Alterations in IGF-I, BDNF and NT-3 levels following experimental brain trauma and the effect of IGF-I administration

The influence of biomimetic conditions on neurogenic and neuroprotective properties of dedifferentiated fat cells

In the era of a constantly growing number of reports on the therapeutic properties of dedifferentiated, ontogenetically rejuvenated cells and their use in the treatment of neurological diseases, the optimization of their derivation and long-term culture methods seem to be crucial. One of the solutions is seen in the use of dedifferentiated fat cells (DFATs) that are characterized by a greater homogeneity. Moreover, these cells seem to possess a higher expression of transcriptional factors necessary to maintain pluripotency (stemness-related transcriptional factors) as well as a greater ability to differentiate in vitro into 3 embryonic germ layers, and a high proliferative potential in comparison to adipose stem/stromal cells. However, the neurogenic and neuroprotective potential of DFATs is still insufficiently understood; hence, our research goal was to contribute to our current knowledge of the subject. To recreate the brain's physiological (biomimetic) conditions, the cells were cultured at 5% oxygen concentration. The neural differentiation capacity of DFATs was assessed in the presence of the N21 supplement containing the factors that are typically found in the natural environment of the neural cell niche or in the presence of cerebrospinal fluid and under various spatial conditions (microprinting). The neuroprotective properties of DFATs were assessed using the coculture method with the ischemically damaged nerve tissue.

Brain-Derived Neurotrophic Factor in Pediatric Acquired Brain Injury and Recovery

We review emerging preclinical and clinical evidence regarding brain-derived neurotrophic factor (BDNF) protein, genotype, and DNA methylation (DNAm) as biomarkers of outcomes in three important etiologies of pediatric acquired brain injury (ABI), traumatic brain injury, global cerebral ischemia, and stroke. We also summarize evidence suggesting that BDNF is (1) involved in the biological embedding of the psychosocial environment, (2) responsive to rehabilitative therapies, and (3) potentially modifiable. BDNF's unique potential as a biomarker of neuroplasticity and neural repair that is reflective of and responsive to both pre- and post-injury environmental influences separates it from traditional protein biomarkers of structural brain injury with exciting potential to advance pediatric ABI management by increasing the accuracy of prognostic tools and informing clinical decision making through the monitoring of therapeutic effects.

Immunomodulatory protein from ganoderma microsporum protects against oxidative damages and cognitive impairments after traumatic brain injury

A traumatic brain injury (TBI) causes abnormal proliferation of neuroglial cells, and over-release of glutamate induces oxidative stress and inflammation and leads to neuronal death, memory deficits, and even death if the condition is severe. There is currently no effective treatment for TBI. Recent interests have focused on the benefits of supplements or natural products like Ganoderma. Studies have indicated that immunomodulatory protein from Ganoderma microsporum (GMI) inhibits oxidative stress in lung cancer cells A549 and induces cancer cell death by causing intracellular autophagy. However, no evidence has shown the application of GMI on TBI. Thus, this study addressed whether GMI could be used to prevent or treat TBI through its anti-inflammation and antioxidative effects. We used glutamate-induced excitotoxicity as in vitro model and penetrating brain injury as in vivo model of TBI. We found that GMI inhibits the generation of intracellular reactive oxygen species and reduces neuronal death in cortical neurons against glutamate excitotoxicity. In neurite injury assay, GMI promotes neurite regeneration, the length of the regenerated neurite was even longer than that of the control group. The animal data show that GMI alleviates TBI-induced spatial memory deficits, expedites the restoration of the injured areas, induces the secretion of brain-derived neurotrophic factors, increases the superoxide dismutase 1 (SOD-1) and lowers the astroglial proliferation. It is the first paper to apply GMI to brain-injured diseases and confirms that GMI reduces oxidative stress caused by TBI and improves neurocognitive function. Moreover, the effects show that prevention is better than treatment. Thus, this study provides a potential treatment in naturopathy against TBI.

The neuropeptide cycloprolylglycine produces antidepressant-like effect and enhances BDNF gene expression in the mice cortex

BACKGROUND

Cycloprolylglycine (CPG) is an endogenous dipeptide with a wide range of psychotropic activity and putative therapeutic potential for depression. A small but growing body of data suggests that antidepressant-like effect of CPG is associated with neuroplastic changes in the brain or 5-HT system modulation. However, the mechanisms of the dipeptide action remain elusive.

AIMS

Here, we characterize the effects of chronic CPG administration on behavior and genes expression of antidepressants sensitive catalepsy (ASC) mice strain, characterized by depressive-like behavior.

METHODS

ASC mice were injected with saline, fluoxetine (10 mg/kg/day), or CPG (1 and 2 mg/kg/day) during 2 weeks. Behavior was studied using the open field test, novel object test, elevated plus maze test, forced swim test, and tail suspension test (TST). The expressions of genes coding BDNF, CREB, 5-HT_1A and 5-HT_2A receptors, TPH2, and SERT in the brain were measured with quantitative real-time reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

Chronic intraperitoneal administration of 1 and 2 mg/kg of CPG revealed the significant antidepressant-like effect by decreasing immobility time in the TST. At the same time, CPG did not negatively affect locomotor activity, cognition, or anxiety. In the real-time quantitative polymerase chain reaction (PCR) assay, chronic CPG treatment (2 mg/kg for 14 days) increased Bdnf mRNA level in the frontal cortex.

CONCLUSIONS

Our findings extend the evidence for the effectiveness of CPG to reduce depressive-like behaviors. The antidepressant-like effect of CPG is mediated, as least in part, by BDNF-dependent mechanism. The exact mechanism remains to be elucidated, and further studies are warranted.

Oral administration of cyclic glycyl-proline facilitates task learning in a rat stroke model

Cyclic glycyl-proline (cGP) exerts neuroprotective effects against ischemic stroke and may promote neural plasticity or network remodeling. We sought to determine to what extent oral administration of cGP could facilitate task learning in rats with ischemic lesions. We trained rats to perform a choice reaction time task using their forepaws. One week after changing the food to pellets containing cGP (no cGP: 0 mg/kg; low cGP: 25 mg/kg; and high cGP: 75 mg/kg), we made a focal ischemic lesion on the left or right forepaw area of the sensorimotor cortex. After recovery of task performance, we altered the correct-response side of the task, and then analyzed the number of training days required for the rat to reach a learning criterion (error rate < 15%) and the regulation of adult neurogenesis in the subventricular zones (SVZs), taking lesion size into account. The low-cGP group required fewer training days for task learning than the no-cGP group. Unexpectedly, rats with larger lesions required fewer training days in the no-cGP and low-cGP groups, but more training days in the high-cGP group. The number of Ki67-immunopositive cells (indicating proliferative cells) in ipsilesional SVZ increased more rapidly in the low-cGP and high-cGP groups than in the no-cGP group. However, lesion size had only a small effect on required training days and the number of Ki67-immunopositive cells. We conclude that oral administration of cGP can facilitate task learning in rats with focal ischemic infarction through neural plasticity and network remodeling, even with minimal neuroprotective effects.

Insulin-like growth factor 1 promotes neurological functional recovery after spinal cord injury through inhibition of autophagy via the PI3K/Akt/mTOR signaling pathway

Spinal cord injury (SCI) is a serious trauma; however, the mechanisms underlying the role of insulin-like growth factor 1 (IGF-1) in autophagy following SCI remain to be elucidated. The present study aimed to investigate the therapeutic effect of IGF-1 on SCI and to determine whether IGF-1 regulates autophagy via the PI3K/Akt/mTOR signaling pathway. SH-SY5Y neuroblastoma cells were assigned to the H₂O₂, IGF-1 and control groups to investigate subsequent neuron injury in vitro. An MTT assay was performed to evaluate cell survival. In addition, Sprague-Dawley rats were randomly assigned to SCI, SCI + IGF-1 and sham groups, and Basso-Beatlie-Bresnahan scores were assessed to determine rat neurological function. Western blotting was used to analyze the autophagy level and the activation of the PI3K/Akt/mTOR signaling pathway. Cell survival was increased significantly in the IGF-1 group compared with the control group in vitro (P<0.05). Furthermore, neurological function was improved in the SCI + IGF-1 group compared with the control group in vivo (P<0.05). The western blotting results further demonstrated that LC3II/LC3I expression was increased in the IGF-1 group compared with the sham group in vivo and compared with the control group in vitro (both P<0.05). In the SCI + IGF-1 group, the expression levels of PI3K, phosphorylated (p)-Akt and p-mTOR were higher compared with those in the sham and SCI groups in vivo (P<0.05). Moreover, in the IGF-1 group, the expression levels of p-Akt and p-mTOR were higher compared with the control and the H₂O₂ groups in vitro (P<0.05). Collectively, the results of the present study suggested that IGF-1 promoted functional recovery in rats following SCI through neuroprotective effects. Furthermore, the underlying mechanism may involve activation of the PI3K/Akt/mTOR signaling pathway, followed by inhibition of autophagy. However, further investigation into the association between IGF-1-regulated autophagy and the activation of different subtypes of PI3K is required.

