Ischemic Neuronal Damage Research Articles

Neuroprotective effects of PEP-1-carbonyl reductase 1 against oxidative-stress-induced ischemic neuronal cell damage

Human carbonyl reductase 1 (CBR1) is a member of the NADPH-dependent short-chain dehydrogenase/reductase superfamily that is known to play an important role in neuronal cell survival via its antioxidant function. Oxidative stress is one of the major causes of degenerative disorders including ischemia. However, the role CBR1 plays with regard to ischemic injury is as yet poorly understood. Protein transduction domains such as PEP-1 are well known and now commonly used to deliver therapeutic proteins into cells. In this study, we prepared PEP-1–CBR1 protein and examined whether it protects against oxidative-stress-induced neuronal cell damage. PEP-1–CBR1 protein was efficiently transduced into hippocampal neuronal HT-22 cells and protected against hydrogen peroxide (H2O2)-induced neuronal cell death. Transduced PEP-1–CBR1 protein drastically inhibited H2O2-induced reactive oxygen species production, the oxidation of intracellular macromolecules, and the activation of mitogen-activated protein kinases, as well as cellular apoptosis. Furthermore, we demonstrated that transduced PEP-1–CBR1 protein markedly protected against neuronal cell death in the CA1 region of the hippocampus resulting from ischemic injury in an animal model. In addition, PEP-1–CBR1 protein drastically reduced activation of glial cells and lipid peroxidation in an animal model. These results indicate that PEP-1–CBR1 protein significantly protects against oxidative-stress-induced neuronal cell death in vitro and in vivo. Therefore, we suggest that PEP-1–CBR1 protein may be a therapeutic agent for the treatment of ischemic injuries as well as oxidative-stress-induced cell damage and death.

Tat-glyoxalase protein inhibits against ischemic neuronal cell damage and ameliorates ischemic injury

Methylglyoxal (MG), a metabolite of glucose, is the major precursor of protein glycation and induces apoptosis. MG is associated with neurodegeneration, including oxidative stress and impaired glucose metabolism, and is efficiently metabolized to S-D-lactoylglutathione by glyoxalase (GLO). Although GLO has been implicated as being crucial in various diseases including ischemia, its detailed functions remain unclear. Therefore, we investigated the protective effect of GLO (GLO1 and GLO2) in neuronal cells and an animal ischemia model using Tat-GLO proteins. Purified Tat-GLO protein efficiently transduced into HT-22 neuronal cells and protected cells against MG- and H2O2-induced cell death, DNA fragmentation, and activation of caspase-3 and mitogen-activated protein kinase. In addition, transduced Tat-GLO protein increased D-lactate in MG- and H2O2-treated cells whereas glycation end products (AGE) and MG levels were significantly reduced in the same cells. Gerbils treated with Tat-GLO proteins displayed delayed neuronal cell death in the CA1 region of the hippocampus compared with a control. Furthermore, the combined neuroprotective effects of Tat-GLO1 and Tat-GLO2 proteins against ischemic damage were significantly higher than those of each individual protein. Those results demonstrate that transduced Tat-GLO protein protects neuronal cells by inhibiting MG- and H2O2-mediated cytotoxicity in vitro and in vivo. Therefore, we suggest that Tat-GLO proteins could be useful as a therapeutic agent for various human diseases related to oxidative stress including brain diseases.

Neuroprotective effect through the cerebral sodium–glucose transporter on the development of ischemic damage in global ischemia

