Newer pharmacological approaches for antioxidant neuroprotection in traumatic brain injury

Brain Delivery of Protein Therapeutics by Cell Matrix-Inspired Biomimetic Nanocarrier

Protein therapeutics are anticipated to offer significant treatment options for central nervous system (CNS) diseases. However, the majority of proteins are unable to traverse the blood-brain barrier (BBB) and reach their CNS target sites. Inspired by the natural environment of active proteins, the cell matrix components hyaluronic acid (HA) and protamine (PRTM) are used to self-assemble with proteins to form a protein-loaded biomimetic core and then incorporated into ApoE3-reconstituted high-density lipoprotein (rHDL) to form a protein-loaded biomimetic nanocarrier (Protein-HA-PRTM-rHDL). This cell matrix-inspired biomimetic nanocarrier facilitates the penetration of protein therapeutics across the BBB and enables their access to intracellular target sites. Specifically, CAT-HA-PRTM-rHDL facilitates rapid intracellular delivery and release of catalase (CAT) via macropinocytosis-activated membrane fusion, resulting in improved spatial learning and memory in traumatic brain injury (TBI) model mice (significantly reduces the latency of TBI mice and doubles the number of crossing platforms), and enhances motor function and prolongs survival in amyotrophic lateral sclerosis (ALS) model mice (extended the median survival of ALS mice by more than 10 days). Collectively, this cell matrix-inspired nanoplatform enables the efficient CNS delivery of protein therapeutics and provides a novel approach for the treatment of CNS diseases.

Oxidative stress in the brain-lung crosstalk: cellular and molecular perspectives

Oxidative stress is caused by an imbalance between the production of reactive oxygen species (ROS) and the body's ability to counteract their harmful effects, playing a key role in the pathogenesis of brain and lung-related diseases. This review comprehensively examines the intricate mechanisms by which oxidative stress influences cellular and molecular pathways, contributing to neurodegenerative, cardiovascular, and respiratory disorders. Emphasizing the detrimental effects on both brain and lung health, we discuss innovative diagnostic biomarkers, such as 8-hydroxy-2'-deoxyguanosine (8-OHdG), and the potential of antioxidant therapies. For these topics, we provide insights into future research directions in the field of oxidative stress treatment, including the development of personalized treatment approaches, the discovery and validation of novel biomarkers, and the development of new drug delivery systems. This review not only provides a new perspective on understanding the role of oxidative stress in brain and lung-related diseases but also offers new insights for future clinical treatments.

Research Progress of Antioxidants in Oxidative Stress Therapy after Spinal Cord Injury

Spinal cord injury (SCI) is a serious problem in the central nervous system resulting in high disability and mortality with complex pathophysiological mechanisms. Oxidative stress is one of the main secondary reactions of SCI, and its main pathophysiological marker is the production of excess reactive oxygen species. The overproduction of reactive oxygen species and insufficient antioxidant capacity lead to the occurrence of oxidative stress and neuroinflammation, and the dysregulation of oxidative stress and neuroinflammation leads to further aggravation of damage. Oxidative stress can initiate a variety of inflammatory and apoptotic pathways, and targeted antioxidant therapy can greatly reduce oxidative stress and reduce neuroinflammation, which has a certain positive effect on rehabilitation and prognosis in SCI. This article reviewed the research on different types of antioxidants and related treatments in SCI, focusing on the mechanisms of oxidative stress.

Antioxidant theranostic copolymer-mediated reduction in oxidative stress following traumatic brain injury improves outcome in a mouse model

Following a traumatic brain injury (TBI), excess reactive oxygen species (ROS) and lipid peroxidation products (LPOx) are generated and lead to secondary injury beyond the primary insult. A major limitation of current treatments is poor target engagement, which has prevented success in clinical trials. Thus, nanoparticle-based treatments have received recent attention because of their ability to increase accumulation and retention in damaged brain. Theranostic neuroprotective copolymers (NPC3) containing thiol functional groups can neutralize ROS and LPOx. Immediate administration of NPC3 following injury in a controlled cortical impact (CCI) mouse model provides a therapeutic window in reducing ROS levels at 2.08-20.83 mg/kg in males and 5.52-27.62 mg/kg in females. This NPC3-mediated reduction in oxidative stress improves spatial learning and memory in males, while females show minimal improvement. Notably, NPC3-mediated reduction in oxidative stress prevents the bilateral spread of necrosis in male mice, which was not observed in female mice and likely accounts for the sex-based spatial learning and memory differences. Overall, these findings suggest sex-based differences to oxidative stress scavenger nanoparticle treatments, and a possible upper threshold of antioxidant activity that provides therapeutic benefit in injured brain since female mice benefit from NPC3 treatment to a lesser extent than male mice.

Oxidative stress following spinal cord injury: From molecular mechanisms to therapeutic targets

Spinal cord injury (SCI) is a medical condition that results from severe trauma to the central nervous system; it imposes great psychological and economic burdens on affected patients and their families. The dynamic balance between reactive oxygen species (ROS) and antioxidants is essential for maintaining normal cellular physiological functions. As important intracellular signaling molecules, ROS regulate numerous physiological activities, including vascular reactivity and neuronal function. However, excessive ROS can cause damage to cellular macromolecules, including DNA, lipids, and proteins; this damage eventually leads to cell death. This review discusses the mechanisms of oxidative stress in SCI and describes some signaling pathways that regulate oxidative injury after injury, with the aim of providing guidance for the development of novel SCI treatment strategies.

Efficacy of Acetylcysteine and Selenium in Aneurysmal Subarachnoid Hemorrhage Patients: A Prospective, Multicenter, Single Blind Randomized Controlled Trial

BACKGROUND

Subarachnoid hemorrhage (SAH) patients have oxidative stress results in inflammation, tissue degeneration and neuronal damage. These deleterious effects cause aggravation of the perihematomal edema (PHE), vasospasm, and even hydrocephalus. We hypothesized that antioxidants may have a neuroprotective role in acute aneurysmal SAH (aSAH) patients.

METHODS

We conducted a prospective, multicenter randomized (single blind) trial between January 2017 and October 2019, investigating whether antioxidants (acetylcysteine and selenium) have the potential to improve the neurologic outcome in aSAH patients. The antioxidant patient group received antioxidants of acetylcysteine (2,000 mg/day) and selenium (1,600 µg/day) intravenously (IV) for 14 days. These drugs were administrated within 24 hours of admission. The non-antioxidant patient group received a placebo IV.

RESULTS

In total, 293 patients were enrolled with 103 patients remaining after applying the inclusion and exclusion criteria. No significant differences were observed in the baseline characteristics between the antioxidant (n = 53) and non-antioxidant (n = 50) groups. Among clinical factors, the duration of intensive care unit (ICU) stay was significantly shortened in patients who received antioxidants (11.2, 95% confidence interval [CI], 9.7-14.5 vs. 8.3, 95% CI, 6.2-10.2 days, P = 0.008). However, no beneficial effects were observed on radiological outcomes.

