Isoflurane preconditioning protects motor neurons from spinal cord ischemia: its dose-response effects and activation of mitochondrial adenosine triphosphate-dependent potassium channel

We examined in a rabbit model of transient spinal cord ischemia (SCI) whether isoflurane (Iso) preconditioning induces ischemic tolerance to SCI in a dose-response manner, and whether this effect is dependent on mitochondrial adenosine triphosphate-dependent potassium (K(ATP)) channel. Eighty-six rabbits were randomly assigned to 10 groups: Control group (n=8) received no pretreatment. Ischemic preconditioning (IPC) group (n=8) received 5 min of IPC 30 min before SCI. The Iso 1, Iso 2 and Iso 3 groups (n=10, 9, 8) underwent 30 min of 1.05, 2.1 and 3.15% Iso inhalation commencing 45 min before SCI. The Iso 1HD, Iso 2HD and Iso 3HD groups (n=9, 9, 8) each received a specific mitochondrial K(ATP) channel blocker, 5-hydroxydecanoic acid (5HD, 20mg/kg), 5 min before each respective Iso inhalation. The 5HD group (n=8) received 5HD without Iso inhalation. The sham group (n=9) had no SCI. SCI was produced by infra-renal aortic occlusion via the inflated balloon of a Swan-Ganz catheter for 20 min. The Iso 1, Iso 2 and Iso 3 groups showed a better neurologic outcome and more viable motor nerve cells (VMNCs) in the anterior spinal cord 72 h after reperfusion than the control group (p<0.05). Iso 3 group showed a better neurologic outcome and more VMNCs than Iso 1 group (p<0.05). And, the Iso 1, Iso 2 and Iso 3 groups showed a better neurologic outcome and higher VMNC numbers than the corresponding Iso 1HD, Iso 2HD and Iso 3HD groups (p<0.05). This study demonstrates that Iso preconditioning protects the spinal cord against neuronal damage due to SCI in a dose-response manner via the activation of mitochondrial K(ATP) channels.     

Delayed preconditioning effect of isoflurane on spinal cord ischemia in rats

Paraplegia is one of the most common complications following aortic aneurysmal surgery. This study was designed to determine if isoflurane-induced delayed preconditioning is mediated by nuclear factor kappaB (NF-kappaB) in the rat spinal cord. The animals were divided into four groups: the control group, the pyrrolidinedithio carbamate (PDTC, an NF-kappaB inhibitor)-treated group, the isoflurane-treated group, and the PDTC/isoflurane-treated group. In the PDTC-treated groups, 2% 100mg/kg PDTC was administered intraperitoneally at 1h before operation and at 24h and 48 h after reperfusion. The rats in the isoflurane-treated groups received 30 min inhalation of 2.8% isoflurane at 24h before spinal cord ischemia. Pretreatment with NF-kappaB inhibitor significantly reduced NF-kappaB expression and the number of intact motor neurons when compared to the control group. Preconditioning with isoflurane increased the number of normal motor neurons, whereas pretreatment with both PDTC and isoflurane significantly decreased them, compared to the isoflurane-treated group. Isoflurane-induced delayed preconditioning on spinal cord ischemia improved histopathological outcomes. This neuroprotective effect of isoflurane preconditioning on spinal cord ischemia is associated with NF-kappaB expression.     

Cardiac sodium/calcium exchanger preconditioning promotes anti-arrhythmic and cardioprotective effects through mitochondrial calcium-activated potassium channel