Diabetes mellitus and impaired glucose metabolism are the most important risk factors for stroke. We recently demonstrated that cerebral ischemic stress causes hyperglycemia (i.e., post-ischemic hyperglycemia) and may worsen ischemic neuronal damage in a mouse model of focal ischemia. However, the detailed mechanisms are still unknown. The sodium–glucose transporter (SGLT) generates inward currents in the process of transporting glucose into cells, resulting in depolarization and increased excitability, which is well known to be caused by cerebral ischemia. Hence, we focused on the role of SGLT on the development of neuronal damage using a global ischemic model.Male ddY mice were subjected to 30min of bilateral carotid artery occlusion (BCAO). The neuronal damage was estimated by histological analysis using HE staining on day 3 after BCAO.Intraperitoneal (i.p.) administration of phlorizin (a specific and competitive inhibitor of SGLT, 200mg/kg immediately after reperfusion) suppressed the development of post-ischemic hyperglycemia on day 1 after BCAO. In contrast, intracerebroventricular (i.c.v.) administration of phlorizin (40μg/mouse immediately and 6h after reperfusion) had no effect on day 1 after BCAO. Interestingly, the development of ischemic neuronal damage was significantly suppressed by i.p. and i.c.v. administration of phlorizin on day 3 after BCAO. In addition, BCAO-induced spasticity was significantly suppressed by PHZ (40μg/mouse, i.c.v.) from using gait analysis.Our results indicated that cerebral SGLT was involved in the development of ischemic neuronal damage in global ischemia.

Relative Higher Hematocrit Attenuates the Cerebral Excitatory Amino Acid Elevation Induced by Deep Hypothermic Circulatory Arrest in Rats

Hemodilution is a commonly used technique in cardiopulmonary bypass (CPB) and deep hypothermic circulation arrest (DHCA). Our previous study showed that lower hematocrit aggravated the brain injury after DCHA. Because the excitatory amino acids are critical pathways of ischemic neuronal damage, the purpose of the present study was to investigate the effects of different degrees of hemodilution on the excitatory amino acid content in different brain areas after DHCA Adult Sprague-Dawley rats were randomly divided into four groups: group I hematocrit (Hct) 10% (H1), group II Hct 20% (H2), group III Hct 30% (H3), and control group (C). All animals except those in the control group underwent DHCA at 18°C for 90 minutes. Different degrees of hemodilution were accomplished by changing the composition and volume of the priming solution used in CPB. High-performance liquid chromatography was used to determine the concentration of glutamate (Glu), aspartate (Asp), glycine (Gly), gamma-aminobutyric acid (GABA), and taurine (Tau) in the cerebral cortex, hippocampus, and thalamus. We found that the concentration of these five amino acids in the hippocampus and cortex were all increased after DHCA. Glu, Asp, and Gly in the hippocampus and cortex were significantly lower in the Hct 30% group than in the other two groups (p<0.05). There was no significant difference in the GABA and Tau concentrations among the three groups. In summary, excitatory amino acids increased significantly after DHCA, and relative higher hematocrit attenuates this response.

Neuroprotective effects of the antioxidant action of 2-cyclopropylimino-3-methyl-1,3-thiazoline hydrochloride against ischemic neuronal damage in the brain

Ischemia is characterized by oxidative stress and changes in the antioxidant defense system. Our recent in vitro study showed that 2-cyclopropylimino-3-methyl-1,3-thiazoline hydrochloride protects cortical astrocytes against oxidative stress. In the current study, we examined the effects of 2-cyclopropylimino-3-methyl-1,3-thiazoline hydrochloride on ischemia-induced neuronal damage in a gerbil ischemia/reperfusion models. Extensive neuronal death in the hippocampal CA1 area was observed 4 days after ischemia/reperfusion. Intraperitoneal injection of 2-cyclopropylimino-3-methyl-1,3-thiazoline hydrochloride (0.3 mg/kg body weight) significantly prevented neuronal death in the CA1 region of the hippocampus in response to transient forebrain ischemia. 2-Cyclopropylimino-3-methyl-1,3-thiazoline hydrochloride administration reduced ischemia-induced increases in reactive oxygen species levels and malondialdehyde content. It also attenuated the associated reductions in glutathione level and superoxide dismutase, catalase, and glutathione peroxidase activities. Taken together, our results suggest that 2-cyclopropylimino-3-methyl-1,3-thiazoline hydrochloride protects against ischemia-induced neuronal damage by reducing oxidative stress through its antioxidant actions. [BMB Reports 2013; 46(7):370-375]

Neuroprotective role of nanoencapsulated quercetin in combating ischemia-reperfusion induced neuronal damage in young and aged rats.