CONCLUSION

In conclusion, antioxidant treatment failed to show the reduction of PHE volume, mid-line shifting, vasospasm and hydrocephalus in acute SAH patients. A significant reduction in ICU stay was observed but need more optimal dosing schedule and precise outcome targets are required to clarify the clinical impacts of antioxidants in these patients.

TRIAL REGISTRATION

Clinical Research Information Service Identifier: KCT0004628.

Chrysin Attenuates Oxidative Stress to Alleviate Sevoflurane-Induced Cognitive Impairments in Aged Rats

OBJECTIVE

Anesthesia-induced cognitive impairments are common for elder patients after surgery. Oxidative stress is the predominant factor contributing to the impairments. This study was to assess the therapeutic potential of an anti-oxidative naturally occurring flavonoid, chrysin, in attenuating sevoflurane-induced cognitive impairments in rat models.

METHODS

Rat models of cognitive impairments were constructed by exposing aged rats (18 months old) to sevoflurane for 2 h. Chrysin was administered via oral gavage at the dose of 25, 50, and 100 mg/kg/day for seven days. The elevated plus maze test was used to assess anxiety and explorative behaviors. Spatial memory tests were performed using novel object recognition test, object location memory task, and water maze experiments. Oxidative stress was evaluated by measuring levels of malondialdehyde, nicotinamide adenine dinucleotide phosphate, 4-hydroxynonenal, and glutathione using colorimetric assays. Quantitative real-time polymerase chain reaction and Western blot were used to analyze how chrysin affects nuclear factor E2-related factor (Nrf) signaling.

RESULTS

While sevoflurane anesthesia led to significant decline in cognitive performance in object recognition test, object location memory task, and water maze test, chrysin exerted significant effects in alleviating the impairments. Oxidative stress was also reduced in the hippocampus tissue of rats after chrysin intake. Nrf signaling was activated by chrysin treatment in sevoflurane-induced cognitive impairment models.

CONCLUSION

Chrysin was effective in alleviating cognitive impairments induced by sevoflurane anesthesia, which was at least in part facilitated by its effects in reducing oxidative stress via activating Nrf signaling.

Multiple mechanisms of curcumin targeting spinal cord injury

Spinal cord injury (SCI) is an irreversible disease process with a high disability and mortality rate. After primary spinal cord injury, the secondary injury may occur in sequence, which is composed of ischemia and hypoxia, excitotoxicity, calcium overload, oxidative stress and inflammation, resulting in massive death of parenchymal cells in the injured area, followed by the formation of syringomyelia. Effectively curbing the process of secondary injury can promote nerve repair and improve functional prognosis. As the main active ingredient in turmeric, curcumin can play an important role in reducing inflammation and oxidation, protecting the neurons, and ultimately reducing spinal cord injury. This article reviews the effects of curcumin on the repair of nerve injury, with emphasis on the various mechanisms by which curcumin promotes the treatment of spinal cord injury.

Comprehensive evaluation of mitochondrial redox profile, calcium dynamics, membrane integrity and apoptosis markers in a preclinical model of severe penetrating traumatic brain injury

Traumatic Brain Injury (TBI) is caused by the external physical assaults damages the brain. It is a heterogeneous disorder that remains a leading cause of death and disability in the military and civilian population of the United States. Preclinical investigations of mitochondrial responses in TBI have ascertained that mitochondrial dysfunction is an acute indicator of cellular damage and plays a pivotal role in long-term injury progression through cellular excitotoxicity. The current study was designed to provide an in-depth evaluation of mitochondrial endpoints with respect to redox and calcium homeostasis, and cell death responses following penetrating TBI (PTBI). To evaluate these pathological cascades, anesthetized adult male rats (N = 6/group) were subjected to either 10% unilateral PTBI or Sham craniectomy. Animals were euthanized at 24 h post-PTBI, and purified mitochondrial fractions were isolated from the brain injury core and perilesional areas. Overall, increased reactive oxygen and nitrogen species (ROS/RNS) production, and elevated oxidative stress markers such as 4-hydroxynonenal (4-HNE), 3-nitrotyrosine (3-NT), and protein carbonyls (PC) were observed in the PTBI group compared to Sham. Mitochondrial antioxidants such as glutathione, peroxiredoxin (PRX-3), thioredoxin (TRX), nicotinamide adenine dinucleotide phosphate (NADPH), superoxide dismutase (SOD), and catalase (CAT) levels were significantly decreased after PTBI. Likewise, PTBI mitochondria displayed significant loss of Ca²⁺ homeostasis, early opening of mitochondrial permeability transition pore (mPTP), and increased mitochondrial swelling. Both, outer and inner mitochondrial membrane integrity markers, such as voltage-dependent anion channels (VDAC) and cytochrome c (Cyt C) expression were significantly decreased following PTBI. The apoptotic cell death was evidenced by significantly decreased B-cell lymphoma-2 (Bcl-2) and increased glyceraldehyde 3-phosphate dehydrogenase (GAPDH) expression after PTBI. Collectively, current results highlight the comprehensive picture of mitochondria-centric acute pathophysiological responses following PTBI, which may be utilized as novel prognostic indicators of disease progression and theragnostic indicators for evaluating neuroprotection therapeutics following TBI.

Ketogenic Diet for Neonatal Hypoxic-Ischemic Encephalopathy

The prevalence of neonatal hypoxic-ischemic encephalopathy (HIE), a devastating neurological injury, is increasing; thus, effective treatments and preventions are urgently needed. The underlying pathology of HIE remains unclear; recent research has focused on elucidating key features of the disease. A variety of diseases can be alleviated by consuming a ketogenic diet (KD) despite differences in pathogenesis and features, given the common mechanisms of KD-induced effects. Dietary modification is the most translatable, cost-efficient, and safest approach to treat acute or chronic neurological disorders and reduces reliance on pharmaceutical treatments. Evidence suggests that the KD can exert beneficial effects in animal models and in humans with brain injuries. The efficacy of the KD in preventing neuronal damage, motor alterations, and cognitive decline varies. Moreover, the KD may provide an alternative source of energy, enhance mitochondrial function, and reduce the expression of inflammatory and apoptotic mediators. Thus, this diet has attracted interest as a potential therapy for HIE. This review examined the role of the KD in HIE treatment and described the mechanisms by which ketone bodies (KBs) exert effects under pathological conditions and protect against brain damage; the evidence supports the implementation of dietary interventions as a therapeutic strategy for HIE. Future research should aim to elucidate the underlying mechanisms of the KD in patients with HIE and determine whether the effect of the KD on clinical outcomes can be reproduced in humans.

