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Objective To evaluate the relationship between p38 mitogen-activated protein kinase (p38MAPK) and G protein-coupled receptor kinase 2 (GRK2) in the development of persistent postoperative pain in rats.Methods Pathogen-free healthy male Sprague-Dawley rats,weighing 200-250 g,aged 2 months,were used in this study.Sixty rats in which intrathecal catheters were successfully implanted were divided into 6 groups (n =10 each) using a random number table method:sham operation group (group S),sham operation plus dimethyl sulfoxide (DMSO) group (group D),sham operation plus GRK2 degradation inhibitor MDL28170 group (group M),persistent postoperative pain group (group PPP),persistent postoperative pain plus DMSO group (group PPP+D) and persistent postoperative pain plus MDL28170 group (group PPP+M).Persistent postoperative pain was evoked by skin/muscle incision and retraction (SMIR).Immediately after operation and at 1,2 and 3 days after operation,normal saline 20 μl was intrathecally injected once a day in S and PPP groups,5％ DMSO 10 μl was intrathecally injected once a day in D and PPP+D groups,and MDL28170 10 μl (50 μg) was intrathecally injected once a day in M and PPP+M groups.The mechanical paw withdrawal threshold (MWT) was measured at 1 day before operation and 3,7,14 and 21 days after operation (T1-4).Four rats in each group were selected after behavioral testing at T3 and sacrificed,and the L4-6 segments of the spinal cord were removed for determination of the expression of phosphorylated p38MAPK (p-p38MAPK) by Western blot.Results There was no significant difference in MWT at each time point or expression of p-p38MAPK among group S,group D and group M (P＞0.05).Compared with group S,the MWT was significantly decreased,and the expression of p-p38MAPK was up-regulated in PPP,PPP+D and PPP +M groups (P＜ 0.05).Compared with group PPP,the MWT was significantly increased,and the expression of p-p38MAPK was down-regulated in group PPP+M (P＜0.05),and no significant change was found in the MWT or expression of p-p38MAPK in group PPP+D (P＞0.05).Conclusion Down-regulated expression of spinal GRK2 can promote the activation of p38MAPK in the spinal cord and is involved in the development of persistent postoperative pain in rats.
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Objective@#To evaluate the relationship between p38 mitogen-activated protein kinase (p38MAPK) and G protein-coupled receptor kinase 2 (GRK2) in the development of persistent postoperative pain in rats.@*Methods@#Pathogen-free healthy male Sprague-Dawley rats, weighing 200-250 g, aged 2 months, were used in this study.Sixty rats in which intrathecal catheters were successfully implanted were divided into 6 groups (n=10 each) using a random number table method: sham operation group (group S), sham operation plus dimethyl sulfoxide (DMSO) group (group D), sham operation plus GRK2 degradation inhibitor MDL28170 group (group M), persistent postoperative pain group (group PPP), persistent postoperative pain plus DMSO group (group PPP+ D) and persistent postoperative pain plus MDL28170 group (group PPP+ M). Persistent postoperative pain was evoked by skin/muscle incision and retraction (SMIR). Immediately after operation and at 1, 2 and 3 days after operation, normal saline 20 μl was intrathecally injected once a day in S and PPP groups, 5% DMSO 10 μl was intrathecally injected once a day in D and PPP+ D groups, and MDL28170 10 μl (50 μg) was intrathecally injected once a day in M and PPP+ M groups.The mechanical paw withdrawal threshold (MWT) was measured at 1 day before operation and 3, 7, 14 and 21 days after operation (T1-4). Four rats in each group were selected after behavioral testing at T3 and sacrificed, and the L4-6 segments of the spinal cord were removed for determination of the expression of phosphorylated p38MAPK (p-p38MAPK) by Western blot.@*Results@#There was no significant difference in MWT at each time point or expression of p-p38MAPK among group S, group D and group M (P>0.05). Compared with group S, the MWT was significantly decreased, and the expression of p-p38MAPK was up-regulated in PPP, PPP+ D and PPP+ M groups (P<0.05). Compared with group PPP, the MWT was significantly increased, and the expression of p-p38MAPK was down-regulated in group PPP+ M (P<0.05), and no significant change was found in the MWT or expression of p-p38MAPK in group PPP+ D (P>0.05).@*Conclusion@#Down-regulated expression of spinal GRK2 can promote the activation of p38MAPK in the spinal cord and is involved in the development of persistent postoperative pain in rats.
