Chronic pain can cause both hyperalgesia and cognitive impairment symptoms and involves long-term alterations in the neural circuits, leading to abnormal cortical activity. GABAergic signaling are particularly emerging as relevant components of pain processing within the prefrontal cortex. The mechanism through which cortical circuits change and cause chronic pain and memory impairment remains unclear to date. We modeled chronic neuropathic pain in mice using chronic constrictive injury (CCI), an open field test, a Y maze spontaneous alternation experiment, a novel object recognition test and barnes maze were used to assess neurobehavioral changes in the mice. Whole-cell patch-clamp technique was used to assess the intrinsic activity of neurons, and fiber photometry recording was used to measure the calcium activity of GABAergic neurons. In vivo multi-channel technique was employed to assess alterations in cortical excitability. Western blot and immunofluorescence were used to measure the expression of activating transcription factor 4 (ATF4) and Neuronal excitability. In this study, persistent elevation of GABAergic neuronal activity in prelimbic cortex layer 5 (PrL-L5) was demonstrated to regulate the chronic pain and memory impairment. This elevated GABAergic neuronal activity affects the excitatory/inhibitory (E/I) imbalance by influencing the excitability of pyramidal neurons. The inhibition of PrL-L5 GABAergic neuronal activity reversed the hypersensitivity and memory deficits. In contrast, the optogenetic activation of PrL-L5 GABAergic neurons induced hypersensitivity and memory impairment in naive mice. Furthermore, ATF4 regulates hyperpathia and memory impairment through impact GABAergic neuronal activity. We revealed a cortical GABAergic neural microcircuit that involved chronic pain and memory impairment through modulating E/I imbalance by influencing the excitability of pyramidal neurons. These findings provide novel insights for targeted interventions in patients with comorbid chronic pain and memory impairment. Not applicable.

Neuropathic pain (NP) is frequently comorbid with anxiety and depression, yet the underlying molecular mechanisms in the brain remain poorly understood, hindering the development of targeted therapies. This study aimed to identify key transcriptional networks and regulatory pathways in the anterior cingulate cortex (ACC) associated with NP-induced anxiodepression. We analyzed transcriptomic data (GSE92718) from the ACC of a mouse model of chronic NP. By comparing differentially expressed genes at a time point manifesting anxiodepressive-like behavior (8-week post-injury) against those with pain alone (2-week), we constructed a weighted gene co-expression network (WGCNA). A key module (blue module) significantly correlated with the anxiodepressive phenotype was enriched for synaptic signaling (glutamatergic/GABAergic), neuroplasticity, and key pathways like MAPK and Ras. Within this module, we identified 7 pivotal lncRNAs and 5 hub mRNAs (Flt1, Slc38a2, Bmpr1b, Pdgfra, Gng2) via integrated lncRNA-mRNA-pathway and protein-protein interaction network analyses. Furthermore, we established a competing endogenous RNA (ceRNA) network, revealing a core regulatory axis comprising 3 hub lncRNAs, 5 hub mRNAs, and 40 miRNAs. The aberrant expression of the five hub mRNAs in the ACC was specifically validated in mice with anxiodepressive phenotypes using RT-PCR. Our findings unveil a critical ceRNA network and implicate dysregulated synaptic genes in the ACC as key drivers of NP-induced anxiodepression, providing novel insights into its molecular basis and highlighting potential diagnostic biomarkers and therapeutic targets.

Macroautophagy/autophagy plays a crucial role in maintaining nervous system homeostasis but its role in chronic postoperative pain (CPOP) remains poorly understood. Here, we identify impaired autophagy and the accumulation of synaptic proteins in the anterior cingulate cortex (ACC) during the maintenance of CPOP after skin/muscle incision and retraction (SMIR). Lysosomal hydrolase levels are reduced upon SMIR, accompanied by a deficiency of the lysosomal trafficking protein transmembrane protein 251 (TMEM251, also named LYSET). TMEM251 overexpression alleviates impaired autophagy, accumulation of synaptic proteins within autophagy substrates, and maintenance of CPOP in SMIR mice. Conversely, TMEM251 knockdown induces autophagy impairment, accumulation of synaptic proteins, and chronic pain phenotypes in naive mice. Autophagy dysfunction is most pronounced in CaMKIIα-positive neurons in the ACC post-surgery, resulting in their activation, which is mitigated by TMEM251 overexpression. Chemogenetic activation of CaMKIIα neurons exacerbates autophagy impairment and CPOP, while their inhibition rescues SMIR-induced autophagy and pain phenotypes. Taken together, our study highlights the close relationship between impaired autophagy and neuronal activation in the promotion of chronic postoperative pain.

