Neuroprotective action of N-acetyl serotonin in oxidative stress-induced apoptosis through the activation of both TrkB/CREB/BDNF pathway and Akt/Nrf2/Antioxidant enzyme in neuronal cells

KIT ligand protects against both light-induced and genetic photoreceptor degeneration

Photoreceptor degeneration is a major cause of blindness and a considerable health burden during aging but effective therapeutic or preventive strategies have not so far become readily available. Here, we show in mouse models that signaling through the tyrosine kinase receptor KIT protects photoreceptor cells against both light-induced and inherited retinal degeneration. Upon light damage, photoreceptor cells upregulate Kit ligand (KITL) and activate KIT signaling, which in turn induces nuclear accumulation of the transcription factor NRF2 and stimulates the expression of the antioxidant gene Hmox1. Conversely, a viable Kit mutation promotes light-induced photoreceptor damage, which is reversed by experimental expression of Hmox1. Furthermore, overexpression of KITL from a viral AAV8 vector prevents photoreceptor cell death and partially restores retinal function after light damage or in genetic models of human retinitis pigmentosa. Hence, application of KITL may provide a novel therapeutic avenue for prevention or treatment of retinal degenerative diseases.

BDNF as a Promising Therapeutic Agent in Parkