The neuroprotective peptide NAP inhibits the aggregation of the beta-amyloid peptide

Delineating the Role of GxxxG Motif in Amyloidogenesis: A New Perspective in Targeting Amyloid-Beta Mediated AD Pathogenesis

The pursuit of a novel structural motif that can shed light on the key functional attributes is a primary focus in the study of protein folding disorders. Decades of research on Alzheimer's disease (AD) have centered on the Amyloid β (Aβ) pathway, highlighting its significance in understanding the disorder. The diversity in the Aβ pathway and the possible silent tracks which are yet to discover, makes it exceedingly intimidating to the interdisciplinary scientific community. Over the course of AD research, Aβ has consistently been at the forefront of scientific inquiry and discussion. In this review, we epitomize the role of a potential structural motif (GxxxG motif) that may provide a new horizon to the Aβ conflict. We emphasize on how comprehensive understanding of this motif from a structure-function perspective may pave the way for designing novel therapeutics intervention in AD and related diseases.

Aβ-oligomers: A potential therapeutic target for Alzheimer's disease

The cascade of amyloid formation relates to multiple complex events at the molecular level. Previous research has established amyloid plaque deposition as the leading cause of Alzheimer's disease (AD) pathogenesis, detected mainly in aged population. The primary components of the plaques are two alloforms of amyloid-beta (Aβ), Aβ_1-42 and Aβ_1-40 peptides. Recent studies have provided considerable evidence contrary to the previous claim indicating that amyloid-beta oligomers (AβOs) as the main culprit responsible for AD-associated neurotoxicity and pathogenesis. In this review, we have discussed the primary features of AβOs, such as assembly formation, the kinetics of oligomer formation, interactions with various membranes/membrane receptors, the origin of toxicity, and oligomer-specific detection methods. Recently, the discovery of rationally designed antibodies has opened a gateway for using synthesized peptides as a grafting component in the complementarity determining region (CDR) of antibodies. Thus, the Aβ sequence motif or the complementary peptide sequence in the opposite strand of the β-sheet (extracted from the Protein Data Bank: PDB) helps design oligomer-specific inhibitors. The microscopic event responsible for oligomer formation can be targeted, and thus prevention of the overall macroscopic behaviour of the aggregation or the associated toxicity can be achieved. We have carefully reviewed the oligomer formation kinetics and associated parameters. Besides, we have depicted a thorough understanding of how the synthesized peptide inhibitors can impede the early aggregates (oligomers), mature fibrils, monomers, or a mixture of the species. The oligomer-specific inhibitors (peptides or peptide fragments) lack in-depth chemical kinetics and optimization control-based screening. In the present review, we have proposed a hypothesis for effectively screening oligomer-specific inhibitors using the chemical kinetics (determining the kinetic parameters) and optimization control strategy (cost-dependent analysis). Further, it may be possible to implement the structure-kinetic-activity-relationship (SKAR) strategy instead of structure-activity-relationship (SAR) to improve the inhibitor's activity. The controlled optimization of the kinetic parameters and dose usage will be beneficial for narrowing the search window for the inhibitors.

Alzheimer's Disease: Innovative Therapeutic Approaches Based on Peptides and Nanoparticles

Alzheimer's disease (AD) is the main cause of dementia in the world and its etiology is not yet fully understood. The pathology of AD is primarily characterized by intracellular neurofibrillary tangles and extracellular amyloid-β plaques. Unfortunately, few treatment options are available, and most treat symptoms, as is the case of acetylcholinesterase inhibitors (IAChE) and N-methyl-d-aspartate receptor antagonists. For more than 20 years pharmaceutical research has targeted the "amyloid cascade hypothesis," but this has not produced meaningful results, leading researchers to focus now on other characteristics of the disease and on multitarget approaches. This review aims to evaluate some new treatments that are being developed and studied. Among these are new treatments based on peptides, which have high selectivity and low toxicity; however, these compounds have a short half-life and encounter challenges when crossing the blood-brain barrier. The present review discusses up-and-coming peptides tested as treatments and explores some nanotechnological strategies to overcome the downsides. These compounds are promising, as they not only act on the symptoms but also aim to prevent progressive neuronal loss.

Breaker peptides against amyloid-β aggregation: a potential therapeutic strategy for Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder, for which blocking the early steps of extracellular misfolded amyloid-β (Aβ) aggregation is a promising therapeutic approach. However, the pathological features of AD progression include the accumulation of intracellular tau protein, membrane-catalyzed cell death and the abnormal deposition of Aβ. Here, we focus on anti-amyloid breaker peptides derived from the Aβ sequence and non-Aβ-based peptides containing both natural and modified amino acids. Critical aspects of the breaker peptides include N-methylation, conformational restriction through cyclization, incorporation of unnatural amino acid, fluorinated molecules, polymeric nanoparticles and PEGylation. This review confers a general idea of such breaker peptides with in vitro and in vivo studies, which may advance our understanding of AD pathology and develop an effective treatment strategy against AD.

Neuroprotective Effect Of Peptide Fractions from Chia (Salvia hispanica) on H2O2-Induced Oxidative Stress-Mediated Neuronal Damage on N1E-115 Cell Line

Neurodegenerative diseases (ND) affect around a billion people worldwide. Oxidative stress plays a critical role in the activation of neuronal death mechanisms, implicated in the ND etiology. In the present research, the neuroprotective effect of the S. hispanica protein derivatives is evaluated, on neuronal cells N1E-115, after the damage induction with H₂O₂. From the protein-rich fraction of S. hispanica, three peptide fractions were obtained (3-5, 1-3 y < 1 kDa) and its neuroprotective effect on neuronal cells N1E-115 was evaluated, through the antioxidant pathway. In the toxicity assay, the peptide fractions showed viability greater than 90%. When N1E-115 cells were incubated with 100 µM H₂O₂, fractions 1-3 and < 1 kDa, presented cell viability of 66.64% ± 3.2 and 67.32% ± 2.8, respectively. Fractions 1-3 and < 1 kDa reduced by 41.73% ± 3.2 and 40.87% ± 2.8, respectively, the ROS production compared to the control, without significant statistical difference between both fractions (p < 0.05), while F3-5 kDa, only reduced the ROS production by 21.95% ± 2.4. The protective effect observed in the < 3 kDa fractions could be associated with its antioxidant activity, which represents an important study target.

