gluta-matergic neurons.Results:As compared to Sham group,SNI-treated mice exhibited significant mechanical and thermal hyperalgesia in bilateral hindpaws at 30 days post-modeling(P＜0.01)and displayed obvious anxiety-like behaviors(P＜0.01).The SNI+EA group showed significant relief in pain and anxiety-like behaviors(P＜0.01).c-Fos expression in M1 glutamatergic neurons was significantly decreased in SNI mice.Conversely,after electroacupuncture(EA)treatment,compared to the SNI group,M1 glutamatergic neurons in the SNI+EA group showed significantly in-creased c-Fos expression(P＜0.01).Conclusion:Electroacupuncture significantly alleviated chronic pain and associ-ated anxiety-like behaviors induced by SNI,which might involve the activation of glutamatergic neurons in the M1 in this process.

Objective:To evaluate the role and molecular mechanism of laminin β1(LAMB1)in cortical neurons in regulation of glutamate receptors.Methods:Recombinant lentivirus(LV-shLamb1)-mediated knockdown of LAMB1 expression in mouse primary cortical neurons was performed,followed by immunofluorescence staining and Western blot to detect changes in F-actin,glutamate receptor subtypes(AMPA receptors GluR1/GluR2,NMDA receptors NR1/NR2A),and ERK-related protein expression in cortical neurons.Results:LV-shLamb1 significantly inhibited LAMB1 expression in mouse cortical neurons.Concurrently,LV-shLamb1 markedly increased F-actin polymerization,as well as the expression of AMPA receptor subunits GluR1 and GluR2,and NMDA receptor subunits NR1 and NR2A.Further,Western blot detection showed that the phosphorylation level of ERK was significantly increased after LV-shLamb1 infec-tion.Conclusion:LAMB1 is expressed in cortical neurons.Suppression of LAMB1 expression in mouse cortical neu-rons activates the ERK pathway,which in turn promotes the polymerization of the cytoskeletal protein F-actin and the expression of glutamate receptors.This suggests that LAMB1 may regulate F-actin homeostasis and glutamate receptor levels through the ERK pathway,thereby playing a potentially important role in neuronal function.

Objective:To observe the therapeutic effects of electroacupuncture(EA)stimulation on chronic pain and associated negative emotions,and to investigate the activity changes of glutamatergic neurons in the primary motor cortex(M1)following EA stimulation.Methods:Male C57BL/6J mice were randomly divided into four groups:sham surgery(Sham),pure electroacupuncture stimulation(EA),nerve injury(SNI)and electroacupuncture treatment of nerve injury(SNI+EA).Thirty days after the SNI model establishment,EA stimulation was administered bilaterally to the Zusanli(ST36)acupoints in mice.von Frey filaments and Hargreaves heat sensitivity testing were used to detect mechanical and thermal hyperalgesia.The elevated plus maze test was conducted to assess the impact on anxiety-like behaviors in mice.Dual immunofluorescence staining was employed to observe changes in c-Fos expression in M1 gluta-matergic neurons.Results:As compared to Sham group,SNI-treated mice exhibited significant mechanical and thermal hyperalgesia in bilateral hindpaws at 30 days post-modeling(P＜0.01)and displayed obvious anxiety-like behaviors(P＜0.01).The SNI+EA group showed significant relief in pain and anxiety-like behaviors(P＜0.01).c-Fos expression in M1 glutamatergic neurons was significantly decreased in SNI mice.Conversely,after electroacupuncture(EA)treatment,compared to the SNI group,M1 glutamatergic neurons in the SNI+EA group showed significantly in-creased c-Fos expression(P＜0.01).Conclusion:Electroacupuncture significantly alleviated chronic pain and associ-ated anxiety-like behaviors induced by SNI,which might involve the activation of glutamatergic neurons in the M1 in this process.

Objective:To observe the effects of electroacupuncture(EA)intervention on norepinephrine(NE)andα2A adrenergic receptors(α2A-R)in the dorsal root ganglion(DRG)of mice with spared nerve injury(SNI).Methods:Male C57BL/6 mice were randomly divided into sham surgery group(Sham),model group(SNI),negative control EA group(SNI+NC-EA),and EA group(SNI+EA).Mechanical and thermal stimuli were used to measure the paw withdrawal mechanical threshold(PWMT)and paw withdrawal thermal latency(PWTL).Immunofluorescence staining was used to detect the sprouting of sympathetic nerve fibers and the co-localization of α2A-R with large-diameter sensory neurons in mouse DRG.Enzyme-linked immunosorbent assay(ELISA)kits were used to measure NE levels in mouse serum and DRG,and Western Blot was used to detect tyrosine hydroxylase(TH)and α2A-R expression levels in DRG.Results:After SNI,the PWMT and PWTL were significantly decreased,and after electroacupuncture treatment,PWMT and PWTL were reversed and increased.Immune fluorescence staining showed that sympathetic ganglion sprouting increased in DRG after SNI,and significantly decreased after electroacupuncture;After SNI,NE,α2A-R,and TH in DRG all significantly increased,and their expression decreased after electroacupuncture intervention,but NE in the serum did not change significantly.Conclusion:In the SNI model,electroacupuncture may regulate the sympathetic-sensory coupling by inhibiting the release of NE and the expression of α2A-R in DRG,thereby producing analgesic effects.

