大鼠脊神经选择性结扎镜像痛模型的筛选建立

目的：研究行为学观察和热辐射缩足反应潜伏期（PWTL）及机械缩足反应潜伏期（MWT）实验筛选建立脊神经选择性结扎（SNL）镜像痛大鼠模型。方法：选取100只成年雄性SD大鼠，将其随机分为SNL组90只和假手术组（Sham组）10只，于术前1 d和术后1、3、7、14、21、28 d进行行为学观察和双足PWTL及MWT实验检测。结果：两组术前行为学观察、PWTL及MWT值比较差异均无统计学意义（P〉0.05），术后SNL组手术足均出现添足、咬足等行为学现象，且PWTL值和MWT值术后1-28 d均明显低于Sham组，差异均有统计学意义（P〈0.05）。SNL组有14只大鼠为手术足，于术后7 d出现添足、咬足等行为学现象，术后14、21、28 d的MWT值均明显低于Sham组，且术后21、28 d的PWTL值均明显低于Sham组，差异均有统计学意义（P〈0.05）。结论：大鼠SNL镜像痛模型筛选和建立成功。     

CCI模型大鼠疼痛行为学观察

目的：探讨CCI（Chronic constrictive injury）模型大鼠一般行为学及痛阈变化。方法：SD（Sprague-Dawley）大鼠48只,6～8周龄,雄性,体重180～200g。随机分为三组,即正常对照组（Nave组：n=16,分7、14d亚组,每亚组8只）、假手术组（Sham组,n=16,分7、14d亚组,每亚组8只）以及CCI组（n=16,分7、14d亚组,每亚组8只）。按Bennet和Xie方法制作CCI模型,通过von Frey测定大鼠神经结扎侧（左侧）及对侧（右侧）后足缩足反射阈值（Mechanical withdrawal threshold,MWT）。结果：与假手术组和正常对照组比较,CCI组大鼠术侧痛阈在术后第3、6、8、10、13天明显降低,且低于术前基础值。结论：CCI大鼠行为学的改变与痛阈的变化有一定联系。     

天麻素对神经病理性疼痛大鼠的镇痛作用及其机制研究

目的探讨天麻素对神经病理性疼痛大鼠的镇痛作用及其机制,为临床开发新的镇痛药物奠定基础。方法 SD大鼠随机分为坐骨神经慢性压迫性损伤组(n=32)和假手术组(n=8),自术后第8天分别腹腔注射天麻素治疗,用电子Von-Frey测痛仪测定大鼠机械缩足反射阈值,热痛刺激仪测定大鼠热痛缩足反应潜伏期。取脊髓腰膨大及L4/L6背根神经节,采用Western blotting法测定脊髓背角和背根神经节p-ERK1/2的表达。结果与假手术组相比,对照组和天麻素治疗组各时点机械缩足反射阈值降低、热痛缩足反应潜伏期缩短,脊髓背角及背根神经节p-ERK1/2均出现表达上调(P<0.05);与对照组相比,天麻素治疗组在给药后7 d机械缩足反射阈值回升、热痛缩足反应潜伏期延长;在给药14 d后脊髓背角及背根神经节p-ERK1/2表达下调(P<0.05)。结论天麻素可减轻大鼠神经病理性痛,其机制可能与抑制脊髓背角和背根神经节p-ERK1/2通路激活有关。     

