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PubMed1996

Synaptogenesis in hemimegalencephaly: the numerical density of asymmetric and symmetric synapses in the cerebral cortex.

Specimens of cerebral cortex were prepared for electron microscopy from cortical resections performed for the treatment of intractable seizures in four cases of hemimegalencephaly (HME). Morphometric analyses were performed to determine mean cortical thickness, the numerical density of synapses (NV, contacts per mm3) and the number of synapses in a column of cortex beneath 1 mm2 of pial surface. The NV were calculated separately for asymmetric and symmetric synapses as well as for axospinous, axodendritic and axosomatic contacts. Four cases of Rasmussen's encephalitis served as controls, with tissue being sampled from a region distant to the site of the inflammatory lesion without obvious necrosis. The NV of synapses did not differ significantly between HME cases and controls. The proportions or asymmetric and symmetric synapses were similar in both groups, as were the proportions of axospinous, axodendritic and axosomatic contacts. However, there was a significant increase in mean cortical thickness in HME cases (130%, P < 0.05). Consequently, there was a significant increase in the total number of synapses in a column of cortex (126%, P < 0.05). In HME the cerebral cortex is characterized by synaptic dysgenesis. Although synaptic density per unit volume of tissue appears relatively normal, the increased thickness and volume of the cerebral cortex provides for an increase in the total number of synapses in a given cytoarchitectonic area.

Brain Diseases↗
PubMed1994

Local immune responses in the rat cerebral cortex after middle cerebral artery occlusion.

This study describes local immune responses in cerebral ischemia induced by permanent occlusion of the middle cerebral artery (MCAO) in the rat. The temporal and spatial pattern of leukocyte infiltration was characterized immunocytochemically using monoclonal antibodies against CD5, a pan T cell marker, against CD4 and CD8 for subtyping of T lymphocytes, and ED1, a marker for macrophages. CD5+ T cells were present in some animals on the pial surface at day 1 and with increasing numbers mainly at the edges of the infarcts at days 3 and 7. By day 14 their number had significantly decreased. Subtyping of T lymphocytes revealed that CD4+ helper/inducer T cells were rare, while CD8+ lymphocytes were abundant. Moreover, CD8+ lymphocytes outnumbered CD5+ T cells indicating the presence of CD5-/CD8+ natural killer (NK) cells. ED1+ macrophages primarily infiltrated the core of the infarct starting on day 1. Infiltrating leukocytes expressed leukocyte function associated antigen-1 and MHC class I and II antigens. Early after infarction, increased expression of the intercellular adhesion molecule-1 was found on vessels and leukocytes. In conclusion, this study shows that lymphocytes enter the nervous system not only in autoimmune diseases, but also in response to primarily 'non-immune' neuronal damage such as stroke.

Animals↗
PubMed2000

Alterations of amino acid levels from striatum, hippocampus, and cerebral cortex induced by global cerebral ischemia in gerbil.

AIM: To investigate global cerebral ischemia-induced alterations in the levels of glutamate, aspartate, gamma-aminobutyric acid (GABA), glutamine, glycine, and taurine from hippocampus, striatum, and cerebral cortex in gerbils. METHODS: The gerbil global cerebral ischemia model was prepared by bilateral carotid artery occlusion; the contents of amino acids were assayed using high performance liquid chromatography (HPLC) combined with fluorescent detection after precolumn derivatization. RESULTS: After the ligation of bilateral carotid artery for 5 min and reperfusion for 60 min, the contents of glutamate from hippocampus, striatum, and cortex in gerbils were increased by 40%, 49%, and 67%, respectively. Similarly, the global cerebral ischemia resulted in increase by 80%, 69%, and 83% of aspartate contents in hippocampus, striatum, and cortex, respectively. Moreover, the same treatment also induced significant increases in the contents of GABA, glutamine, glycine, and taurine from various brain regions in gerbils. Furthermore, pretreatment with ketamine (120 mg/kg, i.p.) reversed ischemia-evoked increases of glutamate, aspartate, glycine, and glutamine in hippocampus, striatum, and cortex of gerbils. However, administration of ketamine (120 mg/kg, i.p.) markedly suppressed but not abolished the ischemia-induced increases of taurine and GABA from hippocampus, striatum, and cortex in gerbils. CONCLUSION: The increases of glutamate, aspartate, glycine, and glutamine induced by acute global cerebral ischemia may constitute the biochemical basis of ischemic brain damage. Correspondingly, the release of GABA and taurine may be an important self-protective mechanism. Ketamine may protect neurons against ischemic insult by inhibiting global cerebral ischemia-evoked increase of glutamate, glycine, and aspartate.

