Cerebral ischemia and trauma-different etiologies yet similar mechanisms: neuroprotective opportunities

Aqueous extract of Cordyceps alleviates cerebral ischemia-induced short-term memory impairment in gerbils

Cerebral ischemia is caused by reduced cerebral blood flow due to a transient or permanent cerebral artery occlusion. Ischemic injury in the brain leads to neuronal cell death, and eventually causes neurological impairments. Cordyceps, the name given to the fungi on insects, has abundant useful natural products with various biological activities. Cordyceps is known to have nephroprotective, hepatoprotective, anti-inflammatory, antioxidative, and antiapoptotic effects. We investigated the effects of Cordyceps on short-term memory, neuronal apoptosis, and cell proliferation in the hippocampal dentate gyrus following transient global ischemia in gerbils. For this study, a step-down avoidance test, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, immunohistochemistry for caspase-3 and 5-bromo-2′-de-oxyuridine, and western blot for Bax, Bcl-2, brain-derived neurotrophic factor (BDNF), and tyrosin kinase B were performed. In the present study, Cordyceps alleviated cerebral ischemia-induced short-term memory impairment. Cordyceps showed therapeutic effects through inhibiting cerebral ischemia-induced apoptosis in the hippocampus. Cordyceps suppressed cerebral ischemia-induced cell proliferation in the hippocampal dentate gyrus due to the reduced apoptotic neuronal cell death. Cordyceps treatment also enhanced BDNF and TrkB expressions in the hippocampus of ischemic gerbils. It can be suggested that Cordyceps overcomes cerebral ischemia-induced neuronal apoptosis, thus facilitates recovery following cerebral ischemia injury.

Physical training decreases susceptibility to pilocarpine-induced seizures in the injured rat brain

There is growing evidence that physical activity ameliorates the course of epilepsy in animal models as well as in clinical conditions. Since traumatic brain injury is one of the strongest determinants of epileptogenesis, the present study focuses on the question whether a moderate long-term physical training can decrease susceptibility to seizures evoked following brain damage. Wistar rats received a mechanical brain injury and were subjected to daily running sessions on a treadmill for 21 days. Thereafter, seizures were induced by pilocarpine injections in trained and non-trained, control groups. During the acute period of status epilepticus, the intensity of seizures was assessed within the six-hour observation period. The trained rats showed considerable amelioration of pilocarpine-induced motor symptoms when compared with their non-trained counterparts. Histological investigations of effects of the brain injury and of physical training detected significant quantitative changes in parvalbumin-, calretinin- and NPY-immunopositive neuronal populations. Some of the injury-induced changes, especially those shoved by parvalbumin-immunopositive neurons, were abolished by the subsequent physical training procedure and could, therefore, be considered as neuronal correlates of the observed functional amelioration of the injured brain.

Co-Ultramicronized Palmitoylethanolamide/Luteolin Promotes Neuronal Regeneration after Spinal Cord Injury

Spinal cord injury (SCI) stimulates activation of astrocytes and infiltration of immune cells at the lesion site; however, the mechanism that promotes the birth of new neurons is still under debate. Neuronal regeneration is restricted after spinal cord injury, but can be stimulated by experimental intervention. Previously we demonstrated that treatment co-ultramicronized palmitoylethanolamide and luteolin, namely co-ultraPEALut, reduced inflammation. The present study was designed to explore the neuroregenerative properties of co-ultraPEALut in an estabished murine model of SCI. A vascular clip was applied to the spinal cord dura at T5-T8 to provoke injury. Mice were treated with co-ultraPEALut (1 mg/kg, intraperitoneally) daily for 72 h after SCI. Co-ultraPEALut increased the numbers of both bromodeoxyuridine-positive nuclei and doublecortin-immunoreactive cells in the spinal cord of injured mice. To correlate neuronal development with synaptic plasticity a Golgi method was employed to analyze dendritic spine density. Co-ultraPEALut administration stimulated expression of the neurotrophic factors brain-derived neurotrophic factor, glial cell-derived neurotrophic factor, nerve growth factor, and neurotrophin-3. These findings show a prominent effect of co-ultraPEALut administration in the management of survival and differentiation of new neurons and spine maturation, and may represent a therapeutic treatment for spinal cord and other traumatic diseases.

Resveratrol attenuates neuronal autophagy and inflammatory injury by inhibiting the TLR4/NF-κB signaling pathway in experimental traumatic brain injury

Previous research has demonstrated that traumatic brain injury (TBI) activates autophagy and a neuroinflammatory cascade that contributes to substantial neuronal damage and behavioral impairment, and Toll-like receptor 4 (TLR4) is an important mediator of this cascade. In the present study, we investigated the hypothesis that resveratrol (RV), a natural polyphenolic compound with potent multifaceted properties, alleviates brain damage mediated by TLR4 following TBI. Adult male Sprague Dawley rats, subjected to controlled cortical impact (CCI) injury, were intraperitoneally injected with RV (100 mg/kg, daily for 3 days) after the onset of TBI. The results demonstrated that RV significantly reduced brain edema, motor deficit, neuronal loss and improved spatial cognitive function. Double immunolabeling demonstrated that RV decreased microtubule-associated protein 1 light chain 3 (LC3), TLR4‑positive cells co-labeled with the hippocampal neurons, and RV also significantly reduced the number of TLR4‑positive neuron‑specific nuclear protein (NeuN) cells following TBI. Western blot analysis revealed that RV significantly reduced the protein expression of the autophagy marker proteins, LC3II and Beclin1, in the hippocampus compared with that in the TBI group. Furthermore, the levels of TLR4 and its known downstream signaling molecules, nuclear factor-κB (NF-κB), and the inflammatory cytokines, interleukin (IL)-1β and tumor necrosis factor (TNF)-α were also decreased after RV treatment. Our results suggest that RV reduces neuronal autophagy and inflammatory reactions in a rat model of TBI. Thus, we suggest that the neuroprotective effect of RV is associated with the TLR4/NF-κB signaling pathway.

The Possible Role of Toll-Like Receptor 4 in the Pathology of Stroke

Stroke is a prevalent and dangerous health problem, which triggers an intense inflammatory response to Toll-like receptor (TLR) activation. TLRs are the essential components of the response of the innate immunity system, and, therefore, they are one of the key factors involved in recognizing pathogens and internal ligands. Among TLRs, TLR4 significantly participates in the induction of inflammation and brain functions; hence, it has been hypothesized that this molecule is associated with several immune-related brain diseases such as stroke. It has also been proved that animals with TLR4 deficiency have higher protection against ischemia and that the absence of TLR4 reduces neuroinflammation and injuries associated with brain trauma. TLR4 deficiency may play a neuroprotective role in the occurrence of stroke. This article reviews recent information regarding the impact of TLR4 on the pathogenicity of stroke.