Ultrasmall polymer-coated cerium oxide nanoparticles as a traumatic brain injury therapy

No medication has been approved for secondary injuries after traumatic brain injury (TBI). While free radicals are considered a major mediator of secondary injury, conventional antioxidants only have modest clinical efficacy. Here, we synthesized CX201 consisting of core cerium oxide nanoparticles coated with 6-aminocaproic acid and polyvinylpyrrolidone in aqueous phase. CX201 with 3.49 ± 1.11 nm of core and 6.49 ± 0.56 nm of hydrodynamic diameter showed multi-enzymatic antioxidant function. Owing to its excellent physiological stability and cell viability, CX201 had a neuroprotective effect in vitro. In a TBI animal model, an investigator-blinded randomized experiment showed a single intravenously injected CX201 significantly improved functional recovery compared to the control. CX201 reduced lipid peroxidation and inflammatory cell recruitment at the damaged brain. These suggest ultrasmall CX201 can efficiently reduce secondary brain injuries after TBI. Given the absence of current therapies, CX201 may be proposed as a novel therapeutic strategy for TBI.

Neuroprotective effects of mild hypothermia against traumatic brain injury by the involvement of the Nrf2/ARE pathway

BACKGROUND

Traumatic brain injury (TBI) is the leading cause of death and disability worldwide. Mild hypothermia (32-35°C) has been found to show neuroprotective effects against TBI. However, the specific mechanism is still elusive. In the current study, we explored the relationship between oxidative damage after TBI and treatment with mild hypothermia as well as the underlying molecular mechanisms.

METHODS

We used the closed cortex injury model to perform the brain injury and a temperature monitoring and control system to regulate the body temperature of mice after injury. Adult male C57BL/6 mice were adopted in this study and divided into four experimental groups. Tissue samples were harvested 24 h after injury.

RESULTS

First, our results showed that treatment with mild hypothermia significantly improved neurobehavioral dysfunction and alleviated brain edema after TBI. Moreover, treatment with mild hypothermia enhanced the activity of the antioxidant enzymes superoxide dismutase and glutathione peroxidase and reduced the accumulation of lipid peroxidation malondialdehyde. Importantly, the expression and activation of the nuclear factor erythroid 2-related factor 2-antioxidant response element (Nrf2-ARE) pathway were upregulated by mild hypothermia after TBI. Finally, treatment with hypothermia significantly decreased the cell apoptosis induced by TBI.

CONCLUSION

Our results showed that the protective effects of mild hypothermia after TBI may be achieved by the upregulation of the Nrf2-ARE pathway and revealed Nrf2 as a potentially important target to improve the prognosis of TBI.

Oxidative stress and mitochondrial dysfunction following traumatic brain injury: From mechanistic view to targeted therapeutic opportunities

Traumatic brain injury (TBI) is one of the most prevalent causes of permanent physical and cognitive disabilities. TBI pathology results from primary insults and a multi-mechanistic biochemical process, termed as secondary brain injury. Currently, there are no pharmacological agents for definitive treatment of patients with TBI. This article is presented with the purpose of reviewing molecular mechanisms of TBI pathology, as well as potential strategies and agents against pathological pathways. In this review article, materials were obtained by searching PubMed, Scopus, Elsevier, Web of Science, and Google Scholar. This search was considered without time limitation. Evidence indicates that oxidative stress and mitochondrial dysfunction are two key mediators of the secondary injury cascade in TBI pathology. TBI-induced oxidative damage results in the structural and functional impairments of cellular and subcellular components, such as mitochondria. Impairments of mitochondrial electron transfer chain and mitochondrial membrane potential result in a vicious cycle of free radical formation and cell apoptosis. The results of some preclinical and clinical studies, evaluating mitochondria-targeted therapies, such as mitochondria-targeted antioxidants and compounds with pleiotropic effects after TBI, are promising. As a proposed strategy in recent years, mitochondria-targeted multipotential therapy is a new hope, waiting to be confirmed. Moreover, based on the available findings, biologics, such as stem cell-based therapy and transplantation of mitochondria are novel potential strategies for the treatment of TBI; however, more studies are needed to clearly confirm the safety and efficacy of these strategies.

Theranostic Copolymers Neutralize Reactive Oxygen Species and Lipid Peroxidation Products for the Combined Treatment of Traumatic Brain Injury

Traumatic brain injury (TBI) results in the generation of reactive oxygen species (ROS) and lipid peroxidation product (LPOx), including acrolein and 4-hydroxynonenal (4HNE). The presence of these biochemical derangements results in neurodegeneration during the secondary phase of the injury. The ability to rapidly neutralize multiple species could significantly improve outcomes for TBI patients. However, the difficulty in creating therapies that target multiple biochemical derangements simultaneously has greatly limited therapeutic efficacy. Therefore, our goal was to design a material that could rapidly bind and neutralize both ROS and LPOx following TBI. To do this, a series of thiol-functionalized biocompatible copolymers based on lipoic acid methacrylate and polyethylene glycol monomethyl ether methacrylate (FW ∼ 950 Da) (O950) were prepared. A polymerizable gadolinium-DOTA methacrylate monomer (Gd-MA) was also synthesized starting from cyclen to facilitate direct magnetic resonance imaging and in vivo tracking of accumulation. These neuroprotective copolymers (NPCs) were shown to rapidly and effectively neutralize both ROS and LPOx. Horseradish peroxidase absorbance assays showed that the NPCs efficiently neutralized H₂O₂, while R-phycoerythrin protection assays demonstrated their ability to protect the fluorescent protein from oxidative damage. ¹H NMR studies indicated that the thiol-functional NPCs rapidly form covalent bonds with acrolein, efficiently removing it from solution. In vitro cell studies with SH-SY5Y-differentiated neurons showed that NPCs provide unique protection against toxic concentrations of both H₂O₂ and acrolein. NPCs rapidly accumulate and are retained in the injured brain in controlled cortical impact mice and reduce post-traumatic oxidative stress. Therefore, these materials show promise for improved target engagement of multiple biochemical derangements in hopes of improving TBI therapeutic outcomes.

Rescuing mitochondria in traumatic brain injury and intracerebral hemorrhages - A potential therapeutic approach

Mitochondria are dynamic organelles responsible for cellular energy production. Besides, regulating energy homeostasis, mitochondria are responsible for calcium homeostasis, signal transmission, and the fate of cellular survival in case of injury and pathologies. Accumulating reports have suggested multiple roles of mitochondria in neuropathologies, neurodegeneration, and immune activation under physiological and pathological conditions. Mitochondrial dysfunction, which occurs at the initial phase of brain injury, involves oxidative stress, inflammation, deficits in mitochondrial bioenergetics, biogenesis, transport, and autophagy. Thus, development of targeted therapeutics to protect mitochondria may improve functional outcomes following traumatic brain injury (TBI) and intracerebral hemorrhages (ICH). In this review, we summarize mitochondrial dysfunction related to TBI and ICH, including the mechanisms involved, and discuss therapeutic approaches with special emphasis on past and current clinical trials.

