Patients suffering from Alzheimer's disease show a sex-dependent decline of cognitive function. The aim of this investigation was to show these differences in an animal model for Alzheimer's disease and to determine whether this effect is correlated to amyloid-beta-induced pathophysiological changes. Therefore, we assessed cognitive performance with the modified hole-board test in female and male Tg2576 and wild type mice at the age of 6, 8, 10, 12, 14, and 16 months and correlated these findings to the total amount of soluble amyloid-beta and insoluble amyloid deposits in the brain. Tg2576 mice perform worse than wild types. Female Tg2576 mice develop an accentuated cognitive impairment (wrong choice total) beginning at the age of 12 months compared to their male littermates. Alterations in the mice's behaviour do not show interference with these deficits. Cognitive impairment is correlated to the amount of soluble amyloid-beta and insoluble amyloid deposits in the brain in a sex-dependent manner.

Background: The intracerebroventricular injection of beta-amyloid (A beta) in mice allows the investigation of acute effects on cognitive function and cellular pathology. The aim of this investigation was to further characterize the time course of A beta-induced cognitive and behavioural changes and to detect potential molecular mechanisms.Methods: Cannulas were implanted in the lateral cerebral ventricle. 14 days after surgery the mice were injected with A beta 1-42 or phosphate buffered saline (PBS). Starting 2, 4 or 8 (PBS only 4) days after injection we evaluated cognitive and behavioural performance using the modified hole board test (mHBT). We determined tumour-necrosis factor alpha (TNF alpha) and caspase 3 by western blotting, on days 10, 12 and 16. Data were analysed using general linear modelling, Kruskall-Wallis and Mann-Whitney-U test.Results: A beta induced a decline in cognitive performance represented as an increased total number of wrong choices during the testing period from day 2-15 (p < 0.05). Behavioural parameters were comparable between mice treated with A beta and PBS. There was no difference regarding TNF alpha levels between the groups. Compared to day 16 Caspase 3 levels were increased on day 10 (p = 0.004).Conclusions: Application of A beta in the lateral ventricle of mice is associated with cognitive impairment of declarative memory in the mHBT. There is no interference caused by altered behaviour. Therefore, it represents a valid model for acute A beta-mediated neurotoxic effects. Although the exact mechanisms remain unclear, changes in levels of Caspase 3 suggest apoptosis as an important factor for the development of cognitive dysfunction.(C) 2017 Elsevier B.V. All rights

Ischemia/reperfusion injury (IRI) contributes to morbidity and mortality after cardiovascular surgery requiring cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA). Multi-organ damage is associated with substantial decreases of blood selenium (Se) levels in patients undergoing cardiac surgery with CPB. We compared the influence of a dietary surplus of Se and pretreatment with ebselen, a mimic of the selenoenzyme glutathione peroxidase, on IRI-induced tissue damage and inflammation. Male Wistar rats were fed either a Se-adequate diet containing 0.3 ppm Se or supplemented with 1 ppm Se (as sodium selenite) for 5 weeks. Two other groups of Se-adequate rats received intraperitoneal injection of ebselen (30 mg/kg) or DMSO (solvent control) before surgery. The animals were connected to a heart-lung-machine and underwent 45 min of global ischemia during circulatory arrest at 16 °C, followed by re-warming and reperfusion. Selenite and ebselen suppressed IRI-induced leukocytosis and the increase in plasma levels of tissue damage markers (AST, ALT, LDH, troponin) during surgery but did not prevent the induction of proinflammatory cytokines (IL-6, TNF-α). Both Se compounds affected phosphorylation and expression of proteins related to stress response and inflammation: Ebselen increased phosphorylation of STAT3 transcription factor in the heart and decreased phosphorylation of ERK1/2 MAP kinases in the lungs. Selenite decreased ERK1/2 phosphorylation and HSP-70 expression in the heart. Pretreatment with selenite or ebselen protected against acute IRI-induced tissue damage during CPB and DHCA. Potential implications of their different actions with regard to molecular stress markers on the recovery after surgery represent promising targets for further investigation.