Dementia resulting from traumatic brain injury

Traumatic brain injury (TBI) represents a significant public health problem in modern societies. It is primarily a consequence of traffic-related accidents and falls. Other recently recognized causes include sports injuries and indirect forces such as shock waves from battlefield explosions. TBI is an important cause of death and lifelong disability and represents the most well-established environmental risk factor for dementia. With the growing recognition that even mild head injury can lead to neurocognitive deficits, imaging of brain injury has assumed greater importance. However, there is no single imaging modality capable of characterizing TBI. Current advances, particularly in MR imaging, enable visualization and quantification of structural and functional brain changes not hitherto possible. In this review, we summarize data linking TBI with dementia, emphasizing the imaging techniques currently available in clinical practice along with some advances in medical knowledge.

NMDA receptor binding in focal epilepsies

OBJECTIVE

To demonstrate altered N-methyl-d-aspartate (NMDA) receptor availability in patients with focal epilepsies using positron emission tomography (PET) and [(18)F]GE-179, a ligand that selectively binds to the open NMDA receptor ion channel, which is thought to be overactive in epilepsy.

METHODS

Eleven patients (median age 33 years, 6 males) with known frequent interictal epileptiform discharges had an [(18)F]GE-179 PET scan, in a cross-sectional study. MRI showed a focal lesion but discordant EEG changes in two, was non-localising with multifocal EEG abnormalities in two, and was normal in the remaining seven patients who all had multifocal EEG changes. Individual patient [(18)F]GE-179 volume-of-distribution (VT) images were compared between individual patients and a group of 10 healthy controls (47 years, 7 males) using Statistical Parametric Mapping.

RESULTS

Individual analyses revealed a single cluster of focal VT increase in four patients; one with a single and one with multifocal MRI lesions, and two with normal MRIs. Post hoc analysis revealed that, relative to controls, patients not taking antidepressants had globally increased [(18)F]GE-179 VT (+28%; p<0.002), and the three patients taking an antidepressant drug had globally reduced [(18)F]GE-179 VT (-29%; p<0.002). There were no focal abnormalities common to the epilepsy group.

CONCLUSIONS

In patients with focal epilepsies, we detected primarily global increases of [(18)F]GE-179 VT consistent with increased NMDA channel activation, but reduced availability in those taking antidepressant drugs, consistent with a possible mode of action of this class of drugs. [(18)F]GE-179 PET showed focal accentuations of NMDA binding in 4 out of 11 patients, with difficult to localise and treat focal epilepsy.

Acute Response of the Hippocampal Transcriptome Following Mild Traumatic Brain Injury After Controlled Cortical Impact in the Rat

We have previously demonstrated that mild controlled cortical impact (mCCI) injury to rat cortex causes indirect, concussive injury to underlying hippocampus and other brain regions, providing a reproducible model for mild traumatic brain injury (mTBI) and its neurochemical, synaptic, and behavioral sequelae. Here, we extend a preliminary gene expression study of the hippocampus-specific events occurring after mCCI and identify 193 transcripts significantly upregulated, and 21 transcripts significantly downregulated, 24 h after mCCI. Fifty-three percent of genes altered by mCCI within 24 h of injury are predicted to be expressed only in the non-neuronal/glial cellular compartment, with only 13% predicted to be expressed only in neurons. The set of upregulated genes following mCCI was interrogated using Ingenuity Pathway Analysis (IPA) augmented with manual curation of the literature (190 transcripts accepted for analysis), revealing a core group of 15 first messengers, mostly inflammatory cytokines, predicted to account for >99% of the transcript upregulation occurring 24 h after mCCI. Convergent analysis of predicted transcription factors (TFs) regulating the mCCI target genes, carried out in IPA relative to the entire Affymetrix-curated transcriptome, revealed a high concordance with TFs regulated by the cohort of 15 cytokines/cytokine-like messengers independently accounting for upregulation of the mCCI transcript cohort. TFs predicted to regulate transcription of the 193-gene mCCI cohort also displayed a high degree of overlap with TFs predicted to regulate glia-, rather than neuron-specific genes in cortical tissue. We conclude that mCCI predominantly affects transcription of non-neuronal genes within the first 24 h after insult. This finding suggests that early non-neuronal events trigger later permanent neuronal changes after mTBI, and that early intervention after mTBI could potentially affect the neurochemical cascade leading to later reported synaptic and behavioral dysfunction.

Inflammation in acute CNS injury: a focus on the role of substance P

Recently, a number of reports have shown that neurogenic inflammation may play a role in the secondary injury response following acute injury to the CNS, including traumatic brain injury (TBI) and stroke. In particular substance P (SP) release appears to be critically involved. Specifically, the expression of the neuropeptide SP is increased in acute CNS injury, with the magnitude of SP release being related to both the frequency and magnitude of the insult. SP release is associated with an increase in blood-brain barrier permeability and the development of vasogenic oedema as well as neuronal injury and worse functional outcome. Moreover, inhibiting the actions of SP through use of a NK1 receptor antagonist is highly beneficial in both focal and diffuse models of TBI, as well as in ischaemic stroke, with a therapeutic window of up to 12 h. We propose that NK1 receptor antagonists represent a novel therapeutic option for treatment of neurogenic inflammation following acute CNS injury.

Current perspectives on the link between neuroinflammation and neurogenesis

The link between neuroinflammation and neurogenesis is an area of intensive research in contemporary neuroscience. The burgeoning amount of evidence accumulated over the past decade has been incredible, and now there remains the figuring out of minutia to give us a more complete picture of what individual, synergistic, and antagonistic events are occurring between neurogenesis and neuroinflammation. An intricate study of the inflammatory microenvironment influenced by the presence of the various inflammatory components like cytokines, chemokines, and immune cells is essential for: 1) understanding how neurogenesis can be affected in such a specialized niche and 2) applying the knowledge gained for the treatment of cognitive and/or motor deficits arising from inflammation-associated diseases like stroke, traumatic brain injury, Alzheimer's disease, and Parkinson's disease. This review is written to provide the reader with up-to-date information explaining how these inflammatory components are effecting changes on neurogenesis.

Advances in stroke therapy

Stroke is a leading cause of death, long-term disability, and socioeconomic costs, highlighting the urgent need for more effective treatments. Intravenous administration of tissue plasminogen activator (t-PA) is the only FDA-approved therapy to re-establish cerebral blood flow. However, because of increased risk of hemorrhage beyond 3 h post stroke, few stroke patients (1-2%) benefit from t-PA; t-PA, which has neurotoxic effects, can also aggravate the extent of reperfusion injury by increasing blood-brain barrier permeability. An alternative strategy is needed to extend the window of intervention, minimize damage from reperfusion injury, and promote brain repair leading to neurological recovery. Reactive oxygen species (ROS), generated soon after ischemia and during reperfusion and thereafter, are considered the main mediators of ischemic injury. Antioxidant enzymes such as catalase, superoxide dismutase, etc. can neutralize ROS-mediated injury but their effective delivery to the brain remains a challenge. In this article, we review various therapeutic approaches including surgical interventions, and discuss the potential of nanoparticle-mediated delivery of antioxidants for stroke therapy.

