Neurons and neuronal stem cells survive in glucose-free lactate and in high glucose cell culture medium during normoxia and anoxia.

Several questions concerning the survival of isolated neurons and neuronal stem and progenitor cells (NPCs) have not been answered in the past: (1) If lactate is discussed as a major physiological substrate of neurons, do neurons and NPCs survive in a glucose-free lactate environment? (2) If elevated levels of glucose are detrimental to neuronal survival during ischemia, do high concentrations of glucose (up to 40 mmol/L) damage neurons and NPCs? (3) Which is the detrimental factor in oxygen glucose deprivation (OGD), lack of oxygen, lack of glucose, or the combination of both? Therefore, in the present study, we exposed rat cortical neurons and NPCs to different concentrations of D: -glucose ranging from 0 to 40 mmol/L, or 10 and 20 mmol/L L-lactate under normoxic and anoxic conditions, as well as in OGD. After 24 h, we measured cellular viability by biochemical assays and automated cytochemical morphometry, pH values, bicarbonate, lactate and glucose concentrations in the cell culture media, and caspases activities. We found that (1) neurons and NPCs survived in a glucose-free lactate environment at least up to 24 h, (2) high glucose concentrations >5 mmol/L had no effect on cell viability, and (3) cell viability was reduced in normoxic glucose deprivation to 50% compared to 10 mmol/L glucose, whereas cell viability in OGD did not differ from that in anoxia with lactate which reduced cell viability to 30%. Total caspases activities were increased in the anoxic glucose groups only. Our data indicate that (1) neurons and NPCs can survive with lactate as exclusive metabolic substrate, (2) the viability of isolated neurons and NPCs is not impaired by high glucose concentrations during normoxia or anoxia, and (3) in OGD, low glucose concentrations, but not low oxygen levels are detrimental for neurons and NPCs.

Increased arterial oxygen content by artificial haemoglobin induces a decrease in regional cerebral blood flow and decreased regional cerebral oxygen delivery.

BACKGROUND AND OBJECTIVE: Under physiological conditions, cerebral oxygen delivery is kept constant by adaptation of the regional cerebral blood flow (CBF) in relation to the oxygen content. So far, decreases of the regional CBF induced by a higher arterial oxygen content have been produced under hyperbaric or hyperviscous conditions. We tested whether local CBF is also reduced by a high haemoglobin (Hb) concentration at a normal haematocrit (Hct). METHODS: Compared with controls (n=8), Hb content was increased to 19 g dl(-1) in conscious rats by isovolaemic replacement of the plasma fraction with an artificially high Hb solution (Hb-based oxygen carriers; HH group, n=8). In another group (n=8), Hct was decreased by isovolaemic exchange with an Hb-based oxygen carrier resulting in a normal Hb content (NH group). Mean and regional CBF was measured by iodo-[(14)C]-antipyrine autoradiography. Oxygen delivery was calculated from arterial oxygen content and CBF. RESULTS: Compared with the controls (Hb 15.3 g dl(-1), Hct 0.44), mean CBF was lower in the HH (Hb 20.3 g dl(-1), Hct 0.44) group by 23% (P < or = 0.05), but remained unchanged in the NH group (Hb 15.0 g dl(-1), Hct 0.29). On a local level, hyperoxygenation reduced CBF in 22 out of 39 brain regions. In the NH group mean CBF was unchanged, whereas local CBF was higher in 10 areas. In both groups, overall cerebral oxygen delivery was unchanged compared with the control group. Locally though, high arterial Hb content decreased oxygen delivery in one-third of the brain structures. CONCLUSION: Whereas the overall cerebral oxygen delivery in the brain is maintained during hyperoxygenation and haemodilution, local oxygen delivery is decreased by high arterial Hb content in some brain regions.

Protein expression differs between neural progenitor cells from the adult rat brain subventricular zone and olfactory bulb.