A Comprehensive Review of Neuronal Changes in Diabetics

There has been an exponential rise in diabetes mellitus (DM) cases on a global scale. Diabetes affects almost every system of the body, and the nervous system is no exception. Although the brain is dependent on glucose, providing it with the energy required for optimal functionality, glucose also plays a key role in the regulation of oxidative stress, cell death, among others, which furthermore contribute to the pathophysiology of neurological disorders. The variety of biochemical processes engaged in this process is only matched by the multitude of clinical consequences resulting from it. The wide-ranging effects on the central and peripheral nervous system include, but are not limited to axonopathies, neurodegenerative diseases, neurovascular diseases, and general cognitive impairment. All language search was conducted on MEDLINE, COCHRANE, EMBASE, and GOOGLE SCHOLAR till September 2021. The following search strings and Medical Subject Headings (MeSH terms) were used: "Diabetes Mellitus," "CNS," "Diabetic Neuropathy," and "Insulin." We explored the literature on diabetic neuropathy, covering its epidemiology, pathophysiology with the respective molecular pathways, clinical consequences with a special focus on the central nervous system and finally, measures to prevent and treat neuronal changes. Diabetes is slowly becoming an epidemic, rapidly increasing the clinical burden on account of its wide-ranging complications. This review focuses on the neuronal changes occurring in diabetes such as the impact of hyperglycemia on brain function and structure, its association with various neurological disorders, and a few diabetes-induced peripheral neuropathic changes. It is an attempt to summarize the relevant literature about neuronal consequences of DM as treatment options available today are mostly focused on achieving better glycemic control; further research on novel treatment options to prevent or delay the progression of neuronal changes is still needed.

Traumatic brain injury-induced cerebral microbleeds in the elderly

Traumatic brain injury (TBI) was shown to lead to the development of cerebral microbleeds (CMBs), which are associated with long term cognitive decline and gait disturbances in patients. The elderly is one of the most vulnerable parts of the population to suffer TBI. Importantly, ageing is known to exacerbate microvascular fragility and to promote the formation of CMBs. In this overview, the effect of ageing is discussed on the development and characteristics of TBI-related CMBs, with special emphasis on CMBs associated with mild TBI. Four cases of TBI-related CMBs are described to illustrate the concept that ageing exacerbates the deleterious microvascular effects of TBI and that similar brain trauma may induce more CMBs in old patients than in young ones. Recommendations are made for future prospective studies to establish the mechanistic effects of ageing on the formation of CMBs after TBI, and to determine long-term consequences of CMBs on clinically relevant outcome measures including cognitive performance, gait and balance function.

Aggravating effects of treadmill exercises during the early-onset period in a rat traumatic brain injury model: When should rehabilitation exercises be initiated?

•

A traumatic brain injury model was prepared in rats by stab wounding.

•

Rats were forced to walk slowly on a treadmill once for 10 min at 24 h or 48 h after wounding.

•

Exercise, particularly at 24 h, aggravated motor impairment while increasing the expression of proinflammatory factors.

•

Exercise for rehabilitation should be initiated after 48 h of severe brain injury onset.

Physical exercise is one of the best interventions for improving traumatic brain injury (TBI) outcomes. However, an argument has been raised regarding the timing at which physical exercise should be initiated. In this study, male Wistar rats were subjected to stab wounding of the right hemisphere to develop a TBI model and were forced to walk once on a treadmill at a 5-m/min pace at 24 h or 48 h after TBI for 10 min. Injured brain tissue was dissected after TBI to evaluate the effects of exercise. Behavioral abnormalities and motor impairment were assessed by various behavioral tests between 2 and 3 weeks after TBI. Exercise did not affect the circulating corticosterone levels and the weight of the adrenal glands. Exercise particularly that at 24 h, worsened the motor impairment of the left forelimbs. Quantitative reverse-transcription polymerase chain reaction showed that exercise at 24 h increased proinflammatory cytokines and chemokines on the third day while suppressing the proinflammatory reactions on the fourth day. Exercise at both time points decreased expression of transforming growth factor (TGF) β1 and its receptor TGFβR1. Exercise at 24 h increased phosphorylation of IκB kinase on the fourth day, which may be correlated with the decreased effects of TGFβ1. Even a low-intensity exercise activity could cause deleterious effects when it is initiated within 48 h after the onset of severe TBI, probably because of the resulting proinflammatory effects. Therefore, rehabilitation exercise programs should be initiated after 48 h of TBI onset.

The effects of aminoguanidine on hippocampal cytokines, amyloid beta, brain-derived neurotrophic factor, memory and oxidative stress status in chronically lipopolysaccharide-treated rats

INTRODUCTION

In the present study, the effects of aminoguanidine (AMG) on hippocampal cytokines, amyloid beta (Aβ), brain-derived neurotrophic factor, oxidative stress status and memory in chronically lipopolysaccharide (LPS) treated rats were investigated.

METHODS

The rats were divided into five groups and were treated: (1) Control (Saline), (2) LPS (1 mg/kg), (3-5) LPS- AMG50, LPS-AMG100, and LPS-AMG150 (AMG 50, 100 and 150 mg/kg 30 min before LPS injection). The treatment started five weeks prior to the behavioral experiments and continued during the behavioral tests (LPS injection two hours before each behavioral evaluation). Finally, the tissue was removed for biochemical measurements.

RESULTS

The escape latency in Morris water maze test and the latency to enter the dark compartment in passive avoidance test in LPS group were significantly greater than the control group (P < 0.001), while, in LPS-AMG 100 and LPS-AMG150 groups they were less than LPS group (P < 0.001). Malondialdehyde (MDA), NO metabolites of hippocampal and cortical tissues and interleukin-6 (IL-6), Aβ and tumor necrosis factor-α (TNFα) concentration in the hippocampus of LPS group were higher than control group (P < 0.001-P < 0.05). However, in LPS-AMG 100 and LPS-AMG150 group they were lower than LPS group (P < 0.001-P < 0.05). The thiol content and the activities of catalase (CAT) and superoxide dismutase (SOD) in both cortical and hippocampal tissues of LPS group were reduced compared to the control group (P < 0.001-P < 0.05). These factors enhanced in LPS-AMG 100 and LPS-AMG150 groups compared to LPS (P < 0.001-P < 0.05). The hippocampal content of brain-derived neurotrophic factor (BDNF) in LPS group was significantly lower compared to the control group (P < 0.001). All treated groups had higher BDNF content in comparison to LPS group (P < 0.01-P < 0.001).

CONCLUSION

The findings indicated that the protective effects of AMG against LPS-induced memory were accompanied by decreasing of inflammatory cytokines, Aβ, oxidative stress and increasing of anti-inflammatory mediators and BDNF.