Cerebral stroke is the leading cause of death and permanent disability among elderly people. In both humans and animals, cerebral ischemia damages the nerve cells in vulnerable regions of the brain, viz., hippocampus, cerebral cortex, cerebellum, and hypothalamus. The present study was conducted to evaluate the therapeutic efficacy of nanoencapsulated quercetin (QC) in combating ischemia-reperfusion-induced neuronal damage in young and aged Swiss Albino rats. Cerebral ischemia was induced by occlusion of the common carotid arteries of both young and aged rats followed by reperfusion. Nanoencapsulated quercetin (2.7 mg/kg b wt) was administered to both groups of animals via oral gavage two hours prior to ischemic insults as well as post-operation till day 3. Cerebral ischemia and 30 min consecutive reperfusion caused a substantial increase in lipid peroxidation, decreased antioxidant enzyme activities and tissue osmolality in different brain regions of both groups of animals. It also decreased mitochondrial membrane microviscosity and increased reactive oxygen species (ROS) generation in different brain regions of young and aged rats. Among the brain regions studied, the hippocampus appeared to be the worst affected region showing increased upregulation of iNOS and caspase-3 activity with decreased neuronal count in the CA1 and CA3 subfields of both young and aged rats. Furthermore, three days of continuous reperfusion after ischemia caused massive damage to neuronal cells. However, it was observed that oral treatment of nanoencapsulated quercetin (2.7 mg/kg b wt) resulted in downregulation of iNOS and caspase-3 activities and improved neuronal count in the hippocampal subfields even 3 days after reperfusion. Moreover, the nanoformulation imparted a significant level of protection in the antioxidant status in different brain regions, thus contributing to a better understanding of the given pathophysiological processes causing ischemic neuronal damage.

3‐[2‐(3,5‐dimethoxyphenyl)vinyl]furan protects hippocampal neurons against ischemic damage

Resveratrol, an ingredient in grapes, has been reported to exhibit anti‐cancer activity, anti‐inflammatory activity, and cardiovascular protection property. Interestingly, resveratrol has been recently reported to have neuroprotective effect. This study reports the neuroprotective effect of a resveratrol derivative, 3‐[2‐(3,5‐ Dimethoxy‐phenyl)‐vinyl]‐furan (DPVF). This synthetic DPVF conferred more protection than resveratrol against neuronal cell damage induced by oxygen and glucose deprivation in a rat hippocampal slice culture. In addition, DPVF inhibited ATP depletion following oxygen and glucose deprivation in the adult hippocampal slice. Moreover, we found that DPVF is neuroprotective against ischemic damage in rats. DPVF showed potent neuroprotection on a 4‐velssel‐occusion model and inhibited iron‐induced malondialdehyde (MDA) formation in the rat brain tissue. These results demonstrate that DPVF might be a useful agent in reducing ischemic neuronal damage.

Spatio-temporal spread of neuronal death after focal photolysis of caged glutamate in neuron/astrocyte co-cultures

Glutamate-mediated excitotoxicity is now accepted as a major mechanism of ischemic neuronal damage. In the infarct core region, massive neuronal death is observed, but neurons in the surroundings of the core (ischemic penumbra) seem viable at the time of stroke. Several hours or days after a stroke, however, many neurons in the penumbra will undergo delayed neuronal death (DND). The mechanisms responsible for such DND are not fully understood. In this study, we investigated whether and how glutamate-mediated localized excitotoxic neuronal death affects surrounding neurons and astrocytes. To induce spatially-restricted excitotoxic neuronal death, a caged glutamate was focally photolyzed by a UV flash in neuron/astrocyte co-cultures. Uncaging of the glutamate resulted in acute neuronal death in the flashed area. After that, DND was observed in the surroundings of the flashed area late after the uncaging. In contrast, DND was not observed in neuron-enriched cultures, suggesting that functional changes in astrocytes, not neurons, after focal acute neuronal death were involved in the induction of DND. The present in vitro study showed that the spatially-restricted excitotoxic neuronal death resulted in DND in the surroundings of the flashed area, and suggested that the nitric oxide (NO)-induced reduction in the expression of astrocytic GLT-1 was responsible for the occurrence of the DND.