BACKGROUND: Neural progenitor cells can be isolated from various regions of the adult mammalian brain, including the forebrain structures of the subventricular zone and the olfactory bulb. Currently it is unknown whether functional differences in these progenitor cell populations can already be found on the molecular level. Therefore, we compared protein expression profiles between progenitor cells isolated from the subventricular zone and the olfactory bulb using a proteomic approach based on two-dimensional gel electrophoresis and mass spectrometry. The subventricular zone and the olfactory bulb are connected by the Rostral Migratory Stream (RMS), in which glial fibrillary acidic protein (GFAP)-positive cells guide neuroblasts. Recent literature suggested that these GFAP-positive cells possess neurogenic potential themselves. In the current study, we therefore compared the cultured neurospheres for the fraction of GFAP-positive cells and their morphology of over a prolonged period of time. RESULTS: We found significant differences in the protein expression patterns between subventricular zone and olfactory bulb neural progenitor cells. Of the differentially expressed protein spots, 105 were exclusively expressed in the subventricular zone, 23 showed a lower expression and 51 a higher expression in the olfactory bulb. The proteomic data showed that more proteins are differentially expressed in olfactory bulb progenitors with regard to proteins involved in differentiation and microenvironmental integration, as compared to the subventricular zone progenitors. Compared to 94% of all progenitors of the subventricular zone expressed GFAP, nearly none in the olfactory bulb cultures expressed GFAP. Both GFAP-positive subpopulations differed also in morphology, with the olfactory bulb cells showing more branching. No differences in growth characteristics such as doubling time, and passage lengths could be found over 26 consecutive passages in the two cultures. CONCLUSION: In this study, we describe differences in protein expression of neural progenitor populations isolated from two forebrain regions, the subventricular zone and the olfactory bulb. These subpopulations can be characterized by differential expression of marker proteins. We isolated fractions of progenitor cells with GFAP expression from both regions, but the GFAP-positive cells differed in number and morphology. Whereas in vitro growth characteristics of neural progenitors are preserved in both regions, our proteomic and immunohistochemical data suggest that progenitor cells from the two regions differ in morphology and functionality, but not in their proliferative capacity.

Acute anoxia stimulates proliferation in adult neural stem cells from the rat brain.

Hypoxic-ischemic damage is a major challenge for neuronal tissue. In the present study, we investigated the effects of anoxia and glucose deprivation on adult neural stem cells (NSCs) in vitro. We assessed glucose deprivation, anoxia and the combination of the latter separately. After 24 h of anoxia, cell numbers increased up to 60% compared to normoxic controls. Whereas nearly all normoxic cells incorporated the mitotic marker BrdU (99%), only 85% of the anoxic cells were BrdU-positive. Counting of interphase chromosomes showed 8-fold higher cell division activity after anoxia. The number of necrotic cells doubled after anoxia (14% compared to 7% after normoxia). Apoptosis was measured by two distinct caspases assays. Whereas the total caspase activity was reduced after anoxia, caspase 3/7 showed no alterations. Glucose deprivation and oxygen glucose deprivation both reduced cell viability by 56 and 53%, respectively. Under these conditions, total caspases activity doubled, but caspase 3/7 activity remained unchanged. Erythropoietin, which was reported as neuroprotective, did not increase cell viability in normoxia, but moderately under oxygen glucose deprivation by up to 6%. Erythropoietin reduced total caspase activity by nearly 30% under all the conditions, whereas caspase 3/7 activity was not affected. Our results show that anoxia increases proliferation and viability of adult NSCs, although a fraction of NSCs does not divide during anoxia. In conclusion, anoxia increased cell viability, cell number and proliferation in NSCs from the rat brain. Anoxia turned out to be a highly stimulating environmental for NSCs and NSCs died only when deprived of glucose. We conclude that the availability of glucose but not of oxygen is a crucial factor for NSC survival, regulating apoptotic pathways via caspases activity other than the caspases 3/7 pathway. Therefore, we conclude that NSCs are dying from glucose deprivation, not from hypoxic-ischemic damage.

The functional genome of CA1 and CA3 neurons under native conditions and in response to ischemia.

