Isquemia cerebral experimental y sus aplicaciones en la investigación en neurociencias / Experimental brain ischemia and its applications on neuroscience research

La enfermedad cerebrovascular (ECV) isquémica es la tercera causa de muerte en Estados Unidos y otros países industrializados, produce una discapacidad importante en sobrevivientes. Una de las consecuencias más importantes del ictus isquémico es el daño cerebral, resultante de una mezcla compleja de procesos entre los que se incluye la excitotoxicidad mediada por el neurotransmisor glutamato. La excitotoxicidad tiene un papel central en la patología cerebrovascular, pero también en situaciones de trauma agudo y diversas enfermedades neurodegenerativas. El modelo de isquemia cerebral focal por oclusión de la arteria cerebral media (ACM) en ratas mediante la técnica del filamento intraluminal, ocasiona una lesión frontoparietal cortical y dorsolateral del estriado, permite evaluar fenómenos de estrés celular en el foco isquémico o en áreas de oligemia o penumbra. La isquemia cerebral desencadena una secuencia de fenómenos moleculares que se inician con el déficit energético relacionado con la interrupción de los procesos de fosforilación oxidativa y la producción de adenosin trifosfato (ATP). Estos procesos puede ser responsables de varias enfermedades neurodegenerativas, tales como la enfermedad de Alzheimer, la lesión cerebral isquémica, epilepsia y esquizofrenia. El estudio de estos procesos podría aumentar la comprensión de la fisiopatología de la isquemia cerebral, permitiendo el avance en el diseño de estrategias neuroprotectoras, logrando una disminución en la mortalidad y la discapacidad de los pacientes con lesión isquémica.

The ischemic brain disease (IBD) or ischemic stroke is the third cause of death in United States and other industrialized countries, and it generates major disabilities in these patients. One of the most important consequences in the ischemic ictus is the cerebral damage, which is a consequence of a complex mixture of biochemical processes. Among them the excitoxicity mediated by glutamate. Not only has excitoxicity a central role in the IBD, but also in situations of acute trauma and in diverse neurodegenerative diseases. The focal model of obstruction of the middle cerebral artery (MCA) in rats by means of intraluminal suture that causes a cortical frontoparietal lesion as well as in the dorsolateral striatum allows evaluating the phenomena of cellular stress in the ischemic focus or in oligaemia areas or ischemic penumbra. The cerebral ischemia unchains a sequence of molecular phenomena that begin with the lack of energy secondary to the interruption of the processes of oxidative phosphorylation and the deficit of adenosin triphosphate (ATP) production. These processes could be responsible for several degenerative illnesses such as Alzheimer's disease, ischemic stroke, epilepsy and schizophrenia. The study of these processes could increase the understanding of the pathophysiology of cerebral ischemia, allowing progress in design of neuroprotective strategies, achieving to decrease the mortality and morbidity of patients with IBD.

Neuroprotective effects of consuming bovine colostrum after focal brain ischemia/reperfusion injury in rat model

To investigate the neuroprotective effects of bovine colostrums (BC), we evaluate the ability of consuming BC after focal brain ischemia/reperfusion injury rat model to reduce serum cytokine levels and infarct volume, and improve neurological outcome. Sprague-Dawley rats were randomly divided into 4 groups; one sham operation and three experimental groups. In the experimental groups, MCA occlusion (2 h) and subsequent reperfusion (O/R) were induced with regional cerebral blood flow monitoring. One hour after MCAO/R and once daily during the experiment, the experimental group received BC while the other groups received 0.9% saline or low fat milk (LFM) orally. Seven days later, serum pro-inflammatory cytokine (IL-1beta, IL-6, and TNF-alpha) and anti-inflammatory cytokine (IL-10) levels were assessed. Also, the infarct volume was assessed by using a computerized image analysis system. Behavioral function was also assessed using a modified neurologic severity score and corner turn test during the experiment. Rats receiving BC after focal brain I/R showed a significant reduction (-26%/-22%) in infarct volume compared to LFM/saline rats, respectively (P < 0.05). Serum IL-1beta, IL-6, and TNF-alpha levels were decreased significantly in rats receiving BC compared to LFM/saline rats (P < 0.05). In behavioral tests, daily BC intake showed consistent and significant improvement of neurological deficits for 7 days after MCAO/R. BC ingestion after focal brain ischemia/reperfusion injury may prevent brain injury by reducing serum pro-inflammatory cytokine levels and brain infarct volume in a rat model.