Neuroprotective roles of pituitary adenylate cyclase-activating polypeptide in neurodegenerative diseases

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a pleiotropic bioactive peptide that was first isolated from an ovine hypothalamus in 1989. PACAP belongs to the secretin/glucagon/vasoactive intestinal polypeptide (VIP) superfamily. PACAP is widely distributed in the central and peripheral nervous systems and acts as a neurotransmitter, neuromodulator, and neurotrophic factor via three major receptors (PAC1, VPAC1, and VPAC2). Recent studies have shown a neuroprotective role of PACAP using in vitro and in vivo models. In this review, we briefly summarize the current findings on the neurotrophic and neuroprotective effects of PACAP in different brain injury models, such as cerebral ischemia, Parkinson’s disease (PD), and Alzheimer’s disease (AD). This review will provide information for the future development of therapeutic strategies in treatment of these neurodegenerative diseases. [BMB Reports 2014; 47(7): 369-375]

Near-infrared photonic energy penetration: can infrared phototherapy effectively reach the human brain?

Traumatic brain injury (TBI) is a growing health concern effecting civilians and military personnel. Research has yielded a better understanding of the pathophysiology of TBI, but effective treatments have not been forthcoming. Near-infrared light (NIR) has shown promise in animal models of both TBI and stroke. Yet, it remains unclear if sufficient photonic energy can be delivered to the human brain to yield a beneficial effect. This paper reviews the pathophysiology of TBI and elaborates the physiological effects of NIR in the context of this pathophysiology. Pertinent aspects of the physical properties of NIR, particularly in regards to its interactions with tissue, provide the background for understanding this critical issue of light penetration through tissue. Our recent tissue studies demonstrate no penetration of low level NIR energy through 2 mm of skin or 3 cm of skull and brain. However, at 10-15 W, 0.45%-2.90% of 810 nm light penetrated 3 cm of tissue. A 15 W 810 nm device (continuous or non-pulsed) NIR delivered 2.9% of the surface power density. Pulsing at 10 Hz reduced the dose of light delivered to the surface by 50%, but 2.4% of the surface energy reached the depth of 3 cm. Approximately 1.22% of the energy of 980 nm light at 10-15 W penetrated to 3 cm. These data are reviewed in the context of the literature on low-power NIR penetration, wherein less than half of 1% of the surface energy could reach a depth of 1 cm. NIR in the power range of 10-15 W at 810 and 980 nm can provide fluence within the range shown to be biologically beneficial at 3 cm depth. A companion paper reviews the clinical data on the treatment of patients with chronic TBI in the context of the current literature.

Oxymatrine reduces neuroinflammation in rat brain: A signaling pathway

Cerebral neuroinflammation models were established by injecting 10 μg lipopolysaccharide into the hippocampus of male Sprague-Dawley rats. The rats were treated with an intraperitoneal injection of 120, 90, or 60 mg/kg oxymatrine daily for three days prior to the lipopolysaccharide injection. Twenty-four hours after model induction, the hippocampus was analyzed by real-time quantitative PCR, and the cerebral cortex was analyzed by enzyme-linked immunosorbent assay and western blot assay. The results of the enzyme-linked immunosorbent assay and the real-time quantitative PCR showed that the secretion and mRNA expression of the pro-inflammatory cytokines interleukin-1β and tumor necrosis factor-α were significantly decreased in the hippocampus and cerebral cortex of model rats treated with oxymatrine. Western blot assay and real-time quantitative PCR analysis indicated that toll-like receptor 4 mRNA and protein expression were significantly decreased in the groups receiving different doses of oxymatrine. Additionally, 120 and 90 mg/kg oxymatrine were shown to reduce protein levels of nuclear factor-κB p65 in the nucleus and of phosphorylated IκBα in the cytoplasm of brain cells, as detected by western blot assay. Experimental findings indicate that oxymatrine may inhibit neuroinflammation in rat brain via downregulating the expression of molecules in the toll-like receptor 4/nuclear factor-κB signaling pathway.

Post-injury treatment with 7,8-dihydroxyflavone, a TrkB receptor agonist, protects against experimental traumatic brain injury via PI3K/Akt signaling

Tropomyosin-related kinase B (TrkB) signaling is critical for promoting neuronal survival following brain damage. The present study investigated the effects and underlying mechanisms of TrkB activation by the TrkB agonist 7,8-dihydroxyflavone (7,8-DHF) on traumatic brain injury (TBI). Mice subjected to controlled cortical impact received intraperitoneal 7,8-DHF or vehicle injection 10 min post-injury and subsequently daily for 3 days. Behavioral studies, histology analysis and brain water content assessment were performed. Levels of TrkB signaling-related molecules and apoptosis-related proteins were analyzed. The protective effect of 7,8-DHF was also investigated in primary neurons subjected to stretch injury. Treatment with 20 mg/kg 7,8-DHF attenuated functional deficits and brain damage up to post-injury day 28. 7,8-DHF also reduced brain edema, neuronal death, and apoptosis at day 4. These changes were accompanied by a significant decrease in cleaved caspase-3 and increase in Bcl-2/Bax ratio. 7,8-DHF enhanced phosphorylation of TrkB, Akt (Ser473/Thr308), and Bad at day 4, but had no effect on Erk 1/2 phosphorylation. Moreover, 7,8-DHF increased brain-derived neurotrophic factor levels and promoted cAMP response element-binding protein (CREB) activation. This beneficial effect was attenuated by inhibition of TrkB or PI3K/Akt. 7,8-DHF also promoted survival and reduced apoptosis in cortical neurons subjected to stretch injury. Remarkably, delayed administration of 7,8-DHF at 3 h post-injury reduced brain tissue damage. Our study demonstrates that activation of TrkB signaling by 7,8-DHF protects against TBI via the PI3K/Akt but not Erk pathway, and this protective effect may be amplified via the PI3K/Akt-CREB cascades.

Mild hypothermia as a treatment for central nervous system injuries: Positive or negative effects

Besides local neuronal damage caused by the primary insult, central nervous system injuries may secondarily cause a progressive cascade of related events including brain edema, ischemia, oxida-tive stress, excitotoxicity, and dysregulation of calcium homeostasis. Hypothermia is a beneficial strategy in a variety of acute central nervous system injuries. Mild hypothermia can treat high intra-cranial pressure following traumatic brain injuries in adults. It is a new treatment that increases sur-vival and quality of life for patients suffering from ischemic insults such as cardiac arrest, stroke, and neurogenic fever following brain trauma. Therapeutic hypothermia decreases free radical produc-tion, inflammation, excitotoxicity and intracranial pressure, and improves cerebral metabolism after traumatic brain injury and cerebral ischemia, thus protecting against central nervous system dam-age. Although a series of pathological and physiological changes as well as potential side effects are observed during hypothermia treatment, it remains a potential therapeutic strategy for central nervous system injuries and deserves further study.

