Mitochondrial hexokinase II (HKII) and phosphoprotein enriched in astrocytes (PEA15) form a molecular switch governing cellular fate depending on the metabolic state.

The metabolic state of a cell is a key determinant in the decision to live and proliferate or to die. Consequently, balanced energy metabolism and the regulation of apoptosis are critical for the development and maintenance of differentiated organisms. Hypoxia occurs physiologically during development or exercise and pathologically in vascular disease, tumorigenesis, and inflammation, interfering with homeostatic metabolism.

In vivo near-infrared fluorescence imaging of matrix metalloproteinase activity after cerebral ischemia.

Matrix metalloproteinases (MMPs) have been implicated in the pathophysiology of cerebral ischemia. In this study, we explored whether MMP activity can be visualized by noninvasive near-infrared fluorescence (NIRF) imaging using an MMP-activatable probe in a mouse model of stroke. C57Bl6 mice were subjected to transient middle cerebral artery occlusion (MCAO) or sham operation.

Hypothermia effects on neurovascular coupling and cerebral metabolic rate of oxygen.

Neuronal activation is accompanied by a local increase in cerebral blood flow (CBF) and in cerebral metabolic rate of oxygen (CMRO(2)), caused by neurovascular and neurometabolic coupling. Hypothermia is used as a neuroprotective approach in surgical patients and therapeutically after cardiac arrest or stroke. The effect of hypothermia on neurovascular coupling is of interest for evaluating brain function in these patients, but has not been determined so far.

Functional imaging with laser speckle contrast analysis: vascular compartment analysis and correlation with laser Doppler flowmetry and somatosensory evoked potentials.

Laser Speckle Contrast Analysis (LASCA), a novel, high-resolution blood flow imaging method, was performed on rat somatosensory cortex during functional activation. In the same animals, cerebral blood flow (CBF) was measured with Laser Doppler Flowmetry. To obtain a quantitative estimate of the underlying neuronal activity, somatosensory evoked potentials were recorded simultaneously with an epidural EEG.

Improved reperfusion and neuroprotection by creatine in a mouse model of stroke.

Stroke leads to energy failure and subsequent neuronal cell loss. Creatine and phosphocreatine constitute a cellular energy buffering and transport system, and dietary creatine supplementation was shown to protect neurons in several models of neurodegeneration. Although creatine has recently been found to reduce infarct size after cerebral ischemia in mice, the mechanisms of neuroprotection remained unclear.

Increased extracellular K+ concentration reduces the efficacy of N-methyl-D-aspartate receptor antagonists to block spreading depression-like depolarizations and spreading ischemia.

Background And Purpose: Spreading depression (SD)-like depolarizations may augment neuronal damage in neurovascular disorders such as stroke and traumatic brain injury. Spreading ischemia (SI), a particularly malignant variant of SD-like depolarization, is characterized by inverse coupling between the spreading depolarization wave and cerebral blood flow. SI has been implicated in particular in the pathophysiology of subarachnoid hemorrhage.

Neuroprotective effects of atorvastatin against glutamate-induced excitotoxicity in primary cortical neurones.

Statins [3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors] exert cholesterol-independent pleiotropic effects that include anti-thrombotic, anti-inflammatory, and anti-oxidative properties. Here, we examined direct protective effects of atorvastatin on neurones in different cell damage models in vitro. Primary cortical neurones were pre-treated with atorvastatin and then exposed to (i) glutamate, (ii) oxygen-glucose deprivation or (iii) several apoptosis-inducing compounds.

HMG-CoA reductase inhibition causes neurite loss by interfering with geranylgeranylpyrophosphate synthesis.

To determine whether neurite outgrowth depends upon the mevalonate pathway, we blocked mevalonate synthesis in nerve growth factor-treated PC12 cells or primary cortical neurones with atorvastatin, a 3-hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, and substituted different intermediates of the mevalonate pathway. We show that HMG-CoA reductase inhibition causes a profound reduction of neurite length, neurite loss and ultimatively cell death in undifferentiated and pre-differentiated PC12 cells and also in rat primary cortical neurones. Geranylgeranylpyrophosphate, but not farnesylpyrophosphate, squalene or cholesterol, completely compensated for the lack of mevalonate.

Preventive antibacterial treatment improves the general medical and neurological outcome in a mouse model of stroke.

Background And Purpose: Epidemiological studies have demonstrated a high incidence of infections after severe stroke and their prominent role in morbidity and mortality in stroke patients. In a mouse model, it has been shown recently that stroke is coupled with severe and long-lasting immunosuppression, which is responsible for the development of spontaneous systemic infections. Here, we investigated in the same model the effects of preventive antibiotic treatment on survival and functional outcome of experimental stroke.