Immune-modulatory Properties of the Octapeptide NAP in Campylobacter jejuni Infected Mice Suffering from Acute Enterocolitis

Human infections with the food-borne zoonotic pathogen Campylobacter jejuni are progressively rising and constitute serious global public health and socioeconomic burdens. Hence, application of compounds with disease-alleviating properties are required to combat campylobacteriosis and post-infectious sequelae. In our preclinical intervention study applying an acute C. jejuni induced enterocolitis model, we surveyed the anti-pathogenic and immune-modulatory effects of the octapeptide NAP which is well-known for its neuroprotective and anti-inflammatory properties. Therefore, secondary abiotic IL-10^−/− mice were perorally infected with C. jejuni and intraperitoneally treated with synthetic NAP from day 2 until day 5 post-infection. NAP-treatment did not affect gastrointestinal C. jejuni colonization but could alleviate clinical signs of infection that was accompanied by less pronounced apoptosis of colonic epithelial cells and enhancement of cell regenerative measures on day 6 post-infection. Moreover, NAP-treatment resulted in less distinct innate and adaptive pro-inflammatory immune responses that were not restricted to the intestinal tract but could also be observed in extra-intestinal and even systemic compartments. NAP-treatment further resulted in less frequent translocation of viable pathogens from the intestinal tract to extra-intestinal including systemic tissue sites. For the first time, we here provide evidence that NAP application constitutes a promising option to combat acute campylobacteriosis.

Direct evidence for binding of aluminum to NAP anti-amyloid peptide and its analogs

NAP (NAPVSIPQ) is a small peptide derived from the activity-dependent neuroprotective protein (ADNP), which provides neuroprotection against amyloid-β peptide toxicity associated with Alzheimer disease. Several metal ions are able to promote the formation of amyloid-β peptide oligomers and protofibrils in human brain tissue. Although the relationship between metal ions and amyloid-β peptide peptides is extensively investigated, that with the NAP peptide is less understood. Nevertheless, our previous research revealed unexpected iron binding to NAP peptide and its analogs. However, a link between aluminum ions, Alzheimer disease and amyloid-β peptide or NAP peptides still remains controversial. Therefore, we have investigated the possible binding of aluminum ions to NAP peptide and its four analogs. Indeed, MALDI-ToF mass spectrometry (MS), including MS/MS study, and Fourier transform infrared (FT-IR) spectroscopy revealed an unexpected pattern of aluminum ion binding to both NAP peptide and its analogs. Our results have been discussed with respect to NAP protection against Alzheimer disease-related neurotoxicity.

Recent advances in the design and applications of amyloid-β peptide aggregation inhibitors for Alzheimer's disease therapy

Alzheimer's disease (AD) is an irreversible neurological disorder that progresses gradually and can cause severe cognitive and behavioral impairments. This disease is currently considered a social and economic incurable issue due to its complicated and multifactorial characteristics. Despite decades of extensive research, we still lack definitive AD diagnostic and effective therapeutic tools. Consequently, one of the most challenging subjects in modern medicine is the need for the development of new strategies for the treatment of AD. A large body of evidence indicates that amyloid-β (Aβ) peptide fibrillation plays a key role in the onset and progression of AD. Recent studies have reported that amyloid hypothesis-based treatments can be developed as a new approach to overcome the limitations and challenges associated with conventional AD therapeutics. In this review, we will provide a comprehensive view of the challenges in AD therapy and pathophysiology. We also discuss currently known compounds that can inhibit amyloid-β (Aβ) aggregation and their potential role in advancing current AD treatments. We have specifically focused on Aβ aggregation inhibitors including metal chelators, nanostructures, organic molecules, peptides (or peptide mimics), and antibodies. To date, these molecules have been the subject of numerous in vitro and in vivo assays as well as molecular dynamics simulations to explore their mechanism of action and the fundamental structural groups involved in Aβ aggregation. Ultimately, the aim of these studies (and current review) is to achieve a rational design for effective therapeutic agents for AD treatment and diagnostics.

Protective effect of a 3 kDa peptide obtained from beef myofibrillar protein using alkaline-AK on neuronal cells

The protective effect of two 3 kDa peptide fractions (AK3KF1 and AK3KF2), obtained from beef myofibrillar protein using an inexpensive enzyme (alkaline-AK) on human neuronal cells (SH-SY5Y) against H₂O₂-induced apoptosis was investigated. These peptides were isolated and further separated by fast protein liquid chromatography (FPLC), and their protective effect against H₂O₂-mediated cell death was measured by determining cell viability, nitric oxide (NO) production, mitochondrial membrane potential (MMP), apoptosis, morphological changes in cell nuclei, and in vitro antioxidant assays. The results indicated that treatment with peptide fractions increased cell viability and MMP, and decreased NO production, fragmentation of cell nuclei, and apoptosis in H₂O₂-treated SH-SY5Y cells. This is the first study to report neuroprotective effects of a peptide obtained from beef myofibrillar protein. The peptide sequence was identified as Thr-Gln-Lys-Lys-Val-Ile-Phe-Cys (TQKKVIFC). Thus, these findings suggest that TQKKVIFC can prevent neuronal cell death and could be useful in preventing neurodegenerative diseases.

Reduction of aluminum ion neurotoxicity through a small peptide application - NAP treatment of Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia in late life. It is difficult to precisely diagnose AD at early stages, making biomarker search essential for further developments. The objective of this study was to identify protein biomarkers associated with aluminum ions toxicity (AD-like toxicity) in a human neuroblastoma cell model, SH-SY5Y and assess potential prevention by NAP (NAPVSIPQ). Complete proteomic techniques were implemented. Four proteins were identified as up-regulated with aluminum ion treatment, CBP80/20-dependent translation initiation factor (CTIF), Early endosome antigen 1 (EEA1), Leucine-rich repeat neuronal protein 4 (LRRN4) and Phosphatidylinositol 3-kinase regulatory subunit beta (PI3KR2). Of these four proteins, EEA1 and PI3KR2 were down-regulated after NAP-induced neuroprotective activity in neuroblastoma cells. Thus, aluminum ions may increase the risk for neurotoxicity in AD, and the use of NAP is suggested as a treatment to provide additional protection against the effects of aluminum ions, via EEA1 and PI3KR2, associated with sorting and processing of the AD amyloid precursor protein (APP) through the endosomal system.

