Effect of propofol on glutamate-induced activation and related inflammatory cytokines of astrocytes from spinal cord dorsal horn

BACKGROUND： Astrocytes participate in central nervous system-mediated physiological or pathological processes, such as pain. Activated dorsal horn astrocytes from the spinal cord produce nerve active substances and proinflammatory cytokines, such as interleukin-lbeta （IL-1 β ）, IL-6, and tumor necrosis factor- α （TNF-α ）, which play important roles in pain transduction and regulation. OBJECTIVE： To investigate the effects of different doses of propofol on activation of cultured spinal cord dorsal horn astrocytes induced by glutamate, as well as changes in IL-1β, IL-6, and TNF- α, and 1L-10 （anti-inflammatory cytokine） expression in rats, and to explore the dose relationship of propofol. DESIGN, TIME AND SETTING： The cellular and molecular biology experiment was performed at the Central Laboratory of Yunyang Medical College between March 2006 and December 2007. MATERIALS： Forty healthy, Wistar rats, aged 2-3 days, were selected. Propofol was provided by Zeneca, UK; glutamate by Sigma, USA; EPICS XL flow cytometry by Beckman culture, USA; rabbit-anti-mouse glial fibrillary acidic protein （GFAP） antibody kit and inflammatory cytokine detection kit were provided by Zhongshan Biotechnology Company Ltd., Beijing; multimedia color pathologic image analysis system was a product of Nikon, Japan. METHODS： Astrocytes were harvested from T11- L6 spinal cord dorsal horn of Wistar rats and incubated for 3 weeks. The cells were divided into seven groups, according to various treatment conditions： control group was cells cultured in Hank＇s buffered saline solution; intralipid group was cells cultured in intralipid （0.2 mL/L）; glutamate group was cells cultured with 100 u mol/L glutamate; propofol group was cells cultured with 250 u mol/L propofol; three glutamate plus propofol groups were cultured in 100 11 mol/L of glutamate, followed by 5, 25, and 250 u mol/L of propofol 10 minutes later. MAIN OUTCOME MEASURES： GFAP-labeled astrocytes were analyzed using a multimedia pathology imaging analysis system to detect area density （AD） and average optical density （AOD） of positive cells. The supernatant concentrations of IL-1β, TNF- α, IL-6, and IL-10 were determined using radioimmune assays. RESULTS： Compared with the control group, cells in the glutamate plus low-dose propofol group were activated and hypertrophic, and AD and AOD were significantly increased （P 〈 0.01 ）. Concentrations of IL-1β, TNF- α, and IL-6 were also significantly increased （P 〈 0.01）, while IL-10 levels remained unchanged （P 〉 0.05）, but still higher than the control and glutamate groups （P 〉 0.05）. Compared with the glutamate group, astrocyte activation was inhibited by moderate and high-dose propotol. In addition, with moderate and high-dose propofol, AD, AOD, IL-1β, TNF- α, and IL-6 concentrations were significantly decreased （P 〈 0.05-0.01）, and IL-10 levels were increased （P 〈 0.01 ）. CONCLUSION： Propofol can effectively inhibit glutamate-induced astrocyte activation in the spinal cord dorsal horn, significantly inhibit production of IL-1 β, TNF- α, and IL-6, and increase IL-10 synthesis and release in a dose-dependent manner.

Chinese Tuina remodels the synaptic structure in neuropathic pain rats by downregulating the expression of N-methyl D-aspartate receptor subtype 2B and postsynaptic density protein-95 in the spinal cord dorsal horn