Spontaneous reinnervation after diaphragmatic paralysis due to trauma, surgery, tumors and spinal cord injuries is frequently observed. A possible explanation could be collateral reinnervation, since the diaphragm is commonly double-innervated by the (accessory) phrenic nerve. Permutation entropy (PeEn), a complexity measure for time series, may reflect a functional state of neuromuscular transmission by quantifying the complexity of interactions across neural and muscular networks. In an established rat model, electromyographic signals of the diaphragm after phrenicotomy were analyzed using PeEn quantifying denervation and reinnervation. Thirty-three anesthetized rats were unilaterally phrenicotomized. After 1, 3, 9, 27 and 81 days, diaphragmatic electromyographic PeEn was analyzed in vivo from sternal, mid-costal and crural areas of both hemidiaphragms. After euthanasia of the animals, both hemidiaphragms were dissected for fiber type evaluation. The electromyographic incidence of an accessory phrenic nerve was 76%. At day 1 after phrenicotomy, PeEn (normalized values) was significantly diminished in the sternal (median: 0.69; interquartile range: 0.66-0.75) and mid-costal area (0.68; 0.66-0.72) compared to the non-denervated side (0.84; 0.78-0.90) at threshold p<0.05. In the crural area, innervated by the accessory phrenic nerve, PeEn remained unchanged (0.79; 0.72-0.86). During reinnervation over 81 days, PeEn normalized in the mid-costal area (0.84; 0.77-0.86), whereas it remained reduced in the sternal area (0.77; 0.70-0.81). Fiber type grouping, a histological sign for reinnervation, was found in the mid-costal area in 20% after 27 days and in 80% after 81 days. Collateral reinnervation can restore diaphragm activity after phrenicotomy. Electromyographic PeEn represents a new, distinctive assessment characterizing intramuscular function following denervation and reinnervation.

Kellermann, K.; Müller, M.; Blobner, M.; Kochs, E. F.; Jungwirth, B. Author Information

Cardiopulmonary bypass (CPB) is a commonly used technique in cardiac surgery. CPB is however associated with a strong induction of systemic inflammatory response syndrome (SIRS) which in conjunction with ischemia and reperfusion may lead to multiple organ failure.

背景 心外科手术中,体外循环(cardiopulmonary bypass,CPB)术后发生的神经认知功能障碍一直影响着患者的生活质量.炎症反应可能是其中的因素之一.本实验中我们检测了年轻大鼠围术期体内IL-6的浓度,海马NF-κB的表达含量和神经认知功能,同时评估了氧合器的大小对上述指标的影响.方法 将大鼠随机分为4组:空白对照组(n=7),假手术组(n=10,麻醉、置管、不连接体外循环)和两组体外循环实验组,CPB组大鼠在麻醉、置管后行90分钟的体外循环,分别使用小容量的大鼠氧合器(n=10)和新生儿氧合器(n=10).在术前、CPB结束时和CPB结束后2小时采集血样检测IL-6的含量.在术后第21天采用免疫组化的方法检测海马NF-κB的表达含量.在术前和术后的21天内对神经功能采用改良孔板实验进行评估.结果 CPB组与假手术组相比,IL-6的水平明显升高,新生儿氧合器组在CPB结束后2小时与大鼠氧合器组相比IL-6的水平更高[CPB/大鼠氧合器组:220 pg/ml (16～415); CPB/新生儿氧合器组:1400 pg/ml (592～5812)](P＜0.05).3组实验组中海马NF-κB的表达含量与对照组(10±4)相比明显升高.CPB组与假手术组(173±24)相比NF-κB表达含量更高(CPB/新生儿氧合器组:271±57; CPB/大鼠氧合器组:269±72).神经认知功能和行为学的评估结果显示组间没有差异.结论 CPB引发显著的全身性炎症反应并伴随着海马中NF-κB蛋白表达的增多并没有导致神经认知功能的损伤.由此可推断,排除体外循环和炎症反应这两个因素,可能有其他因素最终导致了患者CPB术后神经认知功能的障碍.

Kellermann, K.; Kadera, V.; Stigler, M.; Blobner, M.; Kochs, E. F.; Jungwirth, B. Author Information