Background: Reverse-mode of the Na⁺/Ca²⁺ exchanger (NCX) stimulation provides cardioprotective effects for the ischemic/reperfused heart during ischemic preconditioning (IP). This study was designed to test the hypothesis that pretreatment with an inhibitor of cardiac delayed-rectifying K⁺ channel (I_Kr), E4031, increases reverse-mode of NCX activity, and triggers preconditioning against infarct size (IS) and arrhythmias caused by ischemia/reperfusion injury through mitoK_Ca channels. Materials and methods: In the isolated perfused rat heart, myocardial ischemia/reperfusion injury was created by occlusion of the left anterior descending coronary artery for 30 min followed by 120 min reperfusion. Two cycles of coronary occlusion for 5 min and reperfusion were performed, or pretreatment with E4031 or sevoflurane (Sevo) before the 30 min occlusion with the reversed-mode of NCX inhibitor (KB-R7943) or not. Results: E4031 or Sevo preconditioning not only markedly decreased IS but also reduced arrhythmias, which was significantly blunted by KB-R7943. Furthermore, these effects of E4031 preconditioning on IS and arrhythmias were abolished by inhibition of the mitoK_Ca channels. Similarly, pretreatment with NS1619, an opener of the mitoK_Ca channels, for 10 min before occlusion reduced both the infarct size and arrhythmias caused by ischemia/reperfusion. However, these effects weren’t affected by blockade of the NCX with KB-R7943. Conclusion: Taken together, these preliminary results conclude that pretreatment with E4031 reduces infarct size and produces anti-arrhythmic effect via stimulating the reverse-mode NCX, and that the mitoK_Ca channels mediate the protective effects.     

Bradykinin preconditioning induces protective effects on the spinal cord ischemic injury of rats

The study was performed to investigate the effects of bradykinin preconditioning on spinal cord ischemic injury using an in vivo transient spinal cord ischemia model in rats. Prior to ischemia, bradykinin was infused continuously via the left femoral artery starting 15min before ischemia. Neurological functions were evaluated for 7 days postoperatively using modified Tarlov's scores. Tarlov's score outcomes showed a marked improvement in the bradykinin group compared to the ischemia group. The blood-spinal cord barrier (BSCB) permeability was also decreased by bradykinin preconditioning after 72 h reperfusion focal spinal cord in rats, which was greatly reversed by B9430 (bradykinin B2 receptor antagonist). Immunohistochemical and Western blot analysis of spinal cords revealed a significant increase in basic fibroblast growth factor protein (bFGF) levels. The study demonstrated that bradykinin preconditioning induces protection against spinal cord ischemic injury, and this protection is likely due to the protection of the vasculature of the spinal cord and the promotion of neuronal survival.     

缺血预处理快速效应对兔急性缺血脊髓的保护作用

目的:探讨缺血预处理快速相对兔腹主动脉短暂阻断致缺血脊髓的保护作用。方法:36只雄性新西兰兔随机分成3组(n=12):即缺血再灌注损伤组(IR组)、缺血预处理组(IPC+IR组)及假手术组(Sham组)。IR组阻闭兔腹主动脉肾下段20min,复制兔脊髓缺血损伤模型;IPC+IR组预先阻闭腹主动脉肾下段6min,再灌注30min后再次阻闭腹主动脉肾下段20min;Sham组除不夹闭腹主动脉外,其余处理同IR组。再灌注后8h、12h、24h和48h分别对动物神经功能评分,然后,处死动物取脊髓(L_5-7),分别行组织病理学观察及测定脊髓组织中Na⁺,K⁺-ATP酶的活性。结果:Sham组及IPC+IR组神经功能评分各时点均明显高于IR组(P＜0.01);Sham组及IPC+IR组脊髓前角正常神经细胞数明显多于IR组(P＜0.01);Sham组及IPC+IR组脊髓组织中Na⁺,K⁺-ATP酶的活性明显高于IR组(P＜0.01)。结论:缺血预处理快速相对兔急性缺血脊髓有显著的保护作用,这种保护作用可能与稳定Na⁺,K⁺-ATP酶的活性有关。     

Ischemic preconditioning suppresses apoptosis of rabbit spinal neurocytes by inhibiting ASK1-14-3-3 dissociation