Neurotherapeutic effect of cord blood derived CD45+ hematopoietic cells in mice after traumatic brain injury

Treatment of traumatic brain injury (TBI) is still an unmet need. Cell therapy by human umbilical cord blood (HUCB) has shown promising results in animal models of TBI and is under evaluation in clinical trials. HUCB contains different cell populations but to date, only mesenchymal stem cells have been evaluated for therapy of TBI. Here we present the neurotherapeutic effect, as evaluated by neurological score, using a single dose of HUCB-derived mononuclear cells (MNCs) upon intravenous (IV) administration one day post-trauma in a mouse model of closed head injury (CHI). Delayed (eight days post-trauma) intracerebroventricular administration of MNCs showed improved neurobehavioral deficits thereby extending the therapeutic window for treating TBI. Further, we demonstrated for the first time that HUCB-derived pan-hematopoietic CD45 positive (CD45(+)) cells, isolated by magnetic sorting and characterized by expression of CD45 and CD11b markers (96-99%), improved the neurobehavioral deficits upon IV administration, which persisted for 35 days. The therapeutic effect was in a direct correlation to a reduction in the lesion volume and decreased by pre-treatment of the cells with anti-human-CD45 antibody. At the site of brain injury, 1.5-2 h after transplantation, HUCB-derived cells were identified by near infrared scanning and immunohistochemistry using anti-human-CD45 and anti-human-nuclei antibodies. Nerve growth factor and vascular endothelial growth factor levels were differentially expressed in both ipsilateral and contralateral brain hemispheres, thirty-five days after CHI, measured by enzyme-linked immunosorbent assay. These findings indicate the neurotherapeutic potential of HUCB-derived CD45(+) cell population in a mouse model of TBI and propose their use in the clinical setting of human TBI.

Hypothermia protects human neurons

BACKGROUND AND AIMS

Hypothermia provides neuroprotection after cardiac arrest, hypoxic-ischemic encephalopathy, and in animal models of ischemic stroke. However, as drug development for stroke has been beset by translational failure, we sought additional evidence that hypothermia protects human neurons against ischemic injury.

METHODS

Human embryonic stem cells were cultured and differentiated to provide a source of neurons expressing β III tubulin, microtubule-associated protein 2, and the Neuronal Nuclei antigen. Oxygen deprivation, oxygen-glucose deprivation, and H2 O2 -induced oxidative stress were used to induce relevant injury.

RESULTS

Hypothermia to 33°C protected these human neurons against H2 O2 -induced oxidative stress reducing lactate dehydrogenase release and Terminal deoxynucleotidyl transferase dUTP nick end labeling-staining by 53% (P ≤ 0·0001; 95% confidence interval 34·8-71·04) and 42% (P ≤ 0·0001; 95% confidence interval 27·5-56·6), respectively, after 24 h in culture. Hypothermia provided similar protection against oxygen-glucose deprivation (42%, P ≤ 0·001, 95% confidence interval 18·3-71·3 and 26%, P ≤ 0·001; 95% confidence interval 12·4-52·2, respectively) but provided no protection against oxygen deprivation alone. Protection (21%) persisted against H2 O2 -induced oxidative stress even when hypothermia was initiated six-hours after onset of injury (P ≤ 0·05; 95% confidence interval 0·57-43·1).

CONCLUSION

We conclude that hypothermia protects stem cell-derived human neurons against insults relevant to stroke over a clinically relevant time frame. Protection against H2 O2 -induced injury and combined oxygen and glucose deprivation but not against oxygen deprivation alone suggests an interaction in which protection benefits from reduction in available glucose under some but not all circumstances.

Angiotensin receptor type 2 activation induces neuroprotection and neurogenesis after traumatic brain injury

Angiotensin II receptor type 2 (AT(2)) agonists have been shown to limit brain ischemic insult and to improve its outcome. The activation of AT(2) was also linked to induced neuronal proliferation and differentiation in vitro. In this study, we examined the therapeutic potential of AT(2) activation following traumatic brain injury (TBI) in mice, a brain pathology that displays ischemia-like secondary damages. The AT(2) agonist CGP42112A was continuously infused immediately after closed head injury (CHI) for 3 days. We have followed the functional recovery of the injured mice for 35 days post-CHI, and evaluated cognitive function, lesion volume, molecular signaling, and neurogenesis at different time points after the impact. We found dose-dependent improvement in functional recovery and cognitive performance after CGP42112A treatment that was accompanied by reduced lesion volume and induced neurogenesis in the neurogenic niches of the brain and also in the injury region. At the cellular/molecular level, CGP42112A induced early activation of neuroprotective kinases protein kinase B (Akt) and extracellular-regulated kinases ½ (ERK½), and the neurotrophins nerve growth factor and brain-derived neurotrophic factor; all were blocked by treatment with the AT(2) antagonist PD123319. Our results suggest that AT(2) activation after TBI promotes neuroprotection and neurogenesis, and may be a novel approach for the development of new drugs to treat victims of TBI.

Cystatin C has a dual role in post-traumatic brain injury recovery

Cathepsin B is one of the major lysosomal cysteine proteases involved in neuronal protein catabolism. This cathepsin is released after traumatic injury and increases neuronal death; however, release of cystatin C, a cathepsin inhibitor, appears to be a self-protective brain response. Here we describe the effect of cystatin C intracerebroventricular administration in rats prior to inducing a traumatic brain injury. We observed that cystatin C injection caused a dual response in post-traumatic brain injury recovery: higher doses (350 fmoles) increased bleeding and mortality, whereas lower doses (3.5 to 35 fmoles) decreased bleeding, neuronal damage and mortality. We also analyzed the expression of cathepsin B and cystatin C in the brains of control rats and of rats after a traumatic brain injury. Cathepsin B was detected in the brain stem, cerebellum, hippocampus and cerebral cortex of control rats. Cystatin C was localized to the choroid plexus, brain stem and cerebellum of control rats. Twenty-four hours after traumatic brain injury, we observed changes in both the expression and localization of both proteins in the cerebral cortex, hippocampus and brain stem. An early increase and intralysosomal expression of cystatin C after brain injury was associated with reduced neuronal damage.

