Mild hypothermia effects on matrix metalloproteinase-9 expression in the perihematomal region of rats following experimental intracerebral hemorrhage**☆

BACKGROUND： Matrix metalloproteinase-9 （MMP-9） expression increases with intracerebral hemorrhage, and participates in the pathophysiological processes of secondary brain injury after intracerebral hemorrhage.
OBJECTIVE： To investigate the effects of mild hypothermia on MMP-9 expression and brain edema in the perihematomal region of experimental intracerebral hemorrhage rats.
DESIGN, TIME AND SETTING： The randomized, controlled experiment was performed at the Central Laboratory of Shandong Provincial Hospital between May and September 2007.
MATERIALS： Seventy-two, Wistar, male rats, 12-weeks old, were used for this study. Rabbit anti-MMP-9 primary antibody was purchased from Boster, China.
METHODS： Wistar rats were equally and randomly divided into normothermia and mild hypothermia groups. The two groups each comprised control, 6-hour intracerebral hemorrhage, 24-hour intracerebral hemorrhage, 48-hour intracerebral hemorrhage, 72-hour intracerebral hemorrhage, and l-week intracerebral hemorrhage subgroups, with six rats in each subgroup. Rat models of intracerebral hemorrhage were established by injecting 100 μL of autologous blood into the rat caudate nucleus. Rats in the mild hypothermia group received four hours of local mild hypothermia immediately following the injection. lntracerebral temperature was maintained at （33 ± 0.5） ℃. Subsequently, intracerebral temperature was spontaneously recovered at 25 ℃. Rats in the control subgroup were not injected with autologous blood and received only with intracerebral hemorrhage.
MAIN OUTCOME MEASURES： Brain water content and MMP-9 expression surrounding the hematoma region. RESULTS： MMP-9 expression increased at 6 hours, and brain edema reached a peak at 48 hours after intracerebral hemorrhage. MMP-9 expression was significantly decreased in the mild hypothermia group compared with the normothermia group at each time point （P 〈 0.05）.
CONCLUSION： Mild hypothermia can significantly inhibit MMP-9 overexpression and reliev     

局部亚低温对大鼠脑出血后基质金属蛋白酶-9及血脑屏障通透性的影响

目的探讨局部亚低温对大鼠自体血注入法脑出血模型基质金属蛋白酶-9(matrix metalloproteinase-9,MMP-9)mRNA及蛋白表达的影响以及局部亚低温减轻脑出血后水肿的可能机制。方法雄性Wistar大鼠240只,随机分为脑出血(ICH)组和脑出血加局部亚低温(ICH H)组。每组分为对照、脑出血后6h、24h、72h、5d、7d共6个亚组,ICH H组于注血后立即给以4h的局部亚低温治疗,各亚组分别进行血脑屏障(BBB)通透性、脑水含量的检测以及应用RT-PCR及Western印记对MMP-9进行测定。结果ICH组大鼠脑内注血后6h开始出现脑组织水含量(P<0.01)及BBB通透性(P<0.05)的显著增加,二者在72h达到高峰,然后逐渐消退,ICH组MMP-9蛋白表达量与脑含水量和血脑屏障通透性呈正相关(r=0.88和r=0.96),ICH组MMP-9 mRNA表达量也与脑含水量和血脑屏障通透性呈正相关(r=0.78和r=0.85)。ICH H组大鼠脑组织水含量、BBB通透性以及MMP-9蛋白的表达与ICH组各时间点相比较,明显降低,而MMP-9 mRNA的表达与ICH组相比仅有轻度下降。结论脑出血后MMP-9的变化与BBB通透性和脑水肿密切相关,局部亚低温可以抑制脑出血后MMP-9蛋白表达的增加以及脑水肿的形成。提示局部亚低温可能通过影响MMP-9的变化来抑制脑出血后的水肿形成。     