BACKGROUND: The different physiological repertoire of CA3 and CA1 neurons in the hippocampus, as well as their differing behaviour after noxious stimuli are ultimately based upon differences in the expressed genome. We have compared CA3 and CA1 gene expression in the uninjured brain, and after cerebral ischemia using laser microdissection (LMD), RNA amplification, and array hybridization. RESULTS: Profiling in CA1 vs. CA3 under normoxic conditions detected more than 1000 differentially expressed genes that belong to different, physiologically relevant gene ontology groups in both cell types. The comparison of each region under normoxic and ischemic conditions revealed more than 5000 ischemia-regulated genes for each individual cell type. Surprisingly, there was a high co-regulation in both regions. In the ischemic state, only about 100 genes were found to be differentially expressed in CA3 and CA1. The majority of these genes were also different in the native state. A minority of interesting genes (e.g. inhibinbetaA) displayed divergent expression preference under native and ischemic conditions with partially opposing directions of regulation in both cell types. CONCLUSION: The differences found in two morphologically very similar cell types situated next to each other in the CNS are large providing a rational basis for physiological differences. Unexpectedly, the genomic response to ischemia is highly similar in these two neuron types, leading to a substantial attenuation of functional genomic differences in these two cell types. Also, the majority of changes that exist in the ischemic state are not generated de novo by the ischemic stimulus, but are preexistant from the genomic repertoire in the native situation. This unexpected influence of a strong noxious stimulus on cell-specific gene expression differences can be explained by the activation of a cell-type independent conserved gene-expression program. Our data generate both novel insights into the relation of the quiescent and stimulus-induced transcriptome in different cells, and provide a large dataset to the research community, both for mapping purposes, as well as for physiological and pathophysiological research.

Identification of early markers for symptomatic vasospasm in human cerebral microdialysate after subarachnoid hemorrhage: preliminary results of a proteome-wide screening.

A major complication of aneurysmal subarachnoid hemorrhage (SAH) is symptomatic vasospasm, a complex syndrome consisting of neurological deterioration and exclusion of other sources of ischemia. Approximately 30% of SAH patients are affected. Although symptomatic vasospasm is associated with high mortality and poor clinical outcome, it is not possible to identify the individual risk on a molecular level for patients before symptoms have developed. In this study, we hypothesize that protein changes occur in the cerebral microdialysate of patients who later develop symptomatic vasospasm which are not found in matched-pairs control subjects. We searched for changes in protein concentrations in microdialysate sampled from the fronto-temporal brain tissue of five vasospastic and five nonvasospastic SAH patients using proteomics technology based on two-dimensional gel electrophoresis and mass spectrometry. Microdialysate samples were taken at least 1.5 days before the onset of symptomatic vasospasm. Comparing protein expression profiles, we found that the protein concentrations of several isoforms of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were 1.79-fold+/-1.29 (N=5, P<0.05) higher in the group which later developed symptomatic vasospasm, whereas heat-shock cognate 71 kDa protein (HSP7C) isoforms were decreased to 0.50-fold+/-0.19 (N=5, P<0.05; all expression data means+/-s.d.). The changes in protein concentrations were detected 3.8+/-1.7 days (N=5, P<0.05) before symptomatic vasospasm developed. We conclude that GAPDH and HSP7C may be used as early markers indicating the later development of symptomatic vasospasm after SAH, enabling selective early therapeutic intervention in this high-risk group of patients.

Reduced cerebral blood flow but elevated cerebral glucose metabolic rate in erythropoietin overexpressing transgenic mice with excessive erythrocytosis.

To examine the impact of excessive erythrocytosis on local cerebral blood flow (CBF) and cerebral glucose metabolic rate (CMR(glc)), we made use of our constitutively erythropoietin (Epo)-overexpressing transgenic mouse line (tg-6) that reach a mean hematocrit of 0.87. Compared with wild-type (wt) control siblings, CBF decreased by 44% in tg-6 mice, while upon hemodilution (tg-6-HD) to a physiologic hematocrit (e.g., 0.44) tg-6-HD mice returned the CBF to wt levels. Cerebral blood flow was determined in another transgenic mouse line that overexpresses human Epo in the brain only (tg-21): CBF increased by 17% compared with wt controls. However, oxygen delivery was similar in all four mouse groups tested (wt, tg-6, tg-6-HD and tg-21). Mean CMR(glc) was higher in tg-6 (+72%), tg-6-HD mice (+43%) and tg-21 (+22%) than in wt mice. Local CMR(glc) was higher in all 40 brain regions in tg-6 but only in 15 and 8 regions in tg-6-HD and tg-21 mice. These results show that prolonged increases in hematocrit did not alter cerebral oxygen delivery at a decreased CBF and increased CMR(glc). Hemodilution suggests that high blood viscosity is a cause of the decrease in CBF and partly of the increase in CMR(glc). Cerebral glucose metabolic rate may also be increased by a direct effect of Epo in the brain (tg-21 mice).

