Nicotinamide treatment induces behavioral recovery when administered up to 4 hours following cortical contusion injury in the rat

Impact of increasing one-carbon metabolites on traumatic brain injury outcome using pre-clinical models

Traumatic brain injury is a major cause of death and disability worldwide, affecting over 69 million individuals yearly. One-carbon metabolism has been shown to have beneficial effects after brain damage, such as ischemic stroke. However, whether increasing one-carbon metabolite vitamins impacts traumatic brain injury outcomes in patients requires more investigation. The aim of this review is to evaluate how one-carbon metabolites impact outcomes after the onset of traumatic brain injury. PubMed, Web of Science, and Google Scholar databases were searched for studies that examined the impact of B-vitamin supplementation on traumatic brain injury outcomes. The search terms included combinations of the following words: traumatic brain injury, dietary supplementation, one-carbon metabolism, and B-vitamins. The focus of each literature search was basic science data. The year of publication in the literature searches was not limited. Our analysis of the literature has shown that dietary supplementation of B-vitamins has significantly improved the functional and behavioral recovery of animals with traumatic brain injury compared to controls. However, this improvement is dosage-dependent and is contingent upon the onset of supplementation and whether there is a sustained or continuous delivery of vitamin supplementation post-traumatic brain injury. The details of supplementation post-traumatic brain injury need to be further investigated. Overall, we conclude that B-vitamin supplementation improves behavioral outcomes and reduces cognitive impairment post-traumatic brain injury in animal model systems. Further investigation in a clinical setting should be strongly considered in conjunction with current medical treatments for traumatic brain injury-affected individuals.

Nutritional Support Following Traumatic Brain Injury: A Comprehensive Review

Traumatic brain injury (TBI) can contribute to extensive dysbiosis of the gastrointestinal system, leading to worsened outcomes. The importance of nutrition in recovery is underappreciated but highly important. In this focused review, we discuss the timing of nutritional interventions with supporting data. We highlight routes of administration that are important given the extent of injury often seen in TBI. The increased energy demands can be met through these approaches. Furthermore, patients need increased vitamins, minerals, and supplements. These interventions are constantly being refined. The current standards are reviewed with an emphasis on evidence-based practices.

Brain Trauma and the Secondary Cascade in Humans: Review of the Potential Role of Vitamins in Reparative Processes and Functional Outcome

An estimated sixty-nine million people sustain a traumatic brain injury each year. Trauma to the brain causes the primary insult and initiates a secondary biochemical cascade as part of the immune and reparative response to injury. The secondary cascade, although a normal physiological response, may also contribute to ongoing neuroinflammation, oxidative stress and axonal injury, continuing in some cases years after the initial insult. In this review, we explain some of the biochemical mechanisms of the secondary cascade and their potential deleterious effects on healthy neurons including secondary cell death. The second part of the review focuses on the role of micronutrients to neural mechanisms and their potential reparative effects with regards to the secondary cascade after brain injury. The biochemical response to injury, hypermetabolism and excessive renal clearance of nutrients after injury increases the demand for most vitamins. Currently, most research in the area has shown positive outcomes of vitamin supplementation after brain injury, although predominantly in animal (murine) models. There is a pressing need for more research in this area with human participants because vitamin supplementation post-trauma is a potential cost-effective adjunct to other clinical and therapeutic treatments. Importantly, traumatic brain injury should be considered a lifelong process and better evaluated across the lifespan of individuals who experience brain injury.

Reactive oxygen species-responsive HET0016 prodrug-loaded liposomes attenuate neuroinflammation and improve neurological deficit in a rat model of juvenile traumatic brain injury

The arachidonic acid pathway metabolite 20-hydroxyeicosatetraenoic acid (20-HETE) contributes to ischemia/reperfusion brain injury. Inhibition of 20-HETE formation can protect the developing brain from global ischemia. In previous studies, we have found that treatment with the 20-HETE synthesis inhibitor N-hydroxy-N-4-butyl-2-methylphenylformamidine (HET0016) can protect the immature brain from traumatic brain injury (TBI), but its hydrophobic nature limits its full potential. We designed a reactive oxygen species-responsive HET0016 prodrug, which consists of a thioketal link between HET0016 and stearyl alcohol (HET-TK-SA), and used the nanoprodrug strategy to successfully synthesize liposomes HET0016 prodrug liposomes (HPLs) to facilitate the application of HET0016 in protection from TBI. HPLs demonstrated spherical shape, size of about 127.8 nm, a zeta potential of -28.8 mv, a narrow particle size distribution and good stability. Male rats at postnatal day 16-17 underwent controlled cortical impact (CCI) followed by intravenous injection with vehicle or HET0016 (1 mg/kg, 2 h post-injury, once/day for 3 days). The results of the in vivo demonstrated that HPLs has good biosafety and can pass through the blood-brain barrier. Not only that compared with HET0016, HPLs better-inhibited inflammation and improved neuronal degeneration, which further led to lesion volume reduction, upgraded behavioral task performance, and ameliorated the degree of TBI impairment. Our results demonstrated HPLs could be a new strategy for juvenile TBI therapy.

The impact of riboflavin on the duration of sport-related concussion: A randomized placebo-controlled trial

Objectives

The objective of this study was to investigate the time to recovery after an SRC comparing riboflavin 400mg daily to placebo in a group of elite level athletes from multiple sports.

Methods

The study was a double-blind randomized placebo-controlled trial with intention to treat conducted from 2016–2020 at two different academic institutions. The study enrolled varsity student-athletes (SA) at each institution. The investigators and participants were blinded to treatment allocation. The treatment group received 14 capsules of either riboflavin 400mg or placebo to take daily until completed. The team physician made the diagnosis of an SRC within 24 h of the injury.

Results

A total of sixty participants enrolled in the study. Fifty-two participants completed the study. Subjects in the riboflavin group had a statistically significant lower number of average days to recovery of 9.92 days (CI ± 2.8) compared to placebo of 22.2 days (CI ± 11.5) (P < 0.05). Subjects matched for age, gender, history of SRCs, attention deficit hyperactivity disorder and Periodic Health Questionnaire-9 scores.

Conclusions

This is one of the first studies that documents an effective treatment option for an SRC at the time of injury. Riboflavin is safe, inexpensive, and readily available making it an ideal treatment.

Neuro-Inflammation Modulation and Post-Traumatic Brain Injury Lesions: From Bench to Bed-Side

Head trauma is the most common cause of disability in young adults. Known as a silent epidemic, it can cause a mosaic of symptoms, whether neurological (sensory-motor deficits), psychiatric (depressive and anxiety symptoms), or somatic (vertigo, tinnitus, phosphenes). Furthermore, cranial trauma (CT) in children presents several particularities in terms of epidemiology, mechanism, and physiopathology-notably linked to the attack of an immature organ. As in adults, head trauma in children can have lifelong repercussions and can cause social and family isolation, difficulties at school, and, later, socio-professional adversity. Improving management of the pre-hospital and rehabilitation course of these patients reduces secondary morbidity and mortality, but often not without long-term disability. One hypothesized contributor to this process is chronic neuroinflammation, which could accompany primary lesions and facilitate their development into tertiary lesions. Neuroinflammation is a complex process involving different actors such as glial cells (astrocytes, microglia, oligodendrocytes), the permeability of the blood-brain barrier, excitotoxicity, production of oxygen derivatives, cytokine release, tissue damage, and neuronal death. Several studies have investigated the effect of various treatments on the neuroinflammatory response in traumatic brain injury in vitro and in animal and human models. The aim of this review is to examine the various anti-inflammatory therapies that have been implemented.

Nicotinamide reverses deficits in puberty-born neurons and cognitive function after maternal separation

Background

Early life stress (ELS) is associated with the development of schizophrenia later in life. The hippocampus develops significantly during childhood and is extremely reactive to stress. In rodent models, ELS can induce neuroinflammation, hippocampal neuronal loss, and schizophrenia-like behavior. While nicotinamide (NAM) can inhibit microglial inflammation, it is unknown whether NAM treatment during adolescence reduces hippocampal neuronal loss and abnormal behaviors induced by ELS.