C-Terminal Fragment, Aβ39-42-Based Tetrapeptides Mitigates Amyloid-β Aggregation-Induced Toxicity

Since the introduction of acetyl cholinesterase inhibitors as the first approved drugs by the US Food and Drug Administration for Alzheimer's disease (AD) in clinics, less than satisfactory success in the design of anti-AD agents has impelled the scientists to also focus toward inhibition of Aβ aggregation. Considering the specific binding of fragments for their parent peptide, herein, we synthesized more than 40 new peptides based on a C-terminus tetrapeptide fragment of Aβ_1-42. Initial screening by MTT cell viability assay and supportive results by ThT fluorescence assay led us to identify a tetrapeptide showing complete inhibition for Aβ_1-42 aggregation. Peptide 20 displayed 100% cell viability at 20 μM concentration, while at lower concentrations of 10 and 2 μM 76.6 and 70% of cells were viable. Peptide 20 was found to restrict the conformational transition of Aβ_1-42 peptide toward β-sheet structure. Inhibitory activity of tetrapeptide 20 was further evidenced by the absence of Aβ_1-42 aggregates in electron microscopy. Peptide 20 and other significantly active tetrapeptide analogues could prove imperative in the future design of anti-AD agents.

Anti-inflammatory Effects of the Octapeptide NAP in Human Microbiota-Associated Mice Suffering from Subacute Ileitis

The octapeptide NAP is well known for its neuroprotective properties. We here investigated whether NAP treatment could alleviate pro-inflammatory immune responses during experimental subacute ileitis. To address this, mice with a human gut microbiota were perorally infected with one cyst of Toxoplasma gondii (day 0) and subjected to intraperitoneal synthetic NAP treatment from day 1 until day 8 postinfection (p.i.). Whereas placebo (PLC) control animals displayed subacute ileitis at day 9 p.i., NAP-treated mice exhibited less pronounced pro-inflammatory immune responses as indicated by lower numbers of intestinal mucosal T and B lymphocytes and lower interferon (IFN)-γ concentrations in mesenteric lymph nodes. The NAP-induced anti-inflammatory effects were not restricted to the intestinal tract but could also be observed in extra-intestinal including systemic compartments, given that pro-inflammatory cytokines were lower in liver, kidney, and lung following NAP as compared to PLC application, whereas at day 9 p.i., colonic and serum interleukin (IL)-10 concentrations were higher in the former as compared to the latter. Remarkably, probiotic commensal bifidobacterial loads were higher in the ileal lumen of NAP as compared to PLC-treated mice with ileitis. Our findings thus further support that NAP might be regarded as future treatment option directed against intestinal inflammation.

The octapetide NAP alleviates intestinal and extra-intestinal anti-inflammatory sequelae of acute experimental colitis

The octapeptide NAP has been shown to exert neuroprotective properties and reduce neuro-inflammatory responses. The aim of the present study was to investigate if NAP provides anti-inflammatory effects in acute murine colitis. To address this, C57BL/6 j mice were challenged with 3.5% dextran sulfate sodium from day 0 until day 6 to induce colitis, either treated intraperitoneally with NAP or placebo (NaCl 0.9%) from day 1 until day 6 post-induction (p.i.) and subjected to in depth macroscopic, microscopic and immunological evaluations. Whereas NAP application did not alleviate macroscopic (i.e. clinical) sequelae of colitis, lower numbers of apoptotic, but higher counts of proliferating/regenerating colonic epithelial cells could be observed in NAP as compared to placebo treated mice at day 7 p.i. Furthermore, lower numbers of adaptive immune cells such as T lymphocytes and regulatory T cells were abundant in the colonic mucosa and lamina propria upon NAP versus placebo treatment that were accompanied by less colonic secretion of pro-inflammatory mediators including IFN-γ and nitric oxide at day 7 p.i. In mesenteric lymph nodes, pro-inflammatory IFN-γ, TNF and IL-6 concentrations were increased in placebo, but not NAP treated mice at day 7 p.i., whereas interestingly, elevated anti-inflammatory IL-10 levels could be observed in NAP treated mice only. The assessed anti-inflammatory properties of NAP were not restricted to the intestinal tract, given that in extra-intestinal compartments such as the kidneys, IFN-γ levels increased in placebo, but not NAP treated mice upon colitis induction. NAP induced effects were accompanied by distinct changes in intestinal microbiota composition, given that colonic luminal loads of bifidobacteria, regarded as anti-inflammatory, "health-promoting" commensal species, were two orders of magnitude higher in NAP as compared to placebo treated mice and even naive controls. In conclusion, NAP alleviates intestinal and extra-intestinal pro-inflammatory sequelae of acute experimental colitis and may provide novel treatment options of intestinal inflammatory diseases in humans.

Toward a Rational Design to Regulate β-Amyloid Fibrillation for Alzheimer's Disease Treatment

The last decades have witnessed a growing global burden of Alzheimer's disease (AD). Evidence indicates that the onset and progression of AD is associated with β-amyloid (Aβ) peptide fibrillation. As such, there is a strong passion with discovering potent Aβ fibrillation inhibitors that can be developed into anti-amyloiddogenic agents for AD treatment. Current challenges that have arisen with this development involve with Aβ oligomer toxicity suppression and Blood Brain Barrier penetration capability. Considering most natural or biological events, one would observe that there is usually a "seed" to direct natural materials to assemble in response to a certain stimulation. Inspired by this, several materials or compounds, including nanoparticle, peptide or peptide mimics, and organic molecules, have been designed for the purpose of redirecting or impeding Aβ aggregation. Achieving these tasks requires comprehensive understanding on (1) initial Aβ assembly into insoluble deposits, (2) main concerns with fibrillation inhibition, and (3) current major methodologies to disrupt the aggregation. Herein, the objective of this review is to address these three areas, and enable the pathway for a promising therapeutic agent design for AD treatment.

Peptides as Potential Therapeutics for Alzheimer's Disease

Intracellular synthesis, folding, trafficking and degradation of proteins are controlled and integrated by proteostasis. The frequency of protein misfolding disorders in the human population, e.g., in Alzheimer's disease (AD), is increasing due to the aging population. AD treatment options are limited to symptomatic interventions that at best slow-down disease progression. The key biochemical change in AD is the excessive accumulation of per-se non-toxic and soluble amyloid peptides (Aβ(1-37/44), in the intracellular and extracellular space, that alters proteostasis and triggers Aβ modification (e.g., by reactive oxygen species (ROS)) into toxic intermediate, misfolded soluble Aβ peptides, Aβ dimers and Aβ oligomers. The toxic intermediate Aβ products aggregate into progressively less toxic and less soluble protofibrils, fibrils and senile plaques. This review focuses on peptides that inhibit toxic Aβ oligomerization, Aβ aggregation into fibrils, or stabilize Aβ peptides in non-toxic oligomers, and discusses their potential for AD treatment.