Subacute Transplantation of Native and Genetically Engineered Neural Progenitors Seeded on Microsphere Scaffolds Promote Repair and Functional Recovery After Traumatic Brain Injury

There is intense interest and effort toward regenerating the brain after severe injury. Stem cell transplantation after insult to the central nervous system has been regarded as the most promising approach for repair; however, engrafting cells alone might not be sufficient for effective regeneration. In this study, we have compared neural progenitors (NPs) from the fetal ventricular zone (VZ), the postnatal subventricular zone, and an immortalized radial glia (RG) cell line engineered to conditionally secrete the trophic factor insulin-like growth factor 1 (IGF-1). Upon differentiation in vitro, the VZ cells were able to generate a greater number of neurons than subventricular zone cells. Furthermore, differentiated VZ cells generated pyramidal neurons . In vitro, doxycycline-driven secretion of IGF-1 strongly promoted neuronal differentiation of cells with hippocampal, interneuron and cortical specificity. Accordingly, VZ and engineered RG-IGF-1-hemagglutinin (HA) cells were selected for subsequent in vivo experiments. To increase cell survival, we delivered the NPs attached to a multifunctional chitosan-based scaffold. The microspheres containing adherent NPs were injected subacutely into the lesion cavity of adult rat brains that had sustained controlled cortical impact injury. At 2 weeks posttransplantation, the exogenously introduced cells showed a reduction in stem cell or progenitor markers and acquired mature neuronal and glial markers. In beam walking tests assessing sensorimotor recovery, transplanted RG cells secreting IGF-1 contributed significantly to functional improvement while native VZ or RG cells did not promote significant recovery. Altogether, these results support the therapeutic potential of chitosan-based multifunctional microsphere scaffolds seeded with genetically modified NPs expressing IGF-1 to promote repair and functional recovery after traumatic brain injuries.

To Be or Not to Be: Environmental Factors that Drive Myelin Formation during Development and after CNS Trauma

Oligodendrocytes are specialized glial cells that myelinate central nervous system (CNS) axons. Historically, it was believed that the primary role of myelin was to compactly ensheath axons, providing the insulation necessary for rapid signal conduction. However, mounting evidence demonstrates the dynamic importance of myelin and oligodendrocytes, including providing metabolic support to neurons and regulating axon protein distribution. As such, the development and maintenance of oligodendrocytes and myelin are integral to preserving CNS homeostasis and supporting proper functioning of widespread neural networks. Environmental signals are critical for proper oligodendrocyte lineage cell progression and their capacity to form functional compact myelin; these signals are markedly disturbed by injury to the CNS, which may compromise endogenous myelin repair capabilities. This review outlines some key environmental factors that drive myelin formation during development and compares that to the primary factors that define a CNS injury milieu. We aim to identify developmental factors disrupted after CNS trauma as well as pathogenic factors that negatively impact oligodendrocyte lineage cells, as these are potential therapeutic targets to promote myelin repair after injury or disease.

Circulating biomarkers in extremely preterm infants associated with ultrasound indicators of brain damage

AIM

To assess to what extent the blood concentrations of proteins with neurotrophic and angiogenic properties measured during the first postnatal month convey information about the risk of sonographically-identified brain damage among very preterm newborns.

METHODS

Study participants were 1219 children who had a cranial ultrasound scan during their stay in the intensive care nursery and blood specimens collected on 2 separate days at least a week apart during the first postnatal month. Concentrations of selected proteins in blood spots were measured with electrochemiluminescence or with a multiplex immunobead assay and the risks of cranial ultrasound images associated with top-quartile concentrations were assessed.

RESULTS

High concentrations of multiple inflammation-related proteins during the first 2 postnatal weeks were associated with increased risk of ventriculomegaly, while high concentrations of just 3 inflammation-related proteins were associated with increased risk of an echolucent/hypoechoic lesion (IL-6, IL-8, ICAM-1), especially on day 7. Concomitant high concentrations of IL6R and bFGF appeared to modulate the increased risks of ventriculomegaly and an echolucent lesion associated with inflammation. More commonly high concentrations of putative protectors/repair-enhancers did not appear to diminish these increased risks.

CONCLUSION

Our findings provide support for the hypothesis that endogenous proteins are capable of either protecting the brain against damage and/or enhancing repair of damage.

Systemic Inflammation during the First Postnatal Month and the Risk of Attention Deficit Hyperactivity Disorder Characteristics among 10 year-old Children Born Extremely Preterm

Although multiple sources link inflammation with attention difficulties, the only human study that evaluated the relationship between systemic inflammation and attention problems assessed attention at age 2 years. Parent and/or teacher completion of the Childhood Symptom Inventory-4 (CSI-4) provided information about characteristics that screen for attention deficit hyperactive disorder (ADHD) among 793 10-year-old children born before the 28th week of gestation who had an IQ ≥ 70. The concentrations of 27 proteins in blood spots obtained during the first postnatal month were measured. 151 children with ADHD behaviors were identified by parent report, while 128 children were identified by teacher report. Top-quartile concentrations of IL-6R, TNF-α, IL-8, VEGF, VEFG-R1, and VEGF-R2 on multiple days were associated with increased risk of ADHD symptoms as assessed by a teacher. Some of this increased risk was modulated by top-quartile concentrations of IL-6R, RANTES, EPO, NT-4, BDNF, bFGF, IGF-1, PIGF, Ang-1, and Ang-2. Systemic inflammation during the first postnatal month among children born extremely preterm appears to increase the risk of teacher-identified ADHD characteristics, and high concentrations of proteins with neurotrophic properties appear capable of modulating this increased risk.

Identification of Synaptotagmin 10 as Effector of NPAS4-Mediated Protection from Excitotoxic Neurodegeneration

Neuronal degeneration represents a pathogenetic hallmark after different brain insults, such as ischemia and status epilepticus (SE). Excessive release of glutamate triggered by pathophysiologic synaptic activity has been put forward as key mechanism in this context. In response to pathophysiologic synaptic activity, multiple signaling cascades are activated that ultimately initiate expression of specific sets of genes, which may decide between neuronal survival versus death. Recently, a core set of genes ["activity-regulated inhibitor of death" (AID) genes] including the transcription factor (TF) NPAS4 (neuronal PAS domain protein 4) has been found to provide activity-induced protection against neuronal death caused by excitotoxic stimulation. However, the downstream targets of AID action mediating neuroprotection remained so far unknown. Here, we have identified synaptotagmin 10 (Syt10), a vesicular Ca(2+) sensor, as the first neuroprotective effector protein downstream of the TF NPAS4. The expression of Syt10 is strongly upregulated by pathophysiologic synaptic activity after kainic acid (KA) exposure and its absence renders mouse hippocampal neurons highly susceptible to excitotoxic insults. We found NPAS4 as critical for the increase in Syt10 levels and in turn the ability of NPAS4 to confer neuroprotection against KA-induced excitotoxicity to be severely diminished in Syt10 knock-out neurons. In summary, our results point to an important role for signaling of the NPAS4-Syt10 pathway in the neuronal response to strong synaptic activity as a consequence of excitotoxic insults.

SIGNIFICANCE STATEMENT

Aberrant synaptic activity is observed in many neurological disorders and has been suggested as an important factor contributing to the pathophysiology. Intriguingly, pathophysiologic activity can also trigger signaling cascades mediating potentially compensatory neuroprotection against excitotoxic insult. Here, we identify a new neuroprotective signaling cascade involving the activity-induced transcriptional regulator NPAS4 and the vesicular Ca(2+)-sensor protein synaptotagmin 10 (Syt10). Syt10 is required for NPAS4 to protect hippocampal neurons against excitotoxic cell death. NPAS4 in turn controls the activity of the Syt10 gene, which is strongly induced by pathophysiologic activity. Our results uncover an entirely unexpected, novel function of Syt10 underlying the response of neurons to pathophysiologic activity and provide new therapeutic perspectives for neurological disorders.