OBJECTIVE:To investigate whether the Chinese massage system,Tuina,exerts analgesic effects in a rat model of chronic constriction injury(CCI)by remodeling the synaptic structure in the spinal cord dorsal horn(SCDH).METHODS:Sixty-nine male Sprague–Dawley rats were randomly and evenly divided into the normal group,sham group,CCI group,CCI+Tuina group,CCI+MK-801[an N-methyl D-aspartate receptor subtype 2B(NR2B)antagonist]group,and CCI+MK-801+Tuina group.The neuropathic pain model was established using CCI with right sciatic nerve ligation.Tuina was administered 4 d after CCI surgery,using pressing manipulation for 10 min,once daily.Motor function was observed with the inclined plate test,and pain behaviors were observed by the Von Frey test and acetone spray test.At 19 d after surgery,the L3-L5 spinal cord segments were removed.Glutamate,interleukin 1β(IL-1β),and tumor necrosis factor-α(TNF-α)levels were detected by enzyme-linked immunosorbent assay.The protein expression levels of NR2B and postsynaptic density protein-95(PSD-95)were detected by Western blot,and the synaptic structure was observed by transmission electron microscopy(TEM).RESULTS:CCI reduced motor function and caused mechanical and cold allodynia in rats,increased glutamate concentration and TNF-αand IL-1βlevels,and increased expression of synapse-related proteins NR2B and PSD-95 in the SCDH.TEM revealed that the synaptic structure of SCDH neurons was altered.Most of these disease-induced changes were reversed by Tuina and intrathecal injection of MK-801(P<0.05 or<0.01).For the majority of experiments,no significant differences were found between the CCI+MK-801 and CCI+MK-801+Tuina groups.CONCLUSIONS:Chinese Tuina can alleviate pain by remodeling the synaptic structure,and NR2B and PSD-95 receptors in the SCDH may be among its targets.

High-frequency spinal cord stimulation produces longlasting analgesic effects by restoring lysosomal function and autophagic flux in the spinal dorsal horn

High-frequency spinal cord stimulation(HF-SCS) has been established as an effective therapy for neuropathic pain. However, the analgesic mechanisms involved in HF-SCS remain to be clarified. In our study, adult rat neuropathic pain was induced by spinal nerve ligation. Two days after modeling, the rats were subjected to 4 hours of HF-SCS(motor threshold 50%, frequency 10,000 Hz, and pulse width 0.024 ms) in the dorsal horn of the spinal cord. The results revealed that the tactile allodynia of spinal nerve-injured rats was markedly alleviated by HFSCS, and the effects were sustained for 3 hours after the stimulation had ceased. HF-SCS restored lysosomal function, increased the levels of lysosome-associated membrane protein 2(LAMP2) and the mature form of cathepsin D(matu-CTSD), and alleviated the abnormally elevated levels of microtubule-associated protein 1 A/B-light chain 3(LC3)-II and sequestosome 1(P62) in spinal nerve-injured rats. HF-SCS also mostly restored the immunoreactivity of LAMP2, which was localized in neurons in the superficial layers of the spinal dorsal horn in spinal nerve-injured rats. In addition, intraperitoneal administration of 15 mg/kg chloroquine for 60 minutes reversed the expression of the aforementioned proteins and shortened the timing of the analgesic effects of HF-SCS. These findings suggest that HF-SCS may exhibit longlasting analgesic effects on neuropathic pain in rats through improving lysosomal dysfunction and alleviating autophagic flux. This study was approved by the Laboratory Animal Ethics Committee of China Medical University, Shenyang, China(approval No. 2017 PS196 K) on March 1, 2017.

“Three Methods and Three Points” regulates p38 mitogen-activated protein kinase in the dorsal horn of the spinal cord in a rat model of sciatic nerve injury

Tuina is a traditional Chinese treatment for sensory disturbances caused by peripheral nerve injury and related diseases. Our previous studies showed that tuina regulates relevant regions and indices of the spinal dorsal horn using the Dian, Bo, and Rou method in Yinmen（BL37）, Yanglingquan（GB34）, and Weizhong（BL40）. Treatment prevents muscle atrophy, protects spinal cord neurons, and promotes sciatic nerve repair. The mechanisms of action of tuina for treating peripheral nerve injury remain poorly understood. This study established rat models of sciatic nerve injury using the crushing method. Rats received Chinese tuina in accordance with the principle of ＂Three Methods and Three Points,＂ once daily for 20 days. Tuina intervention reduced paw withdrawal latency and improved wet weight of the gastrocnemius muscle, as well as promoting morphological recovery of sciatic nerve fibers, Schwann cells, and axons. The protein expression levels of phospho-p38 mitogen-activated protein kinase, tumor necrosis factor-α, and interleukin-1β also decreased. These findings indicate that ＂Three Methods and Three Points＂ promoted morphological recovery and improved behavior of rats with peripheral nerve injury.