白细胞介素-6在大鼠切割痛后脊髓中的表达和作用

目的探讨白细胞介素-6（IL-6）在大鼠切割痛后脊髓中的表达及作用。方法采用纵行切割大鼠后足作为疼痛模型，取切割后不同时间点（1、6、24、72h）及假手术组（未行手术组）大鼠腰髓节段采用实时定量PCR的方法观察IL-6mRNA的水平，并运用免疫组织化学与免疫荧光双标染色的方法，观察IL-6在腰段脊髓的表达及细胞定位；鞘内注射IL-6抗体中和内源性IL-6后，采用VonFrey尼龙纤维刺激后足以检测大鼠后足机械痛敏。结果大鼠后足切割1、6、24h后，其同侧腰段脊髓IL-6mRNA水平较假手术组分别上调1．43、1．74及1．46倍（t=3．315，P=0．016；t=5．121，P=0．0022；t=2．933，P=0．026），免疫组织化学结果显示切割后6hIL-6在切割侧腰段脊髓后角表达明显增加（t=4．496，P〈0．05），并且主要表达于神经元和内皮细胞中；鞘内给予IL-6抗体可明显增加大鼠后足切割后的缩足阈值。结论IL-6可能参与了大鼠后足切割后机械痛敏的过程，抑制IL-6的表达上调可能成为术后疼痛治疗的新靶点。     

鞘内反复注射布托啡诺对神经源性疼痛大鼠脊髓c-fos表达的影响

目的观察布托啡诺反复鞘内注射对神经源性疼痛大鼠脊髓c-fos的影响，探讨布托啡诺鞘内注射治疗神经源性疼痛的可行性。方法30只SD大鼠随机分为3组，即空白对照组（C组，n=10），模型组（M组，n=10），实验组（B组，n：10）。B组和M组鞘内置管，右肢制备坐骨神经慢性压迫损伤模型。术后第6天开始布托啡诺12μg/10μl鞘内注射，连续给药7d。第12天于给药2h后大鼠灌注固定，采用免疫组化方法检测脊髓背角Fos蛋白。结果B组大鼠2只导管脱出。与C组相比。M组和B组Fos阳性神经细胞明显增加，差异有统计学意义（P〈0．01）；与M组相比，B组Fos阳性神经元明显降低（P〈0．01）。结论布托啡诺反复鞘内给药可以通过减少脊髓Fos表达而发挥镇痛作用，布托啡诺可以通过反复鞘内给药治疗神经源性疼痛。     

Lewis肺癌细胞构建小鼠股骨骨癌痛行为模型

目的 观察骨癌痛行为模型小鼠影像学改变和骨质损害程度.方法 将Lewis肺癌细胞接种于雄性C57BL/6小鼠股骨骨髓腔,构建骨癌痛动物行为模型.术后7 d始隔日观察小鼠自发痛反应、测定行走评分与热缩腿反射潜伏期.术后第7、15、23天,行双侧后肢X线摄片,评估肿瘤诱发的骨组织破坏程度.同时取术侧后肢行苏木精-伊红(HE)染色后观察骨质破坏情况,术后23 d另取腰段脊髓做神经胶质酸性蛋白(GFAP)免疫组化检查.结果 实验组接种后第11d左右出现明显自发痛行为,表现为自发抬足时间延长;第13天左右出现明显行走诱发患肢痛和热痛敏现象,表现为使用评分持续下降与缩腿潜伏期显著降低.术后23 d放射学结果显示,术侧股骨下段骨髓腔消失,骨皮质中断.同时HE染色可见肿瘤细胞充满骨髓腔,且穿破骨皮质向外生长,侵犯周围肌肉组织.免疫组化结果示术侧腰段脊髓星形胶质细胞增生、肥大.结论 采用Lewis肺癌细胞构建小鼠骨癌痛模型是可行的.     

氯胺酮对疼痛抑郁共病大鼠海马ERK/CREB信号通路的影响

目的研究氯胺酮对疼痛抑郁共病大鼠海马ERK/CREB信号通路的影响。方法将38只大鼠随机分为对照组(n=10)和造模组(n=28),造模组采用牛Ⅱ型胶原-完全弗氏佐剂注射。采用机械缩足反应阈值测定(MWT)、强迫游泳实验(FST)判断造模成功后,将模型组随机平均分为氯胺酮组和生理盐水组。采用MWT、FST检测氯胺酮对疼痛抑郁共病的治疗作用。采用免疫印迹法检测大鼠海马组织中磷酸化的ERK1/2、CREB蛋白表达量。结果与生理盐水组比较,氯胺酮组大鼠的FST不动时间缩短,MWT阈值增加(P均<0.05)。氯胺酮组大鼠海马p ERK1/2、p CREB表达量均明显高于生理盐水组(P<0.05)。结论氯胺酮能够有效改善疼痛抑郁共病大鼠的疼痛及抑郁症状,其作用机制可能与海马ERK/CREB信号通路有关。     