Objective:To investigate the changes of melanin concentration hormone receptor 1(MCHR1)in dorsal root ganglion(DRG)of mice with neuropathic pain.Methods:The expression profile of MCHR1 in the DRG of mice were observed by immunofluorescent staining.Neuropathic pain model was established by spared nerve injury(SNI)in mice.Male mice(C57BL/6)were randomly divided into 2 groups:Sham-operated group and SNI group.The paw withdrawal threshold(PWT)and paw withdrawal latency(PWL)were observed by von Frey fibers and thermal radiation stimulation.The mRNA and protein levels of MCHR1 in DRG were detected by real time RT-PCR and West-ern Blot,respectively.Results:MCHR1 was widely distributed in mouse DRG and co-labeled with small and medium-sized neuronal markers calcitonin gene-related peptide(CGRP)and isolectin B4(IB4),as well as large diameter neu-ronal marker NF200.Stable mechanical hyperalgesia and heat hyperalgesia were observed in the ipsilateral hindpaw of mice at 7 days post-SNI.Real time RT-PCR and Western Blot experiments showed that mRNA and protein expression levels in DRG were both significantly up-regulated in SNI-treated mice,as compared with Sham group.Conclusion:MCHR1 was widely distributed in large,medium and small neurons of DRG.After the SNI model mice presented a sta-ble phenomenon of hyperalgesia,the transcription and protein level of MCHR1 in DRG were significantly elevated in SNI mice.These data suggest that MCHR1 in DRG may be involved in the occurrence and development of neuropathic pain.

Objective:To investigate the changes of melanin concentration hormone receptor 1(MCHR1)in dorsal root ganglion(DRG)of mice with neuropathic pain.Methods:The expression profile of MCHR1 in the DRG of mice were observed by immunofluorescent staining.Neuropathic pain model was established by spared nerve injury(SNI)in mice.Male mice(C57BL/6)were randomly divided into 2 groups:Sham-operated group and SNI group.The paw withdrawal threshold(PWT)and paw withdrawal latency(PWL)were observed by von Frey fibers and thermal radiation stimulation.The mRNA and protein levels of MCHR1 in DRG were detected by real time RT-PCR and West-ern Blot,respectively.Results:MCHR1 was widely distributed in mouse DRG and co-labeled with small and medium-sized neuronal markers calcitonin gene-related peptide(CGRP)and isolectin B4(IB4),as well as large diameter neu-ronal marker NF200.Stable mechanical hyperalgesia and heat hyperalgesia were observed in the ipsilateral hindpaw of mice at 7 days post-SNI.Real time RT-PCR and Western Blot experiments showed that mRNA and protein expression levels in DRG were both significantly up-regulated in SNI-treated mice,as compared with Sham group.Conclusion:MCHR1 was widely distributed in large,medium and small neurons of DRG.After the SNI model mice presented a sta-ble phenomenon of hyperalgesia,the transcription and protein level of MCHR1 in DRG were significantly elevated in SNI mice.These data suggest that MCHR1 in DRG may be involved in the occurrence and development of neuropathic pain.

Parvalbumin interneurons belong to the major types of GABAergic interneurons. Although the distribution and pathological alterations of parvalbumin interneuron somata have been widely studied, the distribution and vulnerability of the neurites and fibers extending from parvalbumin interneurons have not been detailly interrogated. Through the Cre recombinase-reporter system, we visualized parvalbumin-positive fibers and thoroughly investigated their spatial distribution in the mouse brain. We found that parvalbumin fibers are widely distributed in the brain with specific morphological characteristics in different regions, among which the cortex and thalamus exhibited the most intense parvalbumin signals. In regions such as the striatum and optic tract, even long-range thick parvalbumin projections were detected. Furthermore, in mouse models of temporal lobe epilepsy and Parkinson's disease, parvalbumin fibers suffered both massive and subtle morphological alterations. Our study provides an overview of parvalbumin fibers in the brain and emphasizes the potential pathological implications of parvalbumin fiber alterations.
Mice ; Animals ; Epilepsy, Temporal Lobe/pathology* ; Parvalbumins/metabolism* ; Parkinson Disease/pathology* ; Neurons/metabolism* ; Interneurons/physiology* ; Disease Models, Animal ; Brain/pathology*