Huperzine A Alleviates Oxidative Glutamate Toxicity in Hippocampal HT22 Cells via Activating BDNF/TrkB-Dependent PI3K/Akt/mTOR Signaling Pathway

Oxidative glutamate toxicity is involved in diverse neurological disorders including epilepsy and ischemic stroke. Our present work aimed to assess protective effects of huperzine A (HupA) against oxidative glutamate toxicity in a mouse-derived hippocampal HT22 cells and explore its potential mechanisms. Cell survival and cell injury were analyzed by MTT method and LDH release assay, respectively. The production of ROS was measured by detection kits. Protein expressions of BDNF, phosphor-TrkB (p-TrkB), TrkB, phosphor-Akt (p-Akt), Akt, phosphor-mTOR (p-mTOR), mTOR, phosphor-p70s6 (p-p70s6) kinase, p70s6 kinase, Bcl-2, Bax, and β-actin were assayed via Western blot analysis. Enzyme-linked immunosorbent assay was employed to measure the contents of nerve growth factor, brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4). Our findings illustrated 10 μM HupA for 24 h significantly protected HT22 from cellular damage and suppressed the generation of ROS. Additionally, after treating with LY294002 or wortmannin [the selective inhibitors of phosphatidylinositol 3 kinase (PI3K)], HupA dramatically prevented the down-regulations of p-Akt, p-mTOR, and p-p70s6 kinase in HT22 cells under oxidative toxicity. Furthermore, it was observed that the protein levels of BDNF and p-TrkB were evidently enhanced after co-treatment with HupA and glutamate in HT22 cells. The elevations of p-Akt and p-mTOR were abrogated under toxic conditions after blockade of TrkB by TrkB IgG. Cellular apoptosis was significantly suppressed (decreased caspase-3 activity and enhanced Bcl-2 protein level) after HupA treatment. It was concluded that HupA attenuated oxidative glutamate toxicity in murine hippocampal HT22 cells via activating BDNF/TrkB-dependent PI3K/Akt/mTOR signaling pathway.

TSPO PIGA Ligands Promote Neurosteroidogenesis and Human Astrocyte Well-Being

The steroidogenic 18 kDa translocator protein (TSPO) is an emerging, attractive therapeutic tool for several pathological conditions of the nervous system. Here, 13 high affinity TSPO ligands belonging to our previously described N,N-dialkyl-2-phenylindol-3-ylglyoxylamide (PIGA) class were evaluated for their potential ability to affect the cellular Oxidative Metabolism Activity/Proliferation index, which is used as a measure of astrocyte well-being. The most active PIGA ligands were also assessed for steroidogenic activity in terms of pregnenolone production, and the values were related to the metabolic index in rat and human models. The results showed a positive correlation between the increase in the Oxidative Metabolism Activity/Proliferation index and the pharmacologically induced stimulation of steroidogenesis. The specific involvement of steroid molecules in mediating the metabolic effects of the PIGA ligands was demonstrated using aminoglutethimide, a specific inhibitor of the first step of steroid biosynthesis. The most promising steroidogenic PIGA ligands were the 2-naphthyl derivatives that showed a long residence time to the target, in agreement with our previous data. In conclusion, TSPO ligand-induced neurosteroidogenesis was involved in astrocyte well-being.

Leukemia Inhibitory Factor Haplodeficiency Desynchronizes Glial Reactivity and Exacerbates Damage and Functional Deficits after a Concussive Brain Injury

Reactions of both astrocytes and microglia to central nervous system injury can be beneficial or detrimental to recovery. To gain insights into the functional importance of gliosis, we developed a new model of adolescent closed-head injury (CHI) and interrogated the behavioral, physiological, and cellular outcomes after a concussive CHI in leukemia inhibitory factor (LIF) haplodeficient mice. These mice were chosen because LIF is important for astrocyte and microglial activation. Behaviorally, the LIF haplodeficient animals were equally impaired 4 h after the injury, but in the subsequent 2 weeks, the LIF haplodeficient mice acquired more severe motor and sensory deficits, compared with wild type mice. The prolonged accumulation of neurological impairment was accompanied by desynchronization of the gliotic response, increased cell death, axonal degeneration, diminished callosal compound action potential, and hypomyelination. Our results clearly show that LIF is an essential injury-induced cytokine that is required to prevent the propagation of secondary neurodegeneration.

IGF-1 as an Important Endogenous Growth Factor for Recovery from Impaired Urethral Continence Function in Rats with Simulated Childbirth Injury

PURPOSE

We examined the functional role of endogenous IGF-1 (insulin-like growth factor-1) in the recovery phase of stress urinary incontinence induced by simulated childbirth trauma using an IGF-1 receptor inhibitor.

MATERIALS AND METHODS

Simulated birth trauma was induced by vaginal distension in female Sprague Dawley® rats. The IGF-1 receptor antagonist JB-1 (10 and 100 μg/kg per day) or vehicle was continuously delivered from 1 day before vaginal distension for 7 days using subcutaneous osmotic pumps. Seven, 14 and 21 days after vaginal distension the effect of JB-1 treatment was examined by functional analyses, including leak point and urethral baseline pressure, and urethral responses during passive increments in intravesical pressure, as well as molecular analyses in urethral tissues, including phosphorylation of Akt, apoptotic changes and peripheral nerve density using Western blot and immunohistochemistry.

RESULTS

On functional analyses vehicle treated rats with vaginal distension had significantly decreased leak point and urethral baseline pressure, and urethral responses at 7 days, which recovered to the normal level 14 and 21 days after vaginal distension. In the JB-1 treated vaginal distension group leak point and urethral baseline pressure, and urethral responses were still significantly reduced 21 days after vaginal distension. On molecular analyses JB-1 treatment increased apoptotic cells, induced a significant decrease in phosphorylated Akt and prolonged the decrease of peripheral nerve density in urethral tissues.

CONCLUSIONS

Suppression of endogenous IGF-1 activity delayed recovery from stress urinary incontinence induced by simulated childbirth trauma in rats. Thus, IGF-1 is likely to be an important endogenous mediator for functional recovery from childbirth related stress urinary incontinence. This suggests that IGF-1 could be an effective target for treating stress urinary incontinence in women.

Neural stem/progenitor cells differentiate into oligodendrocytes, reduce inflammation, and ameliorate learning deficits after transplantation in a mouse model of traumatic brain injury

The central nervous system has limited capacity for regeneration after traumatic injury. Transplantation of neural stem/progenitor cells (NPCs) has been proposed as a potential therapeutic approach while insulin-like growth factor I (IGF-I) has neuroprotective properties following various experimental insults to the nervous system. We have previously shown that NPCs transduced with a lentiviral vector for IGF-I overexpression have an enhanced ability to give rise to neurons in vitro but also in vivo, upon transplantation in a mouse model of temporal lobe epilepsy. Here we studied the regenerative potential of NPCs, IGF-I-transduced or not, in a mouse model of hippocampal mechanical injury. NPC transplantation, with or without IGF-I transduction, rescued the injury-induced spatial learning deficits as revealed in the Morris Water Maze. Moreover, it had beneficial effects on the host tissue by reducing astroglial activation and microglial/macrophage accumulation while enhancing generation of endogenous oligodendrocyte precursor cells. One or two months after transplantation the grafted NPCs had migrated towards the lesion site and in the neighboring myelin-rich regions. Transplanted cells differentiated toward the oligodendroglial, but not the neuronal or astrocytic lineages, expressing the early and late oligodendrocyte markers NG2, Olig2, and CNPase. The newly generated oligodendrocytes reached maturity and formed myelin internodes. Our current and previous observations illustrate the high plasticity of transplanted NPCs which can acquire injury-dependent phenotypes within the host CNS, supporting the fact that reciprocal interactions between transplanted cells and the host tissue are an important factor to be considered when designing prospective cell-based therapies for CNS degenerative conditions.

Role and Importance of IGF-1 in Traumatic Brain Injuries

It is increasingly affirmed that most of the long-term consequences of TBI are due to molecular and cellular changes occurring during the acute phase of the injury and which may, afterwards, persist or progress. Understanding how to prevent secondary damage and improve outcome in trauma patients, has been always a target of scientific interest. Plans of studies focused their attention on the posttraumatic neuroendocrine dysfunction in order to achieve a correlation between hormone blood level and TBI outcomes. The somatotropic axis (GH and IGF-1) seems to be the most affected, with different alterations between the acute and late phases. IGF-1 plays an important role in brain growth and development, and it is related to repair responses to damage for both the central and peripheral nervous system. The IGF-1 blood levels result prone to decrease during both the early and late phases after TBI. Despite this, experimental studies on animals have shown that the CNS responds to the injury upregulating the expression of IGF-1; thus it appears to be related to the secondary mechanisms of response to posttraumatic damage. We review the mechanisms involving IGF-1 in TBI, analyzing how its expression and metabolism may affect prognosis and outcome in head trauma patients.