Davunetide improves spatial learning and memory in Alzheimer's disease-associated rats

Memory loss and cognition decline are the main clinical manifestations of Alzheimer's disease (AD). Amyloid β protein (Aβ) aggregated in the brain is one of the key pathological characteristics of AD and responsible for the deficits in learning and memory. It is reported that davunetide, an octapeptide derived from activity-dependent neuroprotective protein (ADNP), inhibited Aβ aggregation and Aβ-induced neurotoxicity. To further characterize the neuroprotective roles of davunetide and its possible mechanism, the present study investigated the effects of davunetide on Aβ1-42-induced impairments in spatial memory, synaptic plasticity and hippocampal AKT level. In Morris water maze (MWM) test, bilateral intrahippocampal injection of Aβ1-42 significantly increased escape latency and decreased target quadrant swimming time of rats, while three weeks of intranasal application of davunetide reversed the Aβ1-42-induced learning deficits and memory loss in a dose-dependent manner. In vivo field potentiation recording showed that Aβ1-42 suppressed long-term potentiation (LTP) of excitatory postsynaptic potential (fEPSP) in the hippocampal CA1 region of rats, while davunetide effectively blocked the suppression of LTP, without affecting paired-pulse facilitation (PPF). Western blotting experiments showed a significant decrease in the level of hippocampal p-AKT (Ser473), not total AKT, in Aβ1-42 only group, which was mostly antagonized by davunetide treatment. These findings demonstrate that davunetide, probably by enhancing PI3K/AKT pathway, plays an important positive role in attenuating Aβ1-42-induced impairments in spatial memory and synaptic plasticity, suggesting that davunetide could be an effective therapeutic candidate for the prevention and treatment of neurodegenerative disease such as AD.

Rationally Designed Peptides and Peptidomimetics as Inhibitors of Amyloid-β (Aβ) Aggregation: Potential Therapeutics of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease with no clinically accepted treatment to cure or halt its progression. The worldwide effort to develop peptide-based inhibitors of amyloid-β (Aβ) aggregation can be considered an unplanned combinatorial experiment. An understanding of what has been done and achieved may advance our understanding of AD pathology and the discovery of effective therapeutic agents. We review here the history of such peptide-based inhibitors, including those based on the Aβ sequence and those not derived from that sequence, containing both natural and unnatural amino acid building blocks. Peptide-based aggregation inhibitors hold significant promise for future AD therapy owing to their high selectivity, effectiveness, low toxicity, good tolerance, low accumulation in tissues, high chemical and biological diversity, possibility of rational design, and highly developed methods for analyzing their mode of action, proteolytic stability (modified peptides), and blood-brain barrier (BBB) permeability.

Peptide Pharmacological Approaches to Treating Traumatic Brain Injury: a Case for Arginine-Rich Peptides

Traumatic brain injury (TBI) has a devastating effect on victims and their families, and has profound negative societal and economic impacts, a situation that is further compounded by the lack of effective treatments to minimise injury after TBI. The current strategy for managing TBI is partly through preventative measures and partly through surgical and rehabilitative interventions. Secondary brain damage remains the principal focus for the development of a neuroprotective therapeutic. However, the complexity of TBI pathophysiology has meant that single-action pharmacological agents have been largely unsuccessful in combatting the associated brain injury cascades, while combination therapies to date have proved equally ineffective. Peptides have recently emerged as promising lead agents for the treatment of TBI, especially those rich in the cationic amino acid, arginine. Having been shown to lessen the impact of ischaemic stroke in animal models, there are reasonable grounds to believe that arginine-rich peptides may have neuroprotective therapeutic potential in TBI. Here, we review a range of peptides previously examined as therapeutic agents for TBI. In particular, we focus on cationic arginine-rich peptides -- a new class of agents that growing evidence suggests acts through multiple neuroprotective mechanisms.

Letter: Mass spectrometric evidence for iron binding to the neuroprotective peptide NAP and its Cys5 mutant

The NAP peptide (H(2)N-(1)NAPVSIPQ(8)-CONH(2)) is a truncated version of the activity-dependent neuroprotective protein. Its neuroprotective activities consist of the inhibition of Aβ(25-35) and Aβ(1-40) fibrillogenesis as well as protection against Aβ-induced neurotoxicity and prevention of microtubule disruption associated with Alzheimer's disease. Therefore, we synthesized NAP and its mutant peptide with the sequence: H(2)N-(1)NAPVCIPQ(8)-COOH (NAPCOH), by replacing serine S(5) with cysteine C(5). Both native and mutant peptides were further used to study their interaction with iron ions. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry, Fourier transform infrared spectroscopy and also atomic force microscopy were used to probe Fe(3+) binding to both peptides. Contrary to the expected results, the investigated peptides underwent different oxidation processes, with resultant reduced Fe(2+) ions. These ions, and not the original Fe(3+) ions, were found to bind to each of non-oxidized peptides.

Anti-Inflammatory Properties of NAP in Acute Toxoplasma Gondii-Induced Ileitis in Mice

The octapeptide NAP has been shown to exert neuroprotective properties. Here, we investigated potential anti-inflammatory effects of NAP in an acute ileitis model. To address this, C57BL/6j mice were perorally infected with Toxoplasma gondii (day 0). Within 1 week postinfection (p.i.), placebo (PLC)-treated mice developed acute ileitis due to Th1-type immune responses. Mice that were subjected to intraperitoneal NAP treatment from day 1 until day 6 p.i., however, developed less distinct macroscopic and microscopic disease as indicated by less body weight loss, less distinct histopathological ileal changes, and lower ileal apoptotic, but higher proliferating cell numbers, less abundance of neutrophils, macrophages, monocytes, and T lymphocytes, but higher numbers of regulatory T cells in the ileal mucosa and lamina propria, and lower concentrations of pro-inflammatory mediators in the ilea as compared to PLC controls at day 7 p.i. Remarkably, NAP-mediated anti-inflammatory effects could also be observed in extra-intestinal compartments including liver and spleen. Strikingly, lower MCP-1, TNF, and IL-12p70 serum concentrations in NAP as compared to PLC-treated mice at day 7 p.i. indicate a pronounced systemic anti-inflammatory effect of NAP in acute ileitis. These findings provide first evidence for NAP as a potential novel treatment option in intestinal inflammation.