Effects of tadalafil on ischemia/reperfusion injury in rat brain

Cerebral ischemia-reperfusion (I/R) injury is caused by lack of blood supply to the brain. The accumulation of toxic products such as reactive oxygen species (ROS) occurs on reperfusion, when the occlusion is removed. The resulting oxidative stress results in the initiation of pathways leading to necrotic and apoptotic cell death. Tadalafil (TAD) prevents the accumulation of ROS and increases antioxidant cellular protective mechanisms. The aim of this study was to investigate the effect of TAD treatment against short-term global brain I/R injury in rats. The study was carried out on 30 Wistar-albino rats, which were divided into three groups including a control group (n = 10), an I/R group (n = 10) and an I/R + TAD group (n = 10) (2 mg/kg/day for 4 days before ischemia). At the end of the experiment, tissue samples were collected for both biochemical and histopathological analyses. Malondialdehyde was significantly lower in the TAD-administered group (9.06 ± 0.15) than in the I/R group (p < 0.05). However, no significant difference was observed in nitric oxide levels in the TAD-administered group compared to the I/R group. The mean superoxide dismutase level was significantly higher in the I/R-TAD group than the I/R group. There was no statistically significant difference in glutathione peroxidase levels in I/R + TAD group compared to I/R group. Histopathologically, TAD-administered group provided significant morphological improvement compared to the I/R group. We concluded that TAD prevented I/R-induced neurotoxicity as shown by obtained biochemical and histopathological findings.

Initial evaluation of 18F-GE-179, a putative PET Tracer for activated N-methyl D-aspartate receptors

N-methyl D-aspartate (NMDA) ion channels play a key role in a wide range of physiologic (e.g., memory and learning tasks) and pathologic processes (e.g., excitotoxicity). To date, suitable PET markers of NMDA ion channel activity have not been available. (18)F-GE-179 is a novel radioligand that selectively binds to the open/active state of the NMDA receptor ion channel, displacing the binding of (3)H-tenocyclidine from the intrachannel binding site with an affinity of 2.4 nM. No significant binding was observed with 10 nM GE-179 at 60 other neuroreceptors, channels, or transporters. We describe the kinetic behavior of the radioligand in vivo in humans.

METHODS

Nine healthy participants (6 men, 3 women; median age, 37 y) each underwent a 90-min PET scan after an intravenous injection of (18)F-GE-179. Continuous arterial blood sampling over the first 15 min was followed by discrete blood sampling over the duration of the scan. Brain radioactivity (KBq/mL) was measured in summation images created from the attenuation- and motion-corrected dynamic images. Metabolite-corrected parent plasma input functions were generated. We assessed the abilities of 1-, 2-, and 3-compartment models to kinetically describe cerebral time-activity curves using 6 bilateral regions of interest. Parametric volume-of-distribution (V(T)) images were generated by voxelwise rank-shaping regularization of exponential spectral analysis (RS-ESA).

RESULTS

A 2-brain-compartment, 4-rate-constant model best described the radioligand's kinetics in normal gray matter of subjects at rest. At 30 min after injection, 37% of plasma radioactivity represented unmetabolized (18)F-GE-179. The highest mean levels of gray matter radioactivity were seen in the putamina and peaked at 7.5 min. A significant positive correlation was observed between K1 and V(T) (Spearman ρ = 0.398; P = 0.003). Between-subject coefficients of variation of V(T) ranged between 12% and 16%. Voxelwise RS-ESA yielded similar V(T)s and coefficients of variation.

CONCLUSION

(18)F-GE-179 exhibits high and rapid brain extraction, with a relatively homogeneous distribution in gray matter and acceptable between-subject variability. Despite its rapid peripheral metabolism, quantification of (18)F-GE-179 VT is feasible both within regions of interest and at the voxel level. The specificity of (18)F-GE-179 binding, however, requires further characterization with in vivo studies using activation and disease models.

Inosine improves functional recovery after experimental traumatic brain injury

Despite years of research, no effective therapy is yet available for the treatment of traumatic brain injury (TBI). The most prevalent and debilitating features in survivors of TBI are cognitive deficits and motor dysfunction. A potential therapeutic method for improving the function of patients following TBI would be to restore, at least in part, plasticity to the CNS in a controlled way that would allow for the formation of compensatory circuits. Inosine, a naturally occurring purine nucleoside, has been shown to promote axon collateral growth in the corticospinal tract (CST) following stroke and focal TBI. In the present study, we investigated the effects of inosine on motor and cognitive deficits, CST sprouting, and expression of synaptic proteins in an experimental model of closed head injury (CHI). Treatment with inosine (100 mg/kg i.p. at 1, 24 and 48 h following CHI) improved outcome after TBI, significantly decreasing the neurological severity score (NSS, p<0.04 vs. saline), an aggregate measure of performance on several tasks. It improved non-spatial cognitive performance (object recognition, p<0.016 vs. saline) but had little effect on sensorimotor coordination (rotarod) and spatial cognitive functions (Y-maze). Inosine did not affect CST sprouting in the lumbar spinal cord but did restore levels of the growth-associated protein GAP-43 in the hippocampus, though not in the cerebral cortex. Our results suggest that inosine may improve functional outcome after TBI.

Does the neuroprotective role of anandamide display diurnal variations?

The endocannabinoid system is a component of the neuroprotective mechanisms that an organism displays after traumatic brain injury (TBI). A diurnal variation in several components of this system has been reported. This variation may influence the recovery and survival rate after TBI. We have previously reported that the recovery and survival rate of rats is higher if TBI occurs at 1:00 than at 13:00. This could be explained by a diurnal variation of the endocannabinoid system. Here, we describe the effects of anandamide administration in rats prior to the induction of TBI at two different times of the day: 1:00 and 13:00. We found that anandamide reduced the neurological damage at both times. Nevertheless, its effects on bleeding, survival, food intake, and body weight were dependent on the time of TBI. In addition, we analyzed the diurnal variation of the expression of the cannabinoid receptors CB1R and CB2R in the cerebral cortex of both control rats and rats subjected to TBI. We found that CB1R protein was expressed more during the day, whereas its mRNA level was higher during the night. We did not find a diurnal variation for the CB2R. In addition, we also found that TBI increased CB1R and CB2R in the contralateral hemisphere and disrupted the CB1R diurnal cycle.

Spontaneous Wheel Running Exercise Induces Brain Recovery via Neurotrophin-3 Expression Following Experimental Traumatic Brain Injury in Rats

[Purpose] The aim of the present study was to investigate the expression of neurotrophin-3 (NT-3) after applying spontaneous wheel running exercises (SWR) after experimental traumatic brain injury (TBI). [Subjects and Methods] Thirty male Sprague-Dawley rats were divided into 3 groups; 20 rats were subjected to controlled cortical impact for TBI, and then, animals were randomly collected from the SWR group and subjected to wheel running exercise for 3 weeks. Ten rats were not subjected to any injury or running exercise to compare with the effect of TBI and SWR. Immunohistochemistry, Western blotting, skilled ladder rung walking test, and 2,3,5-triphenyltetrazolium chloride staining analysis for the evaluation of NT-3 expression were used to assess brain damage and recovery. [Results] The TBI-induced decrease in NT-3 expression was recovered by wheel running exercise. Moreover, decreased ischemic volume and progressive neurobehavioral outcome were observed in the SWR group. [Conclusion] Spontaneous running exercise promotes brain recovery and motor function through an increase in expression of NT-3.