Dynamic Role of Phospholipases A2 in Health and Diseases in the Central Nervous System

Phospholipids are major components in the lipid bilayer of cell membranes. These molecules are comprised of two acyl or alkyl groups and different phospho-base groups linked to the glycerol backbone. Over the years, substantial interest has focused on metabolism of phospholipids by phospholipases and the role of their metabolic products in mediating cell functions. The high levels of polyunsaturated fatty acids (PUFA) in the central nervous system (CNS) have led to studies centered on phospholipases A2 (PLA2s), enzymes responsible for cleaving the acyl groups at the sn-2 position of the phospholipids and resulting in production of PUFA and lysophospholipids. Among the many subtypes of PLA2s, studies have centered on three major types of PLA2s, namely, the calcium-dependent cytosolic cPLA2, the calcium-independent iPLA2 and the secretory sPLA2. These PLA2s are different in their molecular structures, cellular localization and, thus, production of lipid mediators with diverse functions. In the past, studies on specific role of PLA2 on cells in the CNS are limited, partly because of the complex cellular make-up of the nervous tissue. However, understanding of the molecular actions of these PLA2s have improved with recent advances in techniques for separation and isolation of specific cell types in the brain tissue as well as development of sensitive molecular tools for analyses of proteins and lipids. A major goal here is to summarize recent studies on the characteristics and dynamic roles of the three major types of PLA2s and their oxidative products towards brain health and neurological disorders.

Targeting Oxidative Stress with Antioxidant Duotherapy after Experimental Traumatic Brain Injury

We assessed the effect of antioxidant therapy using the Food and Drug Administration-approved respiratory drug N-acetylcysteine (NAC) or sulforaphane (SFN) as monotherapies or duotherapy in vitro in neuron-BV2 microglial co-cultures and validated the results in a lateral fluid-percussion model of TBI in rats. As in vitro measures, we assessed neuronal viability by microtubule-associated-protein 2 immunostaining, neuroinflammation by monitoring tumor necrosis factor (TNF) levels, and neurotoxicity by measuring nitrite levels. In vitro, duotherapy with NAC and SFN reduced nitrite levels to 40% (p < 0.001) and neuroinflammation to -29% (p < 0.001) compared with untreated culture. The treatment also improved neuronal viability up to 72% of that in a positive control (p < 0.001). The effect of NAC was negligible, however, compared with SFN. In vivo, antioxidant duotherapy slightly improved performance in the beam walking test. Interestingly, duotherapy treatment decreased the plasma interleukin-6 and TNF levels in sham-operated controls (p < 0.05). After TBI, no treatment effect on HMGB1 or plasma cytokine levels was detected. Also, no treatment effects on the composite neuroscore or cortical lesion area were detected. The robust favorable effect of duotherapy on neuroprotection, neuroinflammation, and oxidative stress in neuron-BV2 microglial co-cultures translated to modest favorable in vivo effects in a severe TBI model.

Time-Course Evaluation of Brain Regional Mitochondrial Bioenergetics in a Pre-Clinical Model of Severe Penetrating Traumatic Brain Injury

Mitochondrial dysfunction is a pivotal target for neuroprotection strategies for traumatic brain injury (TBI). However, comprehensive time-course evaluations of mitochondrial dysfunction are lacking in the pre-clinical penetrating TBI (PTBI) model. The current study was designed to characterize temporal responses of mitochondrial dysfunction from 30 min to 2 weeks post-injury after PTBI. Anesthetized adult male rats were subjected to either PTBI or sham craniectomy (n = 6 animals per group × 7 time points). Animals were euthanized at 30 min, 3 h, 6 h, 24 h, 3 days, 7 days, and 14 days post-PTBI, and mitochondria were isolated from the ipsilateral hemisphere of brain regions near the injury core (i.e., frontal cortex [FC] and striatum [ST]) and a more distant region from the injury core (i.e., hippocampus [HIP]). Mitochondrial bioenergetics parameters were measured in real time using the high-throughput procedures of the Seahorse Flux Analyzer (Agilent Technologies, Santa Clara, CA). The post-injury time course of FC + ST showed a biphasic mitochondrial bioenergetics dysfunction response, indicative of reduced adenosine triphosphate synthesis rate and maximal respiratory capacity after PTBI. An initial phase of energy crisis was detected at 30 min (-42%; p < 0.05 vs. sham), which resolved to baseline levels between 3 and 6 h (non-significant vs. sham). This was followed by a second and more robust phase of bioenergetics dysregulation detected at 24 h that remained unresolved out to 14 days post-injury (-55% to -90%; p < 0.05 vs. sham). In contrast, HIP mitochondria showed a delayed onset of mitochondrial dysfunction at 7 days (-74%; p < 0.05 vs. sham) that remained evident out to 14 days (-51%; p < 0.05 vs. sham) post-PTBI. Collectively, PTBI-induced mitochondrial dysfunction responses were time and region specific, evident differentially at the injury core and distant region of PTBI. The current results provide the basis that mitochondrial dysfunction may be targeted differentially based on region specificity post-PTBI. Even more important, these results suggest that therapeutic interventions targeting mitochondrial dysfunction may require extended dosing regimens to achieve clinical efficacy after TBI.

Glutamate, Glutamine, GABA and Oxidative Products in the Pons Following Cortical Injury and Their Role in Motor Functional Recovery

Brain injury leads to an excitatory phase followed by an inhibitory phase in the brain. The clinical sequelae caused by cerebral injury seem to be a response to remote functional inhibition of cerebral nuclei located far from the motor cortex but anatomically related to the injury site. It appears that such functional inhibition is mediated by an increase in lipid peroxidation (LP). To test this hypothesis, we report data from 80 rats that were allocated to the following groups: the sham group (n = 40), in which rats received an intracortical infusion of artificial cerebrospinal fluid (CSF); the injury group (n = 20), in which rats received CSF containing ferrous chloride (FeCl₂, 50 mM); and the recovery group (n = 20), in which rats were injured and allowed to recover. Beam-walking, sensorimotor and spontaneous motor activity tests were performed to evaluate motor performance after injury. Lipid fluorescent products (LFPs) were measured in the pons. The total pontine contents of glutamate (GLU), glutamine (GLN) and gamma-aminobutyric acid (GABA) were also measured. In injured rats, the motor deficits, LFPs and total GABA and GLN contents in the pons were increased, while the GLU level was decreased. In contrast, in recovering rats, none of the studied variables were significantly different from those in sham rats. Thus, motor impairment after cortical injury seems to be mediated by an inhibitory pontine response, and functional recovery may result from a pontine restoration of the GLN-GLU-GABA cycle, while LP may be a primary mechanism leading to remote pontine inhibition after cortical injury.

