The repeated administration of morphine frequently gives rise to tolerance,manifested by a reduction in analgesic efficacy and an elevation in adverse effects.These consequences significantly impinge upon its clinical utility.Synaptic functional plasticity governs long-term alterations in synaptic transmission efficiency through calcium signaling pathways,protein kinase cascade reactions,and glia-neuron interactions,thereby facili-tating the development of morphine tolerance.Structural plasticity encompasses the dynamic remodeling of dendritic spine density and morphology,the establishment or elimination of synaptic connections,and the reconstitution of synaptic active zones.Morphine-induced synaptic plasticity within the central nervous system demonstrates region-specific alterations,which jointly drive the process of tolerance.This review comprehensively synthesizes the research advancements regarding the mechanisms of synaptic plasticity in morphine tolerance,with the aim of furnishing a theoretical foundation for the development of innovative analgesic medications and the optimization of clinical treatment strategies.

The repeated administration of morphine frequently gives rise to tolerance,manifested by a reduction in analgesic efficacy and an elevation in adverse effects.These consequences significantly impinge upon its clinical utility.Synaptic functional plasticity governs long-term alterations in synaptic transmission efficiency through calcium signaling pathways,protein kinase cascade reactions,and glia-neuron interactions,thereby facili-tating the development of morphine tolerance.Structural plasticity encompasses the dynamic remodeling of dendritic spine density and morphology,the establishment or elimination of synaptic connections,and the reconstitution of synaptic active zones.Morphine-induced synaptic plasticity within the central nervous system demonstrates region-specific alterations,which jointly drive the process of tolerance.This review comprehensively synthesizes the research advancements regarding the mechanisms of synaptic plasticity in morphine tolerance,with the aim of furnishing a theoretical foundation for the development of innovative analgesic medications and the optimization of clinical treatment strategies.

Objective:The activation of astrocytes is an important process in the formation of chronic pain.This study aims to observe the activation of A1 reactive astrocytes in the medullary dorsal horn in the rat model of trigeminal neuralgia,and to explore the mechanism of central sensitization caused by A1 reactive astrocyte. Methods:The adult male rats were randomly divided into a sham group and a chronic constriction injury of infraorbital nerve(ION-CCI)group.The facial mechanical pain threshold and thermal withdrawal latency were measured before the operation and on the 1st,3rd,7th,10th,and 14th day after the operation.After pain behavior observation,the expression of glial fibrillary acidic protein(GFAP)in the medullary dorsal horn was observed by immunohistochemistry and immunofluorescence colocalization of GFAP,complement 3(C3)/S100A10,and 4',6-diamidino-2-phenylindole(DAPI)was analyzed.Primary astrocytes were cultured and randomly divided into a naive group and a DHK group.The DHK group was treated with 1 mmol/L of astrocyte activation inhibitor dihydrokainic acid(DHK).Fura-2/AM was used to stain the astrocytes and the calcium wave of the 2 groups under the stimulation of high potassium was recorded and compared.The expression of C3 was detected by Western blotting. Results:The facial mechanical pain threshold and thermal withdrawal latency of the ION-CCI group were significantly lower than those of the sham group(both P<0.05).There were a large number of GFAP positive astrocytes in the medullary dorsal horn of the ION-CCI group.The fluorescence intensity of GFAP in the ION-CCI group was higher than that in the sham group(P<0.05).GFAP and C3/S100A10 were co-expressed in astrocytes.Compared with the sham group,the fluorescence intensity of C3 and the protein expression of C3 in the ION-CCI group were increased(both P<0.05).The expression of C3 in ION-CCI group was significantly increased(P<0.05).Compared with the naive group,the C3 protein expression was significantly decreased in the DHK group(P<0.05).The intensity of calcium fluorescence was increased after high potassium stimulation in both groups.Furthermore,the peak and increase amplitude of calcium fluorescence in the naive group were much higher than those in the DHK group(both P<0.05). Conclusion:A1 reactive astrocytes in the medullary dorsal horn of trigeminal neuralgia model rats are increased significantly,which may participate in central sensitization of trigeminal neuralgia by impacting astrocyte calcium wave.

Pain caused by surgery is an important clinical issue that seriously affects postoperative rehabilitation and health-related quality of life. Failure to effectively manage postoperative pain not only leads to a decrease in patient quality of life, increases medical expenses, but also has a negative impact on patient recovery. Therefore, it is of great clinical significance to address the challenges of acute postoperative pain management, find effective management strategies, and improve the quality of pain management. This article summarizes the current status of acute postoperative pain management in recent years, including the mechanism of pain occurrence, pain assessment methods, drug and non drug management strategies, and predictive factors for chronic postoperative pain. It also looks forward to future research directions and application prospects.