Animals↗
PubMed2004

[Effect of propofol on the activation of nuclear factor-kappa B and expression of inflammatory cytokines in cerebral cortex during transient focal cerebral ischemia-reperfusion: experiment with rats].

OBJECTIVE: To investigate the effect of propofol on the activation of nuclear factor-kappa B (NF-kappa B) and the expression of inflammatory cytokines, such as interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-alpha), and intercellular adhesion molecule-1 (ICAM-1) in cerebral cortex during transient focal cerebral ischemia-reperfusion, and to discuss the probable mechanism of its protective effect. METHODS: Ninety male Wistar rats were randomly divided into 3 equal groups: sham operation group undergoing sham operation; ischemia/reperfusion (I/R) group undergoing thread embolism of the left middle cerebral artery occlusion (MCAO) to cause focal ischemia for 2 hours and then undergoing reperfusion; and propofol group undergoing peritoneal injection of propofol 2 hours before the ischemia-reperfusion of MCAO. Then the rats in the 3 groups were re-divided into subgroups of 5 rats, totally 18 subgroups, to be decapitated 2, 3, 6, 12, 24, and 72 hours after reperfusion for the latter 2 groups, and their brains were taken out and fixed. Immunohistochemistry was used to detect the translocation of NF-kappaB in the neurons and the expression of IL-1, TNF-alpha, and ICAM-1 in the brain. Western blotting was used to detect the expression of NF-kappa B. The opposite non-ischemic cortexes were used as controls. RESULTS: Two to 24 hours after the reperfusion NF-kappaB was significantly translocated from the cytoplasm into the nucleus; however, NF-kappa B remained in the cytoplasm of bilateral cortexes in the sham operation groups, and the nonischemic cortexes in the I/R and protofol groups. The translocation of NF-kappa B from cytoplasm into nucleus was significantly inhibited in the ischemic cortex of the propofol group. The expression values of NF-kappa B in the nuclei of ischemic cortexes in the I/R group 2 to 24 hours after reperfusion were significantly higher than those in the sham operation group and the nonischemic cortexes of the I/R and propofol groups (all P < 0.01). The expression values of NF-kappa B in the ischemic cortex of the propofol group 2 to 24 hours after reperfusion was significantly lower than that of the I/R group (all P < 0.05). The expression values of IL-1, TNF-alpha, and ICAM-1 in the ischemic cortexes were significantly higher than that in the cortex of the sham operation group and those in the nonischemic cortexes of the I/R group and propofol group (P < 0.01 or P < 0.05) and the expression values of IL-1, TNF-alpha, and ICAM-1 in the propofol group were all significantly lower than those in the I/R group (all P < 0.05). CONCLUSION: Propofol inhibits the inflammatory reaction by inhibiting the NF-kappa B activation during focal ischemia-reperfusion which may be one of the mechanisms of its neuroprotective function.

Animals↗
PubMed1977

Cellular events during partial cerebral ischemia. I. Electron microscopy of feline cerebral cortex after middle-cerebral-artery occlusion.

The feline right cerebral hemisphere was subjected to regional (incomplete) ischemia after clipping the middle cerebral artery for 5, 10, 15, 30 or 60 min, respectively. After each ischemic episode, a 10-min recirculation period was allowed, following which the brain was fixed and processed for electron microscopy. The earliest alterations, detected in the cerebral cortex after 15 min, increased in severity with longer ischemic episodes and were distributed multifocally. There was: (a) marked neuronal mitochondrial matrical swelling and progressive condensation of cytoplasm and nucleoplasm; (b) cytoplasmic swelling of astrocytes with preservation of glial mitochondrial volume; (c) capillaries, oligodendrocytes, myelin sheaths and axis cylinders did not change significantly, even after the longest interval studied: 60 min. This type of tissue reaction appears to be common for those forms of cerebral ischemia, in which circulation is either sustained partially (via collateral arteries) or restored after a period of absolute ischemia. Under these conditions, as yet undefined permeability changes in cell membranes lead to pronounced volumetric alterations of cellular compartments. Although no softening is detectable by digital examination, we suggest that such a set of structural abnormalities constitutes encephalomalacia, or the earliest stage of a lesion which is designated infarction, once it reaches irreversibility.

Animals↗
PubMed2002

Gene expression analysis of spontaneously hypertensive rat cerebral cortex following transient focal cerebral ischemia.