Topiramate protects against glutamate excitotoxicity via activating BDNF/TrkB-dependent ERK pathway in rodent hippocampal neurons

Topiramate (TPM) was previously found to have neuroprotection against neuronal injury in epileptic and ischemic models. However, whether TPM protects against glutamate-induced excitotoxicity in hippocampal neurons is elusive. Our present work aimed to evaluate the protective effect of TPM against glutamate toxicity in hippocampal neurons and further figure out the potential molecular mechanisms. The in vitro glutamate excitotoxic model was prepared with 125μM glutamate for 20min. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) analysis and Hoechst 33342 staining were conducted to detect neuronal survival. The protein expressions of brain-derived neurotrophic factor (BDNF), TrkB, mitogen-activated protein kinase (MAPK) cascade (including extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 MAPK), cyclic AMP response element binding protein (CREB), Bcl-2, Bax and β-actin were detected via Western blot assay. Our results demonstrated that TPM protected hippocampal neurons from glutamate toxicity. Meanwhile, the pretreatment of TPM for 10min significantly prevented the down-regulation of BDNF and the phosphorylation of TrkB. Furthermore, the elevation of phosphorylated EKR expression was significantly inhibited after blockade of TrkB by TrkB IgG, while no alterations of phosphorylated JNK and p38 MAPK were found in the cultured hippocampal neurons. Besides, it was also found that the enhanced phosphorylation of CREB was evidently reversed under excitotoxic conditions after treating with U0126 (the selective inhibitor of ERK). The protein level of Bcl-2 was also observed to be remarkably increased after TPM treatment. In conclusion, these findings implicate that TPM exerts neuroprotective effects against glutamate excitotoxicity in hippocampal neurons and its protection may be modulated through BDNF/TrkB-dependent ERK pathway.

The beneficial effects of strength exercise on hippocampal cell proliferation and apoptotic signaling is impaired by anabolic androgenic steroids

Previous studies have shown that strength exercise improves memory and increases expression of a myriad of proteins involved on neuronal survival and synaptic plasticity in the hippocampus. Conversely, chronic exposure to supraphysiological levels of anabolic androgenic steroids (AAS) can induce psychiatric abnormalities, cognitive deficits, impair neurotransmission, alter the levels of neurotrophic factors, decrease cell proliferation and neurogenesis, and enhance neuronal cell death. In the present study, we investigated the effects of the AAS nandrolone decanoate (ND) administration during a strength exercise program on cell proliferation, apoptotic status and brain-derived neurotrophic factor (BDNF) expression in the rat hippocampus. Adult male Wistar rats were subjected to 4 weeks of progressive strength exercise in a vertical ladder apparatus with or without daily doses (5.0 mg/kg, SC) of ND. Immunohistochemistry analysis revealed that strength exercise increased significantly the number of Ki-67-positive cells (a cell proliferation marker) in dentate gyrus (DG) of hippocampus. However, this effect was abrogated when strength exercise was combined with ND. Although western blot analysis of whole hippocampus showed no significant differences in Bax and Bcl-2 protein expression among groups, the immunoreactivity of the pro-apoptotic protein Bax was significantly increased in DG, CA1 and CA3 hippocampal subfields of sedentary rats treated with ND. Moreover, the increase in the immunoreactivity of anti-apoptotic protein Bcl-2 (DG and CA3) induced by strength exercise was diminished by ND. There were no significant differences in BDNF expression among experimental groups. Therefore, the present findings suggest that the beneficial effects of strength exercise on hippocampal cell proliferation and apoptotic signaling are impaired by ND.

Astrocyte-derived growth factors and estrogen neuroprotection: role of transforming growth factor-α in estrogen-induced upregulation of glutamate transporters in astrocytes

Extensive studies from the past decade have completely revolutionized our understanding about the role of astrocytes in the brain from merely supportive cells to an active role in various physiological functions including synaptic transmission via cross-talk with neurons and neuroprotection via releasing neurotrophic factors. Particularly, numerous studies have reported that astrocytes mediate the neuroprotective effects of 17β-estradiol (E2) and selective estrogen receptor modulators (SERMs) in various clinical and experimental models of neuronal injury. Astrocytes contain two main glutamate transporters, glutamate aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1), that play a key role in preventing excitotoxic neuronal death, a process associated with most neurodegenerative diseases. E2 has been shown to increase expression of both GLAST and GLT-1 mRNA and protein and glutamate uptake in astrocytes. Growth factors such as transforming growth factor-α (TGF-α) appear to mediate E2-induced enhancement of these transporters. These findings suggest that E2 exerts neuroprotection against excitotoxic neuronal injuries, at least in part, by enhancing astrocytic glutamate transporter levels and function. Therefore, the present review will discuss proposed mechanisms involved in astrocyte-mediated E2 neuroprotection, with a focus on glutamate transporters.

Diurnal alterations in circadian genes and peptides in major depressive disorder before and after escitalopram treatment

BACKGROUND

Strong links exist between circadian disturbances and some of the most characteristic symptoms of clinical major depressive disorder (MDD). However, changes in the expression of clock genes or neuropeptides related to the regulation of circadian rhythm that may influence the susceptibility to recurrence after antidepressant treatment in MDD have not been investigated.

METHODS

Blood samples were collected at 4h intervals for 24h from 12 male healthy controls and 12 male MDD patients before and after treatment with escitalopram for 8 weeks. The outcome measures included the relative expression of clock gene mRNA (PERIOD1, PERIOD2, PERIOD3, CRY1, BMAL1, NPAS2, and GSK-3β), and the levels of serum melatonin, vasoactive intestinal polypeptide (VIP), cortisol, adrenocorticotropic hormone (ACTH), insulin-like growth factor-1 (IGF-1), and growth hormone (GH).

RESULTS

Compared with healthy controls, MDD patients showed disruptions in the diurnal rhythms of the expression of PERIOD1, PERIOD2, CRY1, BMAL1, NPAS2, and GSK-3β and disruptions in the diurnal rhythms of the release of melatonin, VIP, cortisol, ACTH, IGF-1, and GH. Several of these disruptions (i.e., PER1, CRY1, melatonin, VIP, cortisol, ACTH, and IGF-1) persisted 8 weeks after escitalopram treatment, similar to the increase in the 24h levels of VIP and decreases in the 24h levels of cortisol and ACTH.

CONCLUSION

These persistent neurobiological changes may play a role in MDD symptoms that are thought to contribute to the vulnerability to recurrence and long-term maintenance therapy.

Growth factor signaling and memory formation: temporal and spatial integration of a molecular network

Growth factor (GF) signaling is critically important for developmental plasticity. It also plays a crucial role in adult plasticity, such as that required for memory formation. Although different GFs interact with receptors containing distinct types of kinase domains, they typically signal through converging intracellular cascades (e.g., Ras–MEK–MAPK) to mediate overlapping functional endpoints. Several GFs have been implicated in memory formation, but due to a high level of convergent signaling, the unique contributions of individual GFs as well as the interactions between GF signaling cascades during the induction of memory is not well known. In this review, we highlight the unique roles of specific GFs in dendritic plasticity, and discuss the spatial and temporal profiles of different GFs during memory formation. Collectively, the data suggest that the roles of GF signaling in long-lasting behavioral and structural plasticity may be best viewed as interactive components in a complex molecular network.

Peptidergic drugs for the treatment of traumatic brain injury

Traumatic brain injury (TBI) is a devastating medical condition that has an enormous socioeconomic impact because it affects more than 10 million people annually worldwide and is associated with high rates of hospitalization, mortality and disability. Although TBI survival has improved continuously for decades, particularly in developing countries, implementation of an effective drug therapy for TBI represents an unmet clinical need. All confirmatory trials conducted to date with drugs targeting a single TBI pathological pathway failed to show clinical efficacy, probably because TBI pathophysiology involves multiple cellular and molecular mechanisms of secondary brain damage. According to current scientific evidence of the participation of peptide-mediated mechanisms in the processes of brain injury and repair after TBI, peptidergic drugs represent a multimodal therapy alternative to improve acute outcome and long-term recovery in TBI patients. Preliminary randomized-controlled clinical trials and open-label studies conducted to date with the peptidergic drug Cerebrolysin® (Ever Neuro Pharma GmbH, Unterach, Austria) and with the endogenous neuropeptides progesterone and erythropoietin, showed positive clinical results. Cerebrolysin-treated patients had a faster clinical recovery, a shorter hospitalization time and a better long-term outcome. Treatment with progesterone showed advantages over placebo regarding TBI mortality and clinical outcome, whereas erythropoietin only reduced mortality. Further validation of these promising findings in confirmatory randomized-controlled clinical trials is warranted. This article reviews the scientific basis and clinical evidence on the development of multimodal peptidergic drugs as a therapeutic option for the effective treatment of TBI patients.