Mitochondrial quality control: Epigenetic signatures and therapeutic strategies

Mitochondria are semi-autonomous organelle staging a crucial role in cellular stress response, energy metabolism and cell survival. Maintaining mitochondrial quality control is very important for its homeostasis. Pathological conditions such as oxidative stress and neurodegeneration, disrupt this quality control, and involvement of genetic and epigenetic materials in this disruption have been reported. These regulatory factors trigger mitochondrial imbalance, as seen in many neurodegenerative diseases like Alzheimer's disease, Parkinson's disease, Amyotrophic lateral sclerosis, and Huntington's disease. The dynamic regulatory pathways i.e. mitophagy, biogenesis, permeability pore transitioning, fusion-fission are affected as a consequence and have been reviewed in this article. Moreover, several epigenetic mechanisms such as DNA methylation and histone modulation participating in such neurological disorders have also been discussed. Apart from it, therapeutic approaches targeting mitochondrial quality control have been tremendously explored showing ameliorative effects for these diseases, and have been discussed here with a novel perspective.

Antioxidant thioether core-crosslinked nanoparticles prevent the bilateral spread of secondary injury to protect spatial learning and memory in a controlled cortical impact mouse model of traumatic brain injury

The secondary phase of traumatic brain injury (TBI) is partly caused by the release of excess reactive oxygen species (ROS) from the primary injury. However, there are currently no therapies that have been shown to reduce the secondary spread of injury beyond the primary insult. Nanoparticles offer the ability to rapidly accumulate and be retained in injured brain for improved target engagement. Here, we utilized systemically administered antioxidant thioether core-cross-linked nanoparticles (NP1) that scavenge and inactivate ROS to reduce this secondary spread of injury in a mild controlled cortical impact (CCI) mouse model of TBI. We found that NP1 treatment protected CCI mice from injury induced learning and memory deficits observed in the Morris water maze (MWM) test at 1-month post-CCI. This protection was likely a result of NP1-mediated reduction in oxidative stress in the ipsilateral hemisphere as determined by immunofluorescence imaging of markers of oxidative stress and the spread of neuroinflammation into the contralateral hippocampus as determined by immunofluorescence imaging of activated microglia and neuron-astrocyte-microglia triad formation. These data suggest NP1-mediated reduction in post-traumatic oxidative stress correlates with the reduction in the spread of injury to the contralateral hippocampus to protect spatial memory and learning in CCI mice. Therefore, these materials may offer an improved treatment strategy to reduce the secondary spread of TBI.

Neuropharmacology in traumatic brain injury: from preclinical to clinical neuroprotection?

Traumatic brain injury (TBI) constitutes a major health problem worldwide and is a leading cause of death and disability in individuals, contributing to devastating socioeconomic consequences. Despite numerous promising pharmacological strategies reported as neuroprotective in preclinical studies, the translation to clinical trials always failed, albeit the great diversity of therapeutic targets evaluated. In this review, first, we described epidemiologic features, causes, and primary and secondary injuries of TBI. Second, we outlined the current literature on animal models of TBI, and we described their goals, their advantages and disadvantages according to the species used, the type of injury induced, and their clinical relevance. Third, we defined the concept of neuroprotection and discussed its evolution. We also identified the reasons that might explain the failure of clinical translation. Then, we reviewed post‐TBI neuroprotective treatments with a focus on the following pleiotropic drugs, considered “low hanging fruit” with high probability of success: glitazones, glibenclamide, statins, erythropoietin, and progesterone, that were largely tested and demonstrated efficient in preclinical models of TBI. Finally, our review stresses the need to establish a close cooperation between basic researchers and clinicians to ensure the best clinical translation for neuroprotective strategies for TBI.

Decreased Superoxide Dismutase Concentrations (SOD) in Plasma and CSF and Increased Circulating Total Antioxidant Capacity (TAC) Are Associated with Unfavorable Neurological Outcome after Aneurysmal Subarachnoid Hemorrhage

Background: Subarachnoid hemorrhage (SAH) is a devastating disease with high morbidity and mortality. Hypoxia-induced changes and hemoglobin accumulation within the subarachnoid space are thought to lead to oxidative stress, early brain injury, and delayed vasospasm. This study aimed to evaluate the antioxidant status and its impact on neurological outcome in patients with aneurysmal SAH. Methods: In this prospective observational study, 29 patients with aneurysmal SAH were included (mean age 54.7 ± 12.4). Blood and cerebrospinal fluid (CSF) samples were collected on days (d) 1, 3, and 7. In addition, 29 patients without intracranial hemorrhage served as controls. The antioxidant system was analyzed by glutathione peroxidase (GSH-Px; U/L) and total and free glutathione-sulfhydryl (GSH; mg/L) in the plasma. Superoxide dismutase (SOD, U/mL) and total antioxidant capacity (TAC, µmol/L) were measured in the serum and CSF. Clinical data were compiled on admission (Hunt and Hess grade, Fisher grade, and GCS). Neurological and cognitive outcome (modified Rankin scale (mRS), Glasgow Outcome Scale Extended (GOSE) and Montreal Cognitive Assessment (MoCA)) was assessed after 6 weeks (6 w) and 6 months (6 m). Results: Plasma levels of SOD increased from day 1 to 7 after SAH (d1: 1.22 ± 0.36 U/L; d3: 1.25 ± 0.33 U/L, p = 0.99; d7: 1.52 ± 0.4 U/L, p = 0.019) and were significantly higher compared to controls (1.11 ± 0.27 U/L) at day 7 (p < 0.001). Concordantly, CSF levels of SOD increased from day 1 to 7 after SAH (d1: 1.22 ± 0.41 U/L; d3: 1.77 ± 0.73 U/L, p = 0.10; d7: 2.37 ± 1.29 U/L, p < 0.0001) without becoming significantly different compared to controls (1.74 ± 0.8 U/L, p = 0.09). Mean plasma TAC at day 1 (d1: 77.87 ± 49.72 µmol/L) was not statistically different compared to controls (46.74 ± 32.42 µmol/L, p = 0.25). TAC remained unchanged from day 1 to 7 (d3: 92.64 ± 68.58 µmol/L, p = 0.86; d7: 74.07 ± 54.95 µmol/L, p = 0.8) in plasma. TAC in CSF steeply declined from day 1 to 7 in patients with SAH becoming significantly different from controls at days 3 and 7 (d3: 177.3 ± 108.7 µmol/L, p = 0.0046; d7: 85.35 ± 103.9 µmol/L, p < 0.0001). Decreased SOD levels in plasma and CSF are associated with a worse neurological outcome 6 weeks (mRS: CSF p = 0.0001; plasma p = 0.027/GOSE: CSF p = 0.001; plasma p = 0.001) and 6 months (mRS: CSF p = 0.001; plasma p = 0.09/GOSE: CSF p = 0.001; plasma p = 0.001) after SAH. Increased plasma TAC correlated with a worse neurological outcome 6 weeks (mRS: p = 0.001/GOSE p = 0.001) and 6 months (mRS p = 0.001/GOSE p = 0.001) after SAH. Conclusion: In our study, a reduction in the antioxidative enzyme SOD and elevated TAC were associated with a poorer neurological outcome reflected by mRS and GOSE at 6 weeks and 6 months after SAH. A lower initial SOD CSF concentration was associated with the late deterioration of cognitive ability. These findings support the mounting evidence of the role of oxidative stress in early brain injury formation and unfavorable outcome after SAH.