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Objective To investigate the change of spinal G protein-coupled receptor kinase 2 (GRK2) expression in persistent postoperative pain evoked by skin/muscle incision and retraction (SMIR) in rats.Methods 40 male Sprague Dawley (SD) rats were divided into 2 groups (n =20) using a random number table:sham operation group and skin/muscle incision and retraction group (SMIR group).A rat model of peristent postoperativepain evoked by SMIR was made according to the method described by Flatters.Pain behavior was assessed by paw mechanical withdrawal threshold (MWT) to yon Frey filament stimulationintensity at 1 d before operation (T0) and 3 d (T1),7 d (T2),14 d (T3) and 21 d (T4) after operation.4 rats in each group were sacrificed at T0-4,the L4-L6 segments of the spinal cord were obtained for determination of GRK2 expression in the spinal cord by Western blot.Results Compared with T0,the MWT was significantly decreased and the expression of spinal GRK2 was down-regulated at T1-T4 in SMIR group (P ＜ 0.05).Compared with sham operation group,the MWT and the expression of spinal GRK2 was decreased at T1-T4 in SMIR group (P ＜ 0.05).Conclusions The down-regulation of expression of spinal GRK2 may be involved in the development and maintenance of persistent postoperative pain in rats evoked by SMIR.
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Objective To evaluate the role of p38 mitogen-activated protein kinase (p38MAPK) in the spinal cord in the development of persistent postoperative pain evoked by skin/muscle incision and retraction (SMIR) and the relationship with Toll-like receptor 4 (TLR4).Methods One hundred and twenty male SpragueDawley rats,weighing 200-250 g,aged 2 months,in which intrathecal catheters were successfully implanted,were randomly divided into 5 groups (n =24 each) using a random number table:sham operation group (group S),SMIR group,SMIR + dimethyl sulfoxide (DMSO) group (group DMSO),SMIR + p38MAPK inhibitor SB203580 group (group SB203580) and SMIR + TLR4 small interference RNA (siRNA) group (group TLR4siRNA).The rats were anesthetized with intraperitoneal chloral hydrate 400 mg/kg.The skin and superficial muscle of the medial thigh were incised and a small pair of retractors inserted.This tissue was retracted for 1 h causing potential stretch of the saphenous nerve.2％ DMSO 10 μl and SB203580 5 μg were injected intrathecally at 30 min before operation and 1-12 days after operation in DMSO and SB203580 groups,respectively.TLR4siRNA 2 μg was administered intrathecally at 1 day before operation and 1-12 days after operation once a day in group TLR4siRNA.Mechanical paw withdrawal threshold to von Frey filament stimulation (MWT) was measured at 1 day before operation and 1,3,7,12 and 22 days after operation.Four rats in each group were sacrificed after measurement of MWT at each time point,and the L4-6 segments of the spinal cord were obtained for detection of the expression of phosphorylated p38MAPK (p-p38MAPK) by Western blot analysis.Results Compared with group S,MWT was significantly decreased after operation,and the expression of p-p38MAPK was up-regulated after operation in SMIR and DMSO groups.Compared with group SMIR,MWT was significantly increased after operation,and the expression of p-p38MAPK was down-regulated after operation in SB203580 and TLR4siRNA groups,and no significant changes in MWT and p-p38MAPK expression were found at each time point in group DMSO.Conclusion TLR4-triggered activation of p38MAPK in spinal cord is involved in the development of SMIR-evoked persistent postoperative pain in rats.
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Objective To investigate the role of Toll-like receptor4 (TLR4) activation in spinal cord in a rat model of persistent postoperative pain evoked by skin/muscle incision and retraction(SMIR).Methods Ninetysix male SD rats weighing 200-250 g were randomly divided into 4 groups(n =24 each):group sham operation; group SMIR; group SMIR + IT scramble siRNA and group SMIR + IT TLR4siRNA.The rat model of persistent postoperative pain evoked by SMIR was established according to the method described by Flatters.The TLR4 siRNA were administered intrathecally for 7 days starting from 1 day beforc surgcry.Pain behavior was assessed by paw mechanical withdraw threshold (MWT) to Electronic von Frey Anesthesiometer stimulation at 1 day before and 1,3,7,12,and 22 days after operation.Four animals were sacrificed at each time point in each group for detection of the expression of TLR4 protein in the spinal cord by Western blot analysis.Results Compared to group sham group,MWT was significantly descreased at 3,7,12,and 22 days after operation,while the expression of TLR4 protein in the spinal cord were significantly increased at 3,7,12 days after operation in group SMIR and group SMIR + IT scramble siRNA ; IT TLR4siRNA significantly attenuated the hyperalgesia induced by SMIR and descreased the expression of TLR4 protein at 3,7,12 days after operation in group SMIR + IT TLR4siRNA.Conclusion TLR4 activation in spinal cord plays an important role in the development of SMIR-evoked persistent postoperative pain in rats.