Markers of ischemic neuronal damage, neurological complications of carotid endarterectomy and their management depending on anesthesia type

Aim. to identify the anesthesia method for carotid endarterectomy providing minimal ischemic neuronal damage and decreasing the number of post-surgical complications; to adjust the optimal treatment for associated neurological disorders. Methods. An assessment of anesthesia methods was performed in 190 patients who underwent the carotid endarterectomy. The intravenous anesthesia with propofol (first group, 60 patients), regional anesthesia using deep cervical plexus block (second group, 60 patients), and inhalational anesthesia with sevoflurane (third group, 70 patients) were compared. Brain perfusion parameters, neurological status, ischemic neuronal damage markers were examined. Results. In patients undergoing carotid endarterectomy an ischemic neuronal damage is provoked due to brain perfusion decrease as a result of common carotid artery clipping regardless of anesthesia method. Inhalational anesthesia was associated with relatively lower ischemic neuronal damage markers levels. Some patients form every group have developed serious post-surgical neurological complications (stroke, transient cerebral ischemic attack, neurological status deterioration). Post-surgical complications were registered in 10 (16.7%) patients from the first group, in 9 (15%) patients form the second group, in 3 (4.3%) patients from the third group. Citicoline was the most effective drug for associated neurological disorders treatment. Conclusion. Inhalational anesthesia with sevoflurane compared to intravenous anesthesia with propofol and regional anesthesia using deep cervical plexus block limits the neuronal damage and is associated with lower number of post-surgical neurological complications, which can be treated with citicoline.

Abstract WP259: CaMKII Inhibitor tatCN21 Decreases Neuronal Damage Following Cardiac Arrest and Cardiopulmonary Resuscitation in Mice

INTRODUCTION: Glutamate excitotoxicity is considered an important mechanism of ischemic neuronal damage. However, directly inhibiting glutamate receptors can cause severe side effects due to their key physiological functions in the central nervous system (CNS). Ca2+/calmodulin (CaM)-dependent protein kinase II (CaMKII) is a major downstream target of glutamate-induced Ca2+ signaling. The aim of this study is to examine the neuroprotective potential of the CaMKII inhibitor tatCN21 on experimental cardiac arrest and cardiopulmonary resuscitation (CA/CPR). Methods: Global cerebral ischemia was induced with 8 min of cardiac arrest followed by CPR in C57BL/6 male mice. The mice were randomly administered either tatCN21 (1 mg/kg, n=14) or vehicle (saline, n=13) 2 minutes after resuscitation (intravenous). Hippocampal neuronal damage was analyzed three days after resuscitation by H&amp;E staining. Primary hippocampal neurons were insulted with 400 μm glutamate for 5 min and treated with tatCN21 (5 μm), the scrambled CN peptide (tatRev, 5 μm) or KN93 (10 μm) 1 hr after removal of glutamate, cell viability was measure by LDH release 24 hrs later. Statistical analyses were performed using ANOVA and t tests, with P&lt;0.05 considered statistically significant. Results: Analysis of histological damage 72 hrs after resuscitation revealed that tatCN21 significantly reduces hippocampal CA1 neuronal injury compared to vehicle-treated mice, reducing damage from 72.9±4.5% (n=13) for vehicle to 54.1±7.6% (n=14, P&lt;0.05) for tatCN21 treated mice. tatCN21 significantly reduced glutamate-induced neuronal cell death, but not the classical CaMKII inhibitor KN93 (P&lt;0.05). No difference in body weight, cardiac arrest parameters and survival rates were observed between each groups. Conclusions: Our data showed that the novel CaMKII inhibitor tatCN21 decreases neuronal damage both in vivo and in vitro. Therefore, this study indicated that CaMKII may have an important role in glutamate excititoxicity and that tatCN21 may serve as a potential therapeutic strategy for minimizing brain injury following cardiac arrest.