烟碱提取物对心肌缺血大鼠痛阈影响及心脏保护作用研究

目的:探讨烟碱提取物对大鼠心肌缺血后心电图(ECG)、热痛阈(PWL)、机械痛阈(PWT)、丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-Px)的影响.方法:30只SD大鼠随机分成假手术组、缺血组、烟碱提取物组,除假手术组,另两组复制缺血模型用结扎左冠状动脉手术的方式.烟碱提取物组在缺血模型建成后持续灌胃28 d,检测...     

游泳训练对三甲基氯化锡致记忆障碍模型小鼠学习记忆的影响

目的探讨游泳训练对三甲基氯化锡(TMT)致记忆障碍模型小鼠学习记忆能力的影响及其机制。方法 6~9周龄BALB/c小鼠随机分为生理盐水对照组、TMT组、(生理盐水+训练)组、(TMT+训练)组(前两组各20只,后两组各10只),均腹腔注射给药;前两组不做游泳训练,后两组自给药24 h后,连续进行游泳训练7 d;用Morris水迷宫检测给药后24 h及第8 d小鼠学习记忆能力,采用Western blot法检测给药后24 h及第8 d小鼠海马脑区生长相关蛋白(GAP-43)、突触囊泡蛋白(SYP)。结果给药后24 h及第8 d,与生理盐水组相比,TMT组小鼠逃逸潜伏期明显延长(P<0.05);给药后第8d,与生理盐水组及(生理盐水+训练)组相比,(TMT+训练)组小鼠逃逸潜伏期差异无统计学意义(P>0.05);给药后24 h,与生理盐水组相比,TMT组海马脑区SYP表达降低(P<0.05),GAP-43表达差异无统计意义(P>0.05);给药后第8 d,与TMT组相比,(TMT+训练)组海马脑区GAP-43和SYP表达增加(P<0.05);与(生理盐水+训练)组相比,(TMT+训练)组海马脑区GAP-43、SYP表达差异均无统计学意义(P>0.05)。结论游泳训练有改善TMT致记忆障碍模型小鼠学习记忆能力的作用,其机制可能与海马脑区GAP-43和SYP表达增加有关。     

营养

0330 30　银杏叶提取物对坐骨神经损伤后运动神经元超微结构的影响 /薛　锋…∥复旦学报 (医学版 ) 2 0 0 2 ,2 9( 2 ) 138～ 14 1研究银杏叶提取物 (EGb76 1)对大鼠坐骨神经损伤后脊髓前角运动细胞超微结构的影响。SD大鼠 18只 ,随机分成两组 ,银杏叶提取物 (EGb76 1)组和生理盐水 (SAL)组。切断大鼠坐骨神经并将神经远近端分别反折结扎 ,术后经腹腔分别注射EGb76 1( 10 0mg (kg·d)和同体积的SAL ,于 2、4、6周取材L4～ 6 节段脊髓 ,电镜下观察前角大型运动神经元细胞核及细胞器的超微结构形态变化 ,用体视学方法计算每张照片线…     

Withdrawal from free-choice ethanol consumption results in increased packing density of glutamine synthetase-immunoreactive astrocytes in the prelimbic cortex of alcohol-preferring rats

