0 05) Conclusions Propofol combined with sevoflurane additively potentiates GABA gated chloride current in rat dorsal root ganglia

The whole-cell patch clamp technique and "Y-tube" method were applied to evaluate the effects of sevoflurane (from 0. 3×10-3to 3×10-3 mol/L) on chloride current induced by bath utilization of 3×10-6 mol/L γ-aminobutyric acid (GABA) in the single-cultured rat dorsal root ganglia neurons. Experimental data demonstrated that when peak amplitude of chloride current induced by 3 × 10-6 mol/L GABA was considered as 100 % in the presence of 0. 38×10-3, 0. 76×10-3, 2. 28×10-3, 3. 04×10 -3 mol/L sevoflurane peak amplitude of chloride current was rose to (149±25) %, (203±-27) %, (327±79) %, (331±109) %, (243±71) % correspondingly. This finding suggests that sevoflurane, at concentrations relevant clinical anesthesia, can enhance GABA-mediated chloride current in sensory neurons.

Objective To determine the change in PSD95 mRNA expression in spinal dorsal horn in a rat model of neuropathic pain. Methods Twelve female SD rats weighing 150-200 g were randomized into 2 groups (n = 6 each) : control group in which left sciatic nerve and its branches were exposed but not cut; SNI group in which the branches of the left sciatic nerve-tibial and common fibular nerves were ligated and cut. Pain threshold was measured by foot-lift response to mechanical stimulation of ipsilateral hindpaw with 12 g and 2 g produced by plantar touch stimulator (Ugo Basile Co. Italy) representing hyperalgesia and allodynia respectively, 3 days before, immediately after and on the 1st, 3rd, 5th, 7th, 9th and 11th day after operation. On the 11th day the animals were killed after measurement of pain threshold and L4-6 segment of the spinal cord was removed for determination of expression of NR2B and nNOS by immuno-histochemistry and expression of PSD95 mRNA by RT-PCR.Results Starting from the 5th day after operation all rats in SNI group developed a relative mechanical allodynia. The expression of NR2B and nNOS was mainly distributed in Ⅰ or Ⅱ laminae of dorsal horn. The expression of NR2B and nNOS was significantly higher in SNI group than in control group. The expression of PSD95 mRNA in SNI group was significantly decreased when compared to control group (P

Objective To investigate the effect of PKC? antisense oligonucleotides injected intrathecally on the hyperalgesia and expression of PKC? protein in rats with chronic morphine tolerance. Methods Twenty-four female SD rats weighing 150-180 g were randomly divided into 4 groups ( n = 6 each): group Ⅰ control; group Ⅱ morphine (M); group Ⅲ sense oligonucleotides (S) and group Ⅳ antisense oligonucleotide (A) . An intrathecal catheter was placed in the lumbar subarachnoid space to allow for bolus injections. Chronic morphine tolerance was induced by intrathecal morphine 20 ?g twice a day (at 8:00 and 16:00) for 5 consecutive days. Intrathecal morphine (20 ?g twice a day) was continued in group M, S, and A and normal saline 20 ?l (in group M) or sense oligonucleotide 20 ?g (in group S) or antisense oligonucleotide 20 ?g (in group A) was given intrathecally between the two morphine doses (at 12: 00) for 6 consecutive days. Pain threshold was assessed by measuring the withdrawal response of the hindpaw to radiant heat with a thermal plantar testing apparatus 2 days before intrathecal catheter was placed and on the 2nd, 4th and 6th day after morphine tolerance was induced. The animals were killed on the 6th day of intrathecal NS/oligonucleotide administration after pain threshold was measured. The L2-6 segment of spinal cord was removed for determination of the expression of PKC? mRNA (RT-PCR) and PKC? protein (Western blot) .Results The establishment of morphine tolerance was confirmed by significant shortening of response latency to radiant heat. The thermal withdrawal latency was significantly prolonged in group S and A after intrathecal administration of sense or antisense oligonucleotide as compared with group M but was significantly shorter in group S than in group A. The expression of PKC? protein in spinal dorsal horn was significantly decreased in group S and A as compared to group M, but was significant lower in group A than in group S. The PKC? mRNA expression was significantly lower in group A than in group M but there was no difference in PKC? mRNA expression between group S and M. Conclusion The hyperalgesia induced by chronic morphine tolerance can be reversed by intrathecal PKC? antisense oligonucleotide through reduction of PKC? protein expression in the spinal dorsal horn.