亚低温可促进脑出血大鼠内源性神经干细胞的增殖*

背景：亚低温对脑出血后脑组织保护作用的研究多集中在减轻脑水肿方面,对神经干细胞的增殖是否有促进作用研究很少。 目的：观察亚低温对脑出血大鼠血肿周围、侧脑室旁神经干细胞增殖的影响。 方法：采用自体血注入尾状核制作Wistar大鼠脑出血模型,亚低温组于制作模型后给予局部亚低温4 h,对照组给予常温处理。 结果与结论：脑出血后1,3,7,14 d,亚低温组Longa 5分制法评分低于对照组(P < 0.05)。免疫组织化学方法检测亚低温组各时间点血肿周边及侧脑室旁组织的BrdU阳性细胞数明显多于对照组(P < 0.05)。初步提示亚低温处理可以促进干细胞内源性增殖,对脑出血有保护作用。     

局部亚低温对大鼠脑出血后血红素氧合酶1表达的影响

目的观察局部亚低温对大鼠自体血注入法脑出血模型血红素氧合酶(HO-1)表达的影响,探讨局部亚低温减轻脑出血后脑水肿的可能机制。方法雄性Wistar大鼠120只,随机分为脑出血(control)组和脑出血加局部亚低温(LMH)组。每组分为对照和脑出血后6h、24h、72h,5d、7d共6个亚组,亚低温组于注血后给予4h的局部亚低温治疗,应用Evans-blue测定血脑屏障(BBB)通透性,应用干湿重法测定脑水含量以及应用免疫组化对血肿周围脑组织HO-1的表达进行测定。结果对照组大鼠脑组织含水量、BBB通透性以及HO-1表达的增加始于脑出血后6h均至72h达高峰。HO-1表达的变化与脑血肿周围组织水含量的变化成呈正相关(r=0.79)。LMH组的脑组织水含量、BBB通透性和HO-1各时间点与对照组相比明显下降。结论脑出血后红细胞的破坏可以导致HO-1表达上升。局部亚低温可抑制脑出血后HO-1表达,减轻血脑屏障完整性的破坏,减轻脑出血后脑水肿形成。     

亚低温对脑出血后凝血酶受体Ⅰ表达影响的实验研究

目的观察亚低温对大鼠自体血注入法脑出血模型凝血酶受体(PAR-1)表达的影响,探讨亚低温减轻脑出血后脑水肿的可能机制。方法雄性SD大鼠108只,随机分为生理盐水组、脑出血组和脑出血 亚低温组。每组分为脑出血后24h、72h和7d共3个亚组。脑出血 亚低温组于注血后给予6h亚低温治疗。各组于注血后24h、72h和7d断头取脑组织,测定脑水含量(干湿重法),检测脑内血肿周围微血管壁上PAR-1的表达(免疫组化学法)。结果脑出血组血肿周围微血管壁上PAR-1的表达高于生理盐水组(P<0.05)。亚低温组血肿周围微血管壁上PAR-1的表达低于脑出血组(P<0.01)。同时,亚低温组脑水含量在各时间点与脑出血组比较明显下降(P<0.01)。结论脑出血后血肿周围微血管壁上PAR-1的表达增加,其变化与脑水肿的变化一致,说明PAR-1参与了脑出血后脑水肿的形成;亚低温可能通过抑制出血后微血管壁上PAR-1的表达来发挥其脑保护作用。     

大鼠自体动脉血脑出血动物模型的建立

目的:建立大鼠自体动脉血液脑出血模型,研究脑出血后大鼠行为学改变、脑水肿的变化规律。方法:参照Yang、Lee及Hua等方法,应用立体定向技术,用大鼠自体尾动脉不抗凝动脉血液50μl缓慢注入大鼠尾状核,制成中等量脑出血,通过动脉观察其行为学改变和脑水肿的变化规律建立稳定的脑出血动物模型。结果:对32只大鼠脑出血动物模型采用Longa评分法、肢体对称试验评分法、Berderson评分法和平衡木评分法进行评分,结果显示,大鼠脑出血后其行为学改变与对照组有显著性差异。脑出血周围组织含水量明显高于对照组,病变侧高于病变对侧脑组织,以出血后48～72h最明显。结论:大鼠自体动脉血脑出血后有一系列的行为学改变,其行为学改变能够反映脑血肿对神经功能影响的严重程度和病情的轻重,大鼠自体动脉血脑出血动物模型是比较理想的实验性脑出血模型。     