Local cerebral blood flow is preserved in sepsis.

Sepsis is often complicated by encephalopathy, neuroendocrine dysfunction and cardiovascular autonomic failure. The cause of septic brain dysfunction is not fully understood. The aim of the present study is to explore whether septic brain dysfunction in a common septic model in the rat correlates with abnormalities either of local cerebral blood flow (LCBF) of defined brain areas or of whole brain blood flow (CBF). 45 male Wistar rats (320+/-13 g) were randomly assigned to a sepsis group (31 rats, cecal ligature and puncture, CLP) or a control group (14 rats, sham operation). Of these 45 rats, 16 rats were used for blood analysis; the remaining 29 rats were used for CBF/LCBF measurements. LCBF measurements were performed 24h after initial surgery using quantitative autoradiography with 4-iodo[N-methyl-(14)C]antipyrine, which allows to analyze CBF on a regional/local and global basis. In 42 different brain regions bilateral optical density measurements were performed. Septic rats (vs. control) presented tachycardia (507+/-37 vs. 452+/-44 min(-1), P<0.05), leukocytopenia (2.96+/-2.37 vs. 8.83+/-2.9710(9) x L(-1), P<0.05), hypocapnia (29.3+/-4.6 vs. 36.4+/-3.9 mmHg, P<0.05), and higher serum lactate concentrations (5.7+/-3.9 vs. 2.2+/-2.0 mmol x L(-1), P<0.05). LCBF of all 42 areas, as well as, CBF (116+/-59 vs. 115+/-52 m x 100 g(-1)min(-1), n.s.) did not differ. The results showed that severe sepsis (mortality rate of 43 %) did not induce alterations in mean CBF and LCBF. It is concluded that brain dysfunction is not reflected in changes of CBF during severe sepsis.

The effects of sevoflurane anesthesia on rat brain proteins: a proteomic time-course analysis.

BACKGROUND: Recent studies showed changes in cerebral protein expression up to 3 days after desflurane anesthesia in rats. In the present study, we investigated the existence of persisting changes on the proteome level after sevoflurane anesthesia that persisted for as long as 28 days after anesthesia. METHODS: Rats were anesthetized by spontaneous inhalation of 2.4% sevoflurane in air for 3 h. Animals (n = 6 for each group) were killed either directly, 72 h, or 28 days after anesthesia. Brains were removed and subjected to global protein expression profiling based on two-dimensional gel electrophoresis and mass spectrometry. Expression factors were compared to results from untreated conscious animals at each time point. Data were statistically analyzed by ANOVA (P < 0.01) and a cut of more than two-fold change in the expression factor. RESULTS: We found 11 protein spots differentially regulated directly after anesthesia. Seventeen proteins were differentially expressed 72 h after the anesthesia. Only one spot was differentially regulated 28 days after anesthesia. The plausible targets of these differentially regulated proteins can be attributed to synaptic vesicle handling and cell-cell communication. CONCLUSIONS: Sevoflurane induced relevant changes in protein expression profiles directly and 72 h after an anesthesia with 1 MAC. Twenty-eight days after the anesthesia, all proteins except one had returned to baseline levels of abundance.

The heterogeneity of human mesenchymal stem cell preparations--evidence from simultaneous analysis of proteomes and transcriptomes.