Therapeutic potential of amniotic fluid-derived cells for treating the injured nervous system

There is a need for improved therapy for acquired brain injury, which has proven resistant to treatment by numerous drugs in clinical trials and continues to represent one of the leading causes of disability worldwide. Research into cell-based therapies for the treatment of brain injury is growing rapidly, but the ideal cell source has yet to be determined. Subpopulations of cells found in amniotic fluid, which is readily obtained during routine amniocentesis, can be easily expanded in culture, have multipotent differentiation capacity, are non-tumourigenic, and avoid the ethical complications associated with embryonic stem cells, making them a promising cell source for therapeutic purposes. Beneficial effects of amniotic fluid cell transplantation have been reported in various models of nervous system injury. However, evidence that amniotic fluid cells can differentiate into mature, functional neurons in vivo and incorporate into the existing circuitry to replace lost or damaged neurons is lacking. The mechanisms by which amniotic fluid cells improve outcomes after experimental nervous system injury remain unclear. However, studies reporting the expression and release of neurotrophic, angiogenic, and immunomodulatory factors by amniotic fluid cells suggest they may provide neuroprotection and (or) stimulate endogenous repair and remodelling processes in the injured nervous system. In this paper, we address recent research related to the neuronal differentiation of amniotic fluid-derived cells, the therapeutic efficacy of these cells in animal models of nervous system injury, and the possible mechanisms mediating the positive outcomes achieved by amniotic fluid cell transplantation.

Cortical endogenic neural regeneration of adult rat after traumatic brain injury

Focal and diffuse neuronal loss happened after traumatic brain injury (TBI). With little in the way of effective repair, recent interest has focused on endogenic neural progenitor cells (NPCs) as a potential method for regeneration. Whether endogenic neural regeneration happened in the cortex of adult rat after TBI remains to be determined. In this study, rats were divided into a sham group and a TBI group, and the rat model of medium TBI was induced by controlled cortical impact. Rats were injected with BrdU at 1 to 7 days post-injury (dpi) to allow identification of differentiated cells and sacrificed at 1, 3, 7, 14 and 28 dpi for immunofluorescence. Results showed nestin(+)/sox-2(+) NPCs and GFAP(+)/sox-2(+) radial glial (RG)-like cells emerged in peri-injured cortex at 1, 3, 7, 14 dpi and peaked at 3 dpi. The number of GFAP(+)/sox-2(+) cells was less than that of nestin(+)/sox-2(+) cells. Nestin(+)/sox-2(+) cells from posterior periventricle (pPV) immigrated into peri-injured cortex through corpus callosum (CC) were found. DCX(+)/BrdU(+) newborn immature neurons in peri-injured cortex were found only at 3, 7, 14 dpi. A few MAP-2(+)/BrdU(+) newborn neurons in peri-injured cortex were found only at 7 and 14 dpi. NeuN(+)/BrdU(+) mature neurons were not found in peri-injured cortex at 1, 3, 7, 14 and 28 dpi. While GFAP(+)/BrdU(+) astrocytes emerged in peri-injured cortex at 1, 3, 7, 14, 28 dpi and peaked at 7 dpi then kept in a stable state. In the corresponding time point, the percentage of GFAP(+)/BrdU(+) astrocytes in BrdU(+) cells was more than that of NPCs or newborn neurons. No CNP(+)/BrdU(+) oligodendrocytes were found in peri-injured cortex. These findings suggest that NPCs from pPV and reactive RG-like cells emerge in peri-injured cortex of adult rats after TBI. It can differentiate into immature neurons and astrocytes, but the former fail to grow up to mature neurons.

Blocking neurogenic inflammation for the treatment of acute disorders of the central nervous system

Classical inflammation is a well-characterized secondary response to many acute disorders of the central nervous system. However, in recent years, the role of neurogenic inflammation in the pathogenesis of neurological diseases has gained increasing attention, with a particular focus on its effects on modulation of the blood-brain barrier BBB. The neuropeptide substance P has been shown to increase blood-brain barrier permeability following acute injury to the brain and is associated with marked cerebral edema. Its release has also been shown to modulate classical inflammation. Accordingly, blocking substance P NK1 receptors may provide a novel alternative treatment to ameliorate the deleterious effects of neurogenic inflammation in the central nervous system. The purpose of this paper is to provide an overview of the role of substance P and neurogenic inflammation in acute injury to the central nervous system following traumatic brain injury, spinal cord injury, stroke, and meningitis.

Exogenous administration of PACAP alleviates traumatic brain injury in rats through a mechanism involving the TLR4/MyD88/NF-κB pathway

Pituitary adenylate cyclase-activating polypeptide (PACAP) is effective in reducing axonal damage associated with traumatic brain injury (TBI), and has immunomodulatory properties. Toll-like receptor 4 (TLR4) is an important mediator of the innate immune response. It significantly contributes to neuroinflammation induced by brain injury. However, it remains unknown whether exogenous PACAP can modulate TBI through the TLR4/adapter protein myeloid differentiation factor 88 (MyD88)/nuclear factor-κB (NF-κB) signaling pathway. In this study, we investigated the potential neuroprotective mechanisms of PACAP pretreatment in a weight-drop model of TBI. PACAP38 was microinjected intracerebroventricularly before TBI. Brain samples were extracted from the pericontusional area in the cortex and hippocampus. We found that TBI induced significant upregulation of TLR4, with peak expression occurring 24 h post-trauma, and that pretreatment with PACAP significantly improved motor and cognitive dysfunction, attenuated neuronal apoptosis, and decreased brain edema. Pretreatment with PACAP inhibited upregulation of TLR4 and its downstream signaling molecules MyD88, p-IκB, and NF-κB, and suppressed increases in the levels of the downstream inflammatory agents interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), in the brain tissue around the injured cortex and in the hippocampus. Administration of PACAP both in vitro and in vivo attenuated the ability of the TLR4 agonist lipopolysaccharide (LPS) to increase TLR4 protein levels. Therefore, PACAP exerts a neuroprotective effect in this rat model of TBI, by inhibiting a secondary inflammatory response mediated by the TLR4/MyD88/NF-κB signaling pathway in microglia and neurons, thereby reducing neuronal death and improving the outcome following TBI.