Chronic postoperative pain (CPOP) remains a significant clinical challenge, with central sensitization being an important mechanism. However, the neuronal circuit-mediated mechanisms associated with this disorder are poorly understood. Here, we identified the nucleus accumbens core (AcbC) received excitatory projections from calcium/calmodulin-dependent protein kinase II (CaMKII)-positive neurons in the anterior cingulate cortex (ACC), playing an important role in the development of CPOP. We demonstrated that the AcbC neurons displayed the enhanced responses to both non-nociceptive and nociceptive stimuli following skin/muscle incision and retraction. Furthermore, fiber photometry and electrophysiological recordings confirmed that the activity of the ACCCaMKII-AcbC pathway was also elevated after surgery. Inhibition of AcbC neurons or the ACCCaMKII-AcbC pathway alleviated pain hypersensitivity in CPOP mice, whereas their activation induced pain phenotypes in naive mice. These findings reveal critical roles for the AcbC neurons and ACCCaMKII-AcbC pathway in CPOP pathogenesis, offering potential therapeutic targets for postoperative pain management.

Postoperative cognitive dysfunction (POCD) is common following surgery in elderly patients. The role of the preoperative gut microbiota in POCD has attracted increasing attention, but the potential underlying mechanisms remain unclear. This research aimed to investigate the impact of the preoperative gut microbiota on POCD. Herein, we analyzed the preoperative gut microbiota of POCD patients through a prospective specimen collection and retrospective blinded evaluation study. Then, we transferred the preoperative gut microbiota of POCD patients to antibiotic-treated rats and established POCD model by abdominal surgery to explore the impact of the preoperative gut microbiota on pre- and postoperative cognitive function and systemic inflammation. The gut microbiota was analyzed using 16S rRNA sequencing analysis. The Morris water maze test was performed to evaluate learning and memory abilities. The inflammatory cytokines TNF-α, IL-1β and IL-6 in the serum and hippocampus were measured by ELISA. Microglia were examined by immunofluorescence staining for Iba-1. Based on the decrease in the postoperative MMSE score, 24 patients were identified as having POCD and were matched with 24 control patients. Compared with control patients, POCD patients exhibited higher BMI and lower preoperative MMSE score. The preoperative gut microbiota of POCD patients had lower bacterial richness but a larger distribution, decreased abundance of Firmicutes and increased abundance of Proteobacteria than did that of control patients. Compared with rats that received preoperative fecal samples of control patients, rats that received preoperative fecal samples of POCD patients presented an increased abundance of Desulfobacterota, decreased cognitive function, increased levels of TNF-α and IL-1β in the serum, increased levels of TNF-α and greater microglial activation in the hippocampus. Additionally, correlation analysis revealed a positive association between the abundance of Desulfobacterota and the level of serum TNF-α in rats. Then, we performed abdominal surgery to investigate the impact of the preoperative gut microbiota on postoperative conditions, and the surgery did indeed cause POCD and inflammatory response. Notably, compared with rats that received preoperative fecal samples of control patients, rats that received preoperative fecal samples of POCD patients displayed exacerbated cognitive impairment; increased levels of TNF-α, IL-1β and IL-6 in the serum and hippocampus; and increased activation of microglia in the hippocampus. Our findings suggest that the preoperative gut microbiota of POCD patients can induce preoperative and aggravate postoperative cognitive impairment and systemic inflammation in rats. Modulating inflammation by targeting the gut microbiota might be a promising approach for preventing POCD.