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Objective To investigate the effect of angiotensin converting enzyme (ACE) genetic polymorphism on the cardiovascular response to endotracheal intubation in patients with hypertension.Methods The patients with primary hypertension,ASA Ⅱ or Ⅲ,aged 54-64 yr,weighing 50-70 kg,scheduled for elective operation under general anesthesia,were enrolled in this study.Polymerase chain reaction-restriction fragment length polymorphism was used to detect the polymorphism of ACE gene.The patients were assigned into 3 groups according to their genotypes:homozygote DD group (group DD),heterozygote ID group (group ID),and homozygote Ⅱ group (group Ⅱ).Systolic blood pressure (SBP),diastolic blood pressure (DBP) and heart rate (HR) were recorded before and after induction of anesthesia,and at 0,1.5 and 5.0 min after intubation (T0-4).The rate-pressure product (RPP) was calculated.The cardiovascular events were recorded.Results In groups DD,ID and Ⅱ,40,39 and 40 cases were included in the analysis respectively.Compared with group ID,there was no significant difference in SBP,DBP,HR and RPP at T0-4 in group DD (P ＞ 0.05).Compared with groups DD and ID,SBP,DBP,HR and RPP were significantly deceased at T2,3,and SBP,HR and RPP were significantly deceased at T4 in group Ⅱ (P ＜ 0.05).The incidences of the myocardial ischemia during intubation and cardiovascular response to intubation were significantly lower in group C than in groups DD and ID (P ＜ 0.05).Conclusion ACE genetic polymorphism exerts an effect on the cardiovascular response to endotracheal intubation in patients with hypertension,and homozygote DD and heterozygote ID have the most influence.
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ObjectiveTo investigate the role of phosphatidylinositol 3-kinase/protein-serine-threonine kinases (PI3K-Akt) signal pathway in the protection of myocardium against ischemia-reperfusion (I/R) injury by diasoxide postconditioning in rats.MethodsThirty-six male SD rats weighing 250-300 g were randomly divided into 4 groups using random number table (n =9 each):group I/R; group diazoxide (group D); group wortmannin (PI3K inhibitor) (group W) and group wortmannin + diazoxide (group WD).The animals were anesthetized with intraperitoneal 10％ chloral hydrate 4 ml/kg,intubated and mechanically ventilated.Myocardial I/R was produced by 30 min occlusion of left anterior descending coronary artery followed by 120 min reperfusion.0.1％ dimethyl sulfoxide (the vehicle for diazoxide and wortmannin)/diazoxide at 0.47 mg· kg-1 · min-1/wortmannin at 1 μg·kg-1 ·min-1 was infused for 15 min starting from 25 min of ischemia in groups I/R,D and W respectively.In group DW wortmannin was infused at 5 min before diazoxide infusion.Blood samples were collected from left ventricle at the end of 120 min reperfusion for measurement of lactate dehydrogenase (LDH) activity.Myocardial infarct size was measured.Myocardial specimens were obtained for determination of apoptosis index (the number of apoptotic cells/the total number of cells examined) and expression of Bcl-2 and Bax.Bcl-2/Bax ratio was calculated.ResultsDiazoxide postconditioning significantly decreased plasma LDH activity,myocardial infarct size,apoptosis index and Bax expression in myocardium and increased myocardial Bcl-2 expression and Bcl-2/Bax ratio in group D compared with group I/R.Wortmannin partly counteracted the protective effects of diazoxide postconditioning against myocardial infarct.There was no significant difference in the above variables between groups I/R and W.ConclusionPI3K-Akt signal pathway is involved in the protective effects of diazoxide postconditioning on myocardium against I/R injury.
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ObjectiveTo investigate the role of NF-κB signaling pathway in the spinal cord in persistent postoperative pain evoked by skin/muscle incision and retraction (SMIR) in rats.MethodsNinety male SD rats weighing 200-250 g in which intrathecal (IT) catheter was successfully implanted without complication were randomly divided into 3 groups ( n =30 each):group sham operation ( group S ) ; groups SMIR and group pyrrolidine dithiocarbarnate (a NF-κB inhibitor) (group PDTC).Persistent postoperative pain was evoked by SMIR according to the method described by Flatters in groups SMIR and PDTC.PDTC 10 ng in 10 μl was injected IT over 30 s once a day for 7 consecutive days after operation in group PDTC.Mechanical paw withdrawal threshold to von Frey filament stimulation (MWT) was measured at 1 d before (T0,baseline) and 1,3,7,12 and 22 d after surgery (T1-5).Five animals in each group were sacrificed at each time point after MWT measurement and their lumbar segments of the spinal cord were removed for determination of TNF-α content (by ELISA).ResultsSMIR significantly decreased MWT after operation at T1-5 and increased TNF-α content in the spinal cord at T3-5.PDTC significantly attenuated SMIR-induced hyperalgesia and increase in TNF-α content in the spinal cord.Conclusion NF-κB signaling pathway in the spinal cord plays an important role in the development of SMIR-induced persistent postoperafive pain in rats.