THE PROPERTY OF PERIPHERAL INPUT OF PROJECTION NEURONS IN THE SPINAL CORD DORSAL HORN

Antidromic and orthodromic responses of the projection neurons in the dorsal horn ofthe spinal cord have been recorded by a glass microelectrode in anesthetized and paralyz-ed cats. Furthermore, the effect of cervical segment antidromic stimulation to orthodromicresponse of the projection neurons has been observed by way of conditioning-test stimulation. Among all the spinocervical tract neurons (SCT), the dorsal column postsynaptic neu-rons (DCPS) and the spinocervical tract-dorsal column postsynaptic neurons (SCT-DCPS),which were identified by cervical segment antidromic stimulation, 46% are low-thresholdmechanoreceptive (LTM) and 54% are wide-dynamic-range (WDR) neurons. Most LTMneurons can evoke the same response to both 10 times (10 T) and 50 times (50 T) the thresh-old stimulation on the peroneal nerve. Most WDR neurons to 50 T intensity stimulation arestronger than the 10 T stimulation. Under the antidromic-cervical segment conditioningstimulation, the amount of orthodromic-discharging in most

Up-regulation and time course of protein kinase C immunoreactivity during persistent inflammation of the rat spinal cord

BACKGROUND： It has been reported that activation and/or translocation of protein kinase C （PKC） is related to hyperalgesia, and changes in PKC expression in the dorsal horn of spinal cord take place during inflammatory pain. OBJECTIVE： To observe PKC changes in the dorsal horn of spinal cord using immunohistochemistry and to measure the time-course during persistent pain produced by chemical stimulation with a right hind-paw injection of formalin. DESIGN： Randomized controlled animal experiment. SETTING： Institute of Basic Medical Science, Hebei Medical University MATERIALS： The present experiment was performed at the Department of Pathophysiology, Institute of Basic Medical Science, Hebei Medical University between September 2000 and June 2002. Forty-two Sprague-Dawley rats, weighing 260-280 g, irrespective of gender, were provided by the Center of Animal Experimentation at Hebei Medical University. PKC antibody was provided by Sigma, USA. Immunohistochemistry kits were purchased from Zhongshan Biotechnology Company, Beijing. HPIAS-1000 definition multicolor system was provided by Qianping Wuxiang Project Company of Tongji Medical University. Animal use during experimentation was consistent with the standards of Animal Ethics Committee. METHODS： Sprague-Dawley rats were divided randomly into control （n = 6） and experimental groups （n = 36）. Experimental rats were given an intracutaneous injection of 5% formalin into the planta surface of the right hind-paw. Animals with inflammatory pain were anesthetized and sacrificed to obtain the L5 spinal region at 1, 3, 12 hours, 1, 3, and 7 days after formalin treatment, with 6 rats in each time group. The spinal cords at the L5 region were collected from the control group following sodium chloride injections into the planta surface of the right hind-paw, identical to the experimental group. MAIN OUTCOME MEASURES： Pain reaction of experimental rats after formalin treatment. PKC-positive neurons, and distribution of PKC-immunoreactive particles, in the ipsi- and contralateral dorsal horn were investigated during different stages of inflammatory pain using immunohistochemistry. RESULTS： All 42 rats were included in the final analysis, without any loss. Pain reaction： consistent with previous findings, it was determined that a unilateral injection of formalin into the hind-paw resulted in significant edema and induced a series of nociceptive responses, such as licking, biting, or shaking the injected paw. The maximal inflammation change was observed 1 day after formalin injection and changes did not disappear until the day 7. Number of the PKC positive neurons： results demonstrated that the number of PKC immunoreactive neurons in the dorsal horn increased slightly after formalin injection at 1 hour, compared with the control group. PKC immunoreactivity was up-regulated at day 1, reduced at day 3, and appeared to recover at day 7. The number of PKC-positive neurons in the contralateral side was less than the ipsilateral side at each time sampled. Distribution of PKC immunoparticles over the neurons： PKC immunoreactivity was observed in the nucleus and cytoplasm, as well as on or near the membrane of neurons and synaptosomes in the spinal cord of the control group. PKC activated and translocated from nucleus to the membrane-associated site following formalin treatment. Significant changes were observed at 1 hour and 1 day. The intensity of staining was stronger in the ipsilateral side than the contralateral side at all time points following formalin injection （P 〈 0.01）, whereas the expression patterns of PKC immunoreactivity in the nuclei were very similar in the right and left hemispheres. CONCLUSION： PKC expression in the dorsal horn of the spinal cord peaked at 1 hour and 24 hours, and was very obvious at 24 hours. Protein kinase C expression in the spinal cord increased bilaterally, although it was greater in the ipsilateral hemisphere. In addition, PKC expression at the neuronal membrane and synaptosome was significantly increased. These results indicate that PKC expression is activated in the dorsal horn of the spinal cord during hyperalgesia.