The mechanism by which a brief episode of sublethal ischemia followed by reperfusion (ischemic preconditioning, IPC) prevents the lethal effects of subsequent periods of prolonged ischemia, are poorly understood. A completely randomized, controlled study was designed to study the effect of IPC using a rabbit model of ischemic spinal cord injury. Twenty-four white adult New England rabbits were randomly assigned to one of 3 groups (n=8 per group); the groups were assigned as follows: Group I: sham-operation group, Group II: ischemic reperfusion (I/R) group, and Group III: ischemic preconditioning group. Spinal cord ischemia was induced by introducing an infra renal aortic cross-clamp for 30min. Following injury, rabbits were subjected to 30min, 2h, or 8h of reperfusion in Group II. In Group III, subjects underwent three cycles, 5min each, of ischemia followed by 5min of reperfusion, before receiving 30min of ischemia. We previously reported that the association between ASK1 (apoptosis signal-regulating kinase 1) and 14-3-3 played an important role in regulating ischemia/reperfusion spinal cord injuries. To evaluate the effect of ischemic preconditioning in injured spinal cords, we examined alterations in spinal tissue morphology, activation of key members of the ASK1-mediated signaling pathway, and the association between ASK1 and 14-3-3. Changes in spinal cord morphology were observed with hematoxylin and eosin (H&E) staining and electron microscopy. The phosphorylation levels of ASK1, JNK, and p38 were assessed by immunoblot analysis. The association between ASK1 and 14-3-3 was analyzed by co-immunoprecipitation experiments. We observed that swelling of the neurocyte bodies and hemorrhage of the spinal cord were dramatically decreased in Group III compared to Group II. In addition, the degree of apoptosis among neurocytes was reduced in Group III compared to Group II. Finally, the phosphorylation of ASK1, JNK, p38 and the dissociation of ASK1 from 14-3-3 were dramatically decreased in Group III compared with Group II. These results indicate that ischemic preconditioning may have a protective affect against ASK1/14-3-3 dissociation-induced spinal cord injuries.     

吡格列酮对异氟醚麻醉引起的老年小鼠认知功能损伤的影响*

 目的：研究高选择性的过氧化物酶体增殖物激活受体γ（PPARγ）激动剂吡格列酮（Pi）对异氟醚引起的老年小鼠认知功能障碍和脑内炎症细胞因子的影响。方法：136只11个月大的雄性C57BL/6J 小鼠随机分成5组：对照组（Con）、异氟醚组（Iso）、吡格列酮（10 mg/kg）+异氟醚组（Pi10+Iso）、吡格列酮（20 mg/kg）+异氟醚组（Pi20+Iso）和单纯吡格列酮（20 mg/kg）组（Pi20）。各异氟醚处理组的小鼠吸入混合1.4%异氟醚的氧气2 h;Con和Pi20组的小鼠仅吸入氧气2 h。吡格列酮溶于1%的羧甲基纤维素钠（CMC）,在小鼠吸入异氟醚或单纯氧气前2 h,按10 mg/kg或20 mg/kg灌胃,Con组和Iso组小鼠仅给予相同容量的1% CMC。在异氟醚处理结束后48 h行恐惧记忆实验以检测小鼠的学习记忆功能;6 h时取部分小鼠分离皮质和海马行Western blotting检测PPARγ蛋白及ELISA法检测脑组织IL-1β和TNF-α水平。结果：与Con组比较,Iso组的僵住行为减少（P<0.05）,海马IL-1β水平增加 （P<0.05）;与Iso组比较,Pi10+Iso组的僵住行为和PPARγ蛋白表达无明显变化（P>0.05）,而Pi20+Iso组的僵住行为和PPARγ蛋白表达均明显增加（P<0.05）且海马中IL-1β水平降低（P<0.05）。各组海马和皮质TNF-α水平以及皮质中IL-1β水平无明显差异（P>0.05）。结论：吡格列酮可以减轻异氟醚引起的老年小鼠的认知功能障碍,并可以缓解异氟醚引起的小鼠海马IL-1β含量的增加。     

Emulsified isoflurane postconditioning produces cardioprotection against myocardial ischemia–reperfusion injury in rats

Emulsified isoflurane (EIso) preconditioning can induce cardioprotection. We investigated whether EIso application after ischemia protects hearts against reperfusion injury and whether it is mediated by the inhibition of apoptosis. Rats were subjected to 30-min coronary occlusion followed by 180-min reperfusion. At the onset of reperfusion, rats were intravenously administered saline (sham, control group), 30 % intralipid (IL group) or 2 ml kg^?1 EIso (EIso group) for 30 min. After reperfusion, infarct sizes, myocardial apoptosis and expression of Bcl-2, Bax and caspase-3 proteins were determined. Hemodynamic parameters were not different among groups. Compared with control and intralipid group, EIso limited infarct size, inhibited apoptosis, increased the expression of Bcl-2, decreased the expression of Bax, cleaved caspase-3, and enhanced Bcl-2/Bax ratio. EIso protects hearts against reperfusion injury when administered at the onset of reperfusion, which may be mediated by the inhibition of apoptosis via modulation of the expression of pro- and anti-apoptotic proteins.     