Objective:To retrospectively observe the effect of oxycodone on acute postoperative pain in patients undergoing thoracoscopic surgery.Methods:A retrospective analysis was conducted on the clinical data of 404 patients undergoing thoracoscopic thoracic surgery under combined general anesthesia at the Xiangya Hospital, Central South University from April 1, 2020 to September 30, 2021. They were divided into A group ( n=99, oxycodone group) and B group ( n=305, control group) based on whether oxycodone was used during the surgery. The two groups of patients were further matched 1∶1 using the nearest neighbor matching method. We compared the Visual Analogue Scale (VAS) of activity and resting pain and the incidence of moderate to severe pain between two groups of patients 24 hours after surgery, and observed the incidence and severity of pain related adverse reactions such as nausea, vomiting, itching, and dizziness. Resultsl:After matching the propensity scores of the two groups of patients, the balance was good ( SMD<0.20). There was no statistically significant difference between the groups in age, gender, body mass index, American Society of Anesthesiologist (ASA) grade, surgical time, intraoperative bleeding, and the use of antiemetics and analgesics during the perioperative period (all P>0.05). Compared with the control group, patients in the group A had a resting VAS [(2.03±1.61)points vs (1.62±1.31)points, P=0.049], and activity VAS [(4.13±1.72)points vs (3.51±1.79)points, P=0.013] was even lower, and the incidence of moderate to severe pain (VAS≥4) during activity was lower [59.6%(59/99) vs 37.4%(37/99), P=0.003]. There was no statistically significant difference in the incidence of analgesic related adverse reactions between the two groups ( P>0.05). Conclusions:Intravenous injection of oxycodone can effectively alleviate acute pain in patients undergoing thoracoscopic surgery within 24 hours, and reduce the incidence of moderate to severe pain during activity.

This research focuses on the application of multiple interactive modes in online teaching, combined with the actual teaching cases of the anesthesia equipment course of Xiangya Anesthesiology Specialty of Central South University, showing in detail the preparations for interactive teaching before anesthesia equipment learning, the interaction in online classrooms, the extension of interactive teaching outside the classroom, and the evaluation of interactive teaching feedback mechanism throughout the implementation process. By establishing a "host-guest-viewer" mode, the effect of online live broadcasting is maximized. Through the 360-degree materialized explanation with students as the main body, we will make opening in the pain points and blocking points of online teaching in which students do not go to class and students have no thinking, and promote the improvement of online teaching quality and efficiency. In the following practice, we must continue to work on issues such as the improvement of teacher talent quality, the building of an efficient talent team, and the construction of practical application value evaluation systems for teaching.

To investigate the effect of SB203580, a p38MAPK specific inhibitor, on ropivacaine-induced cytotoxicity in PC12 cells.
 Methods: PC12 cells were divided into three groups: the normal group (Group N), cells were cultured for 48 h; the ropivacaine group (Group R), cells were cultured with 15 mmol/L ropivacaine hydrochloride for 48 h; the ropivacaine+SB203580 group (Group R+S), cells were cultured with 15 mmol/L ropivacaine hydrochloride plus 10 μmol/L SB203580 for 48 h. The cell survival rates were detected by MTT assay. The protein levels of cleaved caspase-3, phosphor-p38 (p-p38) and cystolic cytochrome C (Cyt C) were detected by Western blotting.
 Results: Compared with the Group N, the number and survival rate of PC12 cells in the Group R and the Group R+S were significantly reduced (all P<0.05); the number and survival rate of PC12 cells in the Group R+S were significantly higher than those in the Group R (both P<0.05). Compared with the Group N, the levels of p-p38 and cleaved caspase-3, and the content of cytoplasmic Cyt C in the PC12 cells from the Group R and the Group R+S were significantly enhanced (all P<0.05); compared with the Group R, the levels of p-p38 and cleaved caspase-3, and the content of cytoplasmic Cyt C in the PC12 cells from the Group R+S were decreased (all P<0.05).
 Conclusion: The ropivacaine-induced cytotoxicity can be attenuated via inhibition of p38MAPK; which is related to decrease in Cyt C content and cleaved caspase-3 expression.
Anesthetics, Local ; toxicity ; Animals ; Apoptosis ; Imidazoles ; PC12 Cells ; Pyridines ; Rats ; Ropivacaine ; toxicity ; p38 Mitogen-Activated Protein Kinases ; metabolism

To establish a two-dimensional gel electrophoresis (2-DE) map for comparative proteomic analysis of rat spinal cord with chronic morphine tolerance, and to detect differentially expression proteins that are associated with chronic morphine tolerance.
 Methods: Sixteen male SD rats received the intrathecal catheterization operation and they were randomly divided into a morphine tolerance group (MT group, n=8) and a saline group (NS group, n=8). The lumbar enlargement segments of the MT group and the NS group spinal cord were harvested and proteins were separated by 2-DE. Differential proteome profiles were established and analyzed by means of immobilized pH gradient-based two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The 2-DE maps were visualized after coomassie blue staining and analyzed using PDQuest analysis software. Identification of differential protein spots was conducted by MALDI-TOF-MS, and the Mascot query software was used to search Swiss-Prot database for bioinformatics analysis. Western blotting was used to verify the expression of some differentially expressed proteins.
 Results: A total of 1 000 spots were identified in 2-DE maps of rat spinal cord tissues from the MT group and the NS group, and 36 proteins were significantly differentially expressed in the MT group compared with the NS group. Identification was conducted by MALDI-TOF-MS and Swiss-Prot database through Mascot query software, and a total of 14 proteins were obtained. Among them, 2 protein spots were down-regulated in the MT group compared with that in the NS group, and 12 protein spots were up-regulated in the MT group compared with that in the NS group. Two kinds of proteins (NUDAA, ENOG) were verified by Western blotting and the results were consistent with proteomics data.
 Conclusion: The optimized 2-DE profiles for the proteome of spinal cord tissue in rats with chronic morphine tolerance is established preliminarily, which showed that morphine tolerance can cause changes in the expression of various proteins in the spinal cord.
Animals ; Electrophoresis, Gel, Two-Dimensional ; Male ; Morphine ; Proteome ; Proteomics ; Rats ; Rats, Sprague-Dawley ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ; Spinal Cord