Methods

Twenty-four hours of maternal separation (MS) of Wistar rat pups on post-natal day (PND)9 was used as an ELS. On PND35, animals received a single intraperitoneal injection of BrdU to label dividing neurons and were given NAM from PND35 to PND65. Behavioral testing was performed. Western blotting and immunofluorescence staining were used to detect nicotinamide adenine dinucleotide (NAD⁺)/Sirtuin3 (Sirt3)/superoxide dismutase 2 (SOD2) pathway-related proteins.

Results

Compared with controls, only MS animals in the adult stage (PND56–65) but not the adolescent stage (PND31–40) exhibited pre-pulse inhibition deficits and cognitive impairments mimicking schizophrenia symptoms. MS decreased the survival and activity of puberty-born neurons and hippocampal NAD⁺ and Sirt3 expression in adulthood. These observations were related to an increase in acetylated SOD2, microglial activation, and significant increases in pro-inflammatory IL-1β, TNF-α, and IL-6 expression. All the effects of MS at PND9 were reversed by administering NAM in adolescence (PND35–65).

Conclusions

MS may lead to schizophrenia-like phenotypes and persistent hippocampal abnormalities. NAM may be a safe and effective treatment in adolescence to restore normal hippocampal function and prevent or ameliorate schizophrenia-like behavior.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02591-y.

Supplementation with NAD+ and Its Precursors to Prevent Cognitive Decline across Disease Contexts

The preservation of cognitive ability by increasing nicotinamide adenine dinucleotide (NAD⁺) levels through supplementation with NAD⁺ precursors has been identified as a promising treatment strategy for a number of conditions; principally, age-related cognitive decline (including Alzheimer’s disease and vascular dementia), but also diabetes, stroke, and traumatic brain injury. Candidate factors have included NAD⁺ itself, its reduced form NADH, nicotinamide (NAM), nicotinamide mononucleotide (NMN), nicotinamide riboside (NR), and niacin (or nicotinic acid). This review summarises the research findings for each source of cognitive impairment for which NAD⁺ precursor supplementation has been investigated as a therapy. The findings are mostly positive but have been made primarily in animal models, with some reports of null or adverse effects. Given the increasing popularity and availability of these factors as nutritional supplements, further properly controlled clinical research is needed to provide definitive answers regarding this strategy’s likely impact on human cognitive health when used to address different sources of impairment.

Antioxidant therapies in traumatic brain injury

Oxidative stress plays a crucial role in traumatic brain injury (TBI) pathogenesis. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) formed in excess after TBI synergistically contribute to secondary brain damage together with lipid peroxidation products (reactive aldehydes) and inflammatory mediators. Furthermore, oxidative stress, endoplasmic reticulum stress and inflammation potentiate each other. Following TBI, excessive oxidative stress overloads the endogenous cellular antioxidant system leading to cell death. To combat oxidative stress, several antioxidant therapies were tested in preclinical animal models of TBI. These include free radical scavengers, activators of antioxidant systems, Inhibitors of free radical generating enzymes and antioxidant enzymes. Many of these therapies showed promising outcomes including reduced edema, blood-brain barrier (BBB) protection, smaller contusion volume, and less inflammation. In addition, many antioxidant therapies also promoted better sensory, motor, and cognitive functional recovery after TBI. Overall, preventing oxidative stress is a viable therapeutic option to minimize the secondary damage and to improve the quality of life after TBI.

Traumatic Brain Injury: An Age-Dependent View of Post-Traumatic Neuroinflammation and Its Treatment

Traumatic brain injury (TBI) is a leading cause of death and disability all over the world. TBI leads to (1) an inflammatory response, (2) white matter injuries and (3) neurodegenerative pathologies in the long term. In humans, TBI occurs most often in children and adolescents or in the elderly, and it is well known that immune responses and the neuroregenerative capacities of the brain, among other factors, vary over a lifetime. Thus, age-at-injury can influence the consequences of TBI. Furthermore, age-at-injury also influences the pharmacological effects of drugs. However, the post-TBI inflammatory, neuronal and functional consequences have been mostly studied in experimental young adult animal models. The specificity and the mechanisms underlying the consequences of TBI and pharmacological responses are poorly understood in extreme ages. In this review, we detail the variations of these age-dependent inflammatory responses and consequences after TBI, from an experimental point of view. We investigate the evolution of microglial, astrocyte and other immune cells responses, and the consequences in terms of neuronal death and functional deficits in neonates, juvenile, adolescent and aged male animals, following a single TBI. We also describe the pharmacological responses to anti-inflammatory or neuroprotective agents, highlighting the need for an age-specific approach to the development of therapies of TBI.

Nrf2/HO-1 mediates the neuroprotective effects of pramipexole by attenuating oxidative damage and mitochondrial perturbation after traumatic brain injury in rats

Pramipexole (PPX), a D2-like receptor agonist, is generally used in the treatment of Parkinson's disease and restless leg syndrome. Its neuroprotective effects have been shown against various neurological disorders. Recent research work has demonstrated that PPX exerts neuroprotection through mitochondria. However, the neuromodulator-related effects of PPX against traumatic brain injury (TBI) remain unexplored. The present study, therefore, investigated the mechanism of neuroprotection by PPX against oxidative stress, mitochondrial dysfunction and neuronal damage following TBI in rats. We hypothesized that the neuroprotection by PPX in TBI-subjected rats might involve activation of the Nrf2/HO-1 (also known as Nfe2l2/Hmox1) signaling pathway. PPX was injected intraperitoneally (0.25 mg/kg body weight and 1.0 mg/kg body weight) at different time intervals post-TBI. Several neurobehavioral parameters were assessed at 48 h post-TBI, and the brain was isolated for molecular and biochemical analysis. The results demonstrated that PPX treatment significantly improved the behavioral deficits, decreased the lipid peroxidation rate, increased glutathione levels and decreased 4-hydroxynonenal levels in TBI-subjected rats. PPX also increased the activities of glutathione peroxidase and superoxide dismutase enzymes. In addition, PPX treatment inhibited mitochondrial reactive oxygen species production, restored mitochondrial membrane potential and increased ATP levels after a TBI. Further, PPX treatment reduced the Bax/Bcl2 ratio and translocation of Bax to mitochondria and cytochrome-c to the cytosol. Finally, PPX treatment greatly accelerated the translocation of Nrf2 to the nucleus and upregulated HO-1 protein expression. We conclude that the neuroprotective effects of PPX are mediated by activation of the Nrf2/HO-1 signaling pathway following TBI.This article has an associated First Person interview with the first author of the paper.

Comprehensive Profile of Acute Mitochondrial Dysfunction in a Preclinical Model of Severe Penetrating TBI

Mitochondria constitute a central role in brain energy metabolism, and play a pivotal role in the development of secondary pathophysiology and subsequent neuronal cell death following traumatic brain injury (TBI). Under normal circumstances, the brain consumes glucose as the preferred energy source for adenosine triphosphate (ATP) production over ketones. To understand the comprehensive picture of substrate-specific mitochondrial bioenergetics responses following TBI, adult male rats were subjected to either 10% unilateral penetrating ballistic-like brain injury (PBBI) or sham craniectomy (n = 5 animals per group). At 24 h post-injury, mitochondria were isolated from pooled brain regions (frontal cortex and striatum) of the ipsilateral hemisphere. Mitochondrial bioenergetics parameters were measured ex vivo in the presence of four sets of metabolic substrates: pyruvate+malate (PM), glutamate+malate (GM), succinate (Succ), and β-hydroxybutyrate+malate (BHBM). Additionally, mitochondrial matrix dehydrogenase activities [i.e., pyruvate dehydrogenase complex (PDHC), alpha-ketoglutarate dehydrogenase complex (α-KGDHC), and glutamate dehydrogenase (GDH)] and mitochondrial membrane-bound dehydrogenase activities [i.e., electron transport chain (ETC) Complex I, II, and IV] were compared between PBBI and sham groups. Furthermore, mitochondrial coenzyme contents, including NAD_(t) and FAD_(t), were quantitatively measured in both groups. Collectively, PBBI led to an overall significant decline in the ATP synthesis rates (43-50%; ^* p < 0.05 vs. sham) when measured using each of the four sets of substrates. The PDHC and GDH activities were significantly reduced in the PBBI group (42-53%; ^* p < 0.05 vs. sham), whereas no significant differences were noted in α-KGDHC activity between groups. Both Complex I and Complex IV activities were significantly reduced following PBBI (47-81%; ^* p < 0.05 vs. sham), whereas, Complex II activity was comparable between groups. The NAD_(t) and FAD_(t) contents were significantly decreased in the PBBI group (27-35%; ^* p < 0.05 vs. sham). The decreased ATP synthesis rates may be due to the significant reductions in brain mitochondrial dehydrogenase activities and coenzyme contents observed acutely following PBBI. These results provide a basis for the use of "alternative biofuels" for achieving higher ATP production following severe penetrating brain trauma.