Spinal processing of bee venom-induced pain and hyperalgesia

Subcutaneous injection of bee venom causes long-term neural activation and hypersensitization in the dorsal horn of the spinal cord,which contributes to the development and maintenance of various pain-related behaviors.The unique behavioral 'phenotypes' of nociception and hypersensitivity identified in the rodent bee venom test are believed to reflect a complex pathological state of inflammatory pain and might be appropriate to the study of phenotype-based mechanisms of pain and hyperalgesia.In this review,the spinal processing of the bee venom-induced different 'phenotypes' of pain and hyperalgesia will be described.The accumulative electrophysiological,pharmacological,and behavioral data strongly suggest that different 'phenotypes' of pain and hyperalgesia are mediated by different spinal signaling pathways.Unraveling the phenotype-based mechanisms of pain might be useful in development of novel therapeutic drugs against complex clinic pathological pain.

Effects of Sevoflurane on the discharges of wide dynamic range neurons in spinally transected rats

Objective: To study the effects of clinical concentration of sevoflurane on activity of wide dynamic range neurons. Methods: Eight Spraque-Dawley rats(male) were selected. Their spinal cords were exposed and transected at T 9-10 level. The rate of firings of single neurons in the dorsal horn in response to electrical stimulation of skin was recorded with microelectrodes. The early and late discharges were observed when rats inhaled 0.5%, 1.0%, 1.5%, and 2.0% sevoflurane. Results: Sevoflurane suppressed the early and late discharges at the concentration of 0.5%, 1.0%, 1.5%, and 2.0%. Compared with early discharges, the extent of inhibition of late discharges was wider at the concentration of 1%, 1.5%, and 2.0% of sevoflurane. Conclusion: It is indicated that sevoflurane could suppress the transmission of nociceptive and non-nociceptive stimulation at dorsal horn. The suppression on nociceptive imput is stronger than that on non-nociceptive imput when the concentration of sevoflurane is more than 1%.

背根神经节嘌呤受体亚型P2X3R介导小鼠术后急—慢痛转化

目的探讨不同部位不同嘌呤受体亚型在小鼠切口术后痛转化中的作用差异。方法足底切口恢复后注射PGE_(2)构建术后痛转化模型。第一部分:C57BL/6小鼠随机分为对照(Con)组、假敏化(sHP)组、敏化(HP)组,检测机械痛阈、自发痛评分和焦虑样行为;Western blot检测患侧L 3-5背根神经节(DRG)和脊髓背角(SCDH)中P2X3R和P2X7R蛋白表达变化。第二部分:C57BL/6小鼠随机分为Con组、HP+生理盐水组、HP+P2X3R拮抗剂组或HP+P2X7R拮抗剂组,观察拮抗不同亚型嘌呤受体对小鼠机械痛阈的影响。结果与正常小鼠相比,切口痛小鼠注射PGE_(2)后机械痛阈明显下降,自发痛评分明显增加(P<0.05),未表现出焦虑样行为(P>0.05),且P2X3R蛋白在DRG中表达明显增多(P<0.05),在SCDH中未检出,而P2X7R蛋白在DRG和SCDH各组中表达均无差异(P>0.05)。拮抗P2X3R能阻断术后痛转化的产生,而拮抗P2X7R无明显影响。结论切口痛小鼠经PGE_(2)诱导可出现急慢性痛的转化,不伴发焦虑样情绪,DRG中P2X3R可能是参与术后痛转化的关键受体之一。