To explore the role of vascular endothelial growth factor (VEGF) in diabetic peripheral neuropathic pain in rats.
 Methods: Twenty-four adult male Sprague-Dawley rats aged 8 weeks were randomly divided into 3 groups (n=8 per group). The control group (C group): rats were intraperitoneally injected with sodium citrate solution at 10 mL/kg; the model group (M group): rats were intraperitoneally injected with streptozotocin at 65 mg/kg; the treatment group (T group): rats received intraperitoneal injection of anti-VEGF antibody (10 mg/kg) at the 1st, 3rd, 7th, 10th day after STZ treatment. Meanwhile, rats of C and M group were received with the same volume of sodium citrate solution. Blood glucose was measured before 1 day or at the 1st, 3rd, 7th or 14th day after receiving STZ. Body weight, paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were measured before 1 day or at the 1st, 3rd, 5th, 7th, 10th or 14th day after receiving STZ. All lumbar spinal cords were dissected to examine the p-protein kinase B (p-Akt) and transient receptor potential vanilloid 1 (TRPV1) expression by Western blot.
 Results: After injection with STZ, the body weight showed significant differences at some time point between the M, T or C group (P<0.01); body weight of rat in the C group were increased gradually. Compared with the C group, the fast blood glucose in the M or the T Group at the same time points were increased significantly (P<0.01). The PWMT and PWTL of the M, T or C group were significant difference among various time points (P<0.01). The PWMT and PWTL in the M or T group were obviously reduced compared with those in the C group (P<0.01). Compared with the M group, the PWMT and PWTL in the T group were increased at the 10th or 14th day (P<0.01 or P<0.05). Compared with the C group, the p-Akt and TRPV1 levels in the M and T group were increased (P<0.01). Compared with the M group, p-Akt and TRPV1 levels in T group were decreased (P<0.01).
 Conclusion: VEGF is able to regulate the expression of TRPV1 through PI3K/Akt pathway, which contributes to diabetic peripheral neuropathic pain in rats. Anti-VEGF treatment may be useful for alleviation of diabetic peripheral neuropathic pain.
Animals ; Antibodies ; pharmacology ; therapeutic use ; Diabetes Mellitus, Experimental ; chemically induced ; Diabetic Neuropathies ; chemically induced ; drug therapy ; Gene Expression Regulation ; drug effects ; Male ; Phosphatidylinositol 3-Kinases ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; TRPV Cation Channels ; genetics ; Vascular Endothelial Growth Factor A ; metabolism

Objective To evaluate the effect of neurotrophin-3 (NT-3) on the expression of serine/threonine protein kinase (Akt) during ropivacaine-induced neurotoxicity to the spinal cord of rats.Methods Healthy adult male Sprague-Dawley rats,aged 1-2 months,weighing 280-320 g,were used in the study.A catheter was inserted at L5,6 interspace into the epidural space of rats.A total of 108 rats,in which intrathecal catheters were successfully implanted,were randomly divided into 3 groups (n =36each):control group (group C),1％ ropivacaine group (group R),and 1％ ropivacaine + NT-3 group (group NT).The equal volume of normal saline was given in group C,1％ ropivacaine 0.12 ml/kg was injected via the intrathecal catheter once every 1.5 h for 8 times in total in R and NT groups.In addition,NT-3 0.1 mg/kg was simultanenously injected via the intrathecal catheter in group NT.On days 1,3,5,7,14 and 28 after the end of administration (T1-6),6 rats were sacrificed in each group.Their lumbar enlargements were removed for determination of neuronal apoptosis (using TUNEL) and Akt expression (by immuno-histochemistry).The apoptotic rate was calculated.Results Compared with group C,the apoptotic rate was significantly increased at T1-4,and Akt expression was significantly up-regulated at T1-3 in group R,and the apoptotic rate were significantly increased,and Akt expression was significantly up-regulated at T1-3 in group NT (P＜0.05).Compared with group R,the apoptotic rate was significantly decreased at T3,4,and Akt expression was significantly down-regulated at T2.3 in group NT (P＜0.05).Conclusion The mechanism by which NT-3 reduces ropivacaine-induced neurotoxicity to the spinal cord may be related to down-regulation of the expression of Akt in rats.