Effect of Acupuncture Combined with Herb Decoction on Nerve Cell of Focal Brain Ischemia Rats / 中国中医药信息杂志

Objective To study the mechanism of acupuncture combined with herb decoction for brain occlusion. Methods one-side middle cerebral artery occlusion (McAo) rat by ehermoregulation was used as focal cerebral ischemia experimental animal. All animals were divided into four groups as model group, acupuncture group, herb decoction group, acupuncture combined with herb decoction group. And the dynamic changes of c-fos protein in ischemia region of brain tissue after treatment were observed. Results All of acupuncture group, herb decoction group and combining group could enhance the expression of c-fos protein in all stages of ischemia, and combining group was enhanced significantly. Conclusion Compared with herb decoction or acupuncture, the method of acupuncture combined with herb decoction could improved the stress ability of nerve cells of acute brain ischemia by enhance the content of c-fos protein significantly.

Evaluation of the neuroprotective effect of ketoprofen on rats submitted to permanent focal brain ischemia

OBJECTIVE: To study the neurobehavioral, biochemical and histopathological consequences of permanent focal brain ischemia, and the putative neuroprotective action of ketoprofen. METHOD: One-hundred-and-three Wistar rats divided into groups A and B were respectively submitted to 48 hours and 15 days of ischemia. Each group was divided into 4 subgroups: ischemic not treated, ischemic treated, sham not treated, and sham treated. Ischemic animals had the left middle cerebral artery coagulated. Ketoprofen was administered to treated subgroups 15 minutes before arterial coagulation (manipulation in the sham group). RESULTS: Exploratory activity and defecation were reduced in all ischemic animals in the first postoperative days and constant histopathological changes were observed in each group. The total brain glutamate levels were higher in treated animals 48 hours after surgery. CONCLUSION: No clear parallelism among behavioral, biochemical and histopathological findings was observed. Ketoprofen demonstrated no neuroprotective effect on the behavioral or histopathological aspects of focal permanent brain ischemia.

OBJETIVO: Estudar as conseqüências comportamentais, bioquímicas e histopatológicas da isquemia cerebral focal permanente e o possível efeito neuroprotetor do cetoprofeno. MÉTODO: Foram utilizados 103 ratos Wistar, divididos em grupos A e B, submetidos, respectivamente, a 48 horas e a 15 dias de isquemia. Cada grupo foi dividido em 4 subgrupos: isquêmico não tratado; isquêmico tratado; sham não tratado; sham tratado. Nos animais isquêmicos foi coagulada a artéria cerebral média esquerda. Os subgrupos tratados receberam cetoprofeno 15 minutos antes da oclusão ou manipulação arterial. RESULTADOS: Os animais isquêmicos reduziram a atividade exploratória e as evacuações nos primeiros dias pós-operatórios e mostraram alterações histopatológicas constantes em cada grupo. As concentrações do glutamato total 48 horas após a cirurgia foram maiores nos animais tratados. CONCLUSÃO: Não houve um paralelismo entre os achados comportamentais, bioquímicos e histopatológicos. O cetoprofeno não apresentou efeito protetor contra isquemia cerebral focal permanente, nos aspectos comportamentais e histopatológicos.

Protective effects of NMT on MCAO induced-focal brain ischemia-reperfusion injury in rats / 医学研究生学报

Objectives: To study the protective effects of Nao Mai Tong(NMT) on middle cerebral artery occlusion(MCAO) induced focal brain ischemia reperfusion injury in rats. Methods: After rats were respectively given NMT 1 g/kg, 3 g/kg, 9 g/kg ig everyday for 1 week, the effects of NMT on the histological changes and behavior disorder caused by focal brain ischemia reperfusion which was made by occlusion of middle cerebral artery were investigated. The gasping time after the cutting of the head in ischemia reperfusion rat was recorded. The contents of ATP and LA were determined by radioimmunoassay. Results: NMT significantly reduced the extent of behavior disorder, descended the rate of cerebral infarction area, and improved histological injury of brain tissues. The grasping time after head cutting was prolonged. It was found that the level of ATP was increased and LA was decreased markedly. Conclusions: NMT shows a significant protective effect on histological, behavior and energy metabolic consequences of MCAO induced focal brain ischemia reperfusion injury.

