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Query: UMLS:C0917798 (cerebral ischemia)
 17,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The objective of this study was to determine whether postischemic hypothermia diminishes ischemic injury in gerbil hippocampus. Cerebral ischemia was produced by occluding both carotid arteries for 5 min, while maintaining the temperature of the cranium and rectum at 38 degrees C. Upon recirculation, the animals were divided into three groups: normothermic (38 degrees C), moderately hypothermic (33 degrees C), and deeply hypothermic (23 degrees C). In the normothermic group, cranial and rectal temperatures were maintained at 38 degrees C for 30 min and 2 h, respectively, prior to the removal of the temperature probes. In the moderately hypothermic group, cranial and rectal temperatures were reduced within 10 min to 33 degrees C for 1 h, and then rewarmed to 38 degrees C. In the deeply hypothermic group, rectal temperature was lowered within 10 min to 23 degrees C for 2 h prior to rewarming to 38 degrees C. After recovery for 1 week, the extent of histologic injury in the hippocampus was assessed in stained sections. Maximal injury was present in the CA1 subfield in all three groups. These results indicate that hippocampal injury was not diminished by postischemic hypothermia during the first 2 h of reperfusion. Thus, pharmacologic studies of postischemic protection in the gerbil model may not be strongly influenced by transient postischemic hypothermia.
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PMID:Postischemic hypothermia fails to reduce ischemic injury in gerbil hippocampus. 205 Jul 49

This study addresses the possible involvement of an agonist-induced postischemic hyperactivity in the delayed neuronal death of the CA1 hippocampus in the rat. In two sets of experiments, dialytrodes were implanted into the CA1 either acutely or chronically (24 h of recovery). During 20 min of cerebral ischemia (four-vessel occlusion model) and 8 h of reflow, we followed extracellular amino acids and multiple-unit activity. Multiple-unit activity ceased within 20 sec of ischemia and remained zero during the ischemic insult and for the following 1 h of reflow. During ischemia, extracellular aspartate, glutamate, taurine, and gamma-aminobutyric acid increased in both acute and chronic experiments (seven- to 26-fold). Multiple-unit activity recovered to preischemic levels following 4-6 h of reflow. In the group with dialytrodes implanted acutely, the continuous increase in multiple-unit activity reached 110% of basal at 8 h of reflow. In the group with dialytrodes implanted chronically, multiple-unit activity recovered faster and reached 140% of control at 8 h, paralleled by an increase in extracellular aspartate (5.5-fold) and glutamate (twofold). In conclusion, the postischemic increase of excitatory amino acids and the recovery of the neuronal activity may stress the CA1 pyramidal cells, which could be detrimental in combination with, e.g., postsynaptic impairments.
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PMID:Changes in extracellular amino acids and spontaneous neuronal activity during ischemia and extended reflow in the CA1 of the rat hippocampus. 205 Nov 65

In this report we describe changes in the intracellular redistribution of raf serine/threonine protein kinase (product of the raf proto-oncogene family) in hippocampal neurons following cerebral ischemia in Mongolian gerbils. For immunohistochemical localization studies polyclonal antisera specific for each of the A, B, and Raf-1 isotypes of raf, as well as a pan-raf antisera, were employed. Of these, only sera recognizing B-raf, as well as the general v-raf (raised against the conserved C-terminal region) were positive, indicating that B-raf is the major isotype in this neuronal region. Three different ischemic models were used (repeated 3 times for two min and single 5 or 15 min occlusions, of the common carotid arteries) to demonstrate that ischemic insult causes redistribution of raf protein kinase into the cell nucleus of hippocampal neurons. Increased amounts of raf protein in the nuclei of pyramidal cells following ischemia was confirmed by Western blot analysis of isolated nuclear fractionations. Moreover, an elevation in the level of nuclear raf protein also was detected in the contralateral (i.e. non-occluded hemisphere) neurons of CA1 and CA3 subfields 4 days after the ischemic insult indicating a possible transsynaptic increase in the amount of raf protein along with redistribution. The intranuclear translocation of the immunoreactive material started from the perinucleolar rim and with time extended throughout the nucleus. Enhanced levels and altered redistribution of the raf polypeptide in the nuclei of pyramidal cells of the CA3 subfield appears to be reversible and returns to the normal level 12 days following the ischemic insult.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cerebral ischemia induces transient intracellular redistribution and intranuclear translocation of the raf proto-oncogene product in hippocampal pyramidal cells. 206 47