Davunetide (NAP) protects the retina against early diabetic injury by reducing apoptotic death

Davunetide (NAP) is an eight amino acid peptide that has been shown to provide potent neuroprotection. In the present study, we investigated the neuroprotective effect of NAP in diabetic retinopathy using an in vivo streptozotocin (STZ)-induced diabetic model. A single intraocular injection of NAP (100 μg/mL) or vehicle was administered 1 week after STZ injection. Three weeks after diabetes induction, we assessed the retinal expression and distribution of apoptosis markers, cleaved caspase-3, and Bcl2, by Western blot and immunofluorescent analysis. Furthermore, we evaluated the activation of mitogen-activated protein kinase/extracellular signal-regulated protein kinase (MAPK/ERK) and/or phosphatidylinositol-3 kinase/Akt pathways by measuring the protein levels of p-ERK and p-AKT with or without NAP treatment. Results demonstrated that NAP treatment reduced apoptotic event in diabetic retina, and it restored cleaved caspase-3 expression levels in the retina of STZ-injected rats as well as the decreased Bcl2. NAP treatment improved cellular survival through the activation of the MAPK/ERK pathway. Taken together, these findings suggested that NAP might be useful to treat retinal degenerative diseases.

Notch signalling in adult neurons: a potential target for microtubule stabilization

Cytoskeletal dysfunction has been proposed during the last decade as one of the main mechanisms involved in the aetiology of several neurodegenerative diseases. Microtubules are basic elements of the cytoskeleton and the dysregulation of microtubule stability has been demonstrated to be causative for axonal transport impairment, synaptic contact degeneration, impaired neuronal function leading finally to neuronal loss. Several pathways are implicated in the microtubule assembly/disassembly process. Emerging evidence is focusing on Notch as a microtubule dynamics regulator. We demonstrated that activation of Notch signalling results in increased microtubule stability and changes in axonal morphology and branching. By contrast, Notch inhibition leads to an increase in cytoskeleton plasticity with intense neurite remodelling. Until now, several microtubule-binding compounds have been tested and the results have provided proof of concept that microtubule-binding agents or compounds with the ability to stabilize microtubules may have therapeutic potential for the treatment of Alzheimer's disease and other neurodegenerative diseases. In this review, based on its key role in cytoskeletal dynamics modulation, we propose Notch as a new potential target for microtubule stabilization.

The rescue of microtubule-dependent traffic recovers mitochondrial function in Parkinson's disease

In Parkinson's disease mitochondrial dysfunction can lead to a deficient ATP supply to microtubule protein motors leading to mitochondrial axonal transport disruption. Compromised axonal transport will then lead to a disorganized distribution of mitochondria and other organelles in the cell, as well as, the accumulation of aggregated proteins like alpha-synuclein. Moreover, axonal transport disruption can trigger synaptic accumulation of autophagosomes packed with damaged mitochondria and protein aggregates promoting synaptic failure. We previously observed that neuronal-like cells with an inherent mitochondrial impairment derived from PD patients contain a disorganized microtubule network, as well as, alpha-synuclein oligomer accumulation. In this work we provide new evidence that an agent that promotes microtubule network assembly, NAP (davunetide), improves microtubule-dependent traffic, restores the autophagic flux and potentiates autophagosome-lysosome fusion leading to autophagic vacuole clearance in Parkinson's disease cells. Moreover, NAP is capable of efficiently reducing alpha-synuclein oligomer content and its sequestration by the mitochondria. Most interestingly, NAP decreases mitochondrial ubiquitination levels, as well as, increases mitochondrial membrane potential indicating a rescue in mitochondrial function. Overall, we demonstrate that by improving microtubule-mediated traffic, we can avoid mitochondrial-induced damage and thus recover cell homeostasis. These results prove that NAP may be a promising therapeutic lead candidate for neurodegenerative diseases that involve axonal transport failure and mitochondrial impairment as hallmarks, like Parkinson's disease and related disorders.

Optimization of hydrolysis conditions, isolation, and identification of neuroprotective peptides derived from seahorse Hippocampus trimaculatus

Hippocampus trimaculatus is one of the most heavily traded seahorse species for traditional medicine purposes in many countries. In the present study, we showed neuroprotective effects of peptide derived from H. trimaculatus against amyloid-β42 (Aβ42) toxicity which are central to the pathogenesis of Alzheimer's diseases (AD). Firstly, H. trimaculatus was separately hydrolyzed by four different enzymes and tested for their protective effect on Aβ42-induced neurotoxicity in differentiated PC12 cells. Pronase E hydrolysate exerted highest protection with cell viability value of 88.33 ± 3.33 %. Furthermore, we used response surface methodology to optimize pronase E hydrolysis conditions and found that temperature at 36.69 °C with the hydrolysis time 20.01 h, enzyme to substrate (E/S) ratio of 2.02 % and pH 7.34 were the most optimum conditions. Following several purification steps, H. trimaculatus-derived neuroprotective peptides (HTP-1) sequence was identified as Gly-Thr-Glu-Asp-Glu-Leu-Asp-Lys (906.4 Da). HTP-1 protected PC12 cells from Aβ42-induced neuronal death with the cell viability value of 85.52 ± 2.22 % and up-regulated pro-survival gene (Bcl-2) expressions. These results suggest that HTP-1 has the potential to be used in treatment of neurodegenerative diseases, particularly AD. Identification, characterization, and synthesis of bioactive components derived from H. trimaculatus have the potential to replace or at least complement the use of seahorse as traditional medicine, which further may become an approach to minimize seahorse exploitation in traditional medicine.

Ameliorative effect of NAP on laser-induced retinal damage

PURPOSE

NAP is the smallest active element of activity-dependent neuroprotective protein (ADNP) in the non-myelinated neural tissue. This study evaluated the neuroprotective effect of NAP in reducing the spread of laser-induced retinal damage in rat.

METHODS

Laser lesions were created in 72 DA pigmented rats. Two groups were treated by one intravenous or intravitreal injection of NAP immediately after exposure to laser. Two control groups were similarly administered saline injection. Histological and morphometrical evaluations of the lesions were preformed 3, 20 and 60 days after photocoagulation.