异丙酚对谷氨酸体外激活脊髓背角星形胶质细胞及相关炎性细胞因子的影响

目的观察不同浓度异丙酚对谷氨酸体外激活大鼠脊髓背角星形胶质细胞及促炎性细胞因子（TNF-α、IL-1β、IL-6）和抗炎性细胞因子IL-10变化的影响。方法取新生2~3d Wistar大鼠T11~L6脊髓背角星形胶质细胞原代纯化培养3周。将细胞随机分为7组：正常对照组（C组）加入Hanks液;乳剂对照组（L组）加入乳剂0.2ml/L;谷氨酸组（G组）加入谷氨酸至终浓度100μmol/L;异丙酚组（P组）加入异丙酚至终浓度250μmol/L;GP1、GP2、GP3组先加入谷氨酸至终浓度100μmol/L,10min后分别加入异丙酚至终浓度5、25、250μmol/L。加药后培养24h取各组培养孔上清液检测IL-1β、TNF-αI、L-6和IL-10含量,用神经胶质纤维酸性蛋白（GFAP）标记星形胶质细胞（免疫细胞化学法）,多媒体彩色病理图像分析系统检测阳性细胞面密度（AD）和平均光密度（AOD）。结果与C组比较,G组和GP1组细胞被激活增生肥大,AD和AOD均升高（P〈0.01）,其上清液中IL-1β、IL-6和TNF-α含量上升（P〈0.01）,G组IL-10浓度无明显变化（P〉0.05）,GP1组IL-10浓度升高（分别与C组和G组比较P〈0.05）。与G组比较,GP2组和GP3组细胞激活被抑制,AD、AODI、L-1βI、L-6和TNF-α含量均低（其中GP2组P〈0.05,GP3组P〈0.01）,而IL-10含量均上调（P〈0.01）。结论异丙酚可抑制谷氨酸对体外培养的大鼠脊髓背角星形胶质细胞的激活作用,同时抑制星形胶质细胞分泌IL-1βI、L-6和TNF-α,增强IL-10的合成释放,其作用程度与剂量有关。

MK-801抑制福尔马林实验引起的大鼠脊髓背角环氧合酶-2的表达

应用免疫组织化学方法,观察鞘内注射N-methyl-D-aspartate(NMDA)受体拮抗剂MK-801对福尔马林实验引起的大鼠脊髓背角环氧合酶-2(cyclooxygenase-2,COX-2)表达的影响。结果表明:MK-801对福尔马林实验引起的第1相缩足反射仅有一定抑制作用,但对第2相缩足反射有显著的抑制作用,且呈剂量依赖性。与这种行为学的变化相对应,MK-801可显著抑制福尔马林实验引起的脊髓背角COX-2表达的增加,并且这种抑制作用与MK-801的剂量呈正相关。这些结果表明,在福尔马林实验中,NMDA受体的活动是引起脊髓背角COX-2表达增加的原因之一。

P物质、c-fos在慢性前列腺炎/慢性盆腔疼痛综合征大鼠脊髓中的表达

目的：探讨P物质（P物质（substance P,SP）、c-fos参与慢性前列腺炎/慢性盆腔疼痛综合征（CP/CPPS）疼痛的可能机制。方法：自身免疫法建立CP/CPPS大鼠模型;Von Frey丝检测机械刺激缩足阈（PWT）;免疫组化检测前列腺与脊髓L5～S2节段背角SP、c-fos的表达变化和相关性。结果：造模后大鼠PWT下降,与对照组相比差异有统计学意义[（48.83±1.55）g vs（67.98±5.44）g,（P〈0.05）]。前列腺呈现显著炎症反应,在病变范围、间质淋巴细胞浸润程度方面都较对照组反应加重,差异有统计学意义（P〈0.05）。与对照组相比,模型组前列腺与脊髓L5～S2背角中SP、c-fos阳性表达均上调,差异有统计学意义（P〈0.05）。前列腺与脊髓中SP蛋白表达无相关性（r=0.099,P=0.338）;c-fos蛋白表达亦无相关性（r=0.027,P=0.454）。结论：SP、c-fos可能通过脊髓L5～S2节段的表达上调参与了疼痛的形成和维持。CP/CPPS疼痛的发生过程中脊髓L5～S2节段背角的病理变化可能起着重要的作用。