Cellular protein synthesis was investigated in the rat hippocampus 2-100 h following 20 min of cerebral ischemia induced by four-vessel occlusion. [3H]-Phenylalanine was retrogradely infused through the external carotid artery for 30 min. This method limited the distribution of the tracer to one hemisphere and required 1/50th of the tracer amount used for intravenous tracer infusion. Cellular [3H]phenylalanine incorporation was examined in hematoxyline and eosin-stained sections coated with nuclear emulsion. A score for relative protein synthesis was estimated from counts of silver grains across neuron somata with undamaged morphology. Shortly after ischemia a generalized complete arrest of protein synthesis was observed. In CA1 pyramidal cells, this was followed by a transient incomplete regeneration (9-20 h) and later (46-100 h) persistent cessation of protein synthesis. By contrast protein synthesis in interneurons, CA3c pyramidal cells and granule cells recovered to preischemic levels 9-100 h after ischemia, as did the CA3ab pyramidal cells 46-100 h postischemia. Moreover, eosinophilic cell changes were seen in hilar and CA3c neurons at all postischemic stages and in CA1 pyramidal cells 46-72 h after ischemia. [3H]Phenylalanine incorporation was absent in neurons demonstrating eosinophilic cell changes. From the rapid recovery of protein synthesis in hippocampal interneurons, we conclude that changes in interneuronal protein synthesis per se are not involved in the pathophysiology of the delayed ischemic CA1 pyramidal cell death.
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PMID:Temporal profile of interneuron and pyramidal cell protein synthesis in rat hippocampus following cerebral ischemia. 208 91

Survival, quantitative morphology of the hippocampus, cerebral tissue impedance and regional cerebral blood flow (rCBF) were studied in the Mongolian gerbil after 15 minutes of bilateral common carotid occlusion. A subgroup of animals was placed in cages with free access to running-wheels for two weeks preceding ischaemia to measure voluntary locomotor activity. Survival was enhanced in the running-wheel subgroup, with 90% of the animals still alive after 14 days as compared to 48% of the non-running group. Neuronal loss was found in all animals in the hippocampus (CA1, CA2, CA3 and CA4), and was most pronounced in the CA1 sector. In the running-wheel group, however, neuronal loss was significantly lower in sectors CA2, CA3 and CA4. The increases of cerebral impedance, which indicate ischaemic cell swelling, reached 190% in both groups during ischaemia. During postischaemic recirculation, however, impedance normalized more rapidly in the running-wheel group, indicating earlier resolution of ischaemic cell swelling. In wheel-running gerbils, postischaemic hyperperfusion evolved earlier and was more pronounced as compared to non-runners. No differences in systemic blood pressure were observed during cerebral ischaemia or thereafter.
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PMID:Electrical impedance, rCBF, survival and histology in Mongolian gerbils with forebrain ischaemia. 208 90

The purpose of this study was to examine the distribution of neuronal damage following transient cerebral ischemia in the rat model of four-vessel occlusion utilizing light microscopy as well as 45Ca-autoradiography. Transient ischemia was induced for 30 min. The animals were allowed to survive for 7 d after ischemia. In the animals subjected to ischemia, the most frequently and seriously damaged areas were the paramedian region of hippocampus, the hippocampal CA1 sector, and the dorsolateral part of striatum, followed by the inferior colliculus, the substantia nigra, the frontal cortex, and the thalamus, which were moderate damaged. Furthermore, the cerebellar Purkinje neurons, the hippocampal CA4 sector, the medial geniculate body, and the hippocampal CA3 sector were slightly affected. 45Ca-autoradiographyic study also revealed calcium accumulation in the identical sites of ischemic neuronal damage, except for the frontal cortex. Regional cerebral blood flow during 10 min of ischemia was severely decreased in selectively vulnerable areas. The blood flow in the medial geniculate body, the substantia nigra, the inferior colliculus, and the cerebellum was less pronounced than that in the selectively vulnerable areas. The present study demonstrates that transient cerebral ischemia can produce significant neuronal damage not only in the selectively vulnerable regions, but also in the brainstem.
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PMID:Neuronal damage and calcium accumulation following transient cerebral ischemia in the rat. 209 66

E2001 (2-(4-(p-fluorobenzoyl)-piperidin-1-yl)-2'-acetonaphthone hydrochloride, CAS 107025-80-9) is a novel anti-ischemic agent, which is reported to protect against delayed neuronal death in the CA1 subfield of the hippocampus. The effect of E2001 on ischemia-induced impairment of the passive avoidance response in gerbils was studied. The passive avoidance response was not disturbed by transient cerebral ischemia of 3 min duration, but was impaired by 5-min ischemia. E2001 at oral doses of 3 and 10 mg/kg significantly improved the impaired passive avoidance response induced by 5-min cerebral ischemia. It is speculated that the improvement by E2001 may be partly due to the inhibition of extracellular glutamate accumulation, and the suppression of lipid peroxides formation during cerebral ischemia.
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PMID:Protective effect of the novel anti-ischemic agent 2-(4-(p-fluorobenzoyl)-piperidin-1-yl)-2'-acetonaphthone hydrochloride against ischemia-induced impairment of the passive avoidance response in gerbils. 209 25