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Objective To investigate the role of gamma-aminobutyric acid transporter-1 (GAT-1) in the spinal cord in a rat model of bone cancer pain.Methods Eighty female SD rats weighing 150-180 g were randomly divided into 5 groups (n =16 each): sham operation group(group Ⅰ ),bone cancer pain group(group Ⅲ ),sham operation+ NO-711 group(group Ⅲ ),Ⅳ group BCP + NO-711 group(group Ⅳ ) and BCP + vehicle group (group Ⅴ ).Bone cancer pain was induced by inoculating Walker-256 mammary gland carcinoma cells into medullary cavity of tibia.NO-711 (20 μg,10 μl) was administered intrathecally once a day for 3 consecutive days from the 14th day after operation.Mechanical withdrawl threshold (MWT) of mechanical stimulus was determined the day before operation and at days 3,5,7,10,14 and 16 after operation.The animals were sacrificed on the 16th day after operation,and then the spinal cords were removed for determination of the expression of GAT-1 and double immunostaining of GAT-1 and glial fibrillary acidic protein (GFAP,astrocyte marker).Results MWT were significantly decreased in groups Ⅱ,Ⅳ and Ⅴ as compared with groups.Ⅰ and Ⅲ.The expression of GAT-1 significantly up-regulated in groups Ⅱ,Ⅴ as compared with groups Ⅰ and Ⅲ.NO-711 significantly increased MWT,while decreased the expression of GAT-1 in group Ⅳ compared with groups Ⅱ and Ⅴ.The expression of GAT-1 up-regulation appeared colocalizes with in astrocytes activation in spinal dorsal horn.Conclusion The up-regulation of expression of GAT-1 in spinal cord is involued in the development and maintenance of bone cancer pain,which may be related to the astrocytes activation.
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Objective To investigate the role of microglial activation in spinal cord in a rat model of persistent postoperative pain evoked by skin/muscle incision and retraction (SMIR) .Methods Seventy-two male SD rats weighing 200-250 g in which intrathecal (IT) catheter was successfully inserted were randomly divided into 3 groups ( n = 24 each) : group sham operation; group SMIR and group SMIR + FT minocycline (a specific microglia inhibitor) . The rat model of persistent postoperative pain evoked by SMIR was established according to the method described by Flatters. Pain behavior was assessed by paw mechanical withdrawal threshold ( MWT) to von Frey filament stimulation at 1 day before (T0,baseline) and 3, 7, 12, 22 and 32 days after operation (T1-5,) . Four animals were sacrificed at each time point in each group for detection of the expression of Iba-1 (a specific marker of microglia) in the spinal dorsal horn by immunofluorescence and the microglia was counted. Results MWT was significantly decreasedat T1-4, while the expression of Iba-1 and microglia counts in the spinal dorsal horn were significantly increased at T1, 2 by SMIR in group Ⅱ. IT minocycline significantly attenuated the hyperalgesia induced by SMIR at T1-4 and decreased Iba-1 expression and microglia counts at T1,2 in group Ⅲ. Conclusion Microglial activation in the spinal cord plays an important role in the development and maintenance of SMIR-evoked persistent postoperative pain in rats.
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Objective To investigate the glial activation in the spinal cord in a rat model of persistent postoperative pain. Methods Forty-eight adult male SD rats weighing 200-250 g were randomly divided into 2 groups ( n = 24 each): group Ⅰ sham operation (group S) and group Ⅱ persistent postoperative pain. Persistent postoperative pain was evoked by skin/muscle incision and retraction (SMIR) as described by Flatters. Pawwithdrawal threshold to yon Frey hair stimulation was measured before operation (baseline) and at 1, 3, 12, 22and 32 d after establishment of the model. Four animals were sacrificed at each time point and lumbar segment of the spinal cord was removed for determination of expression of glial fibrillary acidic protein (GFAP) in the astrocytes by immunofluorescence histo-chemistry assay. Results The mechanical threshold started to decrease at 1 d after establishment of the model, and peaked at 12 d after establishment of the mode. Immunofluorescence histochemistry assay demonstrated that GFAP expression in the dorsal horn was significantly increased at 3 d after estabhshment of the model and reached the peak at 12 d and was maintained at the high level until 22 d after establishment of the model. Conclusion Glial activation is involved in the mechanism of persistent postoperative pain evoked by SMIR.