OBJECTIVE: Mesenchymal stem cells (MSC) raise high hopes in clinical applications. However, the lack of common standards and a precise definition of MSC preparations remains a major obstacle in research and application of MSC. Whereas surface antigen markers have failed to precisely define this population, a combination of proteomic data and microarray data provides a new dimension for the definition of MSC preparations. METHODS: In our continuing effort to characterize MSC, we have analyzed the differential transcriptome and proteome expression profiles of MSC preparations isolated from human bone marrow under two different expansion media (BM-MSC-M1 and BM-MSC-M2). RESULTS: In proteomics, 136 protein spots were unambiguously identified by MALDI-TOF-MS and corresponding cDNA spots were selected on our "Human Transcriptome cDNA Microarray." Combination of datasets revealed a correlation in differential gene expression and protein expression of BM-MSC-M1 vs BM-MSC-M2. Genes involved in metabolism were more highly expressed in BM-MSC-M1, whereas genes involved in development, morphogenesis, extracellular matrix, and differentiation were more highly expressed in BM-MSC-M2. Interchanging culture conditions for 8 days revealed that differential expression was retained in several genes whereas it was altered in others. CONCLUSION: Our results have provided evidence that homogeneous BM-MSC preparations can reproducibly be isolated under standardized conditions, whereas culture conditions exert a prominent impact on transcriptome, proteome, and cellular organization of BM-MSC.

Adult neural stem cells express glucose transporters GLUT1 and GLUT3 and regulate GLUT3 expression.

In the brain, glucose is transported by GLUT1 across the blood-brain barrier and into astrocytes, and by GLUT3 into neurons. In the present study, the expression of GLUT1 and GLUT3 mRNA and protein was determined in adult neural stem cells cultured from the subventricular zone of rats. Both mRNAs and proteins were coexpressed, GLUT1 protein being 5-fold higher than GLUT3. Stress induced by hypoxia and/or hyperglycemia increased the expression of GLUT1 and GLUT3 mRNA and of GLUT3 protein. It is concluded that adult neural stem cells can transport glucose by GLUT1 and GLUT3 and can regulate their glucose transporter densities.

Lack of relationship between cellular density and either capillary density or metabolic rate in different regions of the brain.

Whereas a pronounced correlation exists between local cerebral glucose utilization (LCGU) and capillary density in different regions of the brain, it is not known whether these parameters also correlate with the overall density of nuclei (cellularity). Therefore, cellularity was determined by diamidino-phenylindol (DAPI) fluorescent staining of nuclei in acetone-fixed frozen sections of the rat brain. A comparison of the density of nuclei in different brain regions showed much less variation than that observed in LCGU and capillary density. No correlation was found between nuclear density and either LCGU or capillary densities. In conclusion the cellular density is not a determinant of variation in LCGU and capillary density.

Heterologous expression of human VEGF165 in rat brain: dose-dependent, heterogeneous effects on CBF in relation to vascular density and cross-sectional area.

Vascular endothelial growth factor (VEGF) induces increased vessel permeability and formation of abnormal vessels. To investigate cerebral blood flow (CBF) during local overexpression of VEGF recombinant adenoviruses carrying the human VEGF165 complementary DNA (2.3 to 23. 108 pfu/mL) were injected stereotactically into the caudate nucleus of anesthetized rats. Saline and adenoviruses carrying the beta-galactosidase gene served as controls. Eleven days later (1) size and density of vessels were assessed in hematoxylin-eosin-stained sections, (2) vascular permeability was measured by intravenous Evans blue injections, and (3) local CBF (lCBF) was quantified using the iodo-[14C]antipyrine technique. Dose-dependent increases were found in (1) vessel density and size (only vessels >43 microm could be quantified morphologically), (2) Evans blue extravasation and brain edema formation, and (3) lCBF (up to eightfold). At medium doses, hyperemic areas and smaller areas of decreased lCBF were found. In low flow areas, vascular cross-sectional areas were increased 223-fold and vessel density up to 10-fold. In high flow areas, these parameters were increased 32-fold and up to 15-fold, respectively. Adenovirus mediated VEGF overexpression results in (1) increased vessel size and density, (2) areas of increased and of decreased flow, and (3) more and smaller vessels in high flow than in low flow areas. These results indicate a diverging flow pattern of newly formed vessels.

Massive inborn angiogenesis in the brain scarcely raises cerebral blood flow.