In order to evaluate the post-traumatic changes of serum levels of interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF_?) and their relationship to the occurance of multiple system organ failure (MSOF), 80 adult patients with severe multiple trauma(SMT), injury severity score(ISS) 32?14. served as the tested subjects. of which 50 cases received operations and the other did not. Thirty adult patient, scheduled for elective abdominal surgery, were randomly chosen as trauma control, and 20 healthy blood donors acted as normal control. The venous blood samples were taken on that day of injury, 3, 10 and 20 days post-traumatically, and immediately before dis charge. to measure serum concentrations of IL-6 by immunocytochemistry method and TNF_? by enzymo-immunoassay, respectively. The diagnosis of post-traumatic MSOF was made according to Baue's criteria. As compared with normal control levels, the concentrations of IL-6 and TFN_?, increased significantly in patients with SMT(P0.05). In comparison correspondingly with those of trauma control, the levels of IL-6 and TFN_? were elevated markedly (P

Objective To determine effects of propofol combined with diazepam on GABA-activated chloride currents(IGABA). Methods Whole-cell patch clamp recordings were made from cultured rat dorsal root ganglionic neurons dissociated by collagenase and trypsin, and trituration. 3 ?mol/L GABA was administered by pressure ejection, meanwhile, propofol and diazepam were dissolved in the external solution and were given with the "Y tube" technique. Results Co-application of propofol(0.3, 1.0, 3.0?mol/L) and diazepam (100 nmol/L) potentiated the IGABA ,which was significantly larger than the sum of that potentiated by either drug alone. Diazepam (100 nmol/L ) shifted the concentration-response curve of the propofol-potentiated IGABA to the left in parallel fasion, the EC50 value of propofol was decreased by diazepam from (7.6 ?1.8) ?mol/L to (3.9?1.1 )?mol/L.Conclusions Propofol combined with diazepam synergistically potentiates GABA-gated chloride currents in rat sensory neurons.

Objective To investigate the changes in the expression of protein kinase C?and C?(PKC?, PKC?) in the dorsal horn of spinal cord in a rat with neuropathic pain. Methods Twenty-four healthy SD rats weighing 150-250 g were randomly divided into 3 groups (n = 8 each): groupⅠsham operation; groupⅡchronic constructive injury (CCI) and groupⅢspinal nerve ligation (SNL) . CCI was produced by placing 4 loose ligatures on the sciatic nerve at 1 mm intervals with 4-0 catgut and SNL by ligation and transaction of L5 spinal nerve. The threshold to von Frey hair stimulation and radiant heat were measured before operation (baseline) and on the 2nd, 4th and 7th day after operation. The animals were killed after measurement of pain threshold. The lumbar segment (L4-6) of the spinal cord was removed for determination of the expression of PKC?, PKC?and Fos protein by immuno-histochemistry. Results The mechanical and thermal withdrawal latencies were significantly decreased on the 4th and 7th day after operation as compared to the baselines values before operation in CCI and SNL groups. But there was no significant difference in the withdrawal latencies to mechanical and thermal stimuli between CCI and SNL groups. The expression of PKC?, PKC?and Fos protein was significantly higher in CCI and SNL groups than in sham operation group. The expression of PKC?and Fos protein was not significantly different between CCI and SNL groups, while PKC?expression was significantly higher in group SNL than in group CCI.Conclusion The increase in the expression of PKC?and PKC?in the dorsal horn of spinal cord is involved in the mechanism of central sensitization in the neuropathic pain.