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Objective To explore the effects of 7.5% hypertonic saline (HS) and pentoxifylline (PTX) on the pulmonary inflammation in rats with hemorrhagic shock. Method Controlled hemorrhagic shock in rats was induced to 40 mmHg MAP by blood withdrawal and maintained for 60 min. Animals were randomly (random number) divided into 3 groups. In sham shock group ( n = 8), rats underwent cannulation without exsanquination or resuscitation and served as negative controls. In RL-resuscitated animals group ( n = 8), rats received 32 mL/kg RL (Ringers'lactate solution). In HSPTX group, rats received 4 mL/kg of 7.5% NaCl + 25 mg/kg of PTX.PaO2,pH,PaCO2, lung wet/dry weight ratio (W/D) and lung penetrating index were determined, and the percentages of neutrophil in bronchoalveolar lavage fluid (BALF) were detected. The levels of malondialdehyde (MDA) and superoxide dismutase(SOD)were measured. The tumor necrosis factor-α(TNF-α) and interleukin 1β(IL-1β) in BALF supernatant were determined by using ELISA method. Results Compared with RL group, PaO2 and pH of arterial blood more increased and PaCO2 of arterial blood more decreased in HSPTX group ( P ＜ 0. 01).The wet/dry lung weight ratio and the percertages of neutrophil in BALF were reduced in HSPTX group. The level of tumor necrosis factor-αand interleukin 1β in HSPTX group were both more significantly decreased than those in RL group ( P ＜0.01). Conclusions Compared with RL group, the more attenuation of pulmonary inflammation in HSPTX group after shock is associated with less neutrophil activation and decrease in production of the irlammatory cytokines.
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Objective To investigate the effect of intrathecal γ-aminobutyric acid transporter-1 ( GAT-1 )small interfering RNA (siRNA) on neuropathic pain in rats. Methods Male SD rats weighing 200-250 g were studied. The experiment was performed in 3 parts. Part Ⅰ Twenty rats were randomly divided into 5 groups ( n =4 each): GAT-1 siRNA-1 group, GAT-1 siRNA-2 group, GAT-1 siRNA-3 group, negative control siRNA group and DEPC treatment group. Two days after ligation of sciatic nerve, intrathecal siRNA 2 μg or equal volume of DF-PC was injected once a day for 3 consecutive days. The rats were killed and the lumbar segment of the spinal cord was removed at 2nd day after the last intrathecal injection for determination of the expression of GAT-1 in the spinal dorsal horn by Western Blot. Part Ⅱ Thirty rats were randomly divided into 3 groups ( n = 10 each): GAT-1 siRNA-3 + lipo2000 group, GAT-1 siRNA-3 mismatch siRNA + lipo2000 group, and DEPC treatment + lipo2000group. Paw-withdrawl threshold (PWT) to thermal and mechanical stimulation was measured before ligation of sciatic nerve, 3 days after ligation of sciatic nerve and at 1, 3, 5, 7 and 10 days after consecutive administration for 3 days. Part Ⅲ Eighty-four rats were randomly divided into 3 groups as described in Part Ⅱ ( n = 28 each). Four rats were killed at each time point and the lumbar segment of the spinal cord was removed for determination of the expression of GAT-1 in the spinal dorsal horn by Western blot. Results PWT to thermal and mechanical stimulation was significantly inreased and the GAT-1 expression was down-regulated after the injection of GAT-1 siRNA.Conclusion Intrathecal GAT-1 siRNA can reduce the neuropathic pain by inhibiton of up-regulation of the GAT-1 expression in the spinal dorsal horn in rats.
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Objective To investigate the effects of intrathecal (IT) gabapentin on the analgesic efficacy of morphine in a rat model of incisional pain. Methods Forty-eight male SD rats in which IT catheters were successly inserted according to the method described by Yaksh were randomly divided into 6 groups ( n = 8 each): Ⅰ sham operation group, Ⅱ incisional pain group, Ⅲ GBP 50 μg group, Ⅳ morphine 2.5 μg group, Ⅴ morphine 5 μg group, and Ⅵ morphine 2.5 μg + gabapentin 50 μg group. In group Ⅰ , IT artificial cerebrospinal fluid (ACSF)10 μl was injected and then 1.4% isoflurane was inhaled for 5 min. IT ACSF 10 μl, gabapentin 50μg and morphine 2.5 and 5 μg were injected 30 min before the establishement of the model in group Ⅱ -Ⅴ respectively. Paw withdrawl threshold (PWT) to mechanical stimulation and paw withdrawal latency (PWL) to a thermal nociceptive stimulus were measured at 2 h after the establishement of the model. Results Compared with group Ⅰ , MWT was significantly decreased and TWL was significantly shortened in group Ⅱ , Ⅲ and Ⅳ ( P ＜ 0.05), but no significant change in MWT and TWL was found in group Ⅴ and Ⅵ (P＞0.05). Compared with group Ⅱ , MWT was significantly increased and TWL was significantly prolonged in group Ⅴ and Ⅵ (P ＜ 0.05), but no significant change in MWT and TWL was found in group Ⅲ and Ⅳ/ ( P ＞ 0.05). MWT was significantly decreased and TWL was significantly shortened in group Ⅲ and Ⅳ compared with group Ⅵ ( P ＜ 0.05). Conclusion IT gabapentin enhances the analgesic efficacy of morphine in a rat model of incisional pain.