脊髓背角p38MAPK活化在瑞芬太尼诱发术后痛觉过敏中的作用

目的：探讨脊髓背角磷酸化p38丝裂原活化蛋白激酶（p-p38MAPK）在瑞芬太尼诱发术后痛觉过敏中的作用。方法：取鞘内置管成功的雄性SD大鼠40只,体重230~270 g,采用数字表法将其随机分为5组：对照组（C组）、术后切口痛组（I组）、瑞芬太尼组（R组）、p38MAPK特异性抑制剂SB203580组（S组）和SB203580的溶媒二甲基亚砜DMSO组（D组）。C组、I组、R组大鼠鞘内分别给予NS 10μl,S组和D组大鼠鞘内分别给予2.65 mmol SB203580 10μl和溶剂2%DMSO 10μl;I组大鼠在1.5%异氟烷吸入麻醉下行右侧跖底切口手术,C组大鼠不行右侧跖底手术,其余三组均在瑞芬太尼持续泵注下行右侧跖底切开手术。采用热辐射刺激仪和von Frey纤维丝分别测定双侧后爪热刺激缩爪潜伏期及机械性痛阈。应用免疫组织化学法检测脊髓背角p-p38MAPK表达的变化。结果：与I组比较,R组、D组在术后4 h、1 d、2 d、3 d双侧跖底热刺激缩爪潜伏期、机械性痛阈值均降低,双侧脊髓背角p-p38MAPK表达增多;与R组比较,S组双侧跖底的机械性痛阈值、手术侧跖底热刺激缩爪潜伏期值增高,双侧脊髓背角p-p38MAPK表达减少。结论：脊髓背角p38MAPK活化可能参与了瑞芬太尼诱发的术后痛觉过敏。

电针对神经病理性疼痛大鼠痛觉过敏及脊髓背角钾-氯离子协同转运体2表达的影响

目的:观察患侧电针和健侧电针足三里穴、阳陵泉穴对神经病理性疼痛大鼠行为学表现以及脊髓背角钾-氯离子协同转运体2(KCC2)表达的影响,探讨患侧选穴和健侧选穴两种针刺方案的镇痛效应,以及KCC2在电针镇痛效应中的作用。方法:将40只雄性SD大鼠随机分为4组:假模组、模型组、患侧电针组、健侧电针组,每组10只。建立大鼠坐骨神经慢性压迫性损伤(CCI)模型,治疗组于术后1周开始电针治疗,每天1次,连续7天。各组于术前(0天)及术后3、5、7、10、12、14天分别测量大鼠患侧足机械足反射阈值(MWT)和热缩足反射潜伏期(TWL)。术后14天处死大鼠,取脊髓组织行HE染色观察组织病理学改变,并采用免疫组化方法检测脊髓背角KCC2蛋白的表达。结果:与术前比较,CCI各组大鼠痛阈明显降低,出现痛觉过敏(P<0.001),电针治疗后大鼠MWT和TWL均有不同程度的持续升高,且患侧与健侧电针相比无明显差异。HE染色结果提示,患侧电针组与健侧电针组脊髓背角组织及神经元病变程度较模型组减轻。术后14天患侧与健侧电针组较模型组脊髓背角患侧KCC2表达显著增加(P<0.05),并且患侧电针组与健侧电针组无明显差异。结论:患侧电针和健侧电针能产生类似的镇痛效果,均可减轻外周神经损伤后引起的痛觉过敏。患侧电针与健侧电针治疗均可抑制KCC2蛋白的表达下调,电针的镇痛作用可能是通过增加脊髓背角中KCC2的表达实现的。