Effects of nicotinamide on spatial memory and inflammation after juvenile traumatic brain injury

Age is a consistent predictor of outcome following traumatic brain injury (TBI). Although children and adolescents have the highest rate of hospitalizations and long-term disabilities, few preclinical studies have attempted to model and treat TBI in this population. Studies using nicotinamide (NAM), a soluble B-group vitamin, in older animals (3-6 months) have shown improved functional recovery in experimental models of TBI. The purpose of this study was two-fold: to examine the preclinical efficacy of NAM at different doses on behavioral outcomes in juvenile rats and examine the microglial response over time. Groups of juvenile rats (PND 28-60) were assigned to sham, NAM (125 mg/kg, 500 mg/kg, or 1000 mg/kg) or saline (1 mL/kg) and received unilateral cortical contusion injuries (CCI) and received injections at 15 min, 24 h, and 72 h after injury. Animals treated with NAM demonstrated no significant behavioral improvements over saline treatments. NAM treatments did however show slowed cortical loss and reduced microglia compared to saline treated animals. In summary, the preclinical efficacy of NAM as a treatment following CCI in juvenile animals differs from that previously documented in older rat models. While NAM treatments did reduce microglial activity and slowed progression of cortical loss, it did not reduce the total cortical volume lost nor did it improve behavioral outcomes. The findings of this study emphasize the need to examine potential treatments for TBI utilizing juvenile populations and may explain why so many treatments have failed in clinical trials.

The Importance of Therapeutic Time Window in the Treatment of Traumatic Brain Injury

Traumatic brain injury (TBI) is a major cause of death and disability. Despite its importance in public health, there are presently no drugs to treat TBI. Many reasons underlie why drugs have failed clinical trials, one reason is that most drugs to treat TBI lose much of their efficacy before patients are first treated. This review discusses the importance of therapeutic time window; the time interval between TBI onset and the initiation of treatment. Therapeutic time window is complex, as brain injury is both acute and chronic, resulting in multiple drug targets that appear and disappear with differing kinetics. The speed and increasing complexity of TBI pathophysiology is a major reason why drugs lose efficacy as time to first dose increases. Recent Phase III clinical trials treated moderate to severe TBI patients within 4–8 h after injury, yet they turned away many potential patients who could not be treated within these time windows. Additionally, most head trauma is mild TBI. Unlike moderate to severe TBI, patients with mild TBI often delay treatment until their symptoms do not abate. Thus, drugs to treat moderate to severe TBI likely will need to retain high efficacy for up to 12 h after injury; drugs for mild TBI, however, will likely need even longer windows. Early pathological events following TBI progress with similar kinetics in humans and animal TBI models suggesting that preclinical testing of time windows assists the design of clinical trials. We reviewed preclinical studies of drugs first dosed later than 4 h after injury. This review showed that therapeutic time window can differ depending upon the animal TBI model and the outcome measure. We identify the few drugs (methamphetamine, melanocortin, minocycline plus N-acetylcysteine, and cycloserine) that demonstrated good therapeutic windows with multiple outcome measures. On the basis of their therapeutic window, these drugs appear to be excellent candidates for clinical trials. In addition to further testing of these drugs, we recommend that the assessment of therapeutic time window with multiple outcome measures becomes a standard component of preclinical drug testing.

Adaptive responses of neuronal mitochondria to bioenergetic challenges: Roles in neuroplasticity and disease resistance

An important concept in neurobiology is "neurons that fire together, wire together" which means that the formation and maintenance of synapses is promoted by activation of those synapses. Very similar to the effects of the stress of exercise on muscle cells, emerging findings suggest that neurons respond to activity by activating signaling pathways (e.g., Ca²⁺, CREB, PGC-1α, NF-κB) that stimulate mitochondrial biogenesis and cellular stress resistance. These pathways are also activated by aerobic exercise and food deprivation, two bioenergetic challenges of fundamental importance in the evolution of the brains of all mammals, including humans. The metabolic 'switch' in fuel source from liver glycogen store-derived glucose to adipose cell-derived fatty acids and their ketone metabolites during fasting and sustained exercise, appears to be a pivotal trigger of both brain-intrinsic and peripheral organ-derived signals that enhance learning and memory and underlying synaptic plasticity and neurogenesis. Brain-intrinsic extracellular signals include the excitatory neurotransmitter glutamate and the neurotrophic factor BDNF, and peripheral signals may include the liver-derived ketone 3-hydroxybutyrate and the muscle cell-derived protein irisin. Emerging findings suggest that fasting, exercise and an intellectually challenging lifestyle can protect neurons against the dysfunction and degeneration that they would otherwise suffer in acute brain injuries (stroke and head trauma) and neurodegenerative disorders including Alzheimer's, Parkinson's and Huntington's disease. Among the prominent intracellular responses of neurons to these bioenergetic challenges are up-regulation of antioxidant defenses, autophagy/mitophagy and DNA repair. A better understanding of such fundamental hormesis-based adaptive neuronal response mechanisms is expected to result in the development and implementation of novel interventions to promote optimal brain function and healthy brain aging.

Nicotinamide Treatment in Traumatic Brain Injury: Operation Brain Trauma Therapy

Nicotinamide (vitamin B3) was the first drug selected for cross-model testing by the Operation Brain Trauma Therapy (OBTT) consortium based on a compelling record of positive results in pre-clinical models of traumatic brain injury (TBI). Adult male Sprague-Dawley rats were exposed to either moderate fluid percussion injury (FPI), controlled cortical impact injury (CCI), or penetrating ballistic-like brain injury (PBBI). Nicotinamide (50 or 500 mg/kg) was delivered intravenously at 15 min and 24 h after injury with subsequent behavioral, biomarker, and histopathological outcome assessments. There was an intermediate effect on balance beam performance with the high (500 mg/kg) dose in the CCI model, but no significant therapeutic benefit was detected on any other motor task across the OBTT TBI models. There was an intermediate benefit on working memory with the high dose in the FPI model. A negative effect of the low (50 mg/kg) dose, however, was observed on cognitive outcome in the CCI model, and no cognitive improvement was observed in the PBBI model. Lesion volume analysis showed no treatment effects after either FPI or PBBI, but the high dose of nicotinamide resulted in significant tissue sparing in the CCI model. Biomarker assessments included measurements of glial fibrillary acidic protein (GFAP) and ubiquitin carboxyl-terminal hydrolase-1 (UCH-L1) in blood at 4 or 24 h after injury. Negative effects (both doses) were detected on biomarker levels of GFAP after FPI and on biomarker levels of UCH-L1 after PBBI. The high dose of nicotinamide, however, reduced GFAP levels after both PBBI and CCI. Overall, our results showed a surprising lack of benefit from the low dose nicotinamide. In contrast, and partly in keeping with the literature, some benefit was achieved with the high dose. The marginal benefits achieved with nicotinamide, however, which appeared sporadically across the TBI models, has reduced enthusiasm for further investigation by the OBTT Consortium.

Acute Axonal Degeneration Drives Development of Cognitive, Motor, and Visual Deficits after Blast-Mediated Traumatic Brain Injury in Mice

Axonal degeneration is a prominent feature of many forms of neurodegeneration, and also an early event in blast-mediated traumatic brain injury (TBI), the signature injury of soldiers in Iraq and Afghanistan. It is not known, however, whether this axonal degeneration is what drives development of subsequent neurologic deficits after the injury. The Wallerian degeneration slow strain (WldS) of mice is resistant to some forms of axonal degeneration because of a triplicated fusion gene encoding the first 70 amino acids of Ufd2a, a ubiquitin-chain assembly factor, that is linked to the complete coding sequence of nicotinamide mononucleotide adenylyltransferase 1 (NMAT1). Here, we demonstrate that resistance of WldS mice to axonal degeneration after blast-mediated TBI is associated with preserved function in hippocampal-dependent spatial memory, cerebellar-dependent motor balance, and retinal and optic nerve–dependent visual function. Thus, early axonal degeneration is likely a critical driver of subsequent neurobehavioral complications of blast-mediated TBI. Future therapeutic strategies targeted specifically at mitigating axonal degeneration may provide a uniquely beneficial approach to treating patients suffering from the effects of blast-mediated TBI.