BACKGROUND:After adjusting for cofactors, female gender remains an independent risk factor. The aim of our study was to investigate the role of gender on functional outcome 14 days after 45 minutes of deep hypothermic circulatory arrest (DHCA) in rats. METHODS:After institutional animal care committee Institutional Review Board approval, 40 male and 40 female rats were randomly divided into two groups (40 DHCA, 40 controls). The rats were neutered or sham-neutered and 40 of them were subjected to DHCA with 40 controls remaining naïve. Postoperative functional performance was assessed with modified hole-board test. Brain morphology was assessed using hematoxylin and eosin (HE) staining and cerebral inflammation/apoptosis determined immunohistochemically. Data were analyzed using general linear models (post hoc analysis of variance [ANOVA] and Bonferroni t tests) and Kruskal-Wallis (post hoc Mann-Whitney U test) (p < 0.05). RESULTS:Cognition and behavior after 45 minutes of DHCA were comparable to that of four naïve rats in all four DHCA groups. Motor function and morphologic outcome were better in females. Nuclear factor kappa B (NFκB) was upregulated in the female normal group. Activated caspase-3 was higher in females whereas poly(ADP-ribose) polymerase was in males. Of note is the secondary finding of a high drop-out rate during the early postoperative phase in the female groups (16 out of 37). CONCLUSIONS:Postoperative motor skills were better in females, with less neuronal damage, more neuronal NFκB, and activated caspase-3. However, the chance finding of a high mortality rate in females warrants investigation with mortality as the principal aim, focusing on heart, liver, lung, kidney, and intestine with regard to its rate.

Background: Whether the occurrence of postoperative cognitive dysfunction is a result of the effects of surgery or anesthesia is under debate. In this study, we investigated the impact of sevoflurane anesthesia on cognitive performance and cellular mechanisms involved in learning and memory.Methods: Male C57Bl6/J mice (4-5 months) were exposed to one minimum alveolar concentration sevoflurane for two hours. After 24 h, cognitive performance of mice was assessed using the modified hole board test. Additionally, we evaluated hippocampal long-term potentiation and expression levels of different receptor subunits by recording excitatory postsynaptic field potentials and using the western blot technique, respectively. Non-anesthetized mice served as controls.Results: In anesthetized mice, neither cognitive performance nor long-term potentiation was impaired 24 h after anesthesia. Interestingly, sevoflurane anesthesia induced even an improvement of cognitive performance and an elevation of the expression levels of N-methyl-D-aspartate (NMDA) receptor type 1 and 2B subunits in the hippocampus.Conclusions: Since NMDA receptor type 1 and 2B subunits play a crucial role in processes related to learning and memory, we hypothesize that sevoflurane-induced changes in NMDA receptor subunit composition might cause hippocampus-dependent cognitive improvement. The data of the present study are in favor of a minor role of anesthesia in mediating postoperative cognitive dysfunction.

Background and Goal of Study: Female gender is an independent risk factor within the cardiac surgery setting. Aim of the study was to investigate the role of gender and hormonal status on functional and histologic outcome after CPB with 45 min of deep hypothermic circulatory arrest (DHCA) in intact and neutered female and male rats. Materials and Methods: After institutional review board approval animals were assigned to 4 groups: female intact, female neutered, male intact, male neutered. At 12 weeks of age, animals were neutered or sham-neutered according to group assignment. After 28 days to allow for elimination of sex hormones, rats were exposed to 45 min of DHCA. 1 hour after DHCA, rats were allowed to recover. During 14 postoperative days, functional outcome was assessed with the modified Hole Board-Test, histologic outcome with hematoxylin &eosin staining and both scored according to an established protocol (1). The multivariable relationship of potentially predictive variables (histologic score, gender, castration, CPB) and neurologic function score was calculated by a general linear model. Results and Discussion: Significantly fewer female rats survived 14 postoperative days after DHCA (44% in the female-normal, 78% in the female-neutered group versus 100% in the male-normal and 85% in the male-neutered group). Within the surviving female rats, neutered females had a better neurologic outcome compared to the intact females with physiologic hormone status. Within the male groups, neutering worsened postoperative neurologic function significantly. Histological outcome of the surviving rats at postoperative day 14 was improved in females compared to both male groups independent of sex hormone status. Conclusions: While survival and histologic outcome are fundamentally influenced by gender, functional outcome is determined by the presence and character of sex hormones present during CPB with DHCA. References: J Thorac Cardiovasc Surg 2006, 131:805–812.