Ketogenic regimens for acute neurotraumatic events

Dietary modification would be the most translatable, cost-efficient, and, likely, the safest approach available that can reduce the reliance on pharmaceutical treatments for treating acute or chronic neurological disorders. A wide variety of evidence suggests that the ketogenic diet (KD) could have beneficial effects in acute traumatic events, such as spinal cord injury and traumatic brain injury. Review of existing human and animal studies revealed that KD can improve motor neuro-recovery, gray matter sparing, pain thresholds, and neuroinflammation and decrease depression. Although the exact mechanism by which the KD provides neuroprotection is not fully understood, its effects on cellular energetics, mitochondria function and inflammation are likely to have a role.

Neuroprotective effect of nerolidol in traumatic brain injury associated behavioural comorbidities in rats

Traumatic brain injury (TBI) is an insult to the brain from an external mechanical force, leading to temporary/permanent secondary injuries, i.e. impairment of cognitive, physical, and psycho-social functions with altered consciousness. The leading mechanism responsible for neuronal damage following TBI is an increase in oxidative reactions initiated by free radicals generated by the injury along with various other mechanisms. Nerolidol is reported to have potent antioxidant and anti-neuroinflammatory properties. The present study was designed to explore the neuroprotective effect of nerolidol in weight-drop-induced TBI in rats. Animals were injured on the 1st day by dropping a free-falling weight of 200 gm from a height of 1 m through a guide pipe onto the exposed skull. After 14 days of injury, nerolidol (25, 50, and 100 mg/kg, i.p.) treatment was given for the next 14 days. Locomotor activity and motor coordination were evaluated using an actophotometer and rotarod, respectively. Cognitive impairment was observed through the Morris Water Maze and Object Recognition Test. On the 29th day, animals were sacrificed, and their brains were collected for the biochemical estimation. The weight drop model significantly decreased locomotor activity, motor coordination, increased Acetylcholinesterase (AChE) activity, oxidative stress, and induced cognitive deficits in TBI rats. Nerolidol significantly improved locomotor activity, reversed motor incoordination and cognitive impairment, and reduced the AChE activity and oxidative/nitrosative stress. The present study demonstrates the promising neuroprotective effects of nerolidol, which might improve the quality of life of TBI patients.

Strategies to expand the therapeutic potential of superoxide dismutase by exploiting delivery approaches

The overproduction of free radicals can cause oxidative-stress damage to a range of biomolecules, and thus potentially contribute to several pathologies, from neurodegenerative disorders to cardiovascular diseases and metabolic disorders. Endogenous antioxidant enzymes, such as superoxide dismutase (SOD), play an important role in diminishing oxidative stress. SOD supplementation could therefore be an effective preventive strategy to reduce the risk of free-radical overproduction. However, the efficacy of SOD administration is hampered by its rapid clearance. Several different approaches to improve the bioavailability of SOD have been explored in recent decades. This review intends to describe the rationale that underlie the various approaches and chemical strategies that have led to the most recent advances in SOD delivery. This critical description includes SOD conjugates, SOD loaded into particulate carriers (micelles, liposomes, nanoparticles, microparticles) and the most promising and suitable formulations for oral delivery, with a particular emphasis on reports of preclinical/clinical results. Likely future directions are also considered and reported.

The Role of Oxidative Stress in Early Brain Injury after Subarachnoid Hemorrhage

This review focuses on the problem of oxidative stress in early brain injury (EBI) after spontaneous subarachnoid hemorrhage (SAH). EBI involves complex pathophysiological mechanisms, including oxidative stress. In the first section, we describe the main sources of free radicals in EBI. There are several sources of excessive generation of free radicals from mitochondrial free radicals’ generation and endoplasmic reticulum stress, to hemoglobin and enzymatic free radicals’ generation. The second part focuses on the disruption of antioxidant mechanisms in EBI. The third section describes some newly found molecular mechanisms and pathway involved in oxidative stress after EBI. The last section is dedicated to the pathophysiological mechanisms through which free radicals mediate early brain injury.

Revisiting Traumatic Brain Injury: From Molecular Mechanisms to Therapeutic Interventions

Studying the complex molecular mechanisms involved in traumatic brain injury (TBI) is crucial for developing new therapies for TBI. Current treatments for TBI are primarily focused on patient stabilization and symptom mitigation. However, the field lacks defined therapies to prevent cell death, oxidative stress, and inflammatory cascades which lead to chronic pathology. Little can be done to treat the mechanical damage that occurs during the primary insult of a TBI; however, secondary injury mechanisms, such as inflammation, blood-brain barrier (BBB) breakdown, edema formation, excitotoxicity, oxidative stress, and cell death, can be targeted by therapeutic interventions. Elucidating the many mechanisms underlying secondary injury and studying targets of neuroprotective therapeutic agents is critical for developing new treatments. Therefore, we present a review on the molecular events following TBI from inflammation to programmed cell death and discuss current research and the latest therapeutic strategies to help understand TBI-mediated secondary injury.

The role of the brain renin-angiotensin system (RAS) in mild traumatic brain injury (TBI)

There is considerable interest in traumatic brain injury (TBI) induced by repeated concussions suffered by athletes in sports, military personnel from combat-and non-combat related activities, and civilian populations who suffer head injuries from accidents and domestic violence. Although the renin-angiotensin system (RAS) is primarily a systemic cardiovascular regulatory system that, when dysregulated, causes hypertension and cardiovascular pathology, the brain contains a local RAS that plays a critical role in the pathophysiology of several neurodegenerative diseases. This local RAS includes receptors for angiotensin (Ang) II within the brain parenchyma, as well as on circumventricular organs outside the blood-brain-barrier. The brain RAS acts primarily via the type 1 Ang II receptor (AT₁R), exacerbating insults and pathology. With TBI, the brain RAS may contribute to permanent brain damage, especially when a second TBI occurs before the brain recovers from an initial injury. Agents are needed that minimize the extent of injury from an acute TBI, reducing TBI-mediated permanent brain damage. This review discusses how activation of the brain RAS following TBI contributes to this damage, and how drugs that counteract activation of the AT₁R including AT₁R blockers (ARBs), renin inhibitors, angiotensin-converting enzyme (ACE) inhibitors, and agonists at type 2 Ang II receptors (AT₂) and at Ang (1-7) receptors (Mas) can potentially ameliorate TBI-induced brain damage.