Umbilical cord blood-derived CD34⁺ cells improve outcomes of traumatic brain injury in rats by stimulating angiogenesis and neurogenesis

Human umbilical cord blood cells (HUCBCs) have been shown to be beneficial in reducing neurological deficits in rats with brain fluid percussion injury (FPI). This study aimed to assess the basic mechanisms underlying the neuroprotective effects of HUCBC-derived cluster of differentiation 34-positive (CD34⁺) cells. Rats were divided into three major groups: (i) sham-operated controls; (ii) FPI rats treated with phosphate-buffered saline (PBS); (iii) FPI rats treated with 0.2%, 50%, or 95% CD34⁺ cells (in 5 × 10⁵ cord blood lymphocytes and monocytes). Intravenous (IV) administration of 0.3 ml of PBS, 0.2% CD34⁺ cells, 50% CD34⁺ cells, or 95% CD34⁺ cells was conducted immediately after FPI. It was found that 4 days post-FPI, CD34⁺ cells could be detected in the ischemic brain tissues for 50% CD34⁺ cell- or 95% CD34⁺ cell-treated FPI rats, but not for the PBS-treated FPI rats or the 0.2% CD34⁺ cell-treated FPI rats. CD34⁺ cell (0.2%)-treated FPI rats or PBS-treated FPI rats displayed neurological and motor deficits, cerebral contusion and apoptosis [e.g., increased numbers of both TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling)-positive cells and caspase-3-positive cells], and activated inflammation (e.g., increased serum levels of tumor necrosis factor-α). FPI-induced neurological motor dysfunction, cerebral contusion and apoptosis, and activated inflammation could be attenuated by 50% CD34⁺ or 95% CD34⁺ cell therapy. In addition 50% or 95% CD34⁺ cell therapy but not PBS or 0.2% CD34⁺ cell therapy significantly promoted angiogenesis (e.g., increased numbers of both vasculoendothelial growth factor-positive cells and 5-bromodeoxyuridine (BrdU)-endothelial double-positive cells), neurogenesis (e.g., increased numbers of both glial cell line-derived neurotrophic factor-positive cells and BrdU/neuronal nuclei double-positive cells) in the ischemic brain after FPI, and migration of endothelial progenitor cells from the bone marrow. Our data suggest that IV administration of HUCBC-derived CD34⁺ cells may improve outcomes of FPI in rats by stimulating both angiogenesis and neurogenesis.

Hypoxia-inducible factor 1 is essential for spontaneous recovery from traumatic brain injury and is a key mediator of heat acclimation induced neuroprotection

Heat acclimation (HA), a well-established preconditioning model, confers neuroprotection in rodent models of traumatic brain injury (TBI). It increases neuroprotective factors, among them is hypoxia-inducible factor 1α (HIF-1α), which is important in the response to postinjury ischemia. However, little is known about the role of HIF-1α in TBI and its contribution to the establishment of the HA protecting phenotype. Therefore, we aimed to explore HIF-1α role in TBI defense mechanisms as well as in HA-induced neuroprotection. Acriflavine was used to inhibit HIF-1 in injured normothermic (NT) or HA mice. After TBI, we evaluated motor function recovery, lesion volume, edema formation, and body temperature as well as HIF-1 downstream transcription targets, such as glucose transporter 1 (GLUT1), vascular endothelial growth factor, and aquaporin 4. We found that HIF-1 inhibition resulted in deterioration of motor function, increased lesion volume, hypothermia, and reduced edema formation. All these parameters were significantly different in the HA mice. Western blot analysis and enzyme-linked immunosorbent assay showed reduced levels of all HIF-1 downstream targets in HA mice, however, only GLUT1 was downregulated in NT mice. We conclude that HIF-1 is a key mediator in both spontaneous recovery and HA-induced neuroprotection after TBI.

The role of substance p in ischaemic brain injury

Stroke is a leading cause of death, disability and dementia worldwide. Despite extensive pre-clinical investigation, few therapeutic treatment options are available to patients, meaning that death, severe disability and the requirement for long-term rehabilitation are common outcomes. Cell loss and tissue injury following stroke occurs through a number of diverse secondary injury pathways, whose delayed nature provides an opportunity for pharmacological intervention. Amongst these secondary injury factors, increased blood-brain barrier permeability and cerebral oedema are well-documented complications of cerebral ischaemia, whose severity has been shown to be associated with final outcome. Whilst the mechanisms of increased blood-brain barrier permeability and cerebral oedema are largely unknown, recent evidence suggests that the neuropeptide substance P (SP) plays a central role. The aim of this review is to examine the role of SP in ischaemic stroke and report on the potential utility of NK1 tachykinin receptor antagonists as therapeutic agents.

Preconditioning for traumatic brain injury

Traumatic brain injury (TBI) treatment is now focused on the prevention of primary injury and reduction of secondary injury. However, no single effective treatment is available as yet for the mitigation of traumatic brain damage in humans. Both chemical and environmental stresses applied before injury have been shown to induce consequent protection against post-TBI neuronal death. This concept termed "preconditioning" is achieved by exposure to different pre-injury stressors to achieve the induction of "tolerance" to the effect of the TBI. However, the precise mechanisms underlying this "tolerance" phenomenon are not fully understood in TBI, and therefore even less information is available about possible indications in clinical TBI patients. In this review, we will summarize TBI pathophysiology, and discuss existing animal studies demonstrating the efficacy of preconditioning in diffuse and focal type of TBI. We will also review other non-TBI preconditioning studies, including ischemic, environmental, and chemical preconditioning, which maybe relevant to TBI. To date, no clinical studies exist in this field, and we speculate on possible future clinical situations, in which pre-TBI preconditioning could be considered.

The relatively good outcome of cerebellum-brainstem ischemic strokes

BACKGROUND

Our clinical experience suggests that the outcome of cerebellum-brainstem ischemic strokes is better than that of hemispheric ischemic strokes.

METHODS

Within the setting of 2 national Israeli prospective stroke surveys, we analyzed risk factors, etiology, severity at presentation, and prognosis of first ischemic cerebellum-brainstem stroke (259 patients), comparing with strokes within the anterior circulation (1,029 patients).

RESULTS

Patients with cerebellum-brainstem strokes were younger and had less frequently atrial fibrillation and congestive heart failure. Cardioembolic etiology was significantly less prevalent (p < 0.001). Severity at presentation was milder (p < 0.001). At discharge, worsening of the modified Rankin Scale was present in a smaller number of patients (p < 0.001); more returned to their home (p < 0.001). Six-month and 1-year mortality were lower (p < 0.001 for both). Adjusted logistic regression models showed that patients with cerebellum-brainstem strokes had 50% smaller chances of dying (OR 0.55; 95% CI 0.31-0.98) and a smaller chance of worsening of the modified Rankin Scale at discharge (OR 0.61; 95% CI 0.46-0.82).

CONCLUSIONS

Cerebellum-brainstem strokes are less frequently cardioembolic, have a less severe presentation, and carry a better immediate and long-term prognosis.

Sleep deprivation has a neuroprotective role in a traumatic brain injury of the rat

During the process of a brain injury, responses to produce damage and cell death are activated, but self-protective responses that attempt to maintain the integrity and functionality of the brain are also activated. We have previously reported that the recovery from a traumatic brain injury (TBI) is better in rats if it occurs during the dark phase of the diurnal cycle when rats are in the waking period. This suggests that wakefulness causes a neuroprotective role in this type of injury. Here we report that 24h of total sleep deprivation after a TBI reduces the morphological damage and enhances the recovery of the rats, as seen on a neurobiological scale.