Effects of diazepam and flumazenil on forebrain ischaemia in a rat model of benzodiazepine tolerance

Post-ischaemic benzodiazepine administration is neuroprotective, but chronic administration of benzodiazepines can induce tolerance, such that the neuroprotective effect may be reduced. This study investigated whether benzodiazepine tolerance can worsen ischaemic injury and whether neuroprotection by post-ischaemic benzodiazepine administration is affected by benzodiazepine tolerance. We also investigated whether antagonism of benzodiazepine receptors by flumazenil was able to restore neuroprotection during benzodiazepine tolerance. Experiments were performed in both benzodiazepine-tolerant and naive rats. Benzodiazepine tolerance was indeed by 4 weeks administration of flurazepam. Bilateral carotid artery occlusion (BCAO) was performed to cause cerebral ischaemia. Four experiments were performed: (1) BCAO with no further interventions; (2) BCAO followed by administration of diazepam; (3) administration of flumazenil before BAO; and (4) administration of flumazenil before and diazepam after BCAO. Neurological and histological assessment was performed 5 days after BCAO. Benzodiazepine tolerance did not affect neuronal injury in the CA1 and CA3 regions and dentate gyrus of the hippocampus after severe ischaemic insult, but did worsen neuronal damage when mild ischaemia was applied (P<0.05). Neuroprotective efficacy of post-ischaemic diazepam was not observed under conditions of benzodiazepine tolerance. Flumazenil treatment before BCAO reduced ischaemic neuronal damage exacerbated by benzodiazepine tolerance (P<0.05), and restored neuroprotection by post-ischaemic diazepam (P<0.05), the effect of which was reduced by benzodiazepine tolerance (P<0.05). However, pre-ischaemic flumazenil treatment in naive animals reduced neuroprotection provided by post-ischaemic diazepam (P<0.01-0.05). Benzodiazepine tolerance can worsen ischaemic neuronal injury and abolish the neuroprotection provided by post-ischaemic diazepam. Pre-treatment with flumazenil treatment reversed benzodiazepine tolerance and restored neuroprotection by post-ischaemic diazepam. These findings may suggest that management of patient's risk of developing cerebral ischaemia may need to take into account current use.

Orexin-A Suppresses Postischemic Glucose Intolerance and Neuronal Damage through Hypothalamic Brain-Derived Neurotrophic Factor

Orexin-A (a glucose-sensing neuropeptide in the hypothalamus) and brain-derived neurotrophic factor (BDNF; a member of the neurotrophin family) play roles in many physiologic functions, including regulation of glucose metabolism. We previously showed that the development of postischemic glucose intolerance is one of the triggers of ischemic neuronal damage. The aim of this study was to determine whether there was an interaction between orexin-A and BDNF functions in the hypothalamus after cerebral ischemic stress. Male ddY mice were subjected to 2 hours of middle cerebral artery occlusion (MCAO). Neuronal damage was estimated by histologic and behavioral analyses. Expression of protein levels was analyzed by Western blot. Small interfering RNA directed BDNF, orexin-A, and SB334867 [N-(2-methyl-6-benzoxazolyl)-N'-1,5-naphthyridin-4-yl urea; a specific orexin-1 receptor antagonist] were administered directly into the hypothalamus. The level of hypothalamic orexin-A, detected by immunohistochemistry, was decreased on day 1 after MCAO. Intrahypothalamic administration of orexin-A (1 or 5 pmol/mouse) significantly and dose-dependently suppressed the development of postischemic glucose intolerance on day 1 and development of neuronal damage on day 3. The MCAO-induced decrease in insulin receptor levels in the liver and skeletal muscle on day 1 was recovered to control levels by orexin-A, and this effect of orexin-A was reversed by the administration of SB334867 as well as by hypothalamic BDNF knockdown. These results suggest that suppression of postischemic glucose intolerance by orexin-A assists in the prevention of cerebral ischemic neuronal damage. In addition, hypothalamic BDNF may play an important role in this effect of orexin-A.