大鼠脊髓缺血再灌注损伤后caspase-12表达与细胞凋亡

目的:观察大鼠脊髓缺血再灌注损伤过程中细胞凋亡、caspase-12的表达变化规律,以探讨其分子机制。方法:采用自制压迫装置制备脊髓压迫缺血再灌注模型。运用形态学、分子生物学等方法,分别于缺血再灌注后3、7、11、23和47h,观察脊髓缺血再灌注损伤后,脊髓的病理变化和内质网的形态学改变、细胞凋亡及caspase-12的表达变化的规律。结果:脊髓缺血再灌注3h后,出现不同程度的细胞肿胀,神经元退行性变及内质网结构变化;随着再灌注时间的延长,神经元和神经胶质细胞凋亡数明显增加,并伴有caspase-12的表达增强;capspase-12表达与细胞凋亡的时空变化规律相一致。结论:在脊髓缺血再灌注过程中神经细胞凋亡是引起脊髓继发性损伤的主要病理因素,caspase-12可能参与了脊髓缺血再灌注损伤所导致的细胞凋亡。     

右美托咪定在大鼠脊髓缺血再灌注损伤中的 保护作用及机制研究

目的 探讨右美托咪定对大鼠脊髓缺血/再灌注损伤的保护作用及PI3K/Akt传导通路在其中的作用。方法 30只成年雄性大鼠随机分为假手术组、模型组和右美托咪定治疗组,每组10只。建立大鼠脊髓缺血/再灌注损伤模型,对再灌注损伤后6 h、12 h、24 h、48 h实验大鼠后肢运动功能进行评分,检测缺血脊髓前角组织中P-AKT的表达水平及神经元的凋亡指数。结果 右美托咪定可改善脊髓缺血/再灌注损伤后实验大鼠的后肢运动功能(P＜0.05);提高脊髓前角P-AKT的表达水平(P＜0.05),抑制缺血/再灌注损伤所致的脊髓神经元的凋亡(P＜0.05)。结论 右美托咪定对脊髓缺血/再灌注损伤有一定的保护作用,其机制可能与激活PI3K/Akt传导通路,从而抑制神经元的凋亡有关。     

Rapid tolerance to focal cerebral ischemia in rats is induced by preconditioning with electroacupuncture: window of protection and the role of adenosine

The aim of the present study was to investigate the first protective window of preconditioning with electroacupuncture (EA) against focal cerebral ischemia, and to explore whether adenosine is involved in the rapid tolerance phenomenon. Sixty-four male Sprague-Dawley rats were randomly assigned to eight groups (n=8 in each). Animals in the control group received no treatment, and animals in EA1-EA4 groups received EA at 0.5, 1, 2 and 3 h before induction of focal cerebral ischemia, respectively. Rats in DPCPX group were intraperitoneally injected with 1 mg kg-1 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), 3 h before induction of focal cerebral ischemia. Animals in vehicle group and EA+DPCPX group were pretreated with 1 ml kg-1 dimethyl sulfoxide (DMSO, the solvent of DPCPX) and 1 mg kg-1 DPCPX 30 min before preconditioning with EA, respectively. All rats were anesthetized with 40 mg kg-1 pentobarbital sodium intraperitoneally. Animals that required EA preconditioning, received EA with intensity of 1 mA and frequency of 15 Hz at the Baihui acupoint (GV 20) for 30 min. The focal cerebral ischemia was produced by the right middle cerebral artery occlusion (MCAO) for 120 min. The neurologic deficit scores (NDS) and brain infarct volumes were evaluated at 24 h after reperfusion. All rats survived until 24 h after reperfusion. Preconditioning with EA at 2 h before induction of focal cerebral ischemia improved neurologic outcome (P<0.05 versus control) and reduced the infarct volume (P<0.01 versus control) at 24 h after reperfusion. These beneficial effects were reversed by pretreatment with 1 mg kg-1 DPCPX, whereas this agent itself did not affect the NDS and volume in drug-ischemic controls after ischemia. The results show that preconditioning with single EA session induces rapid tolerance to focal cerebral ischemia. The rapid ischemic tolerance appears at 2 h (but not at 0.5, 1, or 3 h) after preconditioning, and is possibly mediated through an adenosine A1 receptor-related mechanism.     