Excess activation of glutamatergic neurotransmission in the cerebral cortex following ethanol withdrawal is considered to contribute to significant behavioural disturbances, and to alcohol craving. Astrocytes may play a role in these manifestations because astrocytes are essential in the regulation of released glutamate and its conversion to glutamine through the enzyme glutamine synthetase (GS). However, it is unclear if withdrawal from free-choice ethanol drinking causes changes in the numbers of astrocytes expressing GS or the cytoskeletal protein of astrocytes glial fibrillary acidic protein (GFAP). Alcohol-preferring (P) rats exposed to free-choice ethanol drinking were either maintained without forced interruption of ethanol drinking, subjected to a 3-day withdrawal period at the end of 2 months, or subjected to three 3-day withdrawal periods along 6 months. At 2 months, P rats were also compared with alcohol-na?ve alcohol non-preferring rats (NP) rats. Packing density of GS and GFAP-immunoreactive (IR) astrocytes was measured in sections from the prelimbic cortex (PLC) using the optical disector probe. An alcohol deprivation effect was observed in P rats with withdrawals during a 6-month ethanol drinking period. Ethanol withdrawal significantly increased the packing density of GS- and GFAP-IR astrocytes in the PLC of P rats as compared with P rats with continuous access to ethanol. In addition, there was a positive correlation between the pre-withdrawal ethanol consumption and the packing density of GS-IR astrocytes. The present results suggest the involvement of astrocytes in the regulation of the glutamatergic activation associated with withdrawal from free-choice ethanol consumption and point to differential adaptations of GS and GFAP to prolonged alcohol drinking in the PLC of P rats.     

The thermal work limit is a simple reliable heat index for the protection of workers in thermally stressful environments

BACKGROUND: Workers in many industries are exposed to thermally stressful work environments. Protection of the health of workers without unnecessarily compromising productivity requires the adoption of a heat index that is both reliable and easy to use. OBJECTIVES: To evaluate the Thermal Work Limit (TWL), in a controlled environment and under field conditions, against these criteria. METHODS: Volunteers performed graded work in a controlled thermal environment to determine the limiting workload for the conditions. Core temperature and heart rate were monitored as indicators of thermoregulation. In the field study, outdoor workers were monitored for signs of physiological strain in thermal environments which were characterized using both the traditional Wet Bulb Globe Temperature (WBGT) and the TWL. Abilities of each of these indices to accurately reflect the thermal stress on workers were evaluated. RESULTS: In the controlled environment, the TWL was found to reliably predict the limiting workload. In the field study, TWL was a more appropriate and realistic index than WBGT, which was found to be excessively conservative. CONCLUSIONS: The results confirm previously published studies evaluating TWL in underground environments, which have led to its widespread adoption in the Australian mining industry. The study extends the applicability of TWL to outdoor environments and generates management guidelines for its implementation.     

Attenuation of ethanol withdrawal signs by high doses of L-arginine in rats

AIMS: Effects of l-arginine, a nitric oxide (NO) precursor, on ethanol withdrawal syndrome were investigated in rats. METHODS: Ethanol (7.2% v/v) was given to rats by a liquid diet for 16 days. l-Arginine (250, 500 and 1000 mg/kg) or saline were injected into rats intraperitoneally 20 min before ethanol withdrawal. All injections were repeated 30 min before the 6th h of the observation period. The effects of l-arginine on ethanol withdrawal syndrome were evaluated during the first 6 h of ethanol withdrawal. RESULTS: l-Arginine (250 mg/kg) potentiated significantly vertical and ambulatory locomotor activities at only the 30th minute of the observation period. l-Arginine (500 and 1000 mg/kg) inhibited behavioural signs of ethanol withdrawal significantly. l-Arginine (1000 mg/kg) also prolonged the latency and attenuated the intensity of audiogenic seizures. This dose of l-arginine also reduced both vertical and ambulatory locomotor hyperactivity of the rats from the 2nd hour of ethanol withdrawal. l-Arginine (1000 mg/kg) did not produce any significant change in the locomotor activities of the naive (non-ethanol-dependent) rats. CONCLUSIONS: Our results indicate that l-arginine at high doses alleviates the signs of ethanol withdrawal syndrome in rats.     