Vitamins and nutrients as primary treatments in experimental brain injury: Clinical implications for nutraceutical therapies

With the numerous failures of pharmaceuticals to treat traumatic brain injury in humans, more researchers have become interested in combination therapies. This is largely due to the multimodal nature of damage from injury, which causes excitotoxicity, oxidative stress, edema, neuroinflammation and cell death. Polydrug treatments have the potential to target multiple aspects of the secondary injury cascade, while many previous therapies focused on one particular aspect. Of specific note are vitamins, minerals and nutrients that can be utilized to supplement other therapies. Many of these have low toxicity, are already FDA approved and have minimal interactions with other drugs, making them attractive targets for therapeutics. Over the past 20 years, interest in supplementation and supraphysiologic dosing of nutrients for brain injury has increased and indeed many vitamins and nutrients now have a considerable body of the literature backing their use. Here, we review several of the prominent therapies in the category of nutraceutical treatment for brain injury in experimental models, including vitamins (B2, B3, B6, B9, C, D, E), herbs and traditional medicines (ginseng, Gingko biloba), flavonoids, and other nutrients (magnesium, zinc, carnitine, omega-3 fatty acids). While there is still much work to be done, several of these have strong potential for clinical therapies, particularly with regard to polydrug regimens. This article is part of a Special Issue entitled SI:Brain injury and recovery.

Combination therapies for neurobehavioral and cognitive recovery after experimental traumatic brain injury: Is more better?

Traumatic brain injury (TBI) is a significant health care crisis that affects two million individuals in the United Sates alone and over ten million worldwide each year. While numerous monotherapies have been evaluated and shown to be beneficial at the bench, similar results have not translated to the clinic. One reason for the lack of successful translation may be due to the fact that TBI is a heterogeneous disease that affects multiple mechanisms, thus requiring a therapeutic approach that can act on complementary, rather than single, targets. Hence, the use of combination therapies (i.e., polytherapy) has emerged as a viable approach. Stringent criteria, such as verification of each individual treatment plus the combination, a focus on behavioral outcome, and post-injury vs. pre-injury treatments, were employed to determine which studies were appropriate for review. The selection process resulted in 37 papers that fit the specifications. The review, which is the first to comprehensively assess the effects of combination therapies on behavioral outcomes after TBI, encompasses five broad categories (inflammation, oxidative stress, neurotransmitter dysregulation, neurotrophins, and stem cells, with and without rehabilitative therapies). Overall, the findings suggest that combination therapies can be more beneficial than monotherapies as indicated by 46% of the studies exhibiting an additive or synergistic positive effect versus on 19% reporting a negative interaction. These encouraging findings serve as an impetus for continued combination studies after TBI and ultimately for the development of successful clinically relevant therapies.

A behavioral and histological comparison of fluid percussion injury and controlled cortical impact injury to the rat sensorimotor cortex

Our primary goal was to evaluate the behavioral and histological outcome of fluid percussion injury (FPI) and cortical contusion injury (CCI) to the sensorimotor cortex (SMC). The SMC has been used to evaluate neuroplasticity following CCI, but has not been extensively examined with FPI. In both the CCI and FPI models, a mechanical force of 4mm in diameter was applied over the SMC, allowing for a direct comparison to measure the relative rates of histology and recovery of function in these models. Gross behavioral deficits were found on the sensory task (tactile adhesive removal task) and multiple motor assessments (forelimb asymmetry task, forelimb placing task, and rotorod). These sensorimotor deficits occurred in the absence of cognitive deficits in the water maze. The CCI model creates focal damage with a localized injury wheras the FPI model creates a more diffuse injury causing widespread damage. Both behavioral and histological deficits ensued following both models of injury to the SMC. The neuroplastic changes and ease at which damage to this area can be measured behaviorally make this an excellent location to assess traumatic brain injury (TBI) treatments. No injury model can completely mimic the full spectrum of human TBI and any potential treatments should be validated across both focal and diffuse injury models. Both of these injury models to the SMC produce severe and enduring behavioral deficits, which are ideal for evaluating treatment options.

A Combination Therapy of Nicotinamide and Progesterone Improves Functional Recovery following Traumatic Brain Injury

Neuroprotection, recovery of function, and gene expression were evaluated in an animal model of traumatic brain injury (TBI) after a combination treatment of nicotinamide (NAM) and progesterone (Prog). Animals received a cortical contusion injury over the sensorimotor cortex, and were treated with either Vehicle, NAM, Prog, or a NAM/Prog combination for 72 h and compared with a craniotomy only (Sham) group. Animals were assessed in a battery of behavioral, sensory, and both fine and gross motor tasks, and given histological assessments at 24 h post-injury to determine lesion cavity size, degenerating neurons, and reactive astrocytes. Microarray-based transcriptional profiling was used to determine treatment-specific changes on gene expression. Our results confirm the beneficial effects of treatment with either NAM or Prog, demonstrating significant improvements in recovery of function and a reduction in lesion cavitation, degenerating neurons, and reactive astrocytes 24 h post-injury. The combination treatment of NAM and Prog led to a significant improvement in both neuroprotection at 24 h post-injury and recovery of function in sensorimotor related tasks when compared with individual treatments. The NAM/Prog-treated group was the only treatment group to show a significant reduction of cortical loss 24 h post-injury. The combination appears to affect inflammatory and immune processes, reducing expression of a significant number of genes in both pathways. Further preclinical trials using NAM and Prog as a combination treatment should be conducted to identify the window of opportunity, determine the optimal duration of treatment, and evaluate the combination in other pre-clinical models of TBI.

Deficits in discrimination after experimental frontal brain injury are mediated by motivation and can be improved by nicotinamide administration

One of the largest challenges in experimental neurotrauma work is the development of models relevant to the human condition. This includes both creating similar pathophysiology as well as the generation of relevant behavioral deficits. Recent studies have shown that there is a large potential for the use of discrimination tasks in rats to detect injury-induced deficits. The literature on discrimination and TBI is still limited, however. The current study investigated motivational and motor factors that could potentially contribute to deficits in discrimination. In addition, the efficacy of a neuroprotective agent, nicotinamide, was assessed. Rats were trained on a discrimination task and motivation task, given a bilateral frontal controlled cortical impact TBI (+3.0 AP, 0.0 ML from bregma), and then reassessed. They were also assessed on motor ability and Morris water maze (MWM) performance. Experiment 1 showed that TBI resulted in large deficits in discrimination and motivation. No deficits were observed on gross motor measures; however, the vehicle group showed impairments in fine motor control. Both injured groups were impaired on the reference memory MWM, but only nicotinamide-treated rats were impaired on the working memory MWM. Nicotinamide administration improved performance on discrimination and motivation measures. Experiment 2 evaluated retraining on the discrimination task and suggested that motivation may be a large factor underlying discrimination deficits. Retrained rats improved considerably on the discrimination task. The tasks evaluated in this study demonstrate robust deficits and may improve the detection of pharmaceutical effects by being very sensitive to pervasive cognitive deficits that occur after frontal TBI.

Spinal SIRT1 activation attenuates neuropathic pain in mice

Abnormal histone acetylation occurs during neuropathic pain through an epigenetic mechanism. Silent information regulator 1 (sir2 or SIRT1), a NAD-dependent deacetylase, plays complex systemic roles in a variety of processes through deacetylating acetylated histone and other specific substrates. But the role of SIRT1 in neuropathic pain is not well established yet. The present study was intended to detect SIRT1 content and activity, nicotinamide (NAM) and nicotinamide adenine dinucleotide (NAD) in the spinal cord using immunoblotting or mass spectroscopy over time in mice following chronic constriction injury (CCI) or sham surgery. In addition, the effect of intrathecal injection of NAD or resveratrol on thermal hyperalgesia and mechanical allodynia was evaluated in CCI mice. Finally, we investigated whether SIRT1 inhibitor EX-527 could reverse the anti-nociceptive effect of NAD or resveratrol. It was found that spinal SIRT1 expression, deacetylase activity and NAD/NAM decreased significantly 1, 3, 7, 14 and 21 days after CCI surgery as compared with sham group. In addition, daily intrathecal injection of 5 µl 800 mM NAD 1 h before and 1 day after CCI surgery or single intrathecal injection of 5 µl 90 mM resveratrol 1 h before CCI surgery produced a transient inhibitory effect on thermal hyperalgesia and mechanical allodynia in CCI mice. Finally, an intrathecal injection of 5 µl 1.2 mM EX-527 1 h before NAD or resveratrol administration reversed the anti-nociceptive effect of NAD or resveratrol. These data indicate that the reduction in SIRT1 deacetylase activity may be a factor contributing to the development of neuropathic pain in CCI mice. Our findings suggest that the enhancement of spinal NAD/NAM and/or SIRT1 activity may be a potentially promising strategy for the prevention or treatment of neuropathic pain.