P物质与香草酸瞬时受体亚型1在慢性非细菌性前列腺炎大鼠神经痛中的作用研究

目的：探讨慢性非细菌性前列腺炎（CNP）疼痛的可能机制。方法：自身免疫法建立CNP大鼠模型;Von Frey丝检测机械刺激缩足阈（PWT）;进行前列腺病理学检查和免疫组化检测前列腺与脊髓L5-S2节段P物质（SP）、香草酸瞬时受体亚型1（TRPV1）表达变化和相关性。结果：造模后大鼠PWT[（48.83±11.55）g]下降,与对照组[（67.98±5.44）g]相比差异有统计学意义（P〈0.05）。前列腺呈现显著炎症反应,病变范围、间质淋巴细胞浸润都较对照组反应程度有所加重,差异有统计学意义（P〈0.05）。与对照组相比,模型组前列腺与脊髓背角L5-S2中SP、TRPV1阳性表达均上调,差异有统计学意义（P〈0.05）。前列腺与脊髓中SP蛋白表达无相关关系（r=0.099,P=0.338）;TRPV1蛋白表达亦无相关关系（r=0.000,P=0.5）。结论：SP、TRPV1可能通过脊髓L5-S2节段的表达上调参与了CNP大鼠疼痛的形成和维持。

神经病理性疼痛大鼠脊髓NMDA受体NR2B亚基的表达

目的研究神经病理性疼痛大鼠脊髓背角NR2B亚基表达的改变。方法体重180～200g的雄性SD大鼠随机分为四组(每组10只):3d(D3)、7d(D7)、14d(D14)组和假手术组。建立外周神经慢性压榨性损伤(CCI)动物模型,假手术组大鼠同样分离坐骨神经,但不结扎神经。各组大鼠分别于术前和术后第3、7、14天及假手术后第3天以VonFrey纤维测定机械痛阈并进行术前术后及组间比较;之后分别于术后第3、7、14天及假手术后第3天断头处死,取患侧L4～L5脊髓背角组织采用Western blot方法测定并比较NR2B亚基的蛋白表达量。结果7d组及14d组大鼠术后机械痛阈均明显低于假手术组(P<0.05);其患侧脊髓背角NR2B蛋白表达量明显高于假手术组(P<0.05)。3d组大鼠术后机械痛阈及患侧脊髓背角NR2B蛋白表达量与假手术组相比差异无统计学意义。结论神经病理性疼痛大鼠的脊髓背角的NR2B蛋白表达水平较假手术组显著升高,此蛋白表达水平的升高可能是导致大鼠神经病理性疼痛的原因之一。

嗅鞘细胞对脊髓后角神经元突起生长的影响

目的:观察嗅鞘细胞对胚胎脊髓后角神经元突起生长的影响。方法:分离孕15d胚胎大鼠脊髓,取纵向分开的后半制备成细胞悬液,培养于:(1)原代培养的嗅鞘细胞单细胞层上;(2)嗅鞘细胞培养上清中;(3)原代培养的成纤维细胞单细胞层上;(4)单纯培养。24h后终止培养,行抗神经丝-200免疫细胞化学染色。每组随机取15个神经元,在LeicaQ-570图像分析仪中测量各组神经元的平均总突起长度及平均单个最长突起长度,进行组间比较。结果:神经元平均总突起长度(1)～(4)组分别为408.62±126.91滋m、336.24±106.34滋m、199.37±76.14滋m和64.61±24.49滋m;平均单个最长突起长度(1)～(4)组分别为180.13±83.54滋m、141.22±53.68滋m、107.29±43.35滋m和23.04±5.30滋m。第(1)、(2)组神经元平均总突起长度和平均单个最长突起长度明显高于第(3)、(4)组(P<0.01),而(1)、(2)组之间没有明显差异(P>0.05)。结论:与嗅鞘细胞共培养能明显促进胚胎脊髓后角神经元突起的生长速度。