The effects of chronic ethanol consumption and ethanol withdrawal on serum cholinesterase activity in rats

AIMS: The effect of chronic ethanol consumption and ethanol withdrawal on serum cholinesterase (ChE) activity was investigated in female Wistar rats. METHODS: Ethanol was administered by a modified liquid diet with 4.8% (v/v) ethanol for 3 days followed by 25 days on a liquid diet in which the ethanol concentration was increased to 7.2%. Control rats were pair-fed with an isocaloric liquid diet not containing ethanol. The blood ethanol concentration and serum ChE activity were measured at the end of the 4.8% ethanol consumption period; after 7, 14 and 35 days of ethanol (7.2%) consumption, and at 24 and 72 h after ethanol withdrawal following ethanol consumption of 35 days. RESULTS: Daily ethanol consumption of the rats ranged from 11.5 to 14.9 g/kg. Serum ChE activity was found significantly increased from the 3rd day of ethanol (4.8%) consumption. Serum ChE activities of the rats receiving 7.2% ethanol also increased significantly compared with rats ingesting 4.8% ethanol. Blood ethanol levels were measured as 121 and 0.88 mg/dl on the 35th day of ethanol (7.2%) consumption (just before ethanol withdrawal) and after 24 h of ethanol withdrawal, respectively. Increased serum ChE activity (1968 U/l) was still observed (1942 U/l) after 24 h of ethanol withdrawal. ChE activity returned to control levels (501 U/l) after 72 h of ethanol withdrawal. Audiogenic seizures indicating development of physical dependence on ethanol were also observed after 8 h of ethanol withdrawal in another individual group of ethanol-fed rats. CONCLUSIONS: Our results show that serum ChE activity is increased by chronic ethanol consumption in rats and that this increase is affected by ethanol concentration and duration of ethanol ingestion.     

Sensitization to 5-HT1C receptor agonist in rats observed following withdrawal from chronic ethanol

Anxiogenic action of m-chlorophenylpiperazine (mCPP), a 5-HT_1C receptor agonist, was studied in naive rats and in ethanol-tolerant rats following withdrawal from chronic ethanol administration. The purpose of this investigation was to determine whether a sensitization to mCPP develops during withdrawal from chronic ethanol. Male Long-Evans hooded rats were fed a liquid diet containing 4.5% ethanol or dextrin (as control) for four days. Twelve hours (acute withdrawal) or 4 days (protracted withdrawal) after the last dose of ethanol, rats were injected with saline or mCPP (0.08–5.0 mg/kg) and were tested in the elevated plus-maze 15 min postinjection. A reduction in percent open-arm activity, indicative of anxiogenic behavior, was observed in ethanol-treated rats injected with saline. Administration of mCPP further reduced the percent open-arm entries and time in ethanol-withdrawn rats. An eightfold reduction in maximum effective dose of mCPP was observed during acute ethanol withdrawal as compared to that in naive rats. During protracted ethanol withdrawal the maximum effective dose of mCPP was reduced by 75%. A shift of the mCPP dose-response curve to the left following withdrawal from chronic ethanol may indicate that 5-HT_1C receptor sites are more sensitive to the activation by an agonist. This effect may be exploited in developing specific 5-HT_1C receptor antagonists for the treatment of ethanol withdrawal symptoms.     

Ethanol withdrawal in rats is attenuated by intracerebroventricular administration of neuropeptide Y

AIMS: The effects of intracerebroventricular administration of neuropeptide Y (NPY) on ethanol withdrawal were studied in rats. METHODS: Ethanol was administered intragastrically five times daily for 4 days. At 16-17 h after the last infusion of ethanol, rats were rated for withdrawal using a score based on three signs: irritability, tremor and rigidity. Subsequently, the rats received an injection of NPY (12 or 24 nmol) or vehicle and were rated for signs of withdrawal. RESULTS: At both doses, NPY significantly reduced ethanol withdrawal, the effect of the larger dose being more pronounced. CONCLUSIONS: Our results are consistent with the concept that NPY receptors are centrally involved in the regulation of neuronal excitability and might form a novel therapeutic target for treatment of ethanol withdrawal and other states of neuronal hyperexcitability.     