Antioxidant status of uric acid, bilirubin, albumin and creatinine during the acute phase after traumatic brain injury: sex-specific features

BACKGROUND

It is known that the alteration of antioxidants can been seen in early phase after traumatic brain injury (TBI) in order to block oxidative damage, but little is known about the influence of sex on antioxidant system in patients with TBI. This study investigates whether there are sex differences in these endogenous antioxidant agents during the acute phase after TBI and their association with the disease.

METHODS

Serum levels of uric acid (UA), bilirubin, albumin and creatinine were measured in 421 individuals included 157 female TBI patients, 156 male TBI patients and 108 age- and sex-matched controls.

RESULTS

The statistically significant changes were found in UA, bilirubin, albumin and creatinine for both sexes with TBI, but the trend of changes in bilirubin and creatinine was opposite for gender groups. Serum levels of UA, bilirubin, albumin and creatinine were associated with the severity of TBI patients for both sexes. Male patient subgroups with elevated UA, albumin and creatinine had higher frequency of regaining consciousness in a month. Moreover, addition of UA and creatinine to the established clinical model had significantly improved the predictive performance over using clinical model alone in male patients with TBI. However, no similar findings were observed on female TBI patients.

CONCLUSION

Our results suggest sex-based differences in the serum endogenous antioxidant response to TBI. Use of serum UA and creatinine could help in the outcome prediction of male patients with TBI in combination with other prognostic factors.

The Potential for Natural Antioxidant Supplementation in the Early Stages of Neurodegenerative Disorders

The neurodegenerative process is characterized by the progressive ultrastructural alterations of selected classes of neurons accompanied by imbalanced cellular homeostasis, a process which culminates, in the later stages, in cell death and the loss of specific neurological functions. Apart from the neuronal cell impairment in selected areas of the central nervous system which characterizes many neurodegenerative diseases (e.g., Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, etc.), some alterations may be found in the early stages including gliosis and the misfolding or unfolding accumulation of proteins. On the other hand, several common pathophysiological mechanisms can be found early in the course of the disease including altered oxidative metabolism, the loss of cross-talk among the cellular organelles and increased neuroinflammation. Thus, antioxidant compounds have been suggested, in recent years, as a potential strategy for preventing or counteracting neuronal cell death and nutraceutical supplementation has been studied in approaching the early phases of neurodegenerative diseases. The present review will deal with the pathophysiological mechanisms underlying the early stages of the neurodegenerative process. In addition, the potential of nutraceutical supplementation in counteracting these diseases will be assessed.

An overview of spirooxindole as a promising scaffold for novel drug discovery

Introduction: Spirooxindole, a unique and versatile scaffold, has been widely studied in some fields such as pharmaceutical chemistry and synthetic chemistry. Especially in the application of medicine, quite a few compounds featuring spirooxindole motif have displayed excellent and broad pharmacological activities. Many identified candidate molecules have been used in clinical trials, showing promising prospects.Areas covered: This article offers an overview of different applications and developments of spirooxindoles (including the related natural products and their derivatives) in the process of drug innovation, including such as in anticancer, antimicrobial, anti-inflammatory, analgesic, antioxidant, antimalarial, and antiviral activities. Furthermore, the crucial structure-activity relationships, molecular mechanisms, pharmacokinetic properties, and main synthetic methods of spirooxindoles-based derivatives are also reviewed.Expert opinion: Recent progress in the biological activity profiles of spirooxindole derivatives have demonstrated their significant position in present-day drug discovery. Furthermore, we believe that the multidirectional development of novel drugs containing this core scaffold will continue to be the research hotspot in medicinal chemistry in the future.

Anti-Phospho-Tau Gene Therapy for Chronic Traumatic Encephalopathy

Chronic traumatic encephalopathy (CTE) is a progressive neurodegenerative disorder caused by repetitive trauma to the central nervous system (CNS) suffered by soldiers, contact sport athletes, and civilians following accident-related trauma. CTE is a CNS tauopathy, with trauma-induced inflammation leading to accumulation of hyperphosphorylated forms of the microtubule-binding protein Tau (pTau), resulting in neurofibrillary tangles and progressive loss of neurons. At present, there are no therapies to treat CTE. We hypothesized that direct CNS administration of an adeno-associated virus (AAV) vector coding for an anti-pTau antibody would generate sufficient levels of anti-pTau in the CNS to suppress pTau accumulation thus interrupting the pathogenic process. Using a serotype AAVrh.10 gene transfer vector coding for a monoclonal antibody directed against pTau, we demonstrate the feasibility of this strategy in a murine CTE model in which pTau accumulation was elicited by repeated traumatic brain injury (TBI) using a closed cortical impact procedure over 5 days. Direct delivery of AAVrh.10 expression vectors coding for either of the two different anti-pTau antibodies to the hippocampus of these TBI mice significantly reduced pTau levels across the CNS. Using doses that can be safely scaled to humans, the data demonstrate that CNS administration of AAVrh.10anti-pTau is effective, providing a new strategy to interrupt the CTE consequences of TBI.

The Importance of Natural Antioxidants in the Treatment of Spinal Cord Injury in Animal Models: An Overview

Patients with spinal cord injury (SCI) face devastating health, social, and financial consequences, as well as their families and caregivers. Reducing the levels of reactive oxygen species (ROS) and oxidative stress are essential strategies for SCI treatment. Some compounds from traditional medicine could be useful to decrease ROS generated after SCI. This review is aimed at highlighting the importance of some natural compounds with antioxidant capacity used in traditional medicine to treat traumatic SCI. An electronic search of published articles describing animal models of SCI treated with natural compounds from traditional medicine was conducted using the following terms: Spinal Cord Injuries (MeSH terms) AND Models, Animal (MeSH terms) AND [Reactive Oxygen Species (MeSH terms) AND/OR Oxidative Stress (MeSH term)] AND Medicine, Traditional (MeSH terms). Articles reported from 2010 to 2018 were included. The results were further screened by title and abstract for studies performed in rats, mice, and nonhuman primates. The effects of these natural compounds are discussed, including their antioxidant, anti-inflammatory, and antiapoptotic properties. Moreover, the antioxidant properties of natural compounds were emphasized since oxidative stress has a fundamental role in the generation and progression of several pathologies of the nervous system. The use of these compounds diminishes toxic effects due to their high antioxidant capacity. These compounds have been tested in animal models with promising results; however, no clinical studies have been conducted in humans. Further research of these natural compounds is crucial to a better understanding of their effects in patients with SCI.