Post-ischemic hyperglycemia exacerbates the development of cerebral ischemic neuronal damage through the cerebral sodium-glucose transporter

Post-ischemic hyperglycemia may be one of the triggers of ischemic neuronal damage. However, the detailed mechanisms of this injury process are still unknown. Here, we focused on the involvement of the sodium-glucose transporter (SGLT), which transports glucose together with Na+ ions, and generates inward currents while transporting glucose into cells, resulting in depolarization and increased excitability. The aim of this study was to determine the involvement of the SGLT in the development of cerebral ischemic stress-induced neuronal damage. Male ddY mice were subjected to 2h of middle cerebral artery occlusion (MCAO). Fasting blood glucose (FBG) was measured using the glucose pilot. Neuronal damage was estimated by histological and behavioral analyses. Phlorizin and glucose were administered by intraperitoneal (i.p.) or intracerebroventricular (i.c.v.) injection. Administration of phlorizin (40, 120 or 200mg/kg, i.p.) significantly and dose-dependently suppressed the elevation of FBG and ischemic neuronal damage. In contrast, phlorizin (10 or 40μg/mouse, i.c.v.) significantly and dose-dependently suppressed ischemic neuronal damage without reducing the elevation of FBG. Moreover, the development of neuronal damage was significantly and dose-dependently exacerbated following i.c.v. administration of glucose (10% or 25% (w/v)), and its exacerbation was suppressed by i.c.v. administration of phlorizin (40μg/mouse). These results suggest that cerebral SGLT is activated by post-ischemic hyperglycemia and may be involved in the exacerbation of ischemic neuronal damage.

Detection of ischemic neuronal damage with [18F]BMS‐747158‐02, a mitochondrial complex‐1 positron emission tomography ligand: Small animal PET study in rat brain

The acute and subacute ischemic neuronal damage in rat brain caused by photochemically induced thrombosis (PIT) was imaged using [¹⁸F]BMS-747158-02 ([¹⁸F]BMS) for mitochondrial complex-1 (MC-1) and [¹¹C](R)-PK11195 ([¹¹C](R)-PK) for peripheral benzodiazepine receptor [PBR; translocator protein] at preischemic "Normal," 1 (day 1), and 7 days (day 7) after ischemic insult. When [¹⁸F]BMS was intravenously injected into "Normal" rat, it was rapidly taken up into the brain, in which it showed a homogeneous distribution, and the uptake was suppressed by rotenone, a specific MC-1 inhibitor. The specificity of [¹⁸F]BMS binding to MC-1 was also confirmed by living brain slice imaging. At day 1, [¹⁸F]BMS uptake was low in infarct and peri-infarct regions where neuronal damage was detected by 2,3,5-triphenyltetrazolium chloride (TTC) staining. At day 7, the damaged areas determined using [¹⁸F]BMS revealed some discrepancy from those detected by TTC staining, suggesting that TTC stained not only surviving cells but also activated microglial cells in the peri-infarct region. This was also confirmed by [¹¹C](R)-PK imaging and immunohistochemical assessment with Iba1 antibody. In contrast, the uptake pattern of [¹⁸F]BMS was consistent with immunohistochemical assessment with NeuN antibody at both days 1 and 7. These results demonstrated that [¹⁸F]BMS could be a promising positron emission tomography ligand to assess the neuronal damage induced by ischemic insult in both acute and subacute phases.