Erythropoietin is a paracrine mediator of ischemic tolerance in the brain: evidence from an in vitro model.

In an in vitro model of cerebral ischemia (oxygen glucose deprivation, OGD) we investigated whether erythropoietin (EPO) plays a critical role in ischemic preconditioning. We found that EPO time and dose-dependently induced protection against OGD in rat primary cortical neurons. Protection was significant at 5 min and reached a maximum at 48 hr after EPO application.

Desferrioxamine induces delayed tolerance against cerebral ischemia in vivo and in vitro.

The widely prescribed drug desferrioxamine is a known activator of the hypoxia-inducible transcription factor 1 (HIF-1) and the subsequent transcription of erythropoietin. In the brain, HIF-1 is a master switch of the transcriptional response to hypoxia, whereas erythropoietin is a potent neuroprotectant. The authors show that desferrioxamine dose-dependently and time-dependently induces tolerance against focal cerebral ischemia in rats and mice, and against oxygen-glucose deprivation in purified cortical neurons.

Differential mechanisms of neuroprotection by 17 beta-estradiol in apoptotic versus necrotic neurodegeneration.

The major goal of this study was to compare mechanisms of the neuroprotective potential of 17 beta-estradiol in two models for oxidative stress-independent apoptotic neuronal cell death with that in necrotic neuronal cell death in primary neuronal cultures derived from rat hippocampus, septum, or cortex. Neuronal apoptosis was induced either by staurosporine or ethylcholine aziridinium (AF64A), as models for necrotic cell death glutamate exposure or oxygen-glucose deprivation (OGD) were applied. Long-term (20 hr) pretreatment (0.

Products of hemolysis in the subarachnoid space inducing spreading ischemia in the cortex and focal necrosis in rats: a model for delayed ischemic neurological deficits after subarachnoid hemorrhage?

Object: The pathogenesis of delayed ischemic neurological deficits after subarachnoid hemorrhage has been related to products of hemolysis. Topical brain superfusion of artificial cerebrospinal fluid (ACSF) containing the hemolysis products K+ and hemoglobin (Hb) was previously shown to induce ischemia in rats. Superimposed on a slow vasospastic reaction, the ischemic events represent spreading depolarizations of the neuronal-glial network that trigger acute vasoconstriction.

Hyperbaric oxygenation induced tolerance against focal cerebral ischemia in mice is strain dependent.

SV129 or C57BL/6 mice were exposed to hyperbaric oxygenation (HBO, 5 days, 1 h every day, 100% O(2) at 3 atm absolute). One day after the 5th HBO session focal cerebral ischemia was induced. In SV129 mice, HBO induced tolerance against permanent focal cerebral ischemia (n=42, mean infarct volume reduction 27%, P=0.

Acute treatment of hypertension increases infarct sizes in spontaneously hypertensive rats.

We studied the effect of dihydralazine treatment of hypertension in spontaneously hypertensive stroke-prone rats in a model of permanent focal cerebral ischemia (stroke). After occlusion of the middle cerebral artery systemic arterial pressure (SAP) was lowered with a computer controlled infusion device from 163 to 135 or 117 mm Hg for 24h. In the control group SAP was not manipulated.

Respiratory chain inhibition induces tolerance to focal cerebral ischemia.

The authors show that the inhibitor of the succinate dehydrogenase, 3-nitroproprionic acid (3-NPA), which in high doses and with chronic administration is a neurotoxin, can induce profound tolerance to focal cerebral ischemia in the rat when administered in a single dose (20 mg/kg) 3 days before ischemia. Infarcts were approximately 70% and 35% smaller in the 3-NPA preconditioned groups of permanent and transient focal cerebral ischemia, respectively. This regimen of 3-NPA preconditioning neither induced necrosis, apoptosis, or any other histologically detectable damage to the brain, nor did it affect behavior of the animals.

Induction of ischemic tolerance in rat cortical neurons by 3-nitropropionic acid: chemical preconditioning.

Sublethal ischemia leads to increased tolerance against subsequent ischemia. We investigated whether tolerance could also be elicited by mild respiratory-chain inhibition (chemical hypoxia) in a rat neuronal-cell enriched culture system. 3-Nitropropionic acid (3-NPA) caused a concentration-dependent inhibition of succinate-dehydrogenase.

Nitric oxide: a modulator, but not a mediator, of neurovascular coupling in rat somatosensory cortex.

We investigated the role of nitric oxide (NO)/cGMP in the coupling of neuronal activation to regional cerebral blood flow (rCBF) in alpha-chloralose-anesthetized rats. Whisker deflection (60 s) increased rCBF by 18 +/- 3%. NO synthase (NOS) inhibition by N(omega)-nitro-L-arginine (L-NNA; topically) reduced the rCBF response to 9 +/- 4% and resting rCBF to 80 +/- 8%.