Subventricular zone-derived neural stem cell grafts protect against hippocampal degeneration and restore cognitive function in the mouse following intrahippocampal kainic acid administration

Temporal lobe epilepsy (TLE) is a major neurological disease, often associated with cognitive decline. Since approximately 30% of patients are resistant to antiepileptic drugs, TLE is being considered as a possible clinical target for alternative stem cell-based therapies. Given that insulin-like growth factor I (IGF-I) is neuroprotective following a number of experimental insults to the nervous system, we investigated the therapeutic potential of neural stem/precursor cells (NSCs) transduced, or not, with a lentiviral vector for overexpression of IGF-I after transplantation in a mouse model of kainic acid (KA)-induced hippocampal degeneration, which represents an animal model of TLE. Exposure of mice to the Morris water maze task revealed that unilateral intrahippocampal NSC transplantation significantly prevented the KA-induced cognitive decline. Moreover, NSC grafting protected against neurodegeneration at the cellular level, reduced astrogliosis, and maintained endogenous granule cell proliferation at normal levels. In some cases, as in the reduction of hippocampal cell loss and the reversal of the characteristic KA-induced granule cell dispersal, the beneficial effects of transplanted NSCs were manifested earlier and were more pronounced when these were transduced to express IGF-I. However, differences became less pronounced by 2 months postgrafting, since similar amounts of IGF-I were detected in the hippocampi of both groups of mice that received cell transplants. Grafted NSCs survived, migrated, and differentiated into neurons-including glutamatergic cells-and not glia, in the host hippocampus. Our results demonstrate that transplantation of IGF-I producing NSCs is neuroprotective and restores cognitive function following KA-induced hippocampal degeneration.

Differential effects of neonatal maternal separation on the expression of neurotrophic factors in rat brain. II: Regional differences in the cerebellum versus the cerebral cortex

This study was conducted in order to examine the effects of early postnatal maternal separation stress on the age-dependent fluctuations in the expression levels of neurotrophic factor ligands and receptors in the developing cerebellum. Wistar rats were separated from their mothers for 3 h each day during postnatal days (PND) 10 to 15. The expression level of mRNA for brain-derived neurotrophic factor (BDNF), tyrosine kinase receptor B (TrkB), insulin-like growth factor-1 (IGF-1), and type-1 IGF receptor (IGF-1R) were evaluated in the cerebellum on PND16, 20, 30, and 60 with real-time RT-PCR. The mRNA levels of cerebellar BDNF in maternally separated rats were increased on PND16, while the other variables showed no significant alterations at any of the time points examined. However, the effects of an identical maternal separation on the cerebral cortex were previously reported to be completely different. These results indicate regional differences in the responses of neurotrophic factor ligands/receptors between the cerebellum and cerebral cortex. Given that neurotrophic factors play important roles in brain development, alterations in these factors may interrupt normal brain development and ultimately, lead to functional disruptions.

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.

The cerebrospinal fluid: regulator of neurogenesis, behavior, and beyond

The cerebrospinal fluid (CSF) has attracted renewed interest as an active signaling milieu that regulates brain development, homeostasis, and disease. Advances in proteomics research have enabled an improved characterization of the CSF from development through adulthood, and key neurogenic signaling pathways that are transmitted via the CSF are now being elucidated. Due to its immediate contact with neural stem cells in the developing and adult brain, the CSF's ability to swiftly distribute signals across vast distances in the central nervous system is opening avenues to novel and exciting therapeutic approaches. In this review, we will discuss the development of the choroid plexus-CSF system, and review the current literature on how the CSF actively regulates mammalian brain development, behavior, and responses to traumatic brain injury.

Neonatal repetitive maternal separation causes long-lasting alterations in various neurotrophic factor expression in the cerebral cortex of rats

AIMS

This study was carried out to examine the effects of early postnatal maternal separation stress on the development of the cerebral cortex with respect to time-dependent fluctuations of neurotrophic factor ligand and receptor expression.

MAIN METHODS

Wistar rats were separated from their mothers for 3h per day during postnatal days (PND) 10 to 15. The cerebral cortex was analyzed by real-time RT-PCR for the evaluation of the expression of mRNA for brain-derived neurotrophic factor (BDNF), TrkB, insulin-like growth factor-1 (IGF-1), and type 1 IGF receptor (IGF-1R) on PND16, 20, 30, and 60.

KEY FINDINGS

The expression of these neurotrophic factor ligands and receptors in the cerebral cortex was enhanced on PND16 and PND20, and then it returned to baseline levels on PND30. By PND60, however, the expression levels were attenuated.

SIGNIFICANCE

The important implication of this study is the persistent abnormal fluctuation of neurotrophic factor expression for a prolonged period, triggered even after the brain growth spurt. Given that neurotrophic factors play important roles in brain development, it can be speculated that the altered expression of these factors induced by maternal separation may interrupt normal brain development and ultimately lead to functional disruption. However, the possibility of such changes leading to various functional disruptions and the underlying mechanisms involved require further study.

Manipulation of the recipient retinal environment by ectopic expression of neurotrophic growth factors can improve transplanted photoreceptor integration and survival

Degeneration of the neural retina is the leading cause of untreatable blindness in the developed world. Stem cell replacement therapy offers a novel strategy for retinal repair. Postmitotic photoreceptor precursors derived from the early postnatal (P) retina are able to migrate and integrate into the adult mouse retina following transplantation into the subretinal space, but it is likely that a large number of these cells would be required to restore vision. The adult recipient retina presents a very different environment to that from which photoreceptor precursor donor cells isolated from the developing postnatal retina are derived. Here we considered the possibility that modulation of the recipient environment by ectopic expression of developmentally regulated growth factors, normally present during photoreceptor development, might enhance the migration and integration of transplanted cells into the adult neural retina. Adeno-associated viral (AAV) vectors were used to introduce three growth factors previously reported to play a role in photoreceptor development, IGF1, FGF2, and CNTF, into the adult retina, prior to transplantation of P4 cells derived from the Nrl.GFP(+ve) neural retina. At 3 weeks posttransplantation the number of integrated, differentiated photoreceptor cells present in AAV-mediated neurotrophic factor-treated eyes was assessed and compared to control treated contralateral eyes. We show, firstly, that it is possible to manipulate the recipient retinal microenvironment via rAAV-mediated gene transfer with respect to these developmentally relevant growth factors. Moreover, when combined with cell transplantation, AAV-mediated expression of IGF1 led to significantly increased levels of cell integration, while overexpression of FGF2 had no significant effect on integrated cell number. Conversely, expression of CNTF led to a significant decrease in cell integration and an exacerbated glial response that led to glial scarring. Together, these findings demonstrate the importance of the extrinsic environment of the recipient retina for photoreceptor cell transplantation and show for the first time that it is possible to manipulate this environment using viral vectors to influence photoreceptor transplantation efficiency.