Melanocortins and the cholinergic anti-inflammatory pathway

Experimental evidence indicates that small concentrations of inflammatory molecules produced by damaged tissues activate afferent signals through ascending vagus nerve fibers, that act as the sensory arm of an "inflammatory reflex". The subsequent activation of vagal efferent fibers, which represent the motor arm of the inflammatory reflex, rapidly leads to acetylcholine release in organs of the reticuloendothelial system. Acetylcholine interacts with α7 subunit-containing nicotinic receptors in tissue macrophages and other immune cells and rapidly inhibits the synthesis/release of tumor necrosis factor-α and other inflammatory cytokines. This neural anti-inflammatory response called "cholinergic anti-inflammatory pathway" is fast and integrated through the central nervous system. Preclinical studies are in progress, with the aim to develop therapeutic agents able to activate the cholinergic anti-inflammatory pathway. Melanocortin peptides bearing the adrenocorticotropin/α-melanocyte-stimulating hormone sequences exert a protective and life-saving effect in animals and humans in conditions of circulatory shock. These neuropeptides are likewise protective in other severe hypoxic conditions, such as prolonged respiratory arrest, myocardial ischemia, renal ischemia and ischemic stroke, as well as in experimental heart transplantation. Moreover, experimental evidence indicates that melanocortins reverse circulatory shock, prevent myocardial ischemia/reperfusion damage and exert neuroprotection against ischemic stroke through activation of the cholinergic anti-inflammatory pathway. This action occurs via stimulation of brain melanocortin MC3/MC4 receptors. Investigations that determine the molecular mechanisms of the cholinergic anti-inflammatory pathway activation could help design of superselective activators of this pathway.

Montelukast inhibits caspase-3 activity and ameliorates oxidative damage in the spinal cord and urinary bladder of rats with spinal cord injury

Spinal cord injury (SCI) leads to an inflammatory response that generates substantial secondary damage within the tissue besides the primary damage. Leukotrienes are biologically active 5-lipoxygenase products of arachidonic acid metabolism that are involved in the mediation of various inflammatory disorders including SCI. In this study, we investigated the possible protective effects of montelukast, a leukotriene receptor blocker, on SCI-induced oxidative damage. Wistar albino rats (n=24) were divided randomly as control, vehicle- or montelukast (10mg/kg, ip)-treated SCI groups. To induce SCI, a standard weight-drop method that induced a moderately severe injury at T10 was used. Vehicle or montelukast were administered to the injured animals 15 min after injury. At seven days post-injury, neurological examination was performed and rats were decapitated. Blood samples were taken to evaluate leukotriene B4 levels, and pro-inflmamatory cytokines (TNF-α, IL-1β) while in spinal cord and urinary bladder samples malondialdehyde (MDA), glutathione (GSH), luminol chemiluminescence (CL) levels and myeloperoxidase (MPO) and caspase-3 activities were determined. Tissues were also evaluated histologically. SCI caused significant decreases in tissue GSH, which were accompanied with significant increases in luminol CL and MDA levels and MPO and caspase-3 activities, while pro-inflammatory cytokines in the plasma were elevated. On the other hand, montelukast treatment reversed these parameters and improved histological findings. In conclusion, SCI caused oxidative tissue injury through the activation of pro-inflammatory mediators and by neutrophil infiltration into tissues, and the neuroprotective and antiapoptotic effects of montelukast are mediated by the inhibition of lipid peroxidation, neutrophil accumulation and pro-inflammatory cytokine release. Moreover, montelukast does not only exert antioxidant and antiapoptotic effects on the spinal cord, but it has a significant impact on the bladder tissue damage secondary to SCI.

Use of hypothermia in the intensive care unit

Used for over 3600 years, hypothermia, or targeted temperature management (TTM), remains an ill defined medical therapy. Currently, the strongest evidence for TTM in adults are for out-of-hospital ventricular tachycardia/ventricular fibrillation cardiac arrest, intracerebral pressure control, and normothermia in the neurocritical care population. Even in these disease processes, a number of questions exist. Data on disease specific therapeutic markers, therapeutic depth and duration, and prognostication are limited. Despite ample experimental data, clinical evidence for stroke, refractory status epilepticus, hepatic encephalopathy, and intensive care unit is only at the safety and proof-of-concept stage. This review explores the deleterious nature of fever, the theoretical role of TTM in the critically ill, and summarizes the clinical evidence for TTM in adults.

Effect of PACAP in central and peripheral nerve injuries

Pituitary adenylate cyclase activating polypeptide (PACAP) is a bioactive peptide with diverse effects in the nervous system. In addition to its more classic role as a neuromodulator, PACAP functions as a neurotrophic factor. Several neurotrophic factors have been shown to play an important role in the endogenous response following both cerebral ischemia and traumatic brain injury and to be effective when given exogenously. A number of studies have shown the neuroprotective effect of PACAP in different models of ischemia, neurodegenerative diseases and retinal degeneration. The aim of this review is to summarize the findings on the neuroprotective potential of PACAP in models of different traumatic nerve injuries. Expression of endogenous PACAP and its specific PAC1 receptor is elevated in different parts of the central and peripheral nervous system after traumatic injuries. Some experiments demonstrate the protective effect of exogenous PACAP treatment in different traumatic brain injury models, in facial nerve and optic nerve trauma. The upregulation of endogenous PACAP and its receptors and the protective effect of exogenous PACAP after different central and peripheral nerve injuries show the important function of PACAP in neuronal regeneration indicating that PACAP may also be a promising therapeutic agent in injuries of the nervous system.

Antibody-conjugated PEGylated cerium oxide nanoparticles for specific targeting of Aβ aggregates modulate neuronal survival pathways

Oxidative stress has been found to be associated with the progression of neurodegenerative diseases such as Alzheimer's, Parkinson's, Lou Gehrig's, etc. In the recent years, cerium oxide nanoparticles (CNPs) have been studied as potent antioxidant agents able to exert neuroprotective effects. This work reports polyethylene glycol (PEG)-coated and antibody-conjugated CNPs for the selective delivering to Aβ aggregates, and the protective effect against oxidative stress/Aβ-mediated neurodegeneration. In this study PEG-coated and anti-Aβ antibody-conjugated antioxidant nanoparticles (Aβ-CNPs-PEG) were developed, and their effects on neuronal survival and brain-derived neurotrophic factor (BDNF) signaling pathway were examined. Aβ-CNPs-PEG specifically targets the Aβ aggregates, and concomitant rescue of neuronal survival better than Aβ-CNPs, by modulating the BDNF signaling pathway. This proof of concept work may allow in the future, once validated in vivo, for the selective delivery of CNPs only to affected brain areas.