Evidence that glypican is a receptor mediating beta-amyloid neurotoxicity in PC12 cells.

Docking of beta-amyloid fibrils to neuronal or glial cell membranes may be an early, necessary and intervenable step during the progression of Alzheimer's disease. Formation of neurofibrillary tangles and amyloid plaques as well as neurotoxicity and inflammation may be direct or indirect consequences. In an attempt to find a receptor that mediates those effects, we assessed rat pheochromocytoma PC12 cell 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) reduction after addition of beta-amyloid to the culture medium.

Increased formation of reactive oxygen species after permanent and reversible middle cerebral artery occlusion in the rat.

In barbiturate-anesthetized rats, we induced 3 hours of permanent middle cerebral artery occlusion (MCAO) by an intraluminal thread (n = 6), or 1 hour MCAO followed by 2 hours of reperfusion (n = 6). Through a closed cranial window over the parietal cortex, the production of reactive oxygen species (ROS) was measured in the infarct border using online in vivo chemiluminescence (CL) while monitoring the appearance of peri-infarct depolarizations (PID). The borderzone localization of the ROS and direct current (DC) potential measurements was confirmed in additional experiments using laser-Doppler scanning, mapping regional CBF changes through the cranial window after permanent (n = 5) or reversible (n = 5) MCAO.

Rapid Ca2+-dependent NO-production from central nervous system cells in culture measured by NO-nitrite/ozone chemoluminescence.

We have established simple and reliable measurement of constitutive nitric oxide (NO) synthase-dependent nitrite formation in supernatants from primary central nervous system (CNS) cells in culture using NO-ozone chemoluminescence. We found that: (1) astrocytes, endothelial cells and cerebellar granule cells produce NO upon stimulation with the calcium ionophore A23187 (1 microM); (2) application of 100 microM glutamate for 2 min results in NO-production in cerebellar granule cells and cortical neurons. NO-formation upon application of 50 mM KCl was found in cortical neurons; (3) in cultivated cerebral endothelial cells, an inducible form of NO-synthase (iNOS) is found under standard culture conditions.

Nitric oxide synthase inhibition does not affect somatosensory evoked potentials in the rat.

Nitric oxide synthase (NOS) inhibition reduces the regional cerebral blood flow (rCBF) responses to somatosensory stimulation. It is controversial whether this is caused by a signalling role of nitric oxide (NO) between neurons and vascular smooth muscle, or by effects of NOS inhibition on neuronal activity. We here report that more than 85% inhibition of NOS activity by topical application of the NOS inhibitor N omega-nitro-L-arginine (L-NNA) for 2 h does not affect somatosensory evoked potentials (SEPs) elicited by vibrissal deflection or electrical forepaw stimulation in choloralose anaesthetised rats equipped with a closed cranial window, whereas cerebral blood flow (CBF) responses due to these stimulation paradigms are reduced by approximately 60%.

Mitochondrial oxidation in rat hippocampus can be preconditioned by selective chemical inhibition of succinic dehydrogenase.

Repeatedly it was reported that a short ischemic episode may ameliorate biochemical and morphological impairment upon succeeding severe ischemia. We investigated whether the pattern of respiratory enzyme activity (RA), adenine nucleotides, and membrane potential in hippocampal slices following low-dose in vivo (20 mg/kg) and high-dose in vitro (1 mM) application of 3-nitropropionic acid (3-np), a specific inhibitor of succinic dehydrogenase (SDH), indicates a similar tolerance phenomenon. One hour in vivo treatment decreased RA, spectrophotometrically quantitated by intensity of staining with 2,3,5-triphenyltetrazolium chloride (TTC), to 48 +/- 5% (mean +/- SE; P<0.

Age-related changes of oxygen free radical production in the rat brain slice after hypoxia: on-line measurement using enhanced chemiluminescence.

Superoxide radical production in brain slices of 12-, 24- and 60-day-old rats was measured online during and after 15 min of hypoxia with lucigenin enhanced chemiluminescence. We found a typical radical burst after reoxygenation which developed with aging and is almost nonexistent in the youngest and most prominent in the oldest group. This cannot be explained by a decreasing tissue superoxide dismutase (SOD) concentration in the brain with aging, since the concentration of the enzyme, determined in the same age groups, increased with age.

Expression of the Huntington disease gene in rodents: cloning the rat homologue and evidence for downregulation in non-neuronal tissues during development.

Huntington's disease (HD) is associated with an expanded and unstable (CAG) > 35 repeat within a gene of unknown function. We isolated the complete coding region of the rat HD gene (rhd) from cDNA libraries and investigated its expression in different developmental stages of rodent tissues. The rat gene exhibits 90% peptide sequence identity to the human and 96% to the murine sequence.