The functional consequences of increased capillary densities in the brain resulting from vascular endothelial growth factor (VEGF165) overexpression are unknown. Therefore, the authors measured local CBF using the iodo-[14C]antipyrine technique in transgenic mice expressing brain-specifically sixfold higher VEGF165 levels and in nontransgenic littermates. To reveal possible compensatory vasoconstriction, CBF was also measured during severe hypercapnia (Paco2 > 130 mm Hg). Simultaneously, local capillary density, perfusion state, and blood-brain-barrier permeability were assessed. Using the 2-[14C]deoxyglucose method, metabolic effects of VEGF over-expression could be excluded. In transgenic mice all capillaries showed normal morphology and a tight blood-brain barrier. However, 3% nonperfused capillaries in some brain structures indicate ongoing angiogenesis. Capillary density was drastically increased in transgenic mice in white matter structures (70% to 185%), the dentate gyrus (143%), and caudate nucleus (86%). In all other brain structures investigated, capillary densities were moderately increased by approximately 20%. Normocapnic CBF did not differ between transgenic and nontransgenic mice. During maximal hypercapnic vasodilation, CBF was 20% to 30% higher in transgenic mice, although only in brain structures where capillary density was increased more than twofold. These findings suggest that attenuated CBF in transgenic mice during normocapnia is only partly due to a compensatory vasoconstriction, and that microvascular networks in transgenic brains might be ineffectively constructed.

Microvascular Basal lamina damage after embolic stroke in the rat: relationship to cerebral blood flow.

Microvascular basal lamina damage has been demonstrated after balloon occlusion of the middle cerebral artery in the nonhuman primate and after intravascular filament occlusion in the rat. The aim of the present study was to investigate in the rat whether microvascular damage can be found in the stroke model of intracarotid clot injection as early as 3 hours after clot injection and whether microvascular damage relates to the level of regional cerebral blood flow (rCBF). Microvascular densities and total stained microvascular areas were determined by immunohistochemistry of collagen type IV in cortex and basal ganglia and automatic video-imaging analysis. rCBF was measured by autoradiography in the same brain areas. Compared with the corresponding areas in the nonischemic hemisphere, a significant loss of microvascular density (-16%) and total stained microvascular areas (-10%) was observed in these areas. The reduction of microvascular basal lamina staining was comparable in all animals and was not related to the value of rCBF when measured 3 hours after onset of embolic stroke. In conclusion, microvascular damage occurs as soon as 3 hours after intracarotid clot injection, even in brain areas in which rCBF has returned to normal values.

The proteome of neural stem cells from adult rat hippocampus.

BACKGROUND: Hippocampal neural stem cells (HNSC) play an important role in cerebral plasticity in the adult brain and may contribute to tissue repair in neurological disease. To describe their biological potential with regard to plasticity, proliferation, or differentiation, it is important to know the cellular composition of their proteins, subsumed by the term proteome. RESULTS: Here, we present for the first time a proteomic database for HNSC isolated from the brains of adult rats and cultured for 10 weeks. Cytosolic proteins were extracted and subjected to two-dimensional gel electrophoresis followed by protein identification through mass spectrometry, database search, and gel matching. We could map about 1141 PlusMinus; 209 (N = 5) protein spots for each gel, of which 266 could be identified. We could group the identified proteins into several functional categories including metabolism, protein folding, energy metabolism and cellular respiration, as well as cytoskeleton, Ca2+ signaling pathways, cell cycle regulation, proteasome and protein degradation. We also found proteins belonging to detoxification, neurotransmitter metabolism, intracellular signaling pathways, and regulation of DNA transcription and RNA processing. CONCLUSIONS: The HNSC proteome database is a useful inventory which will allow to specify changes in the cellular protein expression pattern due to specific activated or suppressed pathways during differentiation or proliferation of neural stem cells. Several proteins could be identified in the HNSC proteome which are related to differentiation and plasticity, indicating activated functional pathways. Moreover, we found a protein for which no expression has been described in brain cells before.

The proteome of human brain microdialysate.