大鼠脑出血周边组织MMP-9、TIMP-1表达对脑水肿的影响

目的:研究大鼠脑出血周边组织基质金属蛋白酶系(MMPs)的成员明胶酶-9(MMP-9)和内源性基质金属蛋白酶抑制物(TIMP-1)表达对脑水肿的影响。方法:Wister大鼠50只随机分为对照组、出血组,各组又分为6、24、48、72、120h等5个时间点。测定脑组织含水量、脑组织示踪剂伊文思蓝(EB)含量和MMP-9、TIMP-1表达。结果:出血后脑组织含水量在72h、EB含量在48h、MMP-9和TIMP-1表达在48h达到高峰,血脑屏障(BBB)在各时间点均有破坏。结论:出血后MMP-9表达可导致BBB通透性增加,TIMP-1通过抑制MMP-9的表达减轻脑水肿。     

亚低温治疗大鼠缺血性脑水肿研究

目的研究亚低温对延迟时间窗再灌注的局灶脑缺血大鼠缺血性脑水肿的治疗作用。方法 SD雄性大鼠96只,线栓法制作大脑中动脉闭塞模型后随机分为缺血3 h组、缺血6 h组、缺血9 h组(每组各30只),分别在造模3 h、6 h和9 h后拔出线栓,使大脑中动脉再灌注。各缺血组按照再灌注后是否给予亚低温治疗及亚低温持续时间分为常温、亚低温3 h和亚低温5 h三个亚组,每个亚组有10只大鼠。另设假手术组6只。缺血组大鼠在再灌注24 h后处死取脑,假手术组在术后24 h处死取脑,干-湿重法测定各组缺血侧脑组织含水量并进行比较。结果与假手术组比较,缺血组缺血侧脑组织含水量明显增高。缺血3 h组中3 h亚低温和5 h亚低温亚组的缺血侧脑组织含水量与缺血3 h常温组比较,差异有统计学意义(79.39%±2.44%vs82.16%±1.50%,P0.05;79.20%±1.55%vs 82.16%±1.50%,P0.05)。其余各缺血组中经过亚低温治疗的大鼠与常温亚组的脑组织含水量无统计学差异。结论亚低温可减轻缺血早期(3 h)再灌注的脑组织水肿,保护缺血脑组织,而对晚期(6 h和9 h)再灌注的缺血性脑水肿无论亚低温时间长短均无明显保护作用。     

亚低温对实验性脑出血后水通道蛋白4表达及脑水肿的影响

目的研究亚低温对脑出血后水通道蛋白4(AQP4)表达及脑水肿的影响,探讨亚低温对出血性脑水肿的作用机制。方法在大鼠苍白球注射胶原酶制作脑出血模型,用冰块降温及白炽灯照射加温的方法调节体温;应用免疫组化方法检测脑组织AQP4表达,采用干湿重法观察脑含水量的动态变化。结果脑出血模型大鼠病灶侧脑含水量、血肿周围AQP4的表达水平明显高于假手术组(均P<0.001);各个时间点亚低温组大鼠病灶侧脑含水量以及血肿周围AQP4的表达水平均明显低于对照组(P<0.05～0.01);AQP4表达水平与脑含水量呈正相关(r=0.977,P<0.001)。结论亚低温能明显减轻脑出血后脑水肿及AQP4的表达,亚低温可能通过抑制AQP4的表达而减轻脑水肿。     