Using the olfactory system as an in vivo model to study traumatic brain injury and repair

Loss of olfactory function is an early indicator of traumatic brain injury (TBI). The regenerative capacity and well-defined neural maps of the mammalian olfactory system enable investigations into the degeneration and recovery of neural circuits after injury. Here, we introduce a unique olfactory-based model of TBI that reproduces many hallmarks associated with human brain trauma. We performed a unilateral penetrating impact to the mouse olfactory bulb and observed a significant loss of olfactory sensory neurons (OSNs) in the olfactory epithelium (OE) ipsilateral to the injury, but not contralateral. By comparison, we detected the injury markers p75(NTR), β-APP, and activated caspase-3 in both the ipsi- and contralateral OE. In the olfactory bulb (OB), we observed a graded cell loss, with ipsilateral showing a greater reduction than contralateral and both significantly less than sham. Similar to OE, injury markers in the OB were primarily detected on the ipsilateral side, but also observed contralaterally. Behavioral experiments measured 4 days after impact also demonstrated loss of olfactory function, yet following a 30-day recovery period, we observed a significant improvement in olfactory function and partial recovery of olfactory circuitry, despite the persistence of TBI markers. Interestingly, by using the M71-IRES-tauLacZ reporter line to track OSN organization, we further determined that inducing neural activity during the recovery period with intense odor conditioning did not enhance the recovery process. Together, these data establish the mouse olfactory system as a new model to study TBI, serving as a platform to understand neural disruption and the potential for circuit restoration.

Comparison of the effects of erythropoietin and anakinra on functional recovery and gene expression in a traumatic brain injury model

The goal of this study was to compare the effects of two inflammatory modulators, erythropoietin (EPO) and anakinra, on functional recovery and brain gene expression following a cortical contusion impact (CCI) injury. Dosage regimens were designed to provide serum concentrations in the range obtained with clinically approved doses. Functional recovery was assessed using both motor and spatial learning tasks and neuropathological measurements conducted in the cortex and hippocampus. Microarray-based transcriptional profiling was used to determine the effect on gene expression at 24 h, 72 h, and 7 days post-CCI. Ingenuity Pathway Analysis was used to evaluate the effect on relevant functional categories. EPO and anakinra treatment resulted in significant changes in brain gene expression in the CCI model demonstrating acceptable brain penetration. At all three time points, EPO treatment resulted in significantly more differentially expressed genes than anakinra. For anakinra at 24 h and EPO at 24 h, 72 h, and 7 days, the genes in the top 3 functional categories were involved in cellular movement, inflammatory response and cell-to-cell signaling. For EPO, the majority of the genes in the top 10 canonical pathways identified were associated with inflammatory and immune signaling processes. This was true for anakinra only at 24 h post-traumatic brain injury (TBI). The immunomodulation effects of EPO and anakinra did not translate into positive effects on functional behavioral and lesion studies. Treatment with either EPO or anakinra failed to induce significant beneficial effects on recovery of function or produce any significant effects on the prevention of injury induced tissue loss at 30 days post-injury. In conclusion, treatment with EPO or anakinra resulted in significant effects on gene expression in the brain without affecting functional outcome. This suggests that targeting these inflammatory processes alone may not be sufficient for preventing secondary injuries after TBI.

The effect of nicotinamide on gene expression in a traumatic brain injury model

Microarray-based transcriptional profiling was used to determine the effect of nicotinamide on gene expression in an experimental traumatic brain injury (TBI) model. Ingenuity Pathway Analysis (IPA) was used to evaluate the effect on relevant functional categories and canonical pathways. At 24 h, 72 h, and 7 days, respectively, 70, 58, and 76%, of the differentially expressed genes were up-regulated in the vehicle treated compared to the sham animals. At 24 h post-TBI, there were 150 differentially expressed genes in the nicotinamide treated animals compared to vehicle; the majority (82%) down-regulated. IPA analysis identified a significant effect of nicotinamide on the functional categories of cellular movement, cell-to-cell-signaling, antigen presentation and cellular compromise, function, and maintenance and cell death. The canonical pathways identified were signaling pathways primarily involved with the inflammatory process. At 72 h post-cortical contusion injury, there were 119 differentially expressed genes in the nicotinamide treated animals compared to vehicle; the majority (90%) was up-regulated. IPA analysis identified a significant effect of nicotinamide on cell signaling pathways involving neurotransmitters, neuropeptides, growth factors, and ion channels with little to no effect on inflammatory pathways. At 7 days post-TBI, there were only five differentially expressed genes with nicotinamide treatment compared to vehicle. Overall, the effect of nicotinamide on counteracting the effect of TBI resulted in significantly decreased number of genes differentially expressed by TBI. In conclusion, the mechanism of the effect of nicotinamide on secondary injury pathways involves effects on inflammatory response, signaling pathways, and cell death.

A comparison of the effects of nicotinamide and progesterone on functional recovery of cognitive behavior following cortical contusion injury in the rat

The primary goal of this study was to compare clinically relevant doses of progesterone and nicotinamide within the same injury model. Progesterone has been shown to reduce edema and inflammation and improve functional outcomes following brain injury. Nicotinamide has also been shown to be an effective neuroprotective agent in a variety of neurological injury models. In the current study, nicotinamide was administered beginning 4 h post-cortical contusion injury (CCI) with a loading dose (75 mg/kg, i.p.) combined with continuous infusion (12 mg/h/kg, s.c.) for 72 h post-injury. Progesterone was administered beginning 4 h post-CCI at a dose of 10 or 20 mg/kg, i.p. every 12 h for 72 h. This resulted in the following groups: Injured-nicotinamide treated, Injured-progesterone-10 treated, Injured-progesterone-20 treated, Injured-vehicle treated, and Sham. Functional recovery was assessed with two spatial memory tasks in the Morris water maze (MWM) the acquisition of a reference memory task and a reversal learning task. Neuropathological assessments were conducted in the cortex and hippocampus. It was found that both progesterone (10 mg/kg) and nicotinamide improved reference memory acquisition and reversal learning in the MWM compared with vehicle treatment. The lower dose of progesterone and nicotinamide also reduced tissue loss in the injured cortex and ipsilateral hippocampus compared with vehicle. The beneficial effects of progesterone appear to be dose dependent with the lower 10 mg/kg dose producing significant effects that were not observed at the higher dose. Direct comparison between nicotinamide and low dose progesterone appears to suggest that both are equally effective. The general findings of this study suggest that both nicotinamide and progesterone produce significant improvements in recovery of function following CCI.

A discrimination task used as a novel method of testing decision-making behavior following traumatic brain injury

Traumatic brain injury (TBI) results in a multitude of deficits following injury. Some of the most pervasive in humans are the changes that affect frontally-mediated cognitive functioning, such as decision making. The assessment of decision-making behavior in rodents has been extensively tested in the field of the experimental analysis of behavior. However, due to the narrow therapeutic window following TBI, time-intensive operant paradigms are rarely incorporated into the battery of tests traditionally used, the majority of which assess motor and sensory functioning. The cognitive measures that are used are frequently limited to memory and do not account for changes in decision-making behavior. The purpose of the present study was to develop a simplified discrimination task that can assess deficits in decision-making behavior in rodents. For the task, rats were required to dig in cocoa-scented sand (versus unscented sand) for a reinforcer. Rats were given 12 sessions per day until a criterion level of 80% accuracy for 3 days straight was reached. Once the criterion was achieved, cortical contusion injuries were induced (frontal, parietal, or sham). Following a recovery period, the rats were re-tested on cocoa versus unscented sand. Upon reaching criterion, a reversal discrimination was evaluated in which the reinforcer was placed in unscented sand. Finally, a novel scent discrimination (basil versus coffee with basil reinforced), and a reversal (coffee) were evaluated. The results indicated that the Dig task is a simple experimental preparation that can be used to assess deficits in decision-making behavior following TBI.