Limiting metabolic rate (thermal work limit) as an index of thermal stress

The development of a rational heat stress index called thermal work limit (TWL) is presented. TWL is defined as the limiting (or maximum) sustainable metabolic rate that euhydrated, acclimatized individuals can maintain in a specific thermal environment, within a safe deep body core temperature (< 38.20 degrees C) and sweat rate (< 1.2 kg/hr(-1)). The index has been developed using published experimental studies of human heat transfer, and established heat and moisture transfer equations through clothing. Clothing parameters can be varied and the protocol can be extended to unacclimatized workers. The index is designed specifically for self-paced workers and does not rely on estimation of actual metabolic rates, a process that is difficult and subject to considerable error. The index has been introduced into several large industrial operations located well inside the tropics, resulting in a substantial and sustained fall in the incidence of heat illness. Guidelines for TWL are proposed along with recommended interventions. TWL has application to professionals from both the human and engineering sciences, as it allows not only thermal strain to be evaluated,. but also the productivity decrement due to heat (seen as a reduced sustainable metabolic rate) and the impact of various strategies such as improved local ventilation or refrigeration to be quantitatively assessed.     

Comparison of two intravenous infusion schedules for inducing physical dependence upon ethanol in rat

Male hooded rats were implanted with intravenous (IV) cannulas and housed in operant chambers. The effectiveness of two infusion schedules for producing physical dependence upon ethanol was assessed. Twenty-three rats (12 ethanol, 11 control) were tested under a 4 hr interinfusion schedule (one infusion every 4 hr, around the clock), and 29 rats (15 ethanol, 14 control) were tested under a 2 hr interinfusion schedule. During the dependence induction phase, which lasted for 6 days, the experimental rats received ethanol (30% v/v) at an average daily dose which ranged from 8.4-11.8 g/kg, and the dose administered per infusion was adjusted according to the degree of intoxication of each animal. The pair-fed control subjects received infusions of isocaloric control solutions (either 29% v/v propylene glycol or 31% v/v glycerol). Following the dependence induction phase, ethanol was withdrawn, and withdrawal symptoms were assessed. Blood ethanol levels (BEL) and signs of intoxication were determined through all phases of the experiment. During the dependence induction phase, mortality was close to zero, and weight loss was held to about 10%. Tolerance to ethanol developed in all experimental rats. During the withdrawal period, all ethanol rats developed clear withdrawal symptoms, while control subjects did not. Ethanol elimination rates ranged between 45-50 mg/dl/hr and withdrawal symptoms began when BEL fell below 200 mg/dl, and were severe when BEL approached zero. The 2 hr schedule proved superior to the 4 hr schedule in that it led to greater stability of BEL during dependence induction, and a tendency for the withdrawal reaction to be more severe.(ABSTRACT TRUNCATED AT 250 WORDS)     

Anxiogenic behavior in rats during acute and protracted ethanol withdrawal: reversal by buspirone.

This study investigated the effectiveness of buspirone in reversing the anxiogenic behaviors occurring during ethanol withdrawal as measured in the elevated plus-maze. In response to anxiogenic drugs, rats spend less time in and make fewer entries onto the open arms of an elevated plus-maze, whereas anxiolytic drugs produce opposite effects. In this study, rats were fed a liquid diet containing 4.5% ethanol for 7 days. Twelve h (acute withdrawal) and 7 days (protracted withdrawal) following cessation of the ethanol diet, rats were tested on the elevated plus-maze. During these withdrawal periods, the percent open-arm entries and time spent on the open arms were significantly reduced relative to animals fed an ethanol-free diet, suggestive of anxiogenic-like symptoms. Buspirone (0.32-1.25 mg/kg) dose dependently reversed the withdrawal-induced decreases in open-arm activity. The anxiolytic-like activity of buspirone observed during ethanol withdrawal may be due to a reduction in serotonergic neurotransmission through activation of presynaptic 5-HT1A autoreceptors. The results obtained in this study suggest that pharmacotherapy with selective 5-HT1A agonists may be beneficial in alleviation of anxiety during ethanol withdrawal.