凝血酶对大鼠脑内MMP-9、MMP-2表达的影响

目的探讨凝血酶对大鼠脑内MMP-9、MMP-2表达的影响。方法Wistar大鼠随机分为假手术组及实验组。实验组脑内注入凝血酶,在不同时间点采用干湿重法测脑水含量,免疫组化方法检测脑内MMP-9、MMP-2的表达。假手术组注入等量生理盐水。结果脑组织水含量在凝血酶注入后6h开始增加,3d达高峰。MMP-9阳性细胞在注射凝血酶后6h即开始表达增加,与对照组相比差异显著(P<0.01),3d达高峰,随后持续下降。阳性微血管数也有相似的变化趋势。MMP-2阳性细胞在注射凝血酶后1d才开始有少量表达,后持续增多,5d达高峰,随后有所下降,但14d仍有明显表达,与对照组相比差异显著(P<0.01)。阳性微血管数也有相似的变化趋势。结论凝血酶在脑出血后脑水肿及脑组织损伤中起了关键的作用,MMP-9、MMP-2参与了急性期脑水肿、炎症反应等过程,MMP-2在损伤修复中可能有重要作用。     

普罗布考对大鼠脑出血后MMP-9表达及血-脑屏障通透性的影响

目的讨论普罗布考对大鼠脑出血后基质金属蛋白酶-9(MMP-9)的表达及血-脑屏障通透性的影响。方法采用自体动脉血注入大鼠尾壳核建立脑出血模型,将7 5只大鼠分成对照组、脑出血组、普罗布考组。各实验组分12h、1d、3d、5d、7d五个时间点,每个时间点5只大鼠。分别采用逆转录聚合酶链法(RT-PCR)、蛋白印迹法(Western blot)、伊文思兰染色法测定不同时间点的MMP-9 mRNA、MMP-9蛋白的表达和血-脑屏障通透性的变化。结果 MMP-9 mRNA、MMP-9蛋白的表达和血-脑屏障通透性在脑出血后1d开始升高,3d达到高峰,5d⁷d开始下降。给予普罗布考治疗后,在1d、3d、5d、7d时间点MMP-9蛋白和血-脑屏障通透性明显下调,与脑出血组相比差异有统计学意义(P<0.01),而MMP-9 mRNA无明显变化(P>0.01)。12h时间点MMP-9蛋白和血-脑屏障通透性在普罗布考组与脑出血组差异无统计学意义(P>0.01)。结论普罗布考可以减轻大鼠脑出血后的MMP-9蛋白的高表达,降低血-脑屏障的通透性,从而减轻脑水肿程度。     

微创清除血肿和重组水蛭素治疗脑出血后脑水肿的实验研究

目的探讨微创清除血肿和局部应用重组水蛭素对大鼠出血性脑水肿的治疗作用。方法成年雄性SD大鼠随机分为生理盐水组、脑出血组、微创组、水蛭素组、微创 水蛭素组,治疗时间点统一为出血后3h,以自体血注入大鼠尾状核方法建立脑出血模型,应用干-湿重法观察脑水肿变化,HE染色观察水肿细胞形态。每组每时相点(12h、24h、48h、72h、7d)6只大鼠。结果脑出血组和各治疗组脑含水量与生理盐水组在12h、24h、48h比,P<0.05;7d时各组间无明显差异(P>0.05);微创组与脑出血组组间比较,P>0.05;微创 水蛭素组与脑出血组组间比较,P<0.05。结论脑出血后早期(<3h)分别予以微创清除血肿、局部应用水蛭素及二者联合治疗可显著改善脑水肿,尤其微创与凝血酶抑制剂联合应用为脑出血治疗开辟新途径。     