Structural and signaling role of lipids in plasma membrane repair

The plasma membrane forms the physical barrier between the cytoplasm and extracellular space, allowing for biochemical reactions necessary for life to occur. Plasma membrane damage needs to be rapidly repaired to avoid cell death. This relies upon the coordinated action of the machinery that polarizes the repair response to the site of injury, resulting in resealing of the damaged membrane and subsequent remodeling to return the injured plasma membrane to its pre-injury state. As lipids comprise the bulk of the plasma membrane, the acts of injury, resealing, and remodeling all directly impinge upon the plasma membrane lipids. In addition to their structural role in shaping the physical properties of the plasma membrane, lipids also play an important signaling role in maintaining plasma membrane integrity. While much attention has been paid to the involvement of proteins in the membrane repair pathway, the role of lipids in facilitating plasma membrane repair remains poorly studied. Here we will discuss the current knowledge of how lipids facilitate plasma membrane repair by regulating membrane structure and signaling to coordinate the repair response, and will briefly note how lipid involvement extends beyond plasma membrane repair to the tissue repair response.

EXPRESS: Products of oxidative stress and TRPA1 expression in the brainstem of rats after lung ischemia-reperfusion injury

Lung ischemia–reperfusion injury is a common clinical concern. As the injury occurs, the pulmonary afferent nerves play a key role in regulating respiratory functions under pathophysiological conditions. The present study was to examine products of oxidative stress and expression of transient receptor potential A1 in the commissural nucleus of the solitary tract after lung ischemia–reperfusion injury; and further to determine molecular mediators linking to activation of oxidative stress and transient receptor potential ankyrin A1. A rat model of lung ischemia–reperfusion injury was used. Enzyme-linked immunosorbent assay and western blot analysis were employed to examine products of oxidative stress (i.e. 8-isoprostaglandin F2α and 8-hydroxy-2′-deoxyguanosine), and expression of transient receptor potential A1, Nrf2-antioxidant response element, and NADPH oxidase. 8-isoprostaglandin F2α and 8-hydroxy-2′-deoxyguanosine were amplified in the commissural nucleus of the solitary tract of lung ischemia–reperfusion injury rats, accompanied with downregulation of Nrf2-antioxidant response element, and upregulation of NOX4 and transient receptor potential A1. Blocking NADPH oxidase (subtype NOX4) decreased products of oxidative stress in the commissural nucleus of the solitary tract and attenuated upregulation of transient receptor potential A1 induced by lung ischemia–reperfusion injury. Our data revealed specific signaling pathways by which lung ischemia–reperfusion injury impairs Nrf2-antioxidant response and activates oxidative stress in the brainstem thereby leading to amplification of transient receptor potential A1 receptor likely via products of oxidative stress. Data suggest the abnormalities in the pulmonary afferent signals at the brainstem level which is likely to affect respiratory functions as lung ischemia–reperfusion injury occurs.

N-acetylcysteine Amide Ameliorates Blast-Induced Changes in Blood-Brain Barrier Integrity in Rats

Traumatic brain injury resulting from exposure to blast overpressure (BOP) is associated with neuropathology including impairment of the blood-brain barrier (BBB). This study examined the effects of repeated exposure to primary BOP and post-blast treatment with an antioxidant, N-acetylcysteine amide (NACA) on the integrity of BBB. Anesthetized rats were exposed to three 110 kPa BOPs separated by 0.5 h. BBB integrity was examined in vivo via a cranial window allowing imaging of pial microcirculation by intravital microscopy. Tetramethylrhodamine isothiocyanate Dextran (TRITC-Dextran, mw = 40 kDa or 150 kDa) was injected intravenously 2.5 h after the first BOP exposure and the leakage of TRITC-Dextran from pial microvessels into the brain parenchyma was assessed. The animals were randomized into 6 groups (n = 5/group): four groups received 40 kDa TRITC-Dextran (BOP-40, sham-40, BOP-40 NACA, and sham-40 NACA), and two groups received 150 kDa TRITC-Dextran (BOP-150 and sham-150). NACA treated groups were administered NACA 2 h after the first BOP exposure. The rate of TRITC-Dextran leakage was significantly higher in BOP-40 than in sham-40 group. NACA treatment significantly reduced TRITC-Dextran leakage in BOP-40 NACA group and sham-40 NACA group presented the least amount of leakage. The rate of leakage in BOP-150 and sham-150 groups was comparable to sham-40 NACA and thus these groups were not assessed for the effects of NACA. Collectively, these data suggest that BBB integrity is compromised following BOP exposure and that NACA treatment at a single dose may significantly protect against blast-induced BBB breakdown.

Incretin Mimetics as Rational Candidates for the Treatment of Traumatic Brain Injury

Traumatic brain injury (TBI) is becoming an increasing public health issue. With an annually estimated 1.7 million TBIs in the United States (U.S) and nearly 70 million worldwide, the injury, isolated or compounded with others, is a major cause of short- and long-term disability and mortality. This, along with no specific treatment, has made exploration of TBI therapies a priority of the health system. Age and sex differences create a spectrum of vulnerability to TBI, with highest prevalence among younger and older populations. Increased public interest in the long-term effects and prevention of TBI have recently reached peaks, with media attention bringing heightened awareness to sport and war related head injuries. Along with short-term issues, TBI can increase the likelihood for development of long-term neurodegenerative disorders. A growing body of literature supports the use of glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), and glucagon (Gcg) receptor (R) agonists, along with unimolecular combinations of these therapies, for their potent neurotrophic/neuroprotective activities across a variety of cellular and animal models of chronic neurodegenerative diseases (Alzheimer's and Parkinson's diseases) and acute cerebrovascular disorders (stroke). Mild or moderate TBI shares many of the hallmarks of these conditions; recent work provides evidence that use of these compounds is an effective strategy for its treatment. Safety and efficacy of many incretin-based therapies (GLP-1 and GIP) have been demonstrated in humans for the treatment of type 2 diabetes mellitus (T2DM), making these compounds ideal for rapid evaluation in clinical trials of mild and moderate TBI.

Ferroptosis and Brain Injury

Ferroptosis is a nonapoptotic form of cell death characterized by the iron-dependent accumulation of toxic lipid reactive oxygen species. Small-molecule screening and subsequent optimization have yielded potent and specific activators and inhibitors of this process. These compounds have been employed to dissect the lethal mechanism and implicate this process in pathological cell death events observed in many tissues, including the brain. Indeed, ferroptosis is emerging as an important mechanism of cell death during stroke, intracerebral hemorrhage, and other acute brain injuries, and may also play a role in certain degenerative brain disorders. Outstanding issues include the practical need to identify molecular markers of ferroptosis that can be used to detect and study this process in vivo, and the more basic problem of understanding the relationship between ferroptosis and other forms of cell death that can be triggered in the brain during injury.