RESULTS

After intravitreal treatment with NAP, a significant reduction in the diameter of the laser-induced lesions was found 3 days after photocoagulation (p < 0.001) but not after 20 and 60 days while the systemic treatment significantly reduced lesion diameter 20 and 60 days after photocoagulation (p = 0.001). Significant difference in photoreceptor cell loss was found in eyes treated intravitreally only 3 days after photocoagulation (p = 0.002). In the systemically treated animals such effect was found only after 20 and 60 days (p < 0.001).

CONCLUSIONS

Treatment with NAP ameliorates laser-induced retinal lesions. Intravitreal treatment had an early short-term effect while the effect of systemic administration was delayed and prolonged. This treatment may be of clinical significance in reducing laser-induced retinal injuries in humans.

A pilot trial of the microtubule-interacting peptide (NAP) in mice overexpressing alpha-synuclein shows improvement in motor function and reduction of alpha-synuclein inclusions

Abnormal accumulation of α-synuclein is associated with several neurodegenerative disorders (synucleinopathies), including sporadic Parkinson's disease (PD). Genetic mutations and multiplication of α-synuclein cause familial forms of PD and polymorphisms in the α-synuclein gene are associated with PD risk. Overexpression of α-synuclein can impair essential functions within the cell such as microtubule-dependent transport, suggesting that compounds that act on the microtubule system may have therapeutic benefit for synucleinopathies. In this study, mice overexpressing human wildtype α-synuclein under the Thy1 promoter (Thy1-aSyn) and littermate wildtype control mice were administered daily the microtubule-interacting peptide NAPVSIPQ (NAP; also known as davunetide or AL-108) intranasally for 2 months starting at 1 month of age, in a regimen known to produce effective concentrations of the peptide in mouse brain. Motor performance, coordination, and activity were assessed at the end of treatment. Olfactory function, which is altered in PD, was measured 1 month later. Mice were sacrificed at 4.5 months of age, and their brains examined for proteinase K-resistant α-synuclein inclusions in the substantia nigra and olfactory bulb. NAP-treated Thy1-aSyn mice showed a 38% decrease in the number of errors per step in the challenging beam traversal test and a reduction in proteinase K-resistant α-synuclein inclusions in the substantia nigra compared to vehicle treated transgenics. The data indicate a significant behavioral benefit and a long lasting improvement of α-synuclein pathology following administration of a short term (2 months) NAP administration in a mouse model of synucleinopathy.

A domain level interaction network of amyloid precursor protein and Abeta of Alzheimer's disease

The primary constituent of the amyloid plaque, beta-amyloid (Abeta), is thought to be the causal "toxic moiety" of Alzheimer's disease. However, despite much work focused on both Abeta and its parent protein, amyloid precursor protein (APP), the functional roles of APP and its cleavage products remain to be fully elucidated. Protein-protein interaction networks can provide insight into protein function, however, high-throughput data often report false positives and are in frequent disagreement with low-throughput experiments. Moreover, the complexity of the CNS is likely to be under represented in such databases. Therefore, we curated the published work characterizing both APP and Abeta to create a protein interaction network of APP and its proteolytic cleavage products, with annotation, where possible, to the level of APP binding domain and isoform. This is the first time that an interactome has been refined to domain level, essential for the interpretation of APP due to the presence of multiple isoforms and processed fragments. Gene ontology and network analysis were used to identify potentially novel functional relationships among interacting proteins.

The neuroprotective peptide NAP does not directly affect polymerization or dynamics of reconstituted neural microtubules

NAP (Asn-Ala-Pro-Val-Ser-Ile-Pro-Gln) is a neuroprotective peptide that shows cognitive protection in patients with amnestic mild cognitive impairment, a precursor to Alzheimer's disease. NAP exhibits potent neuroprotective properties in several in vivo and cellular models of neural injury. While NAP has been found in many studies to affect microtubule assembly and/or stability in neuronal and glial cells at fM concentrations, it has remained unclear whether NAP acts directly or indirectly on tubulin or microtubules. We analyzed the effects of NAP (1 fM-1 microM) on the assembly of reconstituted bovine brain microtubules in vitro and found that it did not significantly (p< 0.05) alter polymerization of either purified tubulin or of a mixture of tubulin and unfractionated microtubule-associated proteins. NAP also had no significant effect (p < 0.05) on the growing and shortening dynamics of steady-state microtubules at their plus ends, nor did it alter the polymerization or dynamics of microtubules assembled in the presence of 3-repeat or 4-repeat tau. Thus, the neuroprotective activity of NAP does not appear to involve a direct action on the polymerization or dynamics of purified tubulin or microtubules.

NAP has no effect on spatial memory after short-term treatment in advanced stage Alzheimer's disease mouse model

NAPVSIPQ (NAP) is a small, active fragment of activity-dependent neuroprotective protein that has neuroprotective and memory enhancing properties at very low concentrations. Previous research demonstrated that 1-2 weeks of treatment provided memory enhancing effects in normal middle-aged and cholinergically lesioned rats. Improvement in cognitive performance was shown in 12-month-old C57Bl6/J mice after 10 days of oral treatment with D-NAP and D-SALLRSIPA. Additionally, NAP-related cognitive benefits on spatial memory were observed in a 3xTg Alzheimer mouse model after 6 months of chronic administration at a moderate stage of disease. In this study, the potential memory enhancing effect of NAP was investigated using the APP23 transgenic mouse model for Alzheimer's disease. Twelve-month-old male heterozygous APP23 mice and their wild-type control littermates were intraperitoneally injected with 0.3 microg NAP/g body weight or with saline vehicle for 22 consecutive days. Cognitive performance training in the Morris Water Maze (MWM) started on day 8 of treatment. The internal validity of our study was demonstrated by the fact that the APP23 mice performed significantly worse in the MWM than wild-type animals. Treatment with NAP, however, did not exert any significant effects on MWM performance. Although we failed to show significant memory enhancing effects in this study, NAP might be a promising peptide for disease-modifying therapy in neurodegenerative disease, but short-term effects are probably not to be expected. Also, most likely, treatment should start in an early stage, i.e. before full-blown pathology is eminent, and the necessary treatment period should enclose several months.