局部亚低温对脑出血后水肿影响的实验研究

目的探讨局部亚低温对大鼠脑出血后水肿形成的影响及其可能机制。方法雄性Wistar大鼠230只随机分为:对照组;脑出血组;脑出血加局部亚低温组;凝血酶加局部亚低温组。应用Evans-Blue测定血脑屏障(BBB)通透性,应用干湿重法测定脑水含量。结果与对照组相比,大鼠注血后6h开始出现脑组织水含量和BBB通透性的增加,在72h达到高峰,然后逐渐消退。不同时程局部亚低温均可以显著降低脑出血后72h时脑组织水含量及BBB通透性(P<0.01),其中给以4h局部亚低温时,降低最明显。注射凝血酶6h后,脑组织水含量及BBB通透性显著增高(P<0.01),于24~48h达高峰,然后逐渐下降。凝血酶 局部亚低温组在各个时间点与凝血酶组相比,脑组织水含量及BBB通透性明显降低(P<0.01)。结论局部亚低温可能是通过抑制凝血酶的毒性作用来减轻脑出血后水肿的形成及血脑屏障的破坏。     

Influence of therapeutic hypothermia on matrix metalloproteinase activity after traumatic brain injury in rats.

Recent evidence suggests that matrix metalloproteinases (MMPs) contribute to acute edema and lesion formation following ischemic and traumatic brain injuries (TBI). Experimental and clinical studies have also reported the beneficial effects of posttraumatic hypothermia on histopathological and behavioral outcome. The purpose of this study was to determine whether therapeutic hypothermia would affect the activity of MMPs after TBI. Male Sprague-Dawley rats were traumatized by moderate parasagittal fluid-percussion (F-P) brain injury. Seven groups (n=5/group) of animals were investigated: sham-operated, TBI with normothermia (37 degrees C), and TBI with hypothermia (33 degrees C). Normothermia animals were killed at 4, 24, 72 h and 5 days, and hypothermia animals at 24 or 72 h. Brain temperature was reduced to target temperature 30 mins after trauma and maintained for 4 h. Ipsilateral and contralateral cortical, hippocampal, and thalamic regions were analyzed by gelatin and in situ zymography. In traumatized normothermic animals, TBI significantly (P<0.005) increased MMP-9 levels in ipsilateral (right) cortical and hippocampal regions, compared with contralateral or sham animals, beginning at 4 h and persisting to 5 days. At 1, 3, and 5 days after TBI, significant increases in MMP-2 levels were observed. In contrast to these findings observed with normothermia, posttraumatic hypothermia significantly reduced MMP-9 levels. Hypothermic treatment, however, did not affect the delayed activation of MMP-2. Clarifying the mechanisms underlying the beneficial effects of posttraumatic hypothermia is an active area of research. Posttraumatic hypothermia may attenuate the deleterious consequences of brain trauma by reducing MMP activation acutely.     

Effects of mild hypothermia on the expression of microtubule-associated protein 2 in neurons of the hippocampal dentate gyrus in a rat model of cerebral ischemia/reperfusion

BACKGROUND： It is widely accepted that mild hypothermia can protect against injury to cerebral ischemia/reperfusion. OBJECTIVE： To observe the effects of mild hypothermia on microtubule-associated protein 2 （MAP2） expression in the hippocampal dentate gyms in rats following cerebral ischemia/reperfusion. Also, to study neuronal ultrastmctural changes in the dentate gyms to investigate the mechanism of the protection against injury to cerebral ischemia/reperfusion conferred by mild hypothermia. DESIGN, TIME AND SETTING： This randomized grouping, neural cell morphology trial was performed at the Laboratory Animal Center of Yijishan Hospital between March and June 2007. MATERIALS： Eighty-five healthy male Sprague Dawley rats were randomly allocated to three groups： mild hypothermia （n = 40）, normothermia （n = 40）, and sham-operated （n = 5）. METHODS： Cerebral ischemia/reperfusion injury was induced by the suture method in the mild hypothermia and normothermia groups, with a threading depth of 180.5 mm. In the sham-operated group, the suture was inserted 15 mm, with no vascular ligafion, and was followed by reperfusion 2 hours later. In the sham-operated and normothermia groups, the rat rectal temperature was maintained at 36-37 ℃ ; in the mild hypothermia group, it was controlled at 32-33 ℃. MAIN OUTCOME MEASURES： The hippocampal dentate gyms was serially sectioned for hematoxylin-eosin staining and MAP2 immunohistochemistry. Ultrastructural changes and the MAP2 absorbance value of the hippocampal dentate gyms were examined by transmission electron microscopy. RESULTS： The sham-operated group exhibited approximately normal ultrastructure of neurons in the bilateral hippocampal dentate gyms. In the normothermia group, ischemic hippocampal dentate gyms neurons were found with markedly fewer normal mitochondria, greatly proliferated rough endoplasmic reticulum, and a swollen and dysmorphic Golgi. In the mild hypothermia group, at each corresponding time point, these abnormal changes w     