IGF-I ameliorates hippocampal neurodegeneration and protects against cognitive deficits in an animal model of temporal lobe epilepsy

Epilepsy is a major neurological disease, and patients often show spatial memory deficits. Thus, there is a need of effective new therapeutic approaches. IGF-I has been shown to be neuroprotective following a number of experimental insults to the nervous system, and in a variety of animal models of neurodegenerative diseases. In the present work, we investigated the possible neuroprotective effects of IGF-I following unilateral intrahippocampal administration of kainic acid (KA), an animal model of temporal lobe epilepsy (TLE). KA induced cell death, as shown by FluoroJade B, and extensive cell loss in both the ipsilateral and contralateral CA3 and CA4 areas, as well as granule cell dispersal in the DG, as revealed by Cresyl violet staining. KA also resulted in intense astrogliosis and microgliosis, as assessed by the number of GFAP and CD11b immunopositive cells, respectively, and increased hippocampal neurogenesis. Exposure to the Morris Water Maze task revealed that mice injected with KA were deficient in spatial learning and both short- and long-term memories, when tested in a larger diameter pool, which requires the use of allocentric strategies. When tested in a smaller pool, only long-term memory was impaired. Administration of IGF-I decreased seizure severity, hippocampal neurogenesis, and protected against neurodegeneration at the cellular level as assessed by FluoroJade B and Cresyl violet staining, as well as the number of GFAP and CD11b immunopositive cells. Furthermore, IGF-I abolished the cognitive deficits. Our results support that IGF-I could have a possible therapeutic potential in TLE.

Lentivirus-mediated expression of insulin-like growth factor-I promotes neural stem/precursor cell proliferation and enhances their potential to generate neurons

Strategies to enhance neural stem/precursor cell (NPC) capacity to yield multipotential, proliferative, and migrating pools of cells that can efficiently differentiate into neurons could be crucial for structural repair after neurodegenerative damage. Here, we have generated a lentiviral vector for expression of insulin-like growth factor-I (IGF-1) and investigated the impact of IGF-1 transduction on the properties of cultured NPCs (IGF-1-NPCs). Under proliferative conditions, IGF-1 transduction promoted cell cycle progression via cyclin D1 up-regulation and Akt phosphorylation. Remarkably upon differentiation-inducing conditions, IGF-1-NPCs cease to proliferate and differentiate to a greater extent into neurons with significantly longer neurites, at the expense of astrocytes. Moreover, using live imaging we provide evidence that IGF-1 transduction enhances the motility and tissue penetration of grafted NPCs in cultured cortical slices. These results illustrate the important consequence of IGF-1 transduction in regulating NPC functions and offer a potential strategy to enhance the prospective repair potential of NPCs.

Temporal and regional changes in IGF-1/IGF-1R signaling in the mouse brain after traumatic brain injury

Although neurotrophic factors such as nerve growth factor, basic fibroblast growth factor, brain-derived neurotrophic factor, and neurotrophin 4/5 are elevated after traumatic brain injury (TBI), little is known about the endogenous response of insulin-like growth factor-1 (IGF-1). We evaluated IGF-1, IGF-1 receptor (IGF-1R), and total and phosphorylated Akt (p-Akt), a known downstream mediator of IGF-1 signaling, using ELISA, Western blotting, and immunohistochemistry at 1, 6, 24, 48, and 72 h following 0.5-mm controlled cortical impact brain injury in adult mice. IGF-1 was transiently upregulated in homogenates of injured cortex at 1 h, and cells with increased IGF-1 immunoreactivity were observed in and around the cortical contusion site up to 48 h. IGF-1R and total Akt levels in cortical homogenates were unchanged, although immunohistochemistry revealed regional changes. In contrast, serine p-Akt levels increased significantly in homogenates at 6 h post-injury. Interestingly, delayed increases in vascular IGF-1R, total Akt, and p-Akt immunostaining were observed in and around the cortical contusion. IGF-1 and its downstream mediators were also upregulated in the subcortical white matter. Our findings indicate that moderate TBI results in a brief induction of IGF-1 and its signaling components in the acute post-traumatic period. This may reflect an attempt at endogenous neuroprotection or repair.

Neuroprotective effects of IGF-I following kainic acid-induced hippocampal degeneration in the rat

Insulin-like growth factor I (IGF-I) has been shown to act as a neuroprotectant both in in vitro studies and in in vivo animal models of ischemia, hypoxia, trauma in the brain or the spinal cord, multiple and amyotrophic lateral sclerosis, Alzheimer's and Parkinson's disease. In the present study, we investigated the neuroprotective potential of IGF-I in the "kainic acid-induced degeneration of the hippocampus" model of temporal lobe epilepsy. Increased cell death--as detected by FluoroJade B staining--and extensive cell loss--as determined by cresyl violet staining--were observed mainly in the CA3 and CA4 areas of the ipsilateral and contralateral hippocampus, 7 days following intrahippocampal administration of kainic acid. Kainic acid injection also resulted in intense astrogliosis--as assessed by the number of glial fibrillary acidic protein (GFAP) immunopositive cells--in both hemispheres, forming a clear astroglial scar ipsilaterally to the injection site. Heat-shock protein 70 (Hsp70) immunopositive cells were also observed in the ipsilateral dentate gyrus (DG) following kainic acid injection. When IGF-I was administered together with kainic acid, practically no signs of degeneration were detected in the contralateral hemisphere, while in the ipsilateral, there was a smaller degree of cell loss, reduced number of FluoroJade B-stained cells, decreased reactive gliosis and fewer Hsp70-positive cells. Our present results extend further the cases in which IGF-I is shown to exhibit neuroprotective properties in neurodegenerative processes in the CNS.

Analysis of neurotrophins in human serum by immunoaffinity capillary electrophoresis (ICE) following traumatic head injury

Neurotrophins, including brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), neurotrophin-3 (NT-3), neurotrophin-4 (NT-4), and beta-nerve growth factor (beta-NGF), play an active role in the development, maintenance and survival of cells of the central nervous system (CNS). Previous research has indicated that a decrease in concentrations of these neurotrophins is often associated with cell death and ultimately patient demise. However, much of the research conducted analyses of samples taken directly from the CNS, i.e., of samples that are not readily available in clinical trauma centers. In an attempt to obtain a method for evaluating neurotrophins in a more readily accessible matrix, i.e., serum, a precise and accurate immunoaffinity capillary electrophoresis (ICE) method was developed and applied to measure neurotrophins in serum from patients with various degrees of head injury. The five neurotrophins of interest were extracted and concentrated by specific immunochemically immobilized antibodies, bound directly to the capillary wall, and eluted and separated in approximately 10min. NT-3, BDNF, CNTF and beta-NGF showed a marked decrease in concentration as the severity of the head injury increased: mild versus severe: 91% decrease for NT-3; 93 % decrease for BDNF; 93 % decrease for CNTF; and a 87 % decrease for beta-NGF. This decrease in concentration is consistent with the neuro-protective roles that neurotrophins play in the maintenance and survival of neuronal cells. The results obtained by the ICE method were closely comparable with those generated by a commercially available ELISA method.

IFATS collection: The conditioned media of adipose stromal cells protect against hypoxia-ischemia-induced brain damage in neonatal rats

Adipose tissue stroma contains a population of mesenchymal stem cells, which support repair when administered to damaged tissues, in large part through secreted trophic factors. We directly tested the ability of media collected from cultured adipose-derived stem cells (ASCs) to protect neurons in a rat model of brain hypoxic-ischemic (HI) injury. Concentrated conditioned medium from cultured rat ASCs (ASC-CM) or control medium was infused through the jugular vein of neonatal Sprague-Dawley rats subjected to HI injury. The ASC-CM was administered either 1 hour before or 24 hours after induction of injury. Analysis at 1 week indicated that administration at both time points significantly protected against hippocampal and cortical volume loss. Analysis of parallel groups for behavioral and learning changes at 2 months postischemia demonstrated that both treated groups performed significantly better than the controls in Morris water maze functional tests. Subsequent post-mortem evaluation of brain damage at the 2-month time point confirmed neuronal loss to be similar to that observed at 1 week for all groups. We have identified several neurotrophic factors in ASC-CM, particularly insulin-like growth factor-1 and brain-derived neurotrophic factor, which are important factors that could contribute to the protective effects of ASCs observed in studies with both in vitro and in vivo neuronal injury models. These data suggest that delivery of the milieu of factors secreted by ASCs may be a viable therapeutic option for treatment of HI, as well as other brain injuries.