Background: Colon adenocarcinoma (COAD) is the most common type of colorectal cancer. Pain is a multidimensional unpleasant experience and various molecular and cellular pathways are implicated in pain signaling. Nevertheless, the exploration of pain-related genes related to colon adenocarcinoma is not clear yet. Methods: In this study, the pathways enriched for pain-related genes were analyzed by Metascape. Then, we obtained pain subtypes versus classical subtypes and explored the link between the two. Next, marker genes for different pain subtypes were identified, the enrichment pathways were explored and these marker genes were used to validate the pain subtypes. We then performed an investigation of survival differences between pain subtypes by selecting specific top pathways in each subtype, calculating top pathway scores, and calculating pathway differences by heatmap and Kruskal test. Finally, we predicted the response of different pain subtypes to immunotherapy. Results: A total of 146 pain-related genes were enrolled in this study and we finally obtained 4 painful subtypes and 4 stable subtypes. The marker genes for subtypes were validated by The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets and found to have a worse prognosis for CS1. The genes of CS1, CS2, CS3 and CS4 markers were mainly enriched in the pathways of Focal adhesion, Human T cell leukemia virus1 infection, Metabolic pathway, and Pertussis, respectively. CS1 and CS4 are more immunogenic. Moreover, CS1 is more sensitive to treatment with CTLA4 inhibitors, CS4 is sensitive to treatment with PD-1 inhibitors. Conclusions: Our study's identification of four pain subtypes of COAD provides new ideas for personalised therapy for patients with COAD.

Neuropathic pain (NP) is the chronic pain in patients resulting from injuries or diseases in the somatosensory nervous system. However, effective treatment remains limited to opioids. Currently, there is an urgent need to develop new specific pharmaceuticals with low abuse potentiality. Cannabinoid receptor 2 (CB2R) is one of the significant receptors in the endocannabinoid system. It is widely expressed in the central nervous system, especially enriched in glial cells, and plays an important role in the occurrence and development of inflammation in the nervous system. CB2R activation has a neuroprotective effect on nerve injury. In this study, we report increased and more reactive microglia (with larger cell body, shorter processes, and fewer endpoints) observed in the spinal dorsal horn of spared nerve injury (SNI) rats. Continuous intrathecal administration of CB2R agonist PM226 attenuated mechanical and cold hyperalgesia in rats and prevented the transition of microglia to the proinflammatory stage. Thus, microglia transitioned into the neuroprotective stage. Meanwhile, the proinflammatory factors TNF-α and iNOS decreased, and the levels of anti-inflammatory factors Arg-1 and IL-10 increased. The content of P2X7 receptors in the spinal dorsal horn of rats increases with time after SNI. After continuous intrathecal administration of PM226, the content of P2X7 protein decreases significantly. The administration of P2X7 inhibitor A-438079 alleviated the mechanical hyperalgesia of rats, reduced the number of microglia, and decreased the content of P2X7. These results indicate that P2X7 is involved in the neuroprotective effect caused by CB2R activation. In conclusion, this study provides new insights into the neuroprotective mechanism of CB2R activation.

Abstract Morphine tolerance is one of the current challenging issues in the treatment of chronic pain. Recent studies have shown that ROS derived by NADPH oxidase (NOX) and endoplasmic reticulum (ER) stress is participated in the development of morphine tolerance. However, which NOX subtype initiates the ER stress during the development of morphine tolerance is not fully clear. NOX4 mainly expressed at intracellular membranes, such as ER and mitochondria, which sole function is to produce ROS as the major product. At present, whether NOX4 is activated and the mechanisms between NOX4 and ER stress during the development of morphine tolerance still need to be confirmed. Here, our research, for the first time, demonstrated that chronic administration of morphine up-regulated the expression of NOX4 at spinal cord through activating the three ER stress sensors (PERK, IRE1, ATF6), and subsequently leading to the activation of LC3B and P62 (a well-known autophagy marker) in GABAergic neurons. Therefore, our results may suggest that regulating NOX4 and the key factor of ER stress or autophagy may be a promising strategy to treat and prevent the development of morphine tolerance.