A combined autoradiographic and immunohistochemical method was used to correlate the extent of focal cerebral ischemia and morphologic ischemic damage following unilateral carotid occlusion in 16 gerbils for 5-30 minutes. Immunohistochemical lesions detectable by the reaction for microtubule-associated proteins 1 and 2 were visible in the subiculum-CA1 and CA2 regions of the hippocampus and layer III/IV of the cerebral cortex after 5 minutes of ischemia (n = 4). Local blood flow was promptly reduced but still heterogeneous after 10 minutes of ischemia (n = 4); local blood flow in immunohistochemical lesions was less than 5 ml/100 g/min except in highly vulnerable regions, where flow values of 5-15 ml/100 g/min were observed. After 15 minutes of ischemia (n = 4) local blood flow in less vulnerable regions including the thalamus and caudoputamen also declined to less than 5 ml/100 g/min, and immunohistochemical lesions became visible in those regions after 30 minutes of ischemia (n = 4). On the other hand, many brain regions tolerated local blood flow of less than 5 ml/100 g/min without ischemic damage. The present study demonstrates that selective tissue vulnerability during progressive cerebral ischemia depends on the degree of hypoperfusion and on factors inherent to neurons in various brain regions.
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PMID:Cerebral blood flow and neuronal damage during progressive cerebral ischemia in gerbils. 212 Aug 2

The protective roles of Ca2+ channel blockers against ischemic hippocampal damage are still debated. We used autoradiography to study postischemic L-type Ca2+ channels (1,4-dihydropyridine Ca2+ channel blocker binding), adenosine A1 receptors, and muscarinic cholinergic receptors in the rat hippocampus using [3H]PN200-110 (PN), [3H]cyclohexyladenosine (CHA), and [3H]quinuclidinyl benzilate (QNB), respectively, in 49 rats subjected to 20 minutes of forebrain ischemia. The rats were decapitated after 1 (n = 7), 3 (n = 7), 6 (n = 8), 12 (n = 7), 24 (n = 6), 48 (n = 6), or 168 (n = 8) hours of recirculation; eight control rats were sham-operated but experienced no cerebral ischemia. Reduced receptor binding preceding the delayed death of CA1 pyramidal cells was first observed in the stratum oriens of the CA1 subfield. Significant reductions in [3H]PN, [3H]CHA, and [3H]QNB bindings of this stratum compared with control were noticed after 3 (35%, p less than 0.01), 12 (31%, p less than 0.01), and 1 (10%, p less than 0.05) hours of recirculation, respectively. By 168 hours after ischemia (when the populations of CA1 pyramidal cells were depleted) all strata in the CA1 subfield had lost most of their receptor sites, and [3H]PN, [3H]CHA, and [3H]QNB bindings in the stratum oriens were decreased to 23%, 30%, and 63% of control (p less than 0.01). Although [3H]PN binding in the CA3 subfield did not change significantly during 168 hours after ischemia, the histologically intact dentate gyrus exhibited a 31% loss of binding sites compared with control (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Calcium antagonist, adenosine A1, and muscarinic bindings in rat hippocampus after transient ischemia. 214 Feb 13

The activation of 5-hydroxytryptamine receptors exerts an inhibitory influence on neuronal activity in a way similar to the activation gamma-amino-n-butyric acid and adenosine A1 receptors. Therefore, we hypothesized that 5-HT1A-receptor agonists might exert a neuroprotective effect. We tested the full agonists Bay R 1531 and 8-OH-DPAT and the partial agonists ipsapirone and gepirone in the model of transient global ischemia in the Mongolian gerbil. Ipsapirone protected 53% of pyramidal neurons (p less than 0.05) in the CA1 area of the hippocampus from ischemic damage at a dose of 3 mg/kg. Bay R 1531 showed a powerful neuroprotective effect with 100% preservation of neurons at a dose of 3 mg/kg (p less than 0.001) while gepirone and 8-OH-DPAT were ineffective. These findings suggest that 5-HT1A-receptor agonists might be effective tools for the therapy of cerebral ischemia. However, the varying results indicate that transient forebrain ischemia in the gerbil may not be the optimal model system to demonstrate clearly the neuroprotective activity of these compounds.
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PMID:Effects of 5-hydroxytryptamine1A-receptor agonists on hippocampal damage after transient forebrain ischemia in the Mongolian gerbil. 214 36


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