A review of neuroprotection pharmacology and therapies in patients with acute traumatic brain injury

Traumatic brain injury (TBI) affects 1.6 million Americans annually. The injury severity impacts the overall outcome and likelihood for survival. Current treatment of acute TBI includes surgical intervention and supportive care therapies. Treatment of elevated intracranial pressure and optimizing cerebral perfusion are cornerstones of current therapy. These approaches do not directly address the secondary neurological sequelae that lead to continued brain injury after TBI. Depending on injury severity, a complex cascade of processes are activated and generate continued endogenous changes affecting cellular systems and overall outcome from the initial insult to the brain. Homeostatic cellular processes governing calcium influx, mitochondrial function, membrane stability, redox balance, blood flow and cytoskeletal structure often become dysfunctional after TBI. Interruption of this cascade has been the target of numerous pharmacotherapeutic agents investigated over the last two decades. Many agents such as selfotel, pegorgotein (PEG-SOD), magnesium, deltibant and dexanabinol were ineffective in clinical trials. While progesterone and ciclosporin have shown promise in phase II studies, success in larger phase III, randomized, multicentre, clinical trials is pending. Consequently, no neuroprotective treatment options currently exist that improve neurological outcome after TBI. Investigations to date have extended understanding of the injury mechanisms and sites for intervention. Examination of novel strategies addressing both pathological and pharmacological factors affecting outcome, employing novel trial design methods and utilizing biomarkers validated to be reflective of the prognosis for TBI will facilitate progress in overcoming the obstacles identified from previous clinical trials.

Natural plant products and extracts that reduce immunoexcitotoxicity-associated neurodegeneration and promote repair within the central nervous system

Our understanding of the pathophysiological and biochemical basis of a number of neurological disorders has increased enormously over the last three decades. Parallel with this growth of knowledge has been a clearer understanding of the mechanism by which a number of naturally occurring plant extracts, as well as whole plants, can affect these mechanisms so as to offer protection against injury and promote healing of neurological tissues. Curcumin, quercetin, green tea catechins, balcalein, and luteolin have been extensively studied, and they demonstrate important effects on cell signaling that go far beyond their antioxidant effects. Of particular interest is the effect of these compounds on immunoexcitotoxicity, which, the authors suggest, is a common mechanism in a number of neurological disorders. By suppressing or affecting microglial activation states as well as the excitotoxic cascade and inflammatory mediators, these compounds dramatically affect the pathophysiology of central nervous system disorders and promote the release and generation of neurotrophic factors essential for central nervous system healing. We discuss the various aspects of these processes and suggest future directions for study.

The effects of a high-fat sucrose diet on functional outcome following cortical contusion injury in the rat

Traumatic brain injury (TBI) is a major public health issue affecting 1.7 million Americans each year, of which approximately 50,000 are fatal. High-fat sucrose (HFS) diets are another public health issue which can lead to obesity, hypertension, and many other debilitating disorders. These two disorders combined can lead to more complicated issues. It has recently been shown that HFS diets can reduce levels of brain-derived neurotrophic factor (BDNF) leading to reductions in neuronal and behavioral plasticity. This reduction in BDNF is suspected of increasing the susceptibility of the brain to injury. To test the effects of a HFS diet on recovery of function post-TBI, male Sprague-Dawley rats were used in this study. Eight weeks prior to TBI, rats were placed on a special HFS diet (n=14) or a standard rodent diet (n=14). Following this eight-week period, rats were prepared with bilateral frontal cortical contusion injuries (CCI) or sham procedures. Beginning two days post-TBI, animals were tested on a battery of behavioral tests to assess somatosensory dysfunction and spatial memory in the Morris water maze, with a reference memory and a working memory task. Following testing, animals were sacrificed and their brains processed for lesion analysis. The HFS diet worsened performance on the bilateral tactile adhesive removal test in sham animals. Injured animals on the Standard diet had a greater improvement in somatosensory performance in the adhesive removal test and had better performance on the working memory task compared to animals on the HFS diet. The HFS diet also resulted in significantly greater loss of cortical tissue post-CCI than in the Standard diet group. This study may aid in determining how nutritional characteristics or habits interact with damage to the brain.

Continuous nicotinamide administration improves behavioral recovery and reduces lesion size following bilateral frontal controlled cortical impact injury

Previous research has demonstrated considerable preclinical efficacy of nicotinamide (NAM; vitamin B(3)) in animal models of TBI with systemic dosing at 50 and 500 mg/kg yielding improvements on sensory, motor, cognitive and histological measures. The current study aimed to utilize a more specific dosing paradigm in a clinically relevant delivery mechanism: continuously secreting subcutaneous pumps. A bilateral frontal controlled cortical impact (CCI) or sham surgery was performed and rats were treated with NAM (150 mg/kg day) or saline (1 ml/kg) pumps 30 min after CCI, continuing until seven days post-CCI. Rats were given a loading dose of NAM (50mg/kg) or saline (1 ml/kg) following pump implant. Rats received behavioral testing (bilateral tactile adhesive removal, locomotor placing task and Morris water maze) starting on day two post-CCI and were sacrificed at 31 days post-CCI and brains were stained to examine lesion size. NAM-treated rats had reductions in sensory, motor and cognitive behavioral deficits compared to vehicle-treated rats. Specifically, NAM-treated rats significantly improved on the bilateral tactile adhesive removal task, locomotor placing task and the reference memory paradigm of the Morris water maze. Lesion size was also significantly reduced in the NAM-treated group. The results from this study indicate that at the current dose, NAM produces beneficial effects on recovery from a bilateral frontal brain injury and that it may be a relevant compound to be explored in human studies.

Effects of testosterone on spatial learning and memory in adult male rats

A male advantage over females for spatial tasks has been well documented in both humans and rodents, but it remains unclear how the activational effects of testosterone influence spatial ability in males. In a series of experiments, we tested how injections of testosterone influenced the spatial working and reference memory of castrated male rats. In the eight-arm radial maze, testosterone injections (0.500 mg/rat) reduced the number of working memory errors during the early blocks of testing but had no effect on the number of reference memory errors relative to the castrated control group. In a reference memory version of the Morris water maze, injections of a wide range of testosterone doses (0.0625-1.000 mg/rat) reduced path lengths to the hidden platform, indicative of improved spatial learning. This improved learning was independent of testosterone dose, with all treatment groups showing better performance than the castrated control males. Furthermore, this effect was only observed when rats were given testosterone injections starting 7 days prior to water maze testing and not when injections were given only on the testing days. We also observed that certain doses of testosterone (0.250 and 1.000 mg/rat) increased perseverative behavior in a reversal-learning task. Finally, testosterone did not have a clear effect on spatial working memory in the Morris water maze, although intermediate doses seemed to optimize performance. Overall, the results indicate that testosterone can have positive activational effects on spatial learning and memory, but the duration of testosterone replacement and the nature of the spatial task modify these effects.

Preclinical efficacy testing in middle-aged rats: nicotinamide, a novel neuroprotectant, demonstrates diminished preclinical efficacy after controlled cortical impact

Age is a consistent predictor of poor outcome following traumatic brain injury (TBI). Although the elderly population has one of the highest rates of TBI-related hospitalization and death, few preclinical studies have attempted to model and treat TBI in the aged population. Recent studies have indicated that nicotinamide (NAM), a soluble B-group vitamin, improved functional recovery in experimental models of TBI in young animals. The purpose of the present study was to examine the preclinical efficacy of NAM in middle-aged rats. Groups of middle-aged (14-month-old) rats were assigned to NAM (500 mg/kg or 50 mg/kg) or saline alone (1 mL/kg) treatment conditions, and received unilateral cortical contusion injuries (CCI) and injections at 1 h and 24 h following injury. The animals were tested on a variety of tasks to assess vestibulomotor (tapered beam) and cognitive performance (reference and working memory in the Morris water maze), and were evaluated for lesion size, blood-brain barrier compromise, astrocytic activation, and edema formation. In summary, the preclinical efficacy of NAM as a treatment following CCI in middle-aged rats differs from that previously documented in younger rats; while treatment with 50 mg/kg NAM appeared to have no effect, the 500-mg/kg dose worsened performance in middle-aged animals. Histological indicators demonstrated more nuanced group differences, indicating that NAM may positively impact some of the cellular cascades following injury, but were not substantial enough to improve functional recovery. These findings emphasize the need to examine potential treatments for TBI utilizing non-standard populations, and may explain why so many treatments have failed in clinical trials.