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BACKGROUND: Mild hypothermia (28-35 ℃) is becoming one of the promising methods in treating acute ischemic stroke. Hypothermia can effectively lessen brain edema, which is one of its neuroprotective roles.OBJECTIVE: To investigate the effect of mild hypothermia on brain water content and aquaporin-4 (AQP4) expression level following global cerebral ischemia-reperfusion injury in rats, so as to study the neuroprotective mechanisms of mild hypothermia.DESIGN: A randomized controlled trial.SETTING: Neurobiological Laboratory of Xuzhou Medical College.MATERIALS: 110 healthy male SD rats with body mass 250-300 g, provided by the Animal Center of Xuzhou Medical College, No. SYNK (Jiangsu) 2002-0079, were selected and randomly divided into 3 groups by SPSS 11.0software: ①sham-operated group (n=10);②normothermiagroup (n=50); ③mild hypothermia group (33 ℃, n=50). Normothermia group and mild hypothermia group were subdivided into five reperfusion subgroups for 6 hours, 1, 2, 3 and 7 days, respectively with 10 rats in each subgroup,in which 5 rats were used for measurement of brain water content, and others for HE staining and immunohistochemistry staining.METHODS: The models of global cerebral ischemia were established in the normothermia group and mild hypothermia group by four-vessel occlusion (4-VO) method with ischemia for 15 minutes as Pulsinelli described.The rats in the sham-operated group were only underwent the electrocauterization of bilateral vertebral arteries and the isolation of common carotid arteries except for occlusion of common carotid arteries. Twenty-four hours later, the rats were decapitated to take out the brains. The brains of rats in the normothermia group and mild hypothermia group were taken out to make sections for HE staining and immunohistochemistry staining, and the dynamic change of pathology of the brain tissue and AQP4 expression level were observed after reperfusion for 6 hours, 1, 2, 3 and 7 days, respectively. The brain wet-to-dry weight measurement was used to measure the brain water content of the rats at each time point of each group.MAIN OUTCOME MEASURES: ①The pathologic changes of brain tissues of rats in the normothermia group and mild hypothermia group. ②The brain water content and the AQP4 expression level of all rats at each time point.RESULTS: ①After 6 hours of reperfusion, brain edema appeared in the normothermia group including amplification of periyascular spaces and intercellular spaces, rarefaction of brain tissues, etc, which got worst after 2 days of reperfusion; the phenomenon of brain edema of the rats in the mild hypothermia group at each time point was relatively lighter than the normothermia group. ②Brain water content of the normothermia group and mild hypothermia group was increased after 6 hours of reperfusion and reached peak at the 2nd day; Although decreased at the 7th day, it was still higher than the sham-operated group. The brain water content of the mild hypothermia group at each time point was less than the normothermia group (values after 6 hour and 7 day, P ＜ 0.01, the rest groups P ＜ 0.05).③AQP4 expression level of the normothermia group and mild hypothermia group was increased after 6 hours of reperfusion and reached peak at the 2nd day. Although decreased at the 7th day, it was still higher than the sham-operated group.The AQP4 expression level of the mild hypothermia group at each time point was lower than the normothermia group (P ＜ 0.01).CONCLUSION:The change tendency of AQP4 level is parallel to that of brain water content after ischemia reperfusion, which indicates that the upregulation of AQP4 expression is one of molecular mechanisms for the for mation of ischemicbrain edema. Mild hypothermia can release ischemic brain edema by inhibiting AQP4 expression, which is one of its mechanisms.