低浓度11,12-EET预干预对大鼠心肌缺血/再灌注损伤的影响

目的:观察外源性低浓度 11,12-EET预干预对大鼠在体心肌缺血/再灌注损伤的影响。方法:雄性Wistar大鼠,开胸,结扎和松开冠状动脉左前降支,复制心肌缺血/再灌注模型;采用缺血 5min/再灌注 5min两次造成缺血预处置。实验分 3组:对照组;缺血预处置组;外源性 11,12-EET预干预组。每组再分为A、B 2小组:A组动物心肌缺血 10min/再灌注 10min,主要观察缺血/再灌注各时程之心律失常;B组动物缺血 6 0min/再灌注 30min,主要观察缺血期心律失常、心功能的变化及再灌注后心肌梗死范围。结果:缺血预处置和 11,12-EET(6 2 4× 10^-8mol/L)预干预均可减轻缺血/再灌注心律失常及心功能的变化,降低心肌梗死范围。结论:11,12-EET预干预具有类缺血预处置样的心肌保护作用.     

Bradykinin preconditioning affects the number of degenerated neurons and the level of antioxidant enzymes in spinal cord ischemia in rabbits

Bradykinin preconditioning has been used for acquisition of tolerance after spinal cord ischemia. Rabbits were preconditioned intraperitoneally with bradykinin 48 h prior to 20 min of abdominal aorta ligation followed by 24 and 48 h of reperfusion. The activities of SOD and catalase were measured and Fluoro Jade B (FJB)-positive degenerated neurons were evaluated. The outcomes of Tarlov scoring system used to assess neurological functions showed significant improvement in bradykinin groups compared to the ischemic group. The number of FJB-positive degenerated neurons was decreased in ventral horns of both bradykinin groups. Significantly decreased activities of total SOD and mitochondrial Mn-SOD were also detected in both bradykinin groups versus ischemic group while CuZn-SOD and catalase activities were significantly decreased only in the bradykinin group after 24 h of reperfusion versus ischemic group. These findings suggest that one of the possibilities of the neuroprotective effect of delayed bradykinin preconditioning against spinal cord ischemic injury could be realized by mitochondrial protection and decreased synthesis of Mn-SOD as well as by promotion of neuronal survival.     

右美托咪啶通过抑制p38和JNK活化减少异氟醚诱导的新生大鼠海马神经元凋亡

 目的：探讨右美托咪啶（dexmedetomidine, Dex）对异氟醚（isoflurane, Iso）诱导的新生大鼠海马神经元凋亡的影响及其与p38丝裂原活化蛋白激酶（p38 mitogen-activated protein kinase,p38）和c-Jun 氨基末端激酶（c-Jun N-terminal kinase, JNK）蛋白活化的关系。方法：48只出生后7 d的SD大鼠随机分为对照组（Con组）、Dex组、Iso组和Iso+Dex组。前2组吸入空气,后2组吸入0.75% Iso 6 h。Dex组和Iso+Dex组在麻醉前20 min和麻醉开始后2 h、4 h经腹腔注射25 μg·kg-1 Dex;Con组和Iso组则在相同的时点注射150 μL生理盐水。麻醉结束后使用TUNEL法检测海马神经元凋亡; Western blotting检测海马组织激活型caspase-3、p38、磷酸化p38（p-p38）、JNK和磷酸化JNK（p-JNK）蛋白表达的变化。结果：(1) Iso组海马CA1区TUNEL阳性细胞数较Con组增加447.57%（P<0.01）,Dex抑制Iso诱导的TUNEL阳性细胞增加达75.18%（P<0.01）。(2) Iso组海马组织激活型caspase-3的表达比Con组增加126.29% （P<0.01）;Dex显著抑制了Iso诱导的caspase-3活化（P<0.01）。(3) Iso组海马p-p38/p38和p-JNK/JNK比值均较Con组明显增加（P<0.01）;Dex显著抑制了Iso诱导的p-p38 和p-JNK表达增加（P<0.01）。结论：Dex能通过减少海马神经元凋亡来减轻Iso对新生大鼠的脑毒性。抑制p38和JNK的磷酸化可能是Dex发挥保护作用的机制之一。     