Spatiotemporal evolution of blood brain barrier damage and tissue infarction within the first 3 h after ischemia onset

Blood brain barrier (BBB) damage that occurs within the thrombolytic time window is increasingly appreciated to negatively impact the safety and efficacy profiles of thrombolytic therapy for ischemic stroke. However, the spatiotemporal evolution of BBB damage in this early stroke stage and the underlying mechanisms remain unclear. Here, we investigated the topographical distribution of BBB damage and its association with tissue injury within the first 3h after ischemia onset and the roles of matrix metalloproteinase (MMP)-2/9 in this process. Rats were subjected to 1, 2, or 3h of middle cerebral artery occlusion (MCAO) followed by 10min reperfusion with fluorescence-labeled dextran as BBB permeability marker. Acute tissue infarction was evidenced by staining defect with triphenyltetrazolium chloride (TTC). Cerebral blood flow (CBF) was measured by magnetic resonance imaging. MMP-2/9 were assessed by gel and in situ zymography. After 2-h MCAO, dextran leakage was seen in the ischemic ventromedial striatum and the preoptic area which showed ~70% CBF reduction, and expanded to other MCA regions including the cortex after 3-h MCAO. Interestingly, high (2000kDa) and low (70kDa) molecular weight dextrans displayed almost identical leakage patterns. Different from BBB damage, tissue infarction was first seen in the ischemic dorsal striatum and the parietal/insular cortex which experienced ~90% CBF reduction. Increased gelatinolytic activity colocalized with dextran leakage, and MMP-2 was found to be the major enzymatic source on gelatin zymograms. Pretreatment with MMP inhibitor GM6001 significantly reduced dextran leakage induced by 2-h and 3-h MCAO. Taken together, our findings reveal substantial differences in the topographic distribution of BBB damage and tissue infarction within the first 3h after MCAO onset. Unlike ischemic neuronal damage, BBB damage appears to develop faster in brain regions with moderately severe ischemia, and MMP-2 contributes to this early ischemic BBB damage.

3-[2-(3,5-Dimethoxyphenyl)vinyl]furan protects hippocampal neurons against ischemic damage

Resveratrol, an ingredient in grapes, has been reported to exhibit anti-cancer activity, anti-inflammatory activity, and cardiovascular protection property. Interestingly, resveratrol has been recently reported to have neuroprotective effect. This study reports the neuroprotective effect of a resveratrol derivative, 3-[2-(3,5-dimethoxyphenyl)vinyl]furan (DPVF). This synthetic DPVF conferred more protection than resveratrol against neuronal cell damage induced by oxygen and glucose deprivation in a rat hippocampal slice culture. In addition, DPVF inhibited ATP depletion following oxygen and glucose deprivation in the adult hippocampal slice. Moreover, we found that DPVF is neuroprotective against ischemic damage in rats. DPVF showed potent neuroprotection on a 4-velssel-occusion model and inhibited iron-induced malondialdehyde (MDA) formation in the rat brain tissue. These results demonstrate that DPVF might be a useful agent in reducing ischemic neuronal damage.

Neuroprotective effects of adipose-derived stem cells against ischemic neuronal damage in the rabbit spinal cord

Transplantation of adipose-derived stem cells (ASCs) is one of the possible therapeutic tools for ischemic damage. In this study, we observed the effects of ASCs against ischemic damage in the ventral horn of L5–6 levels in the rabbit spinal cord. ASCs were isolated from rabbits, and cell type was confirmed by flow cytometry analysis, labeling with CM-DiI dye and differentiation into adipocytes in adipogenesis differentiation medium. ASCs were administered intrathecally into recipient rabbits (2×105) immediately after reperfusion following a 15-min aortic artery occlusion in the subrenal region. Transplantation of ASCs significantly improved functions of the hindlimb and morphology of the ventral horn of spinal cord although CM-DiI-labeled ASCs were not observed in the spinal cord parenchyma. In addition, transplantation of ASCs significantly increased brain-derived neurotrophic factor (BDNF) levels at 72h after ischemia/reperfusion. These results suggest that transplantation of ASCs prevents motor neurons from spinal ischemic damage and reactive gliosis by increasing neurotrophic factors such as BDNF in the spinal cord.