NAP and D-SAL: neuroprotection against the beta amyloid peptide (1-42)

Introduction

NAP (Asn-Ala-Pro-Val-Ser-Ile-Pro-Gln, single amino acid letter code, NAPVSIPQ), an eight amino acid neuroprotective peptide derived from activity-dependent neuroprotective protein (ADNP), exhibits some structural similarity to activity-dependent neurotropic factor-9 (ADNF-9; Ser-Alal-Leu-Leu-Arg-Ser-Ile-Pro-Ala, SALLRSIPA). Both peptides are also active in the all D-amino acid conformation, termed D-NAP and D-SAL. Original results utilizing affinity chromatography coupled to mass spectrometry identified tubulin, the subunit protein of microtubules, as the major NAP-associating protein in brain. The NAP-tubulin association was found to be diminished in the presence of ADNF-9, D-NAP, and D-SAL, suggesting a common target of neuroprotection. The β amyloid peptide interacts with microtubules, and previous studies have demonstrated protection against β amyloid (25–35) toxicity by NAP and ADNF-9. NAP also inhibits β amyloid (25–35 and 1–40) aggregation.

Methods

Cerebral cortical cultures derived from newborn rats were used in neuronal survival assays to test the activity of both NAP and D-SAL against the major Alzheimer's disease toxic peptide β amyloid (1–42).

Results

NAP and D-SAL protected cerebral cortical neurons against the major Alzheimer's disease toxic peptide β amyloid (1–42). Maximal protection of both peptides was observed at concentrations of 10^-15 to 10^-10 mol/l.

Conclusion

These findings, together with those of previous in vivo studies conducted in relevant Alzheimer's disease models, pave the path to drug development. Bioavailability studies indicated that NAP penetrates cells and crosses the blood-brain barrier after nasal or systemic administration. Phase II clinical trials of NAP are currently in progress by Allon Therapeutics Inc.

The neuropeptide NAP provides neuroprotection against retinal ganglion cell damage after retinal ischemia and optic nerve crush

BACKGROUND

NAP, an 8-amino acid peptide (NAPVSIPQ=Asn-Ala-Pro-Val-Ser-Ile-Pro-Gln) derived from activity-dependent neuroprotective protein (ADNP), plays an important role in neuronal differentiation and the survival of neurons in different pathological situations. We already discovered that NAP increases the survival of retinal ganglion cells (RGC) in vitro, and supports neurite outgrowth in retinal explants at femtomolar concentrations. The aim of this study was to investigate the effects of NAP on RGC survival after transient retinal ischemia and optic nerve crush.

METHODS

RGC of male Wistar rats were labelled retrogradely with 6 l FluoroGold injected stereotactically into both superior colliculi. Seven days later, retinal ischemia was induced by elevating the intraocular pressure to 120 mm Hg for 60 minutes or by crushing one optic nerve for 10 s after a partial orbitotomy. NAP was either injected intraperitoneally in the concentration of 100 microg/kg [corrected] 1 day before, directly after, and on the first and the second days after damage, or intravitreally (0.05 or 0.5 microg/eye) [corrected] directly after the optic nerve crush. Controls received the same concentrations of a control peptide. Densities of surviving RGC and activated microglial cells (AMC) were quantified in a masked fashion 10 days after damage by counting FluoroGold-labelled cells.

RESULTS

After retinal ischemia, intraperitoneal injections of NAP increased the number of surviving RGC by 40% (p < 0.005) compared to the control group. After optic nerve crush, NAP raised the number of surviving RGC by 31% (p = 0.07) when injected intraperitoneally and by 54% (p < 0.05) when administered intravitreally.

CONCLUSIONS

NAP acts neuroprotectively in vivo after retinal ischemia and optic nerve crush, and may have potential in treating optic nerve diseases.

Intranasal NAP administration reduces accumulation of amyloid peptide and tau hyperphosphorylation in a transgenic mouse model of Alzheimer's disease at early pathological stage

Accumulation of beta-amyloid (Abeta) peptide and hyperphosphorylation of tau in the brain are pathological hallmarks of Alzheimer's disease (AD). Agents altering these pathological events might modify clinical disease progression. NAP (Asn-Ala-Pro-Val-Ser-Ile-Pro-Gln) is an octapeptide that has shown neuroprotective effects in various in vitro and in vivo neurodegenerative models. Previous studies showed that NAP protected against Abeta-induced neurotoxicity, inhibited Abeta aggregation, and, by binding to tubulin, prevented disruption of microtubules. In this study, we investigated the effect of NAP on Abeta and tau pathology using a transgenic mouse model that recapitulates both aspects of AD. We administered NAP intranasally (0.5 microg/mouse per day, daily from Monday through Friday) for 3 mo, starting from 9 mo of age, which is a prepathological stage in these mice. NAP treatment significantly lowered levels of Abeta 1-40 and 1-42 in brain. In addition, NAP significantly reduced levels of hyperphosphorylated tau. Of particular interest, hyperphosphorylation at the threonine 231 site was reduced; phosphorylation at this site influences microtubule binding. Our results indicate that NAP treatment of transgenic mice initiated at an early stage reduced both Abeta and tau pathology, suggesting that NAP might be a potential therapeutic agent for AD.

A neuronal microtubule-interacting agent, NAPVSIPQ, reduces tau pathology and enhances cognitive function in a mouse model of Alzheimer's disease

Neurofibrillary tangles composed of aggregated, hyperphosphorylated tau in an abnormal conformation represent one of the major pathological hallmarks of Alzheimer's disease (AD) and other tauopathies. However, recent data suggest that the pathogenic processes leading to cognitive impairment occur before the formation of classic tangles. In the earliest stages of tauopathy, tau detaches from microtubules and accumulates in the cytosol of the somatodendritic compartment of cells. Either as a cause or an effect, tau becomes hyperphosphorylated and aggregates into paired helical filaments that comprise the tangles. To assess whether an agent that modulates microtubule function can inhibit the pathogenic process and prevent cognitive deficits in a transgenic mouse model with AD-relevant tau pathology, we administered the neuronal tubulin-preferring agent, NAPVSIPQ (NAP). Three months of treatment with NAP at an early-to-moderate stage of tauopathy reduced the levels of hyperphosphorylated soluble and insoluble tau. A 6-month course of treatment improved cognitive function. Although nonspecific tubulin-interacting agents commonly used for cancer therapy are associated with adverse effects due to their anti-mitotic activity, no adverse effects were found after 6 months of exposure to NAP. Our results suggest that neuronal microtubule interacting agents such as NAP may be useful therapeutic agents for the treatment or prevention of tauopathies.