Ubiquitin and endogenous antioxidant enzymes participate in neuroprotection of the rabbit spinal cord after ischemia and bradykinin postconditioning

The aim of this study was to investigate neuroprotective effect of bradykinin postconditioning on the rabbit spinal cord after 20 min of ischemia and 3 days of reperfusion. Bradykinin was administered by single i.p. application at 1, 6, 12 or 24 h after ischemia. Assessment of neurological function of hind limbs (Tarlov score) was estimated. Quantitative analysis was evaluated by Fluoro Jade B method, NeuN and ubiquitin immunohistochemistry in anterior horn neurons of the spinal cord. Histomorphologically distribution of ubiquitin and endogenous antioxidant enzymes (SOD1, SOD2, catalase) immunoreaction was described. Bradykinin postconditioning showed decreased number of degenerated neurons, increased number of surviving neurons and increase in number of ubiquitin positive neurons in all bradykinin postconditioned groups versus ischemia/reperfusion group. According to our results bradykinin postconditioning applied 24 h after ischemia significantly decreased (p < 0.001) number of degenerated neurons versus ischemia/reperfusion group. The least effective time window for bradykinin postconditioning was at 12 h after ischemia. Tarlov score was significantly improved (p < 0.05) in groups with bradykinin postconditioning applied 1, 6 or 24 h after ischemia versus ischemia/reperfusion group. Tarlov score in group with bradykinin application 12 h after ischemia was significantly decreased (p < 0.05) versus sham control group. Neuronal immunoreaction of ubiquitin, SOD1, SOD2 and catalase influenced by bradykinin postconditioning was dependent on neuronal survival or degeneration. In conclusion, bradykinin postconditioning showed protective effect on neurons in anterior horns of the rabbit spinal cord and improved motor function of hind limbs.     

NADPH-diaphorase activity in the spinal cord after ischemic injury and the effects of pretreatment with Ginkgo biloba extract (EGb 761)

Histochemical analysis of NADPH-diaphorase (NADPH-d) activity was performed on segments of the lumbar spinal cord in rabbit after 7 days pretreatment with the Ginkgo biloba extract Tanakan, and 30 min of ischemia followed by 24 h of reperfusion. In sections of the L5 segment of the spinal cord of untreated controls, NADPH-d-positive neurons were identified in the dorsal horns, in the pericentral region and occasionally in the ventral horns. The rabbits were completely paraplegic after 30 min of ischemia and 24 h of reperfusion. High NADPH-d activity was found in the wall of blood vessels in sections of the L5 segment and the numbers of NADPH-d-positive neurons in all sites was moderately elevated. After 7 days of Tanakan pretreatment, 30 min of ischemia and 24 h of reperfusion, the animals did not show paraplegia. Only a light tremor of the hind limbs was observed. NADPH-d activity in blood vessels and neurons was similar to that in controls. In the dorsal horns, NADPH-d positivity in neurons and fibres was increased. Our results indicate that Tanakan can scavenge free radicals produced during ischemia/reperfusion and may reduce reperfusion damage.     

碱性成纤维细胞生长因子对脊髓缺血／再灌注损伤的保护作用

目的观察碱性成纤维细胞生长因子（basic fibroblast growth factor,bFGF）对脊髓缺血／再灌注损伤的保护作用。方法建立大鼠脊髓缺血／再灌注损伤动物模型。实验分对照组、缺血／再灌注组和bFGF组。测定血浆丙二醛、肌酸磷酸激酶、谷草转氨酶和乳酸脱氢酶含量。测定脊髓标本丙二醛、内皮素、细胞线粒体钙含量和组织湿／干重比值。结果缺血／再灌注组与对照组比较,血浆和脊髓的各项生化指标显著增高（P〈0．05）;使用bFGF后,血浆及脊髓各项测定指标较缺血／再灌注组相比明显降低（P〈0．05）。结论bFGF可减轻脊髓缺血／再灌注损伤,对脊髓有保护作用。     

Effects of hypothermia on blood flow and neural activity in rabbit spinal cord during postischemic reperfusion