Effects of mild hypothermia on heart of rats with focal brain ischemia / 中华物理医学与康复杂志

Objective To investigate the effects of systemic mild hypothermia on heart. Methods Fifty-eight Wistar rats were divided randomly into three groups: control group (n=10), normal thermic group (n=24) and mild hypothermic group (n=24). After the model of middle cerebral artery occlusion (MCAO) was made, electrocardiograph (ECG) was used to monitor the cardiac function of the animals. The changes of myocardial high-energy phosphates (ATP,ADP,AMP) and energy charge (EC) were evaluated after 12 hours of ischemia, and the myocardial ultrastructure observed. Results Compared with the control group, the ATP, ADP and EC in the normal thermic group and mild hypothermic group were lower after 12 hours of ischemia (P

Molecular Biologic Study on the Changes of Glutamate Receptor (mGluR5) in Rat Hippocampus after Brain Ischemia / 대한구급학회지

BACKGROUND: Metabotropic glutamate receptors (mGluRs) participate in the induction of synaptic plasticity phenomena, such as long-term potentiation and long-term depression that are thought to be at the origin of learning and memory. They are also likely to play a role in modulating glutamate-induced neurotoxicity. It will become apparent that mGluRs are excellent targets for the development of drugs that modulate excitatory synaptic transmission. But there were several controversies about the exact role of group 1 mGluRs subtype 5 (mGluR5). This study was designed for evaluation of the neuroprotective role of mGluR5. METHODS: Fifty male Sprague-Dawley rats were divided into three groups, control, MK-801 and lamotrigine. The hippocampus and basal ganglia were removed at 6 hours and 3 days after the one hour transient middle cerebral artery occlusion. The gene expression of mRNA of the brain samples were evaluated by using reverse transcriptase polymerase chain reaction technique. RESULTS: The gene expression of mGluR5 mRNA in hippocampus was increased by 101.96 +/- 18.45% at 6 hours after ischemia and decreased by 50.70 +/- 15.73% at 3 days after ischemia (p<0.01). MK-801 and lamotrigine attenuated the ischemia-induced increases of gene expression of mGluR5 mRNA. In MK-801 group, the expression in basal ganglia was increased by only 0.23 +/- 5.41% at 6 hours after ischemia and decreased by 9.82 +/- 4.35% at 3 days after ischemia. In MK-801 group, the expression in hippocampus was decreased by 3.45 +/- 8.24% and 9.35 5.69% at 6 hours and 3 days after ischemia. In lamotrigine group, the expressions in hippocampus and basal ganglia were decreased by 26.66 +/- 9.85% and 9.45 +/- 5.22% at 6 hours after ischemia. CONCLUSIONS: From these results, the role of mGluR5 was defined as a mediator for neuronal damage after transient focal cerebral ischemia in hippocampus and basal ganglia.

Does Phenylephrine - induced Hypertension during Focal Cerebral Ischemia Aggravate Brain Edema? / 대한마취과학회지

The author investigated the effect of phenylephrine-induced hypertension on the development of cerebral edema and neuronal dysfunction during focal cerebral ischemia. Middle cerebral artery occlusion (MCAO) was performed in isoflurane-anesthetized rats. In the induced hypertension group (n=14), immediately after MCAO, mean arterial pressure (MAP) was increased gradually by 30-35 mmHg above the pre-MCAO level by infusion of phenylephrine. In control animals (n=14), there was no manipulation of MAP. The MAP increase was maintained for three hours at which time the brains were decapitated and sectioned along coronal planes spanning the distribution of the MCA. Specific gravity (SG) was determined in specimens of cortex and sub-cortex. Brain sections adjacent to those used for SG measurement were incubated in 2, 3, 5-triphenyltetrazolium (TTC) and photographed. In both groups, in a coronal section near the center of the MCA distribution, SG was lower (i. e., more edema) in cortex and subcortex ipsilateral to MCAO than in the normal contralateral hemisphere. However, edema accumulation was less (SG was greater) in the induced hypertension group than in control animals (subcortex; 1.046+/-.002 vs 1.042+/-.003, p< 0.05;cortex 1.043+/-.004 vs 1.040+/-.005, p= 0.16). On the brain surface adjacent to the same coronal plane, the area of reduced or absent TTC staining was significantly (p<0.05) less in the induced hypertension group. The data indicate that, in this model, indueed hypertension established soon after the onset of ischemia can serve to reduce the area of neuronal dysfunction, and that not only is edema formation not aggravated, but it is actually reduced.