Identification of novel modulators of ischemic neuronal death helps in developing new strategies to prevent the stroke-induced neurological dysfunction. Hence, the present study evaluated the gene expression changes in rat cerebral cortex at 6 and 24 h of reperfusion following transient middle cerebral artery occlusion (MCAO) by GeneChip analysis. Transient MCAO resulted in selective increased mRNA levels of genes involved in stress, inflammation, transcription and plasticity, and decreased mRNA levels of genes which control neurotransmitter function and ionic balance. In addition to a number of established ischemia-related genes, many genes not previously implicated in transient focal ischemia-induced brain damage [suppressor of cytokine signaling (SOCS)-3, cAMP responsive element modulator (CREM), cytosolic retinol binding protein (CRBP), silencer factor-B, survival motor neuron (SMN), interferon-gamma regulatory factor-1 (IRF-1), galanin, neurotrimin, proteasome subunit RC8, synaptosomal-associated protein (SNAP)-25 A and B, synapsin 1a, neurexin 1-beta, ras-related rab3, vesicular GABA transporter (VGAT), digoxin carrier protein, neuronal calcium sensor-1 and neurodap] were observed to be altered in the ischemic cortex. Real-time PCR confirmed the GeneChip results for several of these transcripts. SOCS-3 is a gene up-regulated after ischemia which modulates inflammation by controlling cytokine levels. Antisense knockdown of ischemia-induced SOCS-3 protein expression exacerbated transient MCAO-induced infarct volume assigning a neuroprotective role to SOCS-3, a gene not heretofore implicated in ischemic neuronal damage.

Animals↗
PubMed1993

The organization of neural systems in the primate cerebral cortex.

The primate cerebral cortex is a sheet composed of many distinct areas. Each of these areas receives a large number of afferent inputs from other cortical areas (and elsewhere) and in return issues a large number of output projections. The cortex is thus innervated by a very large number of cortico-cortical connections, so that the areas and their interconnections form a network of startling complexity. The complexity of this network presents a formidable topological problem that hinders understanding of its organization. Recently, however, an optimization analysis has been applied to the connections between visual cortical areas. This optimization analysis derived a structure for the cortical visual system, a system whose organization has been extensively explored, that is consistent with known organizational features. This paper concerns an application of the same approach to the cortico-cortical connections of other major sensory systems in the primate brain, and to the connections of the entire cerebral cortex, whose organizations have not been extensively explored. The latter analysis suggests the gross topological organization of the cortical information processing system of this animal, and shows the 'place' of individual areas within this organization. The results may be suggestive for further theory and experiment.

Animals↗
PubMed1985

[Modulating influence of the 2d somatosensory cortex of the cerebral cortex on the effects of electroacupuncture on the trigeminal nuclei].

The effect of reversible functional inactivation of the second somatosensory cortex of the cerebral hemispheres on changes in the transmission of the afferent signals in the trigeminal nuclei after electroacupuncture was studied in acute experiments on adult cats anesthetized with hexenal (59 mg/kg i. p.). After functional inactivation of the second somatosensory cortex electroacupuncture failed to facilitate the evoked potentials in the oral trigeminal nucleus by stimulation of the tooth pulp and the lip of the mouth. In the caudal nucleus, the inhibitory effect of electroacupuncture on noxious stimulation decreased. The involvement of this brain cortex in the mechanisms of action of electroacupuncture on functionally different nuclei is discussed.

Acupuncture Therapy↗
PubMed1976

[Catecholaminergic axons in the human cerebral cortex. Observation by histofluorescence of cerebral biopsies in 2 cases of Alzheimer's disease].

Catecholamine axons have been visualized in human cerebral cortex obtained during routine neurosurgical operations. The fluorescence histochemical method of Lindvall et al. was used, slightly modified (calcium-deprived buffer, glyoxylic acid fixation followed by formaldehyde vapours exposition). The frontal cortex was more richely provided with catecholamine terminals than the parietal cortex. Two general types of axon morphology are evident. The most frequent is thin and sinous, sometimes forming clews, or loose basket-like arrangement around presumed nerve cells. The other one is moniliform and demonstrates spherical evenly-spaced varicosities. They look like, respectively, the well characterized dopaminergic and noradrenergic axons of the rat cerebral cortex. In two cases of Alzheimer's disease, noradrenergic-like fibers were missing and voluminous green-fluorescent varicosities, sometimes in obvious connection with typical axons, were observed in the proximity of senile plaques.

Alzheimer Disease↗