氯胺酮对大鼠脊髓背角星形胶质细胞的保护机制

目的探讨氯胺酮对N-甲基-D-天冬氨酸(NMDA)诱导的大鼠脊髓背角星形胶质细胞损伤的保护机制。方法取新生2～3dWistar大鼠40只T12～L5脊髓背角星形胶质细胞,原代纯化培养3周。将细胞随机分六组:NMDA组(N组),氯胺酮组(K组)、NMDA加不同浓度氯胺酮组(标记为NK1～NK3组),对照组(C组)。加药后培养30min或24h取各组细胞检测超氧化物岐化酶(SOD)活性和丙二醛(MDA)含量,免疫细胞化学观察Bcl-2/Bax表达,流式细胞仪检测星形胶质细胞凋亡率和胞内游离钙浓度([Ca2+]i)。结果与C组比较,N组细胞发生大量凋亡(P<0.01),Bax强阳性表达,Bcl-2阴性表达,SOD活性显著降低(P<0.01),MDA含量明显增加(P<0.01),[Ca2+]i显著升高(P<0.01)。与N组比较,NK2、NK3组细胞凋亡明显减少(P<0.05或P<0.01),Bcl-2阳性表达,Bax阴性表达,[Ca2+]i低(P<0.05或P<0.01),SOD活性增加(P<0.01),MDA含量低(P<0.01)。结论氯胺酮抑制激活的背角星形胶质细胞内Ca2+超载,增强Bcl-2蛋白表达,抑制NMDA诱导的细胞凋亡,并增强抗氧化酶活性,抑制脂质过氧化反应引起的细胞损伤。

氧化槐定碱镇痛作用及其对小鼠中枢PKCγ表达的影响

目的研究氧化槐定碱(oxysophoridine,OSR)的镇痛作用及对小鼠脊髓背角、大脑皮层和丘脑蛋白激酶Cγ(Protein kinase C-γ,PKCγ)免疫阳性细胞的影响。方法用热板法观察并分析iv、icv途径给药后OSR镇痛作用强度及作用部位,免疫组织化学方法(SABC法)检测OSR对小鼠脊髓背角、大脑皮层和丘脑PKCγ免疫阳性细胞的影响。结果iv OSR 500、250、125mg·kg-1及icv OSR 100、50、25mg·kg-1均可延长小鼠热板反应舔足潜伏期(P<0.05、P<0.01),痛阈提高率分别为42.51%(iv)和60.70%(icv)。ip OSR 1000mg·kg-1可使小鼠脊髓背角、大脑皮层和丘脑PKCγ免疫阳性细胞明显减少(P<0.01)。结论OSR外周和中枢给药均有镇痛作用,PKCγ参与了OSR的镇痛作用。

紫杉醇诱导神经病理性疼痛大鼠脊髓背角5-羟色胺含量变化

目的观察紫杉醇诱导神经病理性疼痛大鼠脊髓背角5-羟色胺(5-HT)含量变化。方法雄性SD大鼠54只,体重约300 g,随机均分为正常对照组(A组)、紫杉醇溶媒组(B组)和紫杉醇组(C组)。分别于腹腔注药前1 d、注药后3、5、7、9、11、14、18、21 d检测大鼠机械缩爪阈值。腹腔注药前1 d、注药后7、14、21 d每组各处死大鼠4只,取脊髓腰膨大背角组织,用高效液相色谱荧光法测定5-HT含量。腹腔注药后14 d取大鼠右侧坐骨神经,透射电镜观察神经病变情况。结果与注药前1 d比较,C组机械缩爪阈值从紫杉醇注射后7 d开始显著降低,并持续至注药后21 d达最低值(P<0.05),且显著低于A、B组(P<0.05)。坐骨神经超微结构C组纤维髓鞘板层结构松散,排列紊乱、肿胀变形、厚薄不均,A和B组大鼠坐骨神经未见异常。C组脊髓背角5-HT含量注药后7 d开始显著升高,并持续至注射后21 d达最高值(P<0.05),且显著高于A、B组(P<0.05)。C组大鼠脊髓背角5-HT含量与机械缩爪阈值呈显著线性负相关(r=-0.981,P<0.05)。结论紫杉醇诱导的神经病理性疼痛大鼠脊髓背角组织中5-HT含量表达上调,该变化可能参与了紫杉醇所致神经病理性疼痛的发病机制。