BACKGROUND: Cerebral microdialysis has been established as a monitoring tool in neurocritically ill patients suffering from severe stroke. The technique allows to sample small molecules in the brain tissue for subsequent biochemical analysis. In this study, we investigated the proteomic profile of human cerebral microdialysate and if the identified proteins might be useful predictors for disease characteristics in stroke for tissue at risk in the contralateral hemisphere. We analysed cerebral protein expression in microdialysate from three stroke patients sampled from the hemisphere contralateral to the lesion. Using a proteomic approach based on two-dimensional gel electrophoresis and subsequent mass spectrometry, we created a protein map for the global protein expression pattern of human microdialyste. RESULTS: We found an average of 158 +/- 24 (N = 18) protein spots in the human cerebral microdialysate and could identify 95 spots, representing 27 individual proteins. Most of these have been detected in human cerebrospinal fluid before, but 10 additional proteins mainly of cerebral intracellular origin were identified exclusively in the microdialysate. CONCLUSIONS: The 10 proteins found exclusively in human cerebral microdialysate, but not in cerebrospinal fluid, indicate the possibility to monitor the progression of the disease towards deterioration. The correlation of protein composition in the human cerebral microdialysate with the patients' clinical condition and results of cerebral imaging may be a useful approach to future applications for neurological stroke diagnosis, prognosis, and treatment.

Correlation between local monocarboxylate transporter 1 (MCT1) and glucose transporter 1 (GLUT1) densities in the adult rat brain.

Monocarboxylate transporters type 1 (MCT1) facilitate the transport of monocarboxylates across cell membranes of the blood-brain barrier and brain parenchymal cells. The present study had two aims: (1) to determine the local distribution of MCT1 in the brain; and (2) to compare the local densities of MCT1 with the local densities of the main nutritional transporters, glucose transporter GLUT1. Using immunoautoradiography of cryosections from rat brain, 32 brain structures were analyzed. (1) A heterogenous distribution pattern of MCT1 densities was observed throughout the brain. Compared to brain homogenate (100%), MCT1 densities ranged from 43 to 164% in the brain structures investigated. Local GLUT1 densities showed a comparable range (35-145%). (2) A close correlation was found between local MCT1 and local GLUT1 densities. As local GLUT1 densities reflect local glucose metabolism in the brain, we conclude that local MCT1 densities are adjusted to local glucose metabolism and transport.

Expression of vascular endothelial growth factor and its receptors in rat neural stem cells.

Neural stem cells serve neurogenesis in several areas of the adult mammalian brain. The present study investigates an additional feature, i.e. the expression of vascular endothelial growth factor (VEGF) and its receptors in cultured neurospheres from hippocampus, subventricular zone, and olfactory bulb in adult rats. RT-PCR showed that all three lines expressed VEGF mRNA, but different sets of VEGF receptor mRNAs. Stimulation by either 50 ng/ml VEGF-A165 or by 24 h of anoxia resulted in an altered pattern of receptor expression for VEGF-R2 (Flk-1), VEGF-R3 (Flt-4), neuropilin-1, and neuropilin-2, whereas VEGF-R1 (Flt-1) remained unexpressed. The basal expression of VEGF and of several of its receptor mRNAs indicates a hitherto unknown angiogenic potential of neural stem cells.

Cerebral transcriptome analysis of transgenic mice overexpressing erythropoietin.

Erythropoietin (EPO) and its receptor are expressed in the brain, and one of its roles appears to be neuroprotection. This study investigates whether chronic overexpression of EPO changes brain mRNA expression in the brains of transgenic mice. Therefore, cerebral mRNA expression was investigated in transgenic mice overexpressing EPO. Microarray analysis revealed an upregulation (2.8- to 3.6-fold) of N-acetylglucosamine-6-O-sulfotransferase (prolongation of the EPO effect), a translocase of the inner mitochondrial membrane (mitochondrial matrix import of nuclear encoded proteins), a mitochondrial ribosomal protein (mitochondrial protein translation), and a peroxisomal biogenesis factor (formation of peroxisomes). In conclusion, components of oxidative metabolism pathways were activated at the level of transcription which could be related to neuroprotective effects of EPO or could indicate compromised tissue.