Morphine tolerance (MT) is currently a challenging issue related to intractable pain treatment. Studies have shown that reactive oxygen species (ROSs) derived from NADPH oxidase (NOX) and produced in response to endoplasmic reticulum (ER) stress participate in MT development. However, which NOX subtype initiates ER stress during MT development is unclear. NOX4 is mainly expressed on intracellular membranes, such as the ER and mitochondrial membranes, and its sole function is to produce ROS. Whether NOX4 is activated during MT development and the mechanisms underlying the association between NOX4 and ER stress during this process still need to be confirmed. In our study, we used the classic morphine-tolerant rat model and evaluated the analgesic effect of intrathecally injected morphine through a hot water tail-flick assay. Our research demonstrated for the first time that chronic morphine administration upregulates NOX4 expression in the spinal cord by activating three ER stress sensors, protein kinase RNA-like ER kinase (PERK), inositol-requiring enzyme 1 (IRE1) and activating transcription factor 6 (ATF6), subsequently leading to the activation of microtubule-associated protein 1 light chain 3 b (LC3B) and P62 (a well-known autophagy marker) in GABAergic neurons. Our results may suggest that regulating NOX4 and the key mechanism underlying ER stress or autophagy may be a promising strategy to treat and prevent MT development.

Neuropathic pain (NP) is an intractable pain that results from primary nervous system injury and dysfunction. Herein, we demonstrated in animal models that peripheral nerve injury induced enhanced pain perception and anxiety-like behaviors. According to previous reports, nucleus accumbens (NAc) shell is required for complete expression of neuropathic pain behaviors and mood alternations, we found the elevated mRNA and protein level of Prokineticin-2 (Prok2) in the NAc shell after Chronic Constriction Injury (CCI). Prok2 knockdown in the NAc shell reversed NP and anxiety-like behaviors in rats, indicating that Prok2 might play a fundamental role in NP and anxiety co-morbidity. CCI significantly enhanced Prok2 co-expression with NF-κB P-p65 in comparison with control animals. In addition to reversing the established nociceptive hypersensitivities and anxiety simultaneously, NAc microinjection of NF-κB siRNA or specific inhibitor PDTC reversed Prok2 upregulation. Besides, Prok2 was significantly decreased in vitro when co-transfected with si-NF-κB. Dual-Luciferase assay showed NF-κB directly activated Prok2 gene transcriptional activity. Overall, these findings provide new insights into the neurobiological mechanisms behind NP and comorbid anxiety. The NF-κB/Prok2 pathway could be a potential therapeutic target for NP and anxiety disorders.