Background Study protocols involving experimental animals often require the monitoring of different parameters not only in anesthetized, but also in free moving animals. Most animal research involves small rodents, in which continuously monitoring parameters such as temperature and heart rate is very stressful for the awake animals or simply not possible. Aim of the underlying study was to monitor heart rate, temperature and activity and to assess inflammation in the heart, lungs, liver and kidney in the early postoperative phase after experimental cardiopulmonary bypass involving 45 min of deep hypothermic circulatory arrest in rats. Besides continuous monitoring of heart rate, temperature and behavioural activity, the main focus was on avoiding uncontrolled death of an animal in the early postoperative phase in order to harvest relevant organs before autolysis would render them unsuitable for the assessment of inflammation. Findings We therefore set up a telemetry-based system (Data Science International, DSI™) that continuously monitored the rat's temperature, heart rate and activity in their cages. The data collection using telemetry was combined with an analysis software (Microsoft excel™), a webmail application (GMX) and a text message-service. Whenever an animal's heart rate dropped below the pre-defined threshold of 150 beats per minute (bpm), a notification in the form of a text message was automatically sent to the experimenter's mobile phone. With a positive predictive value of 93.1% and a negative predictive value of 90.5%, the designed surveillance and alarm system proved a reliable and inexpensive tool to avoid uncontrolled death in order to minimize suffering and harvest relevant organs before autolysis would set in. Conclusions This combination of a telemetry-based system and software tools provided us with a reliable notification system of imminent death. The system's high positive predictive value helped to avoid uncontrolled death and facilitated timely organ harvesting. Additionally we were able to markedly reduce the drop out rate of experimental animals, and therefore the total number of animals used in our study. This system can be easily adapted to different study designs and prove a helpful tool to relieve stress and more importantly help to reduce animal numbers.

OBJECTIVE:While histological injury following cerebral ischemia has been extensively characterized in rodents, evidence on the effects on executive functioning is still missing. This study was designed to evaluate neuropsychological outcome following different severities of cerebral ischemia in rats with the modified hole board test or the Morris water maze. SETTING:With institutional review board approval, anesthetized rats were exposed to bilateral carotid artery occlusion (BCAO) for escalating time intervals (0-12.5 min). Postoperatively cognitive performance was assessed using either the modified hole board test (mHB) or the Morris water maze (MWM). On postoperative day 14 rats were euthanized and intact neurons in five cerebral regions were counted. RESULTS:Rats of the 0 and 5 min groups showed normal functional outcome with mild histological damage after 5 min of BCAO. Following 7.5 min of BCAO the mHB test showed cognitive deficits reflecting histological damage of the hippocampus while the MWM revealed normal functional outcome. Rats of the 10 and 12.5 min groups showed cognitive deficits in both tests, motor dysfunction and behavioral alterations in the mHB test and profound histological damage. CONCLUSIONS:The results indicate that the mHB is not inferior to the MWM for the evaluation of cognitive impairment following incomplete forebrain ischemia in rats. As the mHB additionally investigates a variety of behavioral dimensions and motor parameters in the same test environment, it is advantageous for the evaluation of interacting and potentially confounding behavioral changes following cerebral ischemia in rats.

CONTEXT:The neuroprotective properties of xenon might improve cerebral outcome after cardiac surgery using cardiopulmonary bypass. However, in the presence of cerebral air emboli, xenon impaired cognitive and histological outcome in a rat cardiopulmonary bypass model, a result which is due to the property of xenon to expand air bubbles. OBJECTIVE:The current study was designed to assess whether cerebral outcome in the setting of cardiopulmonary bypass with cerebral air embolism could be altered by administration of xenon restricted to periods when the occurrence of cerebral air embolism is unlikely. DESIGN:With institutional review board approval, 40 rats were allocated randomly to one of four groups (n = 10) which determined the period of xenon inhalation: 'before', 'during' or 'after' cardiopulmonary bypass or 'none'. SETTING:Rats were subjected to 90  min of normothermic cardiopulmonary bypass combined with 10 small cerebral air emboli. Xenon was administered according to group assignment: the 'none' group received no xenon; in the other groups, the lungs were ventilated with 56% xenon before, during or after cardiopulmonary bypass and cerebral air embolism. MAIN OUTCOME MEASURES:Motor and cognitive outcomes were tested using the modified hole-board test. Cerebral infarction volumes were determined on postoperative day 21. RESULTS:Animals that received xenon after cardiopulmonary bypass and cerebral air embolism had impaired motor function scores [after: median 6.6 (range 0.25-8), before: 0.5 (0-3), during: 1.5 (0.25-2.75), none: 1 (0-1.75)] and cognitive performance [after: 9 (6.5-9), before: 0 (0-5.5), during: 1 (0-5.5), none: 1 (0-4)] compared with all other groups (P < 0.05). Administration of xenon after cardiopulmonary bypass and cerebral air embolism also led to larger cerebral infarction volumes [after: 74 μl (54-157), before: 45 μl (20-82), during: 33 μl (23-54), none: 22 μl (17-78)] compared with the groups that received xenon during cardiopulmonary bypass and cerebral air embolism or no xenon at all (P < 0.05). CONCLUSION:Xenon administered immediately after cardiopulmonary bypass and cerebral air embolism impaired motor, cognitive and histological outcome in rats. At no time did inhalation of xenon lead to any beneficial effects on cerebral outcome when compared with inhalation of nitrogen.

