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.

Aim To investigate effects of calpain inhibitor calpeptin against hypoxia/glucose deprivation injury in rat hippocampal slices.Methods Forty hippocampal slices were randomly divided into two groups:Control group and calpeptin group.Calpeptin group then divided again into 1 ?mol?L-1 group,10 ?mol?L-1 group,100 ?mol?L-1 group and 200 ?mol?L-1 group according to the concentration of calpeptin in ACSF_ OGD(n=8 per group).By using electrophysiology method,changes of OPS and HIP during hypoxia/glucose deprivation process and effects of different concentration of calpeptin on it were observed.We also observed the neuronal apoptosis in hippocampal CA1 region after hypoxia/glucose deprivation and effects of different concentration of calpeptin on it.Results The HIP appearance rate and neuronal apoptosis in hippocampal CA1 region of 10 ?mol?L-1 group,100 ?mol?L-1 group and 200?mol?L-1 group significantly reduced,the OPS recovery amplitude and OPS recovery rate significantly increased,and every index among 10 ?mol?L-1 group,100 ?mol?L-1 group and 200 ?mol?L-1 group had no significant difference.Conclusion(10～200)?mol?L-1 calpeptin improved the hypoxia/glucose deprivation induced brain injury of rat hippocampal slices and the mechanism might be related to the inhibition of the neuronal apoptosis by calpeptin.

Objective Substance P and its receptor are thought to play an important role in the mechanisms of pain The purpose of this study was to investigate the effects of intrathecal (IT) morphine on substance P expression in the dorsal horn of spinal cord in a rat model of incisional pain Methods Sixteen male SD rats weighing 250 300g were randomly divided into four groups of 4 animal each: in group Ⅰ (sham operation) 30 min after IT normal saline(NS) 20 ?l 1 4% isoflurane was inhaled for 5 min but no incision was made; in group Ⅱ (control group) 30 min before incision NS 20 ?l was given IT; in group Ⅲ (postoperative analgesia group) morphine 5 ?g (10 ?l) was given IT 30 min after incision; group Ⅳ ( preemptive analgesia group) morphine 5 ?g (10 ?l) was given IT 30 min before incision The animals were anesthetized with intraperitoneal pentobarbital sodium 40 mg?kg -1 PE 10 catheter was inserted intrathecally to the lumbar region according to method of Yaksh 5 days later incision of 1 cm long was made in the plantar region of left hindpaw parallel to the muscle under isoflurane anesthesia according to the method of Brennan Pain behavior was assessed by a cumulative pain score Immuno histochemistry technique was used to measure the expression of substance P Results IT morphine given either before or after incision decreased the cumulative pain scores Incision made in the plantar region of left hindpaw increased substance P expression in the ipsilateral dorsal horn of spinal cord (0 62?0 07 vs 0 40?0 09) In group Ⅳ increase in substance P expression in the dorsal horn of spinal cord was inhibited Conclusions The analgesia provided by preemptive IT morphine is possibly mediated via the decrease in substance P in the dorsal horn of spinal cord

Objective To investigate the effectiveness of treating postherpetic neuralgia (PHN) by intradermal drug injection.Methods Ten rabbits of both sexes weighing 2.3-2.8 kg were anesthetized with intravenous urethane 1.5 g/kg. In group A (n = 5) 30% horseradish peroxidase(HRP) 500 ?l and in group B (n = 5) 1%-2% fluorescent nuclear yellow (NY) 500?l were injected intradermally at 6-8 points along the both sides of spine in the scapula region. After 48-72 h the animals were sacrificed and C4 -T10 spinal ganglia, cervical and thoracic sympathetic ganglia and celiac ganglia were harvested for identification of labeled neurocytes. Results Labeled neurocytes were found in C4-T10 spinal ganglia, cervical and thoracic sympathetic ganglia and celiac ganglia. There were more labeled neurocytes in the C6-T8 spinal ganglia. There were more labeled neurocytes in the sympathetic ganglia than in the spinal ganglia. The distribution of fluorescent labeled neurocytes corresponded to neurocytes labeled by HRP method. At the same segment there were more fluorescent labeled neurocytes than neurocytes labeled by HRP. Conclusion There is an ascending axoplasma streaming channel from nerver ending to the neurocytes in the ganglion as shown by morphological study and the good therapeutic effect of intradermal drug injection in the treatment of PHN may be related to this channel.