Objective:To explore the effect of enriched environment on pain sensitivity, anxiety- and depressive-like behavior in selective nerve injury(SNI) rats model and its potential mechanism.Methods:A total of 36 male clean grade SD rats aged 6-8 weeks were randomly divided into three groups( n=12 in each group): sham operation+ standard environment group (sham group), SNI+ standard environment group (standard environment group), SNI+ enriched environment group (enriched environment group). The rat model of neuropathic pain was established by SNI.The rats in the enriched enviroment group were placed in an enriched enviroment 7 days before operation until 21 days after operation.The paw withdraw threshold(PWT) and paw withdraw latency (PWL) were performed to assess hyperalgesia.The open field test, elevated plus maze test, novelty suppressed feeding test and forced swimming test were used to assess anxiety and depression like behavior.The expressions of cAMP response element binding protein (CREB), p-CREB, brain-derived neurotrophic factor (BDNF), postsynaptic density-95 (PSD-95) and neuroligin 2 (NLGN2) were detected by Western blot.The expression of CREB and BDNF in contralateral ACC were measured by immunofluorescence.GraphPad prism 8.0 and SPSS 23.0 were used for data analysis.One way ANOVA was used for inter group comparison, repeated measurement ANOVA was used to analyze PWT and PWL results, and Tukey test was used for pairwise comparison. Results:(1) In PWT and PWL experiments, the interaction effect between group and time, group main effect and time main effect of PWT were significant ( F=13.4, 39.6, 369.6, all P<0.05), and the interaction effect between group and time, group main effect and time main effect of PWL were significant ( F=3.8, 10.3, 58.8, all P<0.05). Compared with sham group, PWT((8.0±3.5) g, (2.4±1.4) g, (2.3±1.1) g, (2.2±1.6) g, (1.6±0.5) g) and PWL((8.6±1.3) s, (7.3±1.5) s, (7.9±1.0) s, (6.6±1.1) s, (7.7±1.4) s) in standard environment group decreased at each time point (all P<0.05). (2) Compared with sham group, the number of entrying into the central area (1.3±1.7), the time of entrying into the central area((1.6±1.3) s), the proportion of entering open arms ((8.0±7.8) %) and the proportion of time in the open arms ((1.3±1.2) %) all significantly decreased in standard environment group ( t=4.585, 5.423, 4.682, 5.202, all P<0.05). The eating latency ((365.2±94.4) s) and immobility time ((127.6±24.3) s) dramatically increased ( t=6.008, 14.290, both P<0.05). The number and time of entrying into central area of enriched environment group were both higher than those of standard environment group(both P<0.05), while the eating latency and immobility time of enriched environment group were both lower than those of standard environment group(both P<0.05). (3) Compared with sham group(CREB: (1.6±0.2), (0.8±0.5); BDNF: (0.8±0.5), (1.0±0.4)), the expression of CREB ((1.8±0.1), (1.5±0.2)), BDNF ((0.9±0.6), (1.4±0.3)) in spinal cord and ACC of standard environment group increased (spinal: t=3.283, 4.989; ACC: t=5.502, 4.257, all P<0.05). The expression of PSD-95 ((1.6±0.2), (1.0±0.2) and NLGN2 ((1.5±0.5), (1.1±0.2)) also increased in ACC of standard enviroment group ( t=4.257, 2.214, both P<0.05). Compared with standard environment group, the expression of CREB (1.3±0.3), BDNF (0.7±0.4), PSD-95(1.0±0.3) and NLGN2(1.1±0.4) in spinal cord of enriched environment group decreased ( t=5.007, 2.166, 2.358, 2.322, all P<0.05). The expression of PSD-95(1.2±0.3) and NLGN2(1.1±0.2) also decreased in ACC of enriched environment group ( t=2.674, 2.944, both P<0.05). However, the expression of p-CREB (1.7±0.6) and BDNF (2.4±0.2) increased in ACC ( t=4.180, 7.610, P<0.05). Conclusion:Enriched environment can improve neuropathic pain and anxiety- and depressive-like behavior in SNI rats, which may be related to the change of synaptic plasticity in spinal cord and ACC.

Neuropathic pain is often accompanied by anxiety and depression-like manifestations. Many studies have shown that alterations in synaptic plasticity in the anterior cingulate cortex (ACC) play a critical role, but the specific underlying mechanisms remain unclear. Previously, we showed that cAMP response element-binding protein (CREB) in the dorsal root ganglion (DRG) acts as a transcription factor contributing to neuropathic pain development. At the same time, brain-derived neurotrophic factor (BDNF), as important targets of CREB, is intricate in neuronal growth, differentiation, as well as the establishment of synaptic plasticity. Here, we found that peripheral nerve injury activated the spinal cord and ACC, and silencing the ACC resulted in significant relief of pain sensitivity, anxiety, and depression in SNI rats. In parallel, the CREB/BDNF pathway was activated in the spinal cord and ACC. Central specific knockdown and peripheral non-specific inhibition of CREB reversed pain sensitivity and anxiodepression induced by peripheral nerve injury. Consequently, we identified cingulate CREB/BDNF as an assuring therapeutic method for treating neuropathic pain as well as related anxiodepression.

目的 探讨气腹状态下不同潮气量(VT)所对应每搏量变异度(SVV)之间的线性关系.方法 择期行腹腔镜结直肠根治术患者57例,在常规麻醉后通过FloTrac传感器进行每搏量变异度监测,在建立人工气腹并调整至Trendelenburg体位后对VT进行设置.按随机顺序设置为6、8、10 mL/kg(以标准体质量计算),记录每搏量变异度等相关数据.结果 随着VT增加,SVV呈进行性增加,且其数值之间有显著的相关性(SVV6与SVV8:r=0.927,P<0.01;SVV8与SVV10:r=0.926,P<0.01;SVV6与SVV10:r=0.867,P<0.01).结论 气腹状态下不同VT所对应SVV之间存在一定的线性关系.根据线性回归方程,可以基于给定VT的已知SVV来计算任何不同VT的SVV.