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BACKGROUND: It is indistinct that whether ketamine can exert antinociceptive effect througb influencing the transmission of nocuous information in spinal cord; Nitric oxide (NO) in spinal cord participates mainly in the formation and development of hyperalgesia, and it can also induce Fos protein expression. It is still controversal whether it contributes to the transmission and mediation of ketamine to pain signal.OBJECTIVE: To observe the response to formalin stimulation in spinal cord of the rats and the effect of ketamine.DESIGN: Balanced randomized animal trial.SETTING: Department of Anesthesiology, Affiliated Hospital of Xuzhou Medical College; Jiangsu Provincial Key Laboratory of Anesthesiology.MATERIALS: This trial was carried out in the Jiangsu Provincial Key Laboratory of Anesthesiology, Xuzhou Medical College from January to March 2000. Totally 30 Sprague-Dawley rats were chosen and balanced randomized into 6 groups: formalin group (n=6), formalin + ketamine group (n=6), ketamine +formalin group (n=6), ketamine group (n=6), formalin+normal saline group (n=3) and normal saline group (n=3). The gender ratio was the same in each group.METHODS: Formalin group:The rats were stimulated for one hour by subcutaneous injection of 0.05 volume fraction of 200 μL in the center of palm of unilateral fore-claw. Formalin +ketamine group: The rats were stimulated for 10 minutes by formalin, then for one hour by intraperitoneal injection of 100 rg/kg ketamine. Ketamine + formalin group: The rats were injected with ketamine for 10 minutes, then with formalin for one hour. Ketamine group: the same dosage of ketamine was intraperitoneally injected into the rats for one hour. Formalin + normal saline group: The rats were stimulated for 10 minutes by formalin, then intraperitoneally given 10 mL/kg normal saline for one hour. Normal saline group: the same volume of normal saline was intraperitoneally injected into the rats for one hour.MAIN OUTCOME MEASURES: ① Behavioral performance of the rats in each group. ② Spinal sections were chosen, and stained with c-fos genetic immunohistochemical and NADPH-d histochemical methods. The changes of the number of Fos-like immuno-positive neurons (FLI) and FLI/nitric oxide synthase (NOS) double-labeled neurons in the 4-layer sections (layer Ⅰ -Ⅱ ,layer Ⅲ-Ⅳ ,layerⅤ-Ⅵ ,layer Ⅶ-X )of spinal dorsal horn of the rats were observed.RESULTS: All the thirty rats entered the stage of result analysis. ① Behavioral changes: The rats of formalin group and formalin+ normal salinegroup had apparent pain response; Several minutes after injection with ketamine, righting reflex disappeared and did not recover at perfusion period.Prolonged sleep was found without obvious pain response performance. ② FLI neuron expression: A lot of FLI positive neurons were found in the spinal dorsal horn of injec tion side of the rats in the formalin group and formalin+ normal saline group, and they distributed principally in the layer Ⅰ - Ⅱ of spinal dorsal horn.The distribution in the ketamine + formalin group and formalin + ketamine group was basically similar to that in the formalin group and formalin + normal saline group, but positive neuron counts were significantly reduced (P ＜ 0.01). ③ The expression of FLI/NOS double-labeled neurons: The number of double-labeled neurons in the spinal dorsal horn layer Ⅰ - Ⅱ of the rats in the ketamine+ formalin group and formalin+ ketamine group were significantly less than that in the formalin group and formalin+normal saline group [(1±1), (1±1), (7±3), (8±3),P ＜ 0.01].CONCLUSION: Some neurons of ipsilateral corresponding spinal segments participate in the transmission and mediation of pain signal. Ketamine can suppress the activities of these neurons and exert antinociceptive effect. The antinococeptive function of ketamine may be caused by the activity depression of the NOS-positive neurons in spinal cord.
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To investigate the effect of propofol on the release of glutamate and γ-aminobutyric acid (GABA) from rat hippocampal synatosomes, synaptosomes was made from hippocampus and incubated with artificial cerebrospinal fluid (aCSF). With the experiment of Ca2+-dependent release of glutamate and GABA, dihydrokainic acid (DHK) and nipectic acid were added into aCSF. For the observation of Ca2+-independent release of glutamate and GABA, no DHK, nipectic acid and Ca2+were added from aCSF. The release of glutamate and GABA were evoked by 20μmol/L veratridine or 30 mmol/L KCl. The concentration of glutamate and GABA in aCSF was measured by using high-performance liquid chromatography (HPLC). 30, 100 and 300 μmol/L propofol significantly inhibited veratridine-evoked Ca2+-dependent release of glutamate and GABA (P＜0.01 or P＜0.05). However, propofol showed no effect on elevated KCl-evoked Ca2+-dependent release of glutamate and GABA (P＞0.05). Veratridine or elevated KCl evoked Ca2+ -independent release of glutamate and GABA was not affected significantly by propofol (P＞0.05). Propofol could inhibit Ca2+-dependent release of glutamate and GABA. However, it has no effect on the Ca2+-independent release ofglutamate and GABA.
ABSTRACT
To investigate the effect of propofol on the release of glutamate and gamma-aminobutyric acid (GABA) from rat hippocampal synatosomes, synaptosomes was made from hippocampus and incubated with artificial cerebrospinal fluid (aCSF). With the experiment of Ca(2+)-dependent release of glutamate and GABA, dihydrokainic acid (DHK) and nipectic acid were added into aCSF. For the observation of Ca(2+)-independent release of glutamate and GABA, no DHK, nipectic acid and Ca2+ were added from aCSF. The release of glutamate and GABA were evoked by 20 micromol/L veratridine or 30 mmol/L KCI. The concentration of glutamate and GABA in aCSF was measured by using high-performance liquid chromatography (HPLC). 30, 100 and 300 micromol/L propofol significantly inhibited veratridine-evoked Ca(2+)-dependent release of glutamate and GABA (P 0.05). Veratridine or elevated KCI evoked Ca(2+)-independent release of glutamate and GABA was not affected significantly by propofol (P > 0.05). Propofol could inhibit Ca(2+)-dependent release of glutamate and GABA. However, it has no effect on the Ca(2+)-independent release of glutamate and GABA.