Objective It has been shown that protein kinase C (PKC), especially PKCy is involved in the nociceptive processing at the spinal level. This study was designed to investigate the effects of intrathecal (IT) morphine on PKCy immuno-reactivity in the spinal dorsal horn in a rat model of incisional pain. Methods Twenty-four male SD rats weighing 250-300 g were anesthetized with intraperitoneal pentobarbital 40 mg?kg-1. PE-10 catheter was inserted intrathecally to the lumbar region according to Yaksh. Five days later an incision of 1cm long was made in the plantar region of left hindpaw, parallel to the muscle under isoflurane anesthesia according to Brennan. The animals were randomly divided into 4 groups with 6 animals in each group : group Ⅰ sham-operation group received IT artificial cerebro-spinal fluid (ACSF) 20 ?l and 30 min later inhaled 1.4% isoflurane for S min but no incision was made; group Ⅱ received ACSF 20 ?l IT 30 min before incision was made; group Ⅲ post-incisional morphine group received morphine 5 ?g IT 30 min after incision and group Ⅳ pre-incisional morphine group received morphine 5 ?g IT 30 min before incision. The animals were sacrificed under general anesthesia 2 h after incision. The L4-5 segment of spinal cord was removed for determination of the expression of PKC? in the spinal dorsal horn by immuno-histochemical method.Results In group Ⅱ the PKC?-IR gray density in the spinal dorsal horn of the operated side was significantly higher than that of contralateral side and that in group Ⅰ( P

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.

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.

BACKGROUND: Erigeron, the inhibitor of protein kinase C, functions to decrease the death of neurocytes caused by cerebral ischemia reperfusion.OBJECTIVE: To study the effects of erigeron on hippocampus adenosine triphosphate (ATP) and adenosine triphosphatase (ATPase) of gerbils with cerebral ischemia reperfusion injury.DESIGN: A random controlled experiment.SETTING: Anesthesia Department of the Fourth Hospital of Suzhou University, Anesthesia Department of the Fourth People's Hospital of Wuxi City, and Anesthesia Department of the Affiliated Hospital of Xuzhou Medical College.MATERIALS: The experiment was done in the key laboratory of anesthesiology of Jiangsu Province from March 2002 to May 2003. The 90 Mongolian gerbils were divided into 9 groups: sham operated group, cerebral ischemia group, cerebral ischemia reperfusion 1 hour group, cerebral ischemia reperfusion 12 hours group, cerebral ischemia reperfusion 24 hours group, erigeron + cerebral ischemia group, erigeron + cerebral ischemia reperfusion 1 hour group, erigeron + cerebral ischemia reperfusion 12 hours group, and erigeron + cerebral ischemia reperfusion 24 hours group,with 10 gerbils in each. The erigeron injection with flavone 4.5 g/mL was made by the Biomedicine Factory of Yunnan Province and numbered 990103.METHODS: Apart from the sham operated group, all groups were established the ischemia reperfusion models. The erigeron groups were abdominally injected erigeron 10 mL/kg 30 minutes before the ischemia. Meanwhile, the other groups were injected the normal saline 10 mL/kg. The 6 gerbils of each group were taken blood for testing ATP content and ATPase activity and the rest 4 were only examined the pathological changes of neurocytes of hippocampus CA1 region. During the ischemia, the temperature of drum membrane (reflecting the brain temperature) was monitored and kept at (37±0.2)℃ in order to avoid the influence of temperature on the result. The comparison among groups was shown with the single factor analysis of variance.CA1 region.of ATP content and ATPase activity: Compared with the cerebral ischemia reperfusion 24 hours group, the ATP content of the erigeron 1, 12, 24 hours groups was obviously increased [(0.25 ±0.08), (0.81 ±0.12), (0.58 ±0.07),(0.43±0.09) mmol/kg, P ＜ 0.01], the Na+-K+-ATPase activity was obviously P ＜ 0.01], and the Ca2+-ATPase activity was also obviously promoted days after ischemia, the findings under the low power lens were: the pyramidal belt of the cerebral ischemia reperfusion groups became thinner and loose and even disappeared, but that of the erigeron groups became obviously wider and thicker; the findings under the high power lens were: most of the pyramidal cells of the cerebral ischemia reperfusion groups were in the state of coagulation necrosis, and those survived pyramidal cells with complete nuclear membrane and clear nucleole were very few, but the survived pyramidal cells of the erigeron groups were obviously more than those of the cerebral ischemia reperfusion groups.CONCLUSION: Erigeron increases obviously the ATP content after ischemia reperfusion, especially at the early stage of reperfusion, and at the same time, the ATPase activity is also in an improved tendency, relieving the ischemia reperfusion injury and protecting the neurocytes.