Novel avenues of drug discovery and biomarkers for diabetes mellitus

Globally, developed nations spend a significant amount of their resources on health care initiatives that poorly translate into increased population life expectancy. As an example, the United States devotes 16% of its gross domestic product to health care, the highest level in the world, but falls behind other nations that enjoy greater individual life expectancy. These observations point to the need for pioneering avenues of drug discovery to increase life span with controlled costs. In particular, innovative drug development for metabolic disorders such as diabetes mellitus becomes increasingly critical given that the number of diabetic people will increase exponentially over the next 20 years. This article discusses the elucidation and targeting of novel cellular pathways that are intimately tied to oxidative stress in diabetes mellitus for new treatment strategies. Pathways that involve wingless, β-nicotinamide adenine dinucleotide (NAD(+)) precursors, and cytokines govern complex biological pathways that determine both cell survival and longevity during diabetes mellitus and its complications. Furthermore, the role of these entities as biomarkers for disease can further enhance their utility irrespective of their treatment potential. Greater understanding of the intricacies of these unique cellular mechanisms will shape future drug discovery for diabetes mellitus to provide focused clinical care with limited or absent long-term complications.

COG1410, an apolipoprotein E-based peptide, improves cognitive performance and reduces cortical loss following moderate fluid percussion injury in the rat

COG1410, a small, novel ApoE-mimetic peptide derived from the receptor binding region of apolipoprotein E (ApoE), has been classified as anti-inflammatory in nature and improves motor, sensorimotor, and cognitive dysfunction following cortical contusion injury (CCI). In order to further examine COG1410's preclinical efficacy on cognitive recovery, the present study evaluated COG1410 following moderate fluid percussion injury (FPI). Animals were prepared with a moderate, unilateral FPI over the hippocampus. Following FPI, animals received a regimen of five doses of COG1410 or vehicle at 2 and 4h (1.0mg/kg, i.v.) followed by additional doses administered 24, 48, and 72 h (1.0mg/kg, i.p.). Prior to injury, animals were trained for 4 days (4 trials/day) in the Morris water maze (MWM) and then tested for retrograde amnesia on post-FPI day 11 and then on a working memory task on day 18. Testing for motor dysfunction on the tapered balanced beam began on day 2 post-FPI. Administration of this regimen of COG1410 significantly improved retention of memory in the retrograde amnesia test compared to vehicle post-FPI. However, COG1410 did not significantly improve acquisition of working memory in the MWM. Motor dysfunction on the tapered beam post-FPI was improved in the COG1410-treated group compared to vehicle treatment. Cortical lesion analysis revealed that the COG1410-treated animals demonstrated significantly less tissue loss compared to vehicle-treated animals. The results of this study suggest that COG1410 significantly limited the behavioral dysfunction and tissue loss associated with FPI and demonstrated continued preclinical efficacy for TBI.

Pyridoxine administration improves behavioral and anatomical outcome after unilateral contusion injury in the rat

The purpose of this project was to evaluate the preclinical efficacy of pyridoxine, or vitamin B(6). Rats received a 3.0 mm unilateral controlled cortical impact (CCI) injury of the sensorimotor cortex or sham surgery. Treatment with vitamin B(6) (600 or 300 mg/kg IP) or vehicle was administered at 30 min and 24 h post-CCI. Somatosensory dysfunction was evaluated with the vibrissae-forelimb placing and bilateral tactile adhesive removal tests. Sensorimotor dysfunction was evaluated with the locomotor placing and the forelimb asymmetry tests. On the forelimb asymmetry test both treatment groups displayed no asymmetry bias on any of the testing days post-CCI and were statistically no different than the shams. Both vitamin B(6) groups displayed a significant improvement in behavioral performance on the locomotor placing test compared to the vehicle-treated group. Administration of 600 mg/kg also significantly reduced tactile adhesive removal latencies on days 2, 4, 6, and 12 post-CCI. Both treatment groups were improved in their rate of recovery post-CCI on the vibrissae-forelimb placing test, but only the recovery seen in the 600-mg/kg group was significantly improved compared to vehicle. Finally, the 600-mg/kg dose resulted in significant cortical sparing compared to the vehicle-treated group. In general, the effects of vitamin B(6) on recovery of function were dose-dependent, with the 600-mg/kg dose consistently showing greater recovery than the 300-mg/kg dose. More experimental analyses are warranted to evaluate the potential preclinical efficacy and mechanistic action of vitamin B(6).

Diabetes mellitus: channeling care through cellular discovery

Diabetes mellitus (DM) impacts a significant portion of the world's population and care for this disorder places an economic burden on the gross domestic product for any particular country. Furthermore, both Type 1 and Type 2 DM are becoming increasingly prevalent and there is increased incidence of impaired glucose tolerance in the young. The complications of DM are protean and can involve multiple systems throughout the body that are susceptible to the detrimental effects of oxidative stress and apoptotic cell injury. For these reasons, innovative strategies are necessary for the implementation of new treatments for DM that are generated through the further understanding of cellular pathways that govern the pathological consequences of DM. In particular, both the precursor for the coenzyme beta-nicotinamide adenine dinucleotide (NAD(+)), nicotinamide, and the growth factor erythropoietin offer novel platforms for drug discovery that involve cellular metabolic homeostasis and inflammatory cell control. Interestingly, these agents and their tightly associated pathways that consist of cell cycle regulation, protein kinase B, forkhead transcription factors, and Wnt signaling also function in a broader sense as biomarkers for disease onset and progression.

Vitamin B3, the nicotinamide adenine dinucleotides and aging

Organism aging is a process of time and maturation culminating in senescence and death. The molecular details that define and determine aging have been intensely investigated. It has become appreciated that the process is partly an accumulation of random yet inevitable changes, but it can be strongly affected by genes that alter lifespan. In this review, we consider how NAD(+) metabolism plays important roles in the random patterns of aging, and also in the more programmatic aspects. The derivatives of NAD(+), such as reduced and oxidized forms of NAD(P)(+), play important roles in maintaining and regulating cellular redox state, Ca(2+) stores, DNA damage and repair, stress responses, cell cycle timing and lipid and energy metabolism. NAD(+) is also a substrate for signaling enzymes like the sirtuins and poly-ADP-ribosylpolymerases, members of a broad family of protein deacetylases and ADP-ribosyltransferases that regulate fundamental cellular processes such as transcription, recombination, cell division, proliferation, genome maintenance, apoptosis, stress resistance and senescence. NAD(+)-dependent enzymes are increasingly appreciated to regulate the timing of changes that lead to aging phenotypes. We consider how metabolism, specifically connected with Vitamin B3 and the nicotinamide adenine dinucleotides and their derivatives, occupies a central place in the aging processes of mammals.

Sustained delivery of nicotinamide limits cortical injury and improves functional recovery following traumatic brain injury

Previously, we have demonstrated that nicotinamide (NAM), a neuroprotective soluble B-group vitamin, improves recovery of function following traumatic brain injury (TBI). However, no prior studies have examined whether NAM is beneficial following continuous infusions over 7 days post-TBI. The purpose of this study was to investigate the preclinical efficacy of NAM treatment as it might be delivered clinically; over several days by slow infusion. Rats were prepared with either unilateral controlled cortical impact (CCI) injuries or sham procedures and divided into three groups: CCI-NAM, CCI-vehicle, and sham. Thirty minutes following CCI, Alzet osmotic mini-pumps were implanted subcutaneously. NAM was delivered at a rate of 50 mg/kg/day for 7 days immediately post-CCI. On day 7 following injury, the pumps were removed and blood draws were collected for serum NAM and nicotinamide adenine dinucleotide (NAD+) analyses. Starting on day 2 post-CCI, animals were tested on a battery of sensorimotor tests (bilateral tactile adhesive removal, locomotor placing, and limb-use asymmetry). Continuous infusion of NAM resulted in a significant serum elevation in NAM, but not NAD+. Statistical analyses of the tactile removal and locomotor placing data revealed that continuous administration of NAM significantly reduced the initial magnitude of the injury deficit and improved overall recovery compared to the vehicle-treated animals. NAM treatment also significantly decreased limb-use asymmetries compared to vehicle-treated animals. The overall extent of the cortical damage was also reduced by NAM treatment. No detrimental effects were seen following continuous infusion. The present results suggest that NAM delivered via a clinically relevant therapeutic regimen may truncate behavioral damage following TBI. Thus our results offer strong support for translation into the clinical population.