Subject(s)
Anesthetics, Intravenous/pharmacology , Calcium/metabolism , Glutamic Acid/biosynthesis , Hippocampus/metabolism , Propofol/pharmacology , Rats, Sprague-Dawley , Synaptosomes/metabolism , gamma-Aminobutyric Acid/biosynthesisABSTRACT
BACKGROUND: The extracellular signal-related kinase(ERK) cascade is activated by its specific upstream kinase MAPK/ERK kinase(MEK) and identified as a critical regulator of cell growth, memory formation and long-term neuronal plasticity.OBJECTIVE: To investigate the role of ERK activation in establishment and maintenance of chronic neuropathic pain.DESIGN: A randomized controlled experiment based on the animals.SETTING: Department of Anesthesiology of a university-affiliated hospital.MATERIALS: The experiment was performed in the Medical Institute of Anesthesiology of Jiangsu Province from September 2003 to June 2004. Totally 115 male clean SD rats weighting 220 to 300 g were provided by the Experimental Animal Center of Xuzhou Medical Colleg e. The rats were raised in separate cages with natural lighting at 20 to 25 ℃, having free access to food and water.INTERVENTIONS: Five days after chronic constrictive injury(CCI) model was established, different doses of U0126 were intrathecally injected according to Mestre' s method. The control group received sterile intrathecal injection of 50 g/L dimethylsulfoxide.hyperalgesia by using von Frey filaments and thermal hyperalgesia stimulator activation and translocation of ERK in spinal cord dorsal horn by immunohistochemistry and Western blot analysis.RESULTS: CCI could increase the activity of EPK in spinal cord dorsal horn. Intrathecal injection of U0126 significantly attenuated CCI-induced mechanical and thermal hyperalgesia.CONCLUSION: Activation and translocation of ERK contribute to formation and maintenance of CCI-induced neuropathic pain.
ABSTRACT
BACKGROUND: Pyramidal cells in hippocampal CA1 region are neurons most susceptible to ischemia-hypoxia damage. Their membrane potential is shown as hyperpolarization of cell membrane during early hypoxia. With the progress of hypoxia time, cell membrane has slow and rapid hyperpolarization, which causes irreversible damage to neurons.OBJECTIVE: To investigate the effects of the blocker of N-methyl-D-aspartate receptor MK801 on the electrophysiological changes of CA1 neurons during hypoxia in isolated hippocampal slices of rats with intracellular recording technique.DESIGN: Observational and controlled study.SETTING: The 97th Hospital of the Chinese PLA, Provincial Key Anesthesiology Laboratory of Xuzhou Medical College; Center of Health Science, State University of New York.MATERIALS: The experiment was conducted from September 2002 to March 2003 in the State University of New York. Five adult male SD rats were anesthetized with 0.02 volume of isoflurane after 3 minutes' pre-oxygenation with oxygen.METHODS: The hippocampal slices from the rats were randomly divided into simple anoxia group (n=10) and MK801 group (n=10). The slices in simple anoxia group were only subjected to 10-minute hypoxia with the artificial cerebrospinal fluid (ACSF), and the slices in MK801 group were treated with 100 μmol/L MK801 for 10 minutes before and during 10 minutes of hypoxia. The neuronal membrane potential before hypoxia, the rate of slow depolarization, the amplitude of and time to rapid depolarization were recorded with intracellular recording technique described in the literature. Meanwhile, the neuronal response to the intracellular current injection and Schaffer collateral stimulation were observed respectively at the end of 60 minutes' re-oxygenation.gion of hippocampal slices: It was significantly higher in simple anoxia group than in MK801 group [(0.20±0.05) mV/s, (0.08±0.03) mV/s, P ＜ 0.05].hippocampal slices: It was significantly higher in MK801 group than in of rapid depolarization of pyramidal cells in CA1 region of hippocampal slices: It was significantly lower in MK801 group than in simple anoxia sponse to stimuli was recovered in 9 out of 10 neurons.CONCLUSION: MK801 blocker of N-methyl-D-aspartate receptor can decrease the rate of slow depolarization of neurons induced by hypoxia, postpone the onset of rapid depolarization of neurons, and decrease the amplitude of rapid depolarization of neurons. This suggests that the blocker of N-methyl-D-aspartate receptor can relieve the hypoxic damage to neurons and promote the functional recovery of neurons.