Phenylephrine - induced Hypertension Decreases the Area of Ischemia Following Middle Cerebral Artery Occlusion in the Rat / 대한마취과학회지

The influence of phenylephrine-indueed hypertension on the area of ischemia during brief middle cerebral artery occlusion was studied. Rats were anesthetized with 1. 2 MAC isoflurane and the middle cerebral artery was occluded via a subtemporal craniectomy. Immediately thereafter, in one group (n= 9), arterial pressure was increased 30-35mmHg above the pre-ocelusion level by i. v. infusion of phenylephrine. In a second group (N=10), there was no manipulation of blood pressure. Local cerebral blood flow (1-CBF) was determined autoradiographically 15 min after occlusion. The areas, expressed as a percentage of the total coronal cross sectional area, in which 1-CBF fell within three CBF range: 0-6ml/100 g/min (rapid neuronal death probable); 6-15ml/100 g/min (delayed neuronal death prob- able); and 15-'23 ml/100 g/min (electrophysiologic dysfunction with prolonged survival probable) were measured. The areas in which CBF fell within the two more severely ischemic ranges were smaller in the phenylephrine group than in control animals. For example, in the coronal section in the middle of the MCA distribution, CBF was 0-6 ml/100 g/min in 6.7+/-1.4% of the section in normotensive animals but was in the same CBF range in only 1.7+/-0.6% of the area during phenylephring-induced hyperten sion (p<0.05). For the 6-15ml/100g/min range, the areas were 6.8+/-0.8% (control) and 3.8+/-0.7% (phenylephrine) (p<0.05). For the 15-23 CBF range, there were no differences. The data suggest that phenylephrine-induced hypertension can acutely improve 1-CBF in an area of focal ischemia.

Phenylephrine - induced Hypertension Decreases the Area of Ischemia Following Middle Cerebral Artery Occlusion in the Rat / 대한마취과학회지

The influence of phenylephrine-indueed hypertension on the area of ischemia during brief middle cerebral artery occlusion was studied. Rats were anesthetized with 1. 2 MAC isoflurane and the middle cerebral artery was occluded via a subtemporal craniectomy. Immediately thereafter, in one group (n= 9), arterial pressure was increased 30-35mmHg above the pre-ocelusion level by i. v. infusion of phenylephrine. In a second group (N=10), there was no manipulation of blood pressure. Local cerebral blood flow (1-CBF) was determined autoradiographically 15 min after occlusion. The areas, expressed as a percentage of the total coronal cross sectional area, in which 1-CBF fell within three CBF range: 0-6ml/100 g/min (rapid neuronal death probable); 6-15ml/100 g/min (delayed neuronal death prob- able); and 15-'23 ml/100 g/min (electrophysiologic dysfunction with prolonged survival probable) were measured. The areas in which CBF fell within the two more severely ischemic ranges were smaller in the phenylephrine group than in control animals. For example, in the coronal section in the middle of the MCA distribution, CBF was 0-6 ml/100 g/min in 6.7+/-1.4% of the section in normotensive animals but was in the same CBF range in only 1.7+/-0.6% of the area during phenylephring-induced hyperten sion (p<0.05). For the 6-15ml/100g/min range, the areas were 6.8+/-0.8% (control) and 3.8+/-0.7% (phenylephrine) (p<0.05). For the 15-23 CBF range, there were no differences. The data suggest that phenylephrine-induced hypertension can acutely improve 1-CBF in an area of focal ischemia.