Reductions in qEEG slowing over 1 year and after treatment with Cerebrolysin in patients with moderate-severe traumatic brain injury

Changes in quantitative EEG (qEEG) recordings over a 1-year period and the effects of Cerebrolysin (Cere) on qEEG slowing and cognitive performance were investigated in postacute moderate-severe traumatic brain injury (TBI) patients. Time-related changes in qEEG activity frequency bands (increases of alpha and beta, and reductions of theta and delta relative power) and in qEEG slowing (reduction of EEG power ratio) were statistically significant in patients with a disease progress of less than 2 years at baseline, but not in those patients having a longer disease progress time. Slowing of qEEG activity was also found to be significantly reduced in TBI patients after 1 month of treatment with Cere and 3 months later. Therefore, Cere seems to accelerate the time-related reduction of qEEG slowing occurring in untreated patients. The decrease of qEEG slowing induced by Cere correlated with the improvement of attention and working memory. Results of this exploratory study suggest that Cere might improve the functional recovery after brain injury and encourage the conduction of further controlled clinical trials.

Neuroprotection by Imipramine against lipopolysaccharide-induced apoptosis in hippocampus-derived neural stem cells mediated by activation of BDNF and the MAPK pathway

Depression is accompanied by the activation of the inflammatory-response system, and increased production of proinflammatory cytokines may play a role in the pathophysiology of depressive disorders. Imipramine (IM), a tricyclic antidepressant drug, has recently been shown to promote neurogenesis and improve the survival rate of neurons in the hippocampus. However, whether IM elicits a neuroprotective or anti-inflammatory effect, or promotes the differentiation of neural stem cells (NSCs) remains to be elucidated. In this study, we cultured NSCs derived from the hippocampal tissues of adult rats as an in vitro model to evaluate the NSCs drug-modulation effects of IM. Our results showed that 3 microM IM treatment significantly increased the survival rate of NSCs, and up-regulated the mRNA and protein expression of brain-derived neurotrophic factor (BDNF) and Bcl-2 in Day-7 IM-treated NSCs. Similar to BDNF-treated effect, incubation of NSCs with 3 microM IM increased Bcl-2 protein levels and further prevented lipopolysaccharide (LPS)-induced apoptosis through the activation of the mitogen-activated protein kinase (MAPK)/extracellular-regulated kinase (ERK) pathway. Inhibition of BDNF expression with small interfering RNA (siRNA), or blocking the MAPK pathway with U0126 further significantly decreased Bcl-2 protein levels and abrogated the neuroprotective effects of IM against LPS-induced apoptosis in NSCs. In addition, the percentages of serotonin and MAP-2-positive neuronal cells in the Day 7 culture of IM-treated NSCs were significantly increased. By using microdialysis with high performance liquid chromatography-electrochemical detection, the functional release of serotonin in the process of serotoninergic differentiation of IM-treated NSCs was concomitantly increasing and mediated by the activation of the BDNF/MAPK/ERK pathway/Bcl-2 cascades. In sum, the study results indicate that IM can increase the neuroprotective effects, suppress the LPS-induced inflammatory process, and promote serotoninergic differentiation in NSCs via the modulation of the BDNF/MAPK/ERK pathway/Bcl-2 cascades.

Evidence of Abeta- and transgene-dependent defects in ERK-CREB signaling in Alzheimer's models

Extracellular-signal regulated kinase (ERK) signaling is critical for memory and tightly regulated by acute environmental stimuli. In Alzheimer disease transgenic models, active ERK is shown to first be increased, then later reduced, but whether these baseline changes reflect disruptions in ERK signaling is less clear. We investigated the influence of the familial Alzheimer's disease transgene APPsw and beta-amyloid peptide (Abeta) immunoneutralization on cannulation injury-associated (i.c.v. infusion) ERK activation. At both 12 and 22 months of age, the trauma-associated activation of ERK observed in Tg(-) mice was dramatically attenuated in Tg(+). In cortices of 22-month-old non-infused mice, a reduction in ERK activation was observed in Tg(+), relative to Tg(-) mice. Intracerebroventricular (i.c.v.) anti-Abeta infusion significantly increased phosphorylated ERK, its substrate cAMP-response element-binding protein (CREB) and a downstream target, the NMDA receptor subunit. We also demonstrated that Abeta oligomer decreased active ERK and subsequently active CREB in human neuroblastoma cells, which could be prevented by oligomer immunoneutralization. Abeta oligomers also inhibited active ERK and CREB in primary neurons, in addition to reducing the downstream post-synaptic protein NMDA receptor subunit. These effects were reversed by anti-oligomer. Our data strongly support the existence of an APPsw transgene-dependent and Abeta oligomer-mediated defect in regulation of ERK activation.

Running exercise- and antidepressant-induced increases in growth and survival-associated signaling molecules are IGF-dependent

It is known that physical exercise increases hippocampal brain-derived neurotrophic factor (BDNF) mRNA and protein, as well as the expression of several pro-survival signaling proteins and that many of these effects depend on the uptake of peripheral insulin-like growth factor-1 (IGF-1) into the CNS. Because treatment with antidepressants has similar effects upon neurotrophin expression, we investigated whether antidepressant-induced BDNF changes also depend on IGF-1 uptake, as well as whether IGF-1 plays a role in the exercise/antidepressant-induced expression of molecules associated with plasticity/growth (GAP-43, SCG-10) and the intracellular activation of molecules associated with neuronal survival (Akt, ERK1/2). We evaluated the effects of a well known monoamine oxidase inhibitor, tranylcypromine, on BDNF mRNA and protein levels and phospho-Akt and phospho-ERK1/2 immunoreactivity, both with and without systemic blockade of IGF-1 uptake through the use of an antiserum raised against IGF-1. Anti-IGF-1 reversed the increase in BDNF mRNA and protein elicited by exercise as well as tranylcypromine. Exercise also significantly enhanced transcription of axon growth protein, GAP-43, an effect that was also evidenced to be IGF-1-dependent. The combination of exercise-plus-tranylcypromine also increased several cell survival signaling measures, but the BDNF changes associated with the combination treatment appeared to be independent of IGF-1 uptake. Together, these results indicate that the uptake of peripheral IGF-1 in the CNS is essential for antidepressant- as well as exercise-induced enhancement in hippocampal BDNF expression and thus, enhanced hippocampal neuronal survival and plasticity.

Insulin-like growth factor-I enhances the biological activity of brain-derived neurotrophic factor on cerebrocortical neurons

Insulin-like growth factor (IGF)-I and brain-derived neurotrophic factor (BDNF) act within the brain to enhance neuronal survival and plasticity. We extend these findings by showing that the presence of both neurotrophins is required to depress the rise in intracellular Ca2+ caused by glutamate in primary cultures of cerebrocortical neurons. IGF-I enhanced expression of BDNF receptors (Trk-B) and increased the ability of BDNF to induce ERK1/2 phosphorylation. This IGF-I-induced increase in BDNF responsiveness describes a new interaction between these peptides in the brain.

Traumatic Brain Injury Induced Neuroprotection of Retinal Ganglion Cells to Optic Nerve Crush

Optic nerve crush injury leads to death of retinal ganglion cells (RGCs), both as a direct result of the primary injury and via secondary degeneration induced by neurotoxins secreted by dying RGCs. Studies have shown that, if optic nerve crush is preceded by an unrelated injury to another part of the central nervous system, for example, the spinal cord, the ensuing T cell-mediated protective autoimmunity results in a significant increase in RGC survival. In this study, we used the controlled cortical impact paradigm to induce unilateral traumatic brain injury (TBI) in rats at different times before they were contralaterally subjected to a mild optic nerve crush. Survival of RGCs, assessed 2 weeks after crush injury, was significantly increased when the crush was inflicted 11 days after TBI, but not when the two injuries were concomitant. The beneficial effect was unaffected by injection of low-dose methylprednisolone MP (1 mg/kg), but was inhibited after a high-dose injection (30 mg/kg). Brain-derived neurotrophic factor (BDNF) mRNA, assayed at intervals after TBI, was increased in the retina ipsilateral to TBI but decreased in the contralateral retina. BDNF peaked 1 day after TBI, decreased on day 11, and rose again on day 21. It thus seems that brain injury sustained a certain time before optic nerve injury has a protective effect on RGC survival. This neuroprotective effect, which appears unrelated to retinal BDNF, is inhibited by high-dose MP, commonly used clinically to treat traumatic optic neuropathy.