Interactive sequences in the molecular chaperone, human alphaB crystallin modulate the fibrillation of amyloidogenic proteins

Multiple interactive domains are involved in the activity of the stress protein, alphaB crystallin that protects against the unfolding, aggregation, and toxicity of amyloidogenic proteins. Six peptides corresponding to the interactive sequences 41STSLSPFYLRPPSFLRAP58, 73DRFSVNLDVKHFS85, 101HGKHEERQDE110, 113FISREFHR120, 131LTITSSLSSDGV142, and 156ERTIPITRE164 in human alphaB crystallin were synthesized and evaluated in Thioflavin T fluorescence assays for their effects on the modulation of fibrillation of four disease-related amyloidogenic proteins: amyloid-beta, alpha-synuclein, transthyretin, and beta2-microglobulin. The 73DRFSVNLDVKHFS85 and 101HGKHEERQDE110 peptides in the conserved alpha crystallin core domain of alphaB crystallin were the most effective fibril inhibitors. 73DRFSVNLDVKHFS85 completely inhibited alpha-synuclein fibrillation and reduced the fibrillation of amyloid-beta, transthyretin, and beta2-microglobulin by >50%. 101HGKHEERQDE110 completely inhibited amyloid-beta fibrillation and reduced the fibrillation of alpha-synuclein, transthyretin, and beta2-microglobulin by >50%. The peptides FSVN, NLDV, HGKH, and HEER, which are synthetic fragments of 73DRFSVNLDVKHFS85 and 101HGKHEERQDE110, inhibited fibrillation of all four amyloidogenic proteins by >75%. In contrast, the peptides FISREFHR, ERTIPITRE, DRFS, KHFS, and EERQ were the strongest promoters of fibrillation. Molecular modeling of the interactions between transthyretin and beta2-microglobulin and the synthetic bioactive peptides determined that residues Phe-75, Ser-76, Val-77, Asn-78, Leu-79, and Asp-80 in 73DRFSVNLDVKHFS85 and residues His-101, Lys-103, His-104, Glu-105, and Arg-107 in 101HGKHEERQDE110 interact with exposed residues in the beta strands, F and D of transthyretin and beta2-microglobulin, respectively, to modulate fibrillation. This is the first characterization of specific bioactive peptides synthesized on the basis of interactive domains in the small heat shock protein, alphaB crystallin that protect against the fibrillation of amyloidogenic proteins.

VIP provides cellular protection through a specific splice variant of the PACAP receptor: a new neuroprotection target

Vasoactive intestinal peptide (VIP) was known to provide neuroprotection. Three VIP receptors have been cloned: VPAC1, VPAC2 and PAC1. A specific splice variant of PAC1 in the third cytoplasmatic loop, hop2, was implicated in VIP-related neuroprotection. We aimed to clone the hop2 splice variant, examine its affinity to VIP and investigate whether it mediates the VIP-related neuroprotective activity. The PAC1 cDNA was cloned from rat cerebral astrocytes. Using genetic manipulation the hop2 splice variant was obtained, then inserted into an expression vector and transfected into COS-7 cells that were used for binding assays. Results showed that VIP bound the cloned hop2 splice variant. Stearyl-neurotensin(6-11) VIP(7-28) (SNH), an antagonist for VIP, was also found to bind hop2. In addition, VIP protected COS-7 cells expressing hop2 from oxidative stress. Parallel assays demonstrated that VIP increased cAMP accumulation in COS-7 cells expressing hop2. These results support the hypothesis that hop2 mediates the cytoprotective effects attributed to VIP.

Neuroprotective effect of the peptides ADNF-9 and NAP on hypoxic-ischemic brain injury in neonatal rats

Perinatal asphyxia is an important cause of neonatal mortality and subsequent serious sequelae such as motor and cognitive deficits and seizures. Recent studies have demonstrated that short peptides derived from activity-dependent neurotrophic factor (ADNF) and activity-dependent neuroprotective protein (ADNP) are neuroprotective at femtomolar concentrations. However, the effect of these peptides on the hypoxic-ischemic brain injury model is unknown. The aim of this study is to investigate the effects of the peptides ADNF-9 and NAP on neurodegeneration and cerebral nitric oxide (NO) production in a neonatal rat model of hypoxic-ischemic brain injury. Seven-day-old Wistar Albino rat pups have been used in the study (n=42). Experimental groups in the study were: sham-operated group, ADNF-9-treated hypoxia-ischemia group, NAP-treated hypoxia-ischemia group, ADNF-9+NAP-treated hypoxia-ischemia group, and vehicle-treated group. In hypoxia-ischemia groups, left common carotid artery was ligated permanently on the seventh postnatal day. Two hours after the procedure, hypoxia (92% nitrogen and 8% oxygen) was applied for 2.5 h. ADNF-9, NAP, and ADNF-9+NAP were injected (intraperitoneally; i.p.) as a single dose immediately after the hypoxia period. Brain nitrite levels, neuronal cell death, and apoptosis were evaluated in both hemispheres (carotid ligated or nonligated) 72 h after the hypoxic-ischemic insult. Histopathological evaluation demonstrated that ADNF-9 and NAP significantly diminished number of "apoptotic cells" in the hippocampal CA1, CA2, CA3, and gyrus dentatus regions in both hemispheres (ligated and nonligated). When compared with vehicle-treated group, combination treatment with ADNF-9+NAP did not significantly reduce "apoptotic cell death" in any of the hemispheres. ADNF-9 and NAP, when administered separately, significantly preserved the number of neurons CA1, CA2, CA3, and dentate gyrus regions of the hippocampus, when compared with vehicle-treated group. The density of the CA1, CA2, and dentate gyrus neurons was significantly higher when combination therapy with ADNF-9+NAP was used in the carotid ligated hemispheres. In the nonligated hemispheres, combination therapy preserved the number of neurons only in the CA1 and dentate gyrus regions. Brain nitrite levels were evaluated by Griess reagent and showed that hypoxic-ischemic injury caused a significant increase in NO production. Brain nitrite levels in ADNF-9+NAP-treated animals were not different in carotid ligated or nonligated hemispheres. The peptides ADNF-9 and NAP significantly decreased NO overproduction in the hypoxic-ischemic hemisphere, whereas no significant change appeared in hypoxia alone and also in the sham-operated group. These results suggest the beneficial neuroprotective effect of ADNF-9 and NAP in this model of neonatal hypoxic-ischemic brain injury. To our knowledge, this is the first study that demonstrates a protective effect of these peptides against hypoxia-ischemia in the developing brain.