补体在脑出血后脑组织损伤机制中的作用

目的研究补体C9在大鼠实验性脑出血(ICH)后血肿周围组织中的表达情况,探讨补体C9在ICH后脑水肿中的作用以及应用眼镜蛇毒因子(CVF)干预后对血肿周围组织C9表达及脑组织含水量变化的影响。方法采用立体定向技术,将自体不凝血注入大鼠尾状核制备ICH模型,将动物分为假手术组、出血组和CVF干预组,分别在不同时间断头取脑,连续切片分别作补体C9免疫组化染色和HE染色,并进行脑组织含水量测定(干湿重法)。结果ICH后2h血肿周围脑组织开始表达C9,24h达高峰。血肿周围脑组织含水量在ICH后2h开始增加(P<0.05),6h明显增加,24～72h达高峰(P<0.01),此后逐渐回落,1周基本恢复正常水平,脑组织含水量与C9的表达呈正相关关系(r=0.938,P<0.01);对侧半球相应部位及假手术对照组脑组织含水量没有明显变化;经CVF干预后,血肿周围组织C9表达明显下降,干预组与出血组之间比较有显著差异(P<0.01)。CVF干预组脑组织含水量明显低于常规ICH组(P<0.01)。结论脑出血后补体级联激活C9表达明显增加,并证明通过CVF干预后,C9表达下降,脑水肿减轻,能达到神经保护作用。     

大鼠脑出血后基质金属蛋白酶的动态表达及七叶皂苷钠对其表达的影响

目的 观察大鼠脑出血(ICH)后基质金属蛋白酶-2( MMP-2)、MMP-9蛋白动态表达及其与血肿周围脑组织含水量的关系,以及观察七叶皂苷钠对MMP-2、MMP-9表达的影响.方法 Wistar大鼠250只随机分为4组:正常对照组10只、假手术组、ICH组和七叶皂苷钠治疗组各80只,于制模后6 h、12 h、24 h、48 h、72 h、120 h、7 d、15 d 8个时间点,测定各组血肿周围脑组织含水量、MMP-2和MMP-9的蛋白表达.结果 治疗组神经功能缺损较ICH组明显改善,尤以6 h～7 d时明显(P<0.01～0.05);6～120 h各治疗组血肿周围脑组织含水量较ICH组明显减少(P<0.01～0.05);ICH后MMP-2蛋白表达在6 h达到高峰,12 h时下降,与正常对照组相比具有统计学意义 (均P<0.01),治疗组MMP-2蛋白表达在各时间点较ICH组明显减少(均P<0.01);ICH后MMP-9蛋白表达在6 h开始上升,24～48 h达高峰,72 h时下降,与正常对照组相比,具有统计学意义(均P<0.01),其表达水平与血肿周围脑组织含水量呈正相关 (r=0.949, P<0.05);治疗组MMP-9蛋白表达在各时间点较ICH组明显减少(均P<0.01).结论 大鼠ICH后MMP-2、MMP-9蛋白的表达是ICH后早、中期脑水肿形成主要因素,七叶皂苷钠能降低MMP-2、MMP-9蛋白表达和脑组织含水量,对ICH具有保护作用.     