The effects of hypothermia on blood flow and neural activity were investigated in rabbit spinal cord during the acute phase of ischemia/reperfusion. Rabbits were exposed to ischemia for 10 or 40 min by occluding the abdominal aorta, using a balloon catheter. The body temperature was maintained either at 38 degrees C (normothermia) or 34 degrees C (hypothermia). Hyperperfusion was observed within 10 min after the cessation of ischemia in all rabbits exposed to ischemia. The magnitude of hyperperfusion in spinal cord blood flow (SCBF) was not significantly different between the 10 and 40 min ischemia rabbits, but the time for 50% recovery from the hyperperfusion was longer in the 40 min ischemia group (26.1 +/- 2.5 min) than in the 10 min group (15.1 +/- 2.1 min). The amplitude of evoked spinal cord potential decreased during ischemia and recovered to the baseline level during 8 h of reperfusion in the 10 min ischemia group. However, in the 40 min ischemia group, the amplitude was 40 +/- 8% of the baseline value after 8 h of reperfusion. Hypothermia prevented the delay of recovery from hyperperfusion and the reduction of evoked spinal cord potential. These results suggest that hypothermia plays a beneficial role in protecting tissue injury in the acute phase of ischemia/reperfusion in the spinal cord by shortening the time for recovery from postischemic hyperperfusion.     

他克莫司后处理诱导缺血脊髓对再灌注损伤的耐受*

目的探讨他克莫司后处理能否诱导大鼠缺血脊髓对再灌注损伤的耐受。方法成年雄性SD大鼠30只,随机分为假手术（s0）组、缺血再灌注（IR）组和他克莫司后处理（TP）组,每组10只大鼠,采用经股动脉置管球囊扩张制备脊髓缺血模型,SO组仅行置管,IR组在脊髓缺血20分钟后行再灌注,TP组在脊髓缺血20分钟后再灌注,即刻经左颈总动脉一次性注射他克莫司0．5mg／kg。再灌注后7、14天采用Tarlov评分法检测大鼠后肢运动功能,脊髓组织切片HE染色观察病理学改变。结果SO组大鼠各时间点后肢Tarlov评分均为5分,形态学检测显示脊髓组织结构正常;IR组大鼠Tarlov评分明显降低,脊髓组织呈现出坏死、水肿、空腔形成等缺血再灌注损伤表现;TP组大鼠Tarlov评分结果显著优于IR组,脊髓组织病理变化较IR组为轻。结论建立大鼠脊髓缺血再灌注损伤模型,并初步证实他克莫司后处理能诱导缺血脊髓对再灌注损伤的耐受。     

Isoflurane preconditioning improves short-term and long-term neurological outcome after focal brain ischemia in adult rats

Isoflurane preconditioning improved short-term neurological outcome after focal brain ischemia in adult rats. It is not known whether desflurane induces a delayed phase of preconditioning in the brain and whether isoflurane preconditioning-induced neuroprotection is long-lasting. Two months-old Sprague–Dawley male rats were exposed to or were not exposed to isoflurane or desflurane for 30 min and then subjected to a 90 min middle cerebral arterial occlusion (MCAO) at 24 h after the anesthetic exposure. Neurological outcome was evaluated at 24 h or 4 weeks after the MCAO. The density of the terminal deoxynucleotidyl transferase biotinylated UTP nick end labeling (TUNEL) positive cells in the penumbral cerebral cortex were assessed 4 weeks after the MCAO. Also, rats were pretreated with isoflurane or desflurane for 30 min. Their cerebral cortices were harvested for quantifying B-cell lymphoma-2 (Bcl-2) expression 24 h later. Here, we showed that pretreatment with 1.1% or 2.2% isoflurane, but not with 6% or 12% desflurane, increased Bcl-2 expression in the cerebral cortex, improved neurological functions and reduced infarct volumes evaluated at 24 h after the MCAO. Isoflurane preconditioning also improved neurological functions and reduced brain infarct volumes in rats evaluated 4 weeks after the MCAO. Isoflurane preconditioning also decreased the density of TUNEL-positive cells in the penumbral cerebral cortex. We conclude that isoflurane preconditioning improves short-term and long-term neurological outcome and reduces delayed cell death after transient focal brain ischemia in adult rats. Bcl-2 may be involved in the isoflurane preconditioning effect. Desflurane pretreatment did not induce a delayed phase of neuroprotection.