BACKGROUND: It is demonstrated that ropivacaine has less toxicity than bupivacaine, but bupivacaine has higher liposolubility and efficacy, so a less dose of bupivacaine is needed in clinical comparing with ropivacaine. Serious convulsion is usually followed by cardiotoxicity induced by local anesthetics. The ratio of medial lethal dose (CD50) and median convulsant doses (LD50) is usually used to assess the comparative safety of local anesthetics.OBJECTIVE: To establish CD50 and LD50 of 2% lidocaine, 0.75% bupivacaine and 0.75% ropivacaine for Kunming mice and select proper indicator for neurotoxicity, then to compare neurotoxicity of the three local anesthetics on central nervous system.DESIGN: Randomized and controlled study.SETTING: Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology.MATERIALS: This study was carried out from July to December in 2002 in the Laboratory of Anesthesiology, Tongji Hospital, Tonji Medical College, Huazhong University of Science and Technology. Totally 310Kunming mice aged of 1-month with clean grade were enrolled in this study.METHODS: ① To determine the relation of dose of local anesthetics with conclusion rate and death rate in mice. Todetermine the dose-effect relationship for ropivacaine, 50 mice were selected and divided into 5 groups with 10rates in each group who received dose of 76.80, 68.69, 61.44,49.15, 31.46 mg/kg respectively. For bupivacaine, 90 mice were divided into 9 groups, with 10 rates in each group who received intraperitoneal dose of 50.00, 47.29, 44.72, 42.29, 40.00, 35.78, 32.00, 28.62, 25.60 mg/kg respectively. For lidocaine, 100 mice were divided into 10 groups,with10rates in each group who received dose of 183.11, 163.77, 146.48,131.02, 117.19, 93.75, 75.00, 60.00, 48.00, 38.40 mg/kg respectively. For each local anes thetic, the rates of convulsion or death were tried to distribute on both sides of 50% symmetrically. On the dose-response curve, 4or 5 well-spaced points were obtained for probit analysis to determine CD50 and LD50 of each agent. ② The effect of different dose of lidocaine on conclusion duration and c-fos expression in brain with different doses.Forty mice were divided into 4 groups with 10 rates in each group who received 0, 30%, 60% and 90% convulsant doses of lidocaine intraperitoneally. The duration of convulsion were recorded carefully for the convulsant mice that should be marked correctly for next procedure. Two hours later, the convulsant mice were anesthetized deeply and fixed by transcardiac perfusion for Immunohistochemistry to detect c-Fos expression. ③ Comparison of neurotoxicity induced by CD50 of three agents.Thirty mice were randomly divided into 3 groups with 10 rates in each group who received intraperitoneally CD50 of lidocaine, bupivacaine and ropivacaine respectively. The duration of convulsion and the number of neurons expressed with c-Fos in mice brain were compared among these three groups.MAIN OUTCOME MEASURES: The response of mice to intraperitoneal local anesthestics, duration of convusion and c-Fos expression using immunohistochemistry methods.RESULTS: Date of totally 310 mice was entered into final results analysis. ① The relation of dose of local anesthetics and conclusion rate or death rate in mice. The therapeutic index (LD50/CD50) of 2% lidocaine,0.75% bupivacaine and 0.75% ropivacaine were 2.89, 1.48 and 1.34, respectively. ② c-Fos expression induced by lidocaine in mice brain: The cFos expression in mice brain was mainly distributed in three zones-thalamencephal, hypothalamus, amydyla and pyriform cortex. ③ Compare of the duration of convulsion and number of neurons with c-Fos expression induced by different dose oflidocaine. Compared with control group, the duration of convulsion and number of neurons with c-Fos expression in amydyla and pyriform cortex all increased significantly in CD30, CD60and CD90 group (P ＜ 0.05). ④ Neurotoxicity induced by CD50 of lidoacaine, bupivacaine and ropivacasine The duration of convulsion and expression of c-fos in amydyla and pyriform cortex were significantly increased in ropivacaine group compared to bupivacaine or lidocaine group intraperitoneally (P ＜ 0.05). There were no significant differences in the duration of convulsion and expression of c-Fos between lidocaine and bupivacaine group (P ＞ 0.05).CONCLUSION: Compared with bupivacaine, ropivacaine produced less toxicity when identical dose was used in clinic. It is indicated that if an accidental convulsion induced by ropivacaine, it may be more severe than that induced by correspondent either lidocaine or bupivacaine. It may be the reason that ropivacaine have less lipid solubility, absorbed easily from this tissue compartment, and to get a high concentration in blood.

Obiective To investigate the effect ofisoflurane on expression of IL-1β mRNA,IL-6 mRNA and TNF-α mRNA in the hippocampus of immature rats.Methods sixty-four 7-clay-old SD rats were randomly assigned into 2 groups(n=32 each):control group(group C)and isoflurane group(group S).group S was exposed to 1.5% isoflurane for 6 h while group C to air.Fore animals were killed before anesthesia(T0,baseline),at 2,4,6 h(T1-3)of isoflurane anesthesia and 4,6,12 and 24 h after anesthesia(T4-7).The hippocampi were immediately removed for determimation of the expression of IL-1β mRNA,IL-6 mRNA and TNF-α mRNA by RT-PCR.Results Compared with group C,the expression of IL-1β mRNA at T1-5,IL-6 mRNA at T2.3 and TNF-α mRNA at T1-6 in the hippocampus was upregulated in group S.Conclusion The expression of IL-1β mRNA,IL-6 mRNA and TNF-β mRNA was elevated in the hippocampus of immature rats after being exposed to isoflurane.

Objective To investigate the signaling pathways involved in the activation of neuron and glia in spinal cord in rats with neuropathic pain. Methods Twelve female SD rats (weighted 150 to 200 g) were randomized into two groups of spared nerve injury(group SNI) and control(group C). Surgery was performed to build model of SNI neuropathic pain in group SNI. Foot-lift response frequency to mechanical stimulation for ipsilateral hindpaw was assessed by 12 g and 2 g touch stimulator at different times. On the 11~(th) day after operation, 3 rats from each group were fixed by perfusion and the expressions of mitogen-activated/extracellular signal-regulated kinase (MEK), p-mitogen-activated/extracellular signal-regulated kinase (p-MEK), p-extracellular regulated protein kinase(p-ERK) and nuclear factor kappa B (NF-κB) were detected by immunohistochemistry method. And proteins from ipsilateral LA-6 spinal cord in other 3 rats from each group were extracted for Western Blot analysis. Western Blot and immunohistochemistry were performed with antibodies specific for MEK, p-MEK, pERK and NF-κB. Results All rats in group SNI developed a relative unchangeable mechanical allodynia since the 5~(th) day after operation. The results of immunohistochemistry method showed that the expression of MEK was mainly in cytoplasm, p-MEK in cell nuclear, p-ERK in astrocyte and NF-κB in neuron according to morphologic observation. Western Blot analysis indicated that the expressions of p-MEK, p-ERK and NF-κB in group SNI were increased significantly compared with those in group C(P<0. 05). Conclusion In the spinal cord of rats with neuropathic pain, MEK-ERK signaling pathway is activated in astrocytes and NF-κB in neurons, which may contribute to the development of neuropathic pain.