脑出血患者血清基质金属蛋白酶-9的动态变化研究

目的观察脑出血患者血清基质金属蛋白酶-9(MMP-9)水平的动态变化,并探讨其与水肿体积的关系。方法应用ELISA法对46例脑出血患者血清MMP-9水平进行动态检测,同时与头部CT扫描所显示的血肿周围水肿(PHE)体积作相关性分析。结果脑出血组血清MMP-9水平在发病24小时、3天及7天与对照组比较显著升高(P<0.05),MMP-9含量在不同血肿体积中具有显著性差异(P<0.05),发病3天及7天的MMP-9水平与血肿周围水肿体积呈正相关(P<0.05)。结论脑出血后血清MMP-9表达水平增高,血清MMP-9水平是早期反映脑出血患者血肿周围水肿严重程度和预后的敏感指标。     

亚低温治疗自发性脑出血的临床疗效和安全性

目的 探讨亚低温治疗自发性脑出血的疗效和安全性。方法 2015年1月至2017年3月收治急性自发性脑出血78例,按术后体温控制方法分为低温组（n=39）和常温组（n=39）。均采用急诊手术清除血肿。低温组术后采用全身物理降温,将直肠温度维持于34~35 ℃,3 d后缓慢复温,复温速率不超过0.5 ℃/6 h。常温组病人维持正常体温（36~37 ℃）。结果 低温组病人低温维持时间3~7 d,平均（4.7±1.6）d。低温启动前,两组各项指标无明显差异（P>0.05）。随治疗时间的延长,低温组病人心率、动脉pH值、动脉剩余碱和血清钾离子浓度显著低于常温组（P<0.05）。术后24~120 h,亚低温组病人颅内压、脑脊液胶质纤维酸性蛋白和泛素C末端水解酶L1水平均明显低于常温组（P<0.05）。低温组病人肺部感染发生率和低钾血症发生率较常温组明显增高（P<0.05）。发病后6个月,低温组病死率（30.8%）明显低于常温组（53.8%;P<0.05）,低温组预后良好率（GOS评分4~5分,46.2%）明显高于常温组（20.5%;P<0.05）。结论 亚低温可降低自发性脑出血病人颅内压,保护脑组织,改善临床结局,但是治疗期间应注意早期防治并发症。     

Hypothermia during reperfusion after asphyxial cardiac arrest improves functional recovery and selectively alters stress-induced protein expression.

This study examined whether prolonged hypothermia induced 1 hour after resuscitation from asphyxial cardiac arrest would improve neurologic outcome and alter levels of stress-related proteins in rats. Rats were resuscitated from 8 minutes of asphyxia resulting in cardiac arrest. Brain temperature was regulated after resuscitation in three groups: normothermia (36.8 degrees C x 24 hours), immediate hypothermia (33 degrees C x 24 hours, beginning immediately after resuscitation), and delayed hypothermia (33 degrees C x 24 hours, beginning 60 minutes after resuscitation). Mortality and neurobehavioral deficits were improved in immediate and delayed hypothermia rats relative to normothermia rats. Furthermore, both immediate and delayed hypothermia improved neuronal survival in the CA1 region of the hippocampus assessed at 14 days. In normothermia rats, the 70-kDa heat shock protein (Hsp70) and 40-kDa heat shock protein (Hsp40) were increased within 12 hours after resuscitation in the hippocampus. Delayed hypothermia attenuated the increase in Hsp70 levels in the hippocampus but did not affect Hsp70 induction in the cerebellum. Hippocampal expression of Hsp40 was not affected by hypothermia. These data indicate that prolonged hypothermia during later reperfusion improves neurologic outcome after experimental global ischemia and is associated with selective changes in the pattern of stress-induced protein expression.