Histamine enhances excitability and may augment neuroprotection in the Syrian hamster hippocampus

Previous studies showed that the neuromodulator histamine (HA) increases hibernation bout duration and, in non‐hibernating species, attenuates ischemic neuronal damage. We tested the hypotheses that: (1) HA directly enhances CA1 and CA3 Syrian hamster (Mesocricetus auratus) pyramidal cell excitability and (2) HA promotes recovery from an anoxic insult. HA (10μM) was applied directly to hippocampal slices and evoked responses (ERs) were recorded before, during, and after HA perfusion at 30ºC. ERs were also recorded before, during, and after a 15 min anoxic insult (95%N2/5%CO2). We found that HA increased ERs recorded from the CA1 region (23% increase, P&lt; 0.05) and shortened the latency to the ER peaks (16–26% decrease, P&lt;0.01) in 7 slices from 5 hamsters. In the CA3 region, HA had similar, though smaller, effects on latency and amplitude. Following anoxia, in the presence of HA, 5 slices recovered faster, 2 slower, and 1 was unaffected vs. slices without HA. Data are consistent with both hypotheses and suggest that HA has multiple, synergistic effects on pyramidal cells. Moreover, the observed HA‐induced enhanced excitability of pyramidal cells supports the view that these cells play a key role in the neural pathway regulating hibernation bout duration. The increased rate of recovery suggests that HA also has a neuroprotective role, ensuring reliable signal processing in a hibernating hamster.

RETRACTED ARTICLE: Honokiol suppresses the development of post-ischemic glucose intolerance and neuronal damage in mice

Honokiol, a constituent of Magnolia obovata, has various pharmacological effects, including protection against cerebral ischemia. However, few studies have been conducted to evaluate the possible neuroprotective effects of honokiol against cerebral ischemia. We recently reported that cerebral ischemic neuronal damage could be triggered by glucose intolerance that develops after the onset of ischemic stress (i.e., post-ischemic glucose intolerance). In addition, suppression of post-ischemic glucose intolerance significantly ameliorated ischemic neuronal damage. Here, we investigated the effects of honokiol on the development of post-ischemic glucose intolerance and neuronal damage. Mice were subjected to middle cerebral artery occlusion (MCAO) for 2h. The development of post-ischemic glucose intolerance on day 1 and neuronal damage on day 3 after MCAO were significantly reduced by intraperitoneal administration of honokiol (10mg/kg) compared with the vehicle-treated group. Honokiol did not affect serum insulin or adiponectin levels. However, honokiol significantly decreased the expression of phosphoenolpyruvate carboxykinase and increased the expression of 5'-AMP-activated protein kinase (AMPK) on day 1 after MCAO, compared with the vehicle-treated MCAO group. The results of this study suggest that honokiol could prevent post-ischemic glucose intolerance in an AMPK-dependent manner, which may be involved in the neuroprotective effects of honokiol against cerebral ischemia.

Protective effects of incensole acetate on cerebral ischemic injury

The resin of Boswellia species is a major anti-inflammatory agent that has been used for centuries to treat various conditions including injuries and inflammatory conditions. Incensole acetate (IA), a major constituent of this resin, has been shown to inhibit NF-κB activation and concomitant inflammation, as well as the neurological deficit following head trauma. Here, we show that IA protects against ischemic neuronal damage and reperfusion injury in mice, attenuating the inflammatory nature of ischemic damage. IA given post-ischemia, reduced infarct volumes and improved neurological activities in the mouse model of ischemic injury in a dose dependent fashion. The protection from damage was accompanied by inhibition of TNF-α, IL-1β and TGF-β expression, as well as NF-κB activation following injury. In addition, IA is shown to have a therapeutic window of treatment up to 6h after ischemic injury. Finally, the protective effects of IA were partially mediated by TRPV3 channels as determined by the TRPV3 deficient mice and channel blocker studies. This study suggests that the anti-inflammatory and neuroprotective activities of IA may serve as a novel therapeutic treatment for ischemic and reperfusion injury, and as a tool in the ongoing research of mechanisms for neurological damage.