Kellermann, K.; Gordan, M. L.; Friedrich, S.; Blobner, M.; Kochs, E. F.; Jungwirth, B. Author Information

Objective: Moxifloxacin reduces infectious complications after cerebral damage, such as ischemia and stroke. This study investigated whether moxifloxacin treatment influences cerebral inflammation and improves cognitive outcome after cardiopulmonary bypass with deep hypothermic circulatory arrest in rats.Methods: Rats were randomly assigned to deep hypothermic circulatory arrest (n = 40), sham operation (n = 40), and untreated control (n = 20) groups. Deep hypothermic circulatory arrest and sham groups were equally subdivided into moxifloxacin and placebo subgroups, receiving 63100 mg/kg moxifloxacin or saline solution every 2 hours intraperitoneally. Hippocampal tumor necrosis factor a, nuclear factor kappa B, cyclooxygenase 2, and macrophages were assessed immunohistochemically. Histologic outcome was determined with hematoxylin and eosin. Neurologic outcome was assessed preoperatively and postoperatively. Cognitive performance was tested with the modified hole board test for 14 postoperative days.Results: On postoperative day 14, deep hypothermic circulatory arrest moxifloxacin group was lower than deep hypothermic circulatory arrest placebo group in hippocampal neurons positive for tumor necrosis factor alpha (1.33, 0.73-2.37, vs 4.10, 2.42-18.67), nuclear factor kappa B (3.03, 1.33-5.20, vs 9.32, 2.53-24.14), and cyclooxygenase 2 (3.16, 0.68-6.04, vs 8.07, 3.27-19.91) and also had fewer macrophages than all other groups (72, 60-90, vs deep hypothermic circulatory arrest placebo 128, 76-203, sham moxifloxacin 89, 48-96, and sham placebo 81, 47-87). On postoperative day 14, both deep hypothermic circulatory arrest groups showed impaired motor, cognitive, and histologic outcomes relative to sham-operated groups, with no difference between deep hypothermic circulatory arrest subgroups.Conclusions: Moxifloxacin transiently reduces cerebral inflammatory reaction, but without impact on neurologic function, histologic outcome, or long-term cognitive performance. (J Thorac Cardiovasc Surg 2011; 141:796-802)

Objective: Deep hypothermia is used as a neuroprotectant during cardiac surgery utilizing deep hypothermic circulatory arrest (DHCA), although the ideal rewarming strategy is not known yet. Some of the neuroprotective properties of hypothermia seem to be mediated by Nuclear Factor Kappa B (NFκB) as an important transcription factor. The current study was designed to investigate the effect of the rewarming rate on histologic outcome and cerebral NFκB expression one day following DHCA in rats. Methods: With IRB approval, 20 rats were cannulated for cardiopulmonary bypass (CPB), cooled to a rectal temperature of 15-18°C, subjected to 45min of DHCA and randomly assigned to either a slow (40 min) or a fast (20 min) rewarming protocol. At 24 hours post DHCA, the number of eosinophilic neurons was analyzed with hematoxylin and eosin (HE) staining, and NFκB expression immunohistochemically. The two experimental groups were compared with untreated control rats. Results: HE staining showed more eosinophilic neurons in the motor cortex following fast rewarming (60 [15-388]) compared to slow rewarming (15 [10—21]) (p<0.05). Neuronal expression of NFκB was increased in the fast rewarming group in both brain areas, the motor cortex (fast: 258 [135-393]; slow: 165 [80—212]; control: 73 [44-111]) as well as the hippocampus (fast: 243 [209-314]; slow: 202 [187-239]; control: 86 [68-108]) (p<0.05). Hyperthermic episodes were strictly avoided. Conclusions: Fast rewarming with strict avoidance of hyperthermia after DHCA in rats was accompanied by pronounced histologic damage and accentuated cerebral NFκB expression.