Sustained delivery of nicotinamide limits cortical injury and improves functional recovery following traumatic brain injury

Previously, we have demonstrated that nicotinamide (NAM), a neuroprotective soluble B-group vitamin, improves recovery of function following traumatic brain injury (TBI). However, no prior studies have examined whether NAM is beneficial following continuous infusions over 7 days post-TBI. The purpose of this study was to investigate the preclinical efficacy of NAM treatment as it might be delivered clinically; over several days by slow infusion. Rats were prepared with either unilateral controlled cortical impact (CCI) injuries or sham procedures and divided into three groups: CCI-NAM, CCI-vehicle, and sham. Thirty minutes following CCI, Alzet osmotic mini-pumps were implanted subcutaneously. NAM was delivered at a rate of 50 mg/kg/day for 7 days immediately post-CCI. On day 7 following injury, the pumps were removed and blood draws were collected for serum NAM and nicotinamide adenine dinucleotide (NAD+) analyses. Starting on day 2 post-CCI, animals were tested on a battery of sensorimotor tests (bilateral tactile adhesive removal, locomotor placing, and limb-use asymmetry). Continuous infusion of NAM resulted in a significant serum elevation in NAM, but not NAD+. Statistical analyses of the tactile removal and locomotor placing data revealed that continuous administration of NAM significantly reduced the initial magnitude of the injury deficit and improved overall recovery compared to the vehicle-treated animals. NAM treatment also significantly decreased limb-use asymmetries compared to vehicle-treated animals. The overall extent of the cortical damage was also reduced by NAM treatment. No detrimental effects were seen following continuous infusion. The present results suggest that NAM delivered via a clinically relevant therapeutic regimen may truncate behavioral damage following TBI. Thus our results offer strong support for translation into the clinical population.

The effects of hypertonic saline and nicotinamide on sensorimotor and cognitive function following cortical contusion injury in the rat

Hypertonic saline (HTS) is an accepted treatment for traumatic brain injury (TBI). However, the behavioral and cognitive consequences following HTS administration have not thoroughly been examined. Recent preclinical evidence has suggested that nicotinamide (NAM) is beneficial for recovery of function following TBI. The current study compared the behavioral and cognitive consequences of HTS and NAM as competitive therapeutic agents for the treatment of TBI. Following controlled cortical impact (CCI), bolus administrations of NAM (500 mg/kg), 7.5% HTS, or 0.9% saline Vehicle (1.0 mL/kg) were given at 2, 24, and 48 h post-CCI. Behavioral results revealed that animals treated with NAM and HTS showed significant improvements in beam walk and locomotor placing compared to the Vehicle group. The Morris water maze (MWM) retrograde amnesia test was conducted on day 12 post-CCI and showed that all groups had significant retention of memory compared to injured, Vehicle-treated animals. Working memory was also assessed on days 8-20 using the MWM. The NAM and Vehicle groups quickly acquired the task; however, HTS animals showed no acquisition of this task. Histological examinations revealed that the HTS-treated animals lost significantly more cortical tissue than either the NAM or Vehicle-treated animals. HTS-treated animals showed a greater loss of hippocampal tissue compared to the other groups. In general, NAM showed a faster rate of recovery than HTS without this associated tissue loss. The results of this study reiterate the strengths of NAM following injury and show concerns with bolus administrations of HTS due to the differential effects on cognitive performance and apparent tissue loss.

Histone deacetylases as targets for the treatment of human neurodegenerative diseases

Histone deacetylases (HDACs) are a family of proteins that play an important role in regulating transcription as well as the function of a variety of cellular proteins. While these proteins are expressed abundantly in the brain, little is known about their roles in brain function. A growing body of evidence suggests that HDACs regulate neuronal survival. Results from studies conducted in vertebrate and mammalian experimental systems indicate that while some of these proteins are involved in promoting neuronal death, a majority of the HDACs studied thus far protect against neurodegeneration. Here we review the research performed on the role played by individual members of the HDAC family in the regulation of neuronal death. Chemical inhibitors of HDACs have been used in a variety of models of neurodegenerative disorders. We summarize the results from these studies, which indicate that HDAC inhibitors show great promise as therapeutic agents for human neurodegenerative disorders.

The adhesive removal test: a sensitive method to assess sensorimotor deficits in mice

Long-term functional deficits after a brain injury are difficult to assess in the mouse. If no deficit is observed, researchers could conclude either that the animal has fully recovered or that the tests they used were not appropriate or sensitive enough to the modality of the deficits. We present here a detailed protocol describing how to conduct an adhesive removal test for this species. It consists of applying adhesive tape on each forepaw of the animal and measuring the time-to-contact and the time-to-remove them. This behavior implies correct paw and mouth sensitivity (time-to-contact) and correct dexterity (time-to-remove). To decrease interindividual differences, we recommend a training session (1 week, 1 trial per day) before surgical procedures so that mice to reach optimal performances.

The vitamin nicotinamide: translating nutrition into clinical care

Nicotinamide, the amide form of vitamin B(3) (niacin), is changed to its mononucleotide compound with the enzyme nicotinic acide/nicotinamide adenylyltransferase, and participates in the cellular energy metabolism that directly impacts normal physiology. However, nicotinamide also influences oxidative stress and modulates multiple pathways tied to both cellular survival and death. During disorders that include immune system dysfunction, diabetes, and aging-related diseases, nicotinamide is a robust cytoprotectant that blocks cellular inflammatory cell activation, early apoptotic phosphatidylserine exposure, and late nuclear DNA degradation. Nicotinamide relies upon unique cellular pathways that involve forkhead transcription factors, sirtuins, protein kinase B (Akt), Bad, caspases, and poly (ADP-ribose) polymerase that may offer a fine line with determining cellular longevity, cell survival, and unwanted cancer progression. If one is cognizant of the these considerations, it becomes evident that nicotinamide holds great potential for multiple disease entities, but the development of new therapeutic strategies rests heavily upon the elucidation of the novel cellular pathways that nicotinamide closely governs.

Enhanced tolerance against early and late apoptotic oxidative stress in mammalian neurons through nicotinamidase and sirtuin mediated pathways

Focus upon therapeutic strategies that intersect between pathways that govern cellular metabolism and cellular survival may offer the greatest impact for the treatment of a number of neurodegenerative and metabolic disorders, such as diabetes mellitus. In this regard, we investigated the role of a Drosophila nicotinamidase (DN) in mammalian SH-SY5Y neuronal cells during oxidative stress. We demonstrate that during free radical exposure to nitric oxide generators DN neuronal expression significantly increased cell survival and blocked cellular membrane injury. Furthermore, DN neuronal expression prevented both apoptotic late DNA degradation and early phosphatidylserine exposure that may serve to modulate inflammatory cell activation in vivo. Nicotinamidase activity that limited nicotinamide cellular concentrations appeared to be necessary for DN neuroprotection, since application of progressive nicotinamide concentrations could abrogate the benefits of DN expression during oxidative stress. Pathways that involved sirtuin activation and SIRT1 were suggested to be vital, at least in part, for DN to confer protection through a series of studies. First, application of resveratrol increased cell survival during oxidative stress either alone or in conjunction with the expression of DN to a similar degree, suggesting that DN may rely upon SIRT1 activation to foster neuronal protection. Second, the overexpression of either SIRT1 or DN in neurons prevented apoptotic injury specifically in neurons expressing these proteins during oxidative stress, advancing the premise that DN and SIRT1 may employ similar pathways for neuronal protection. Third, inhibition of sirtuin activity with sirtinol was detrimental to neuronal survival during oxidative stress and prevented neuronal protection during overexpression of DN or SIRT1, further supporting that SIRT1 activity may be necessary for DN neuroprotection during oxidative stress. Implementation of further work to elucidate the cellular mechanisms that govern nicotinamidase activity in mammalian cells may offer novel avenues for the treatment of disorders tied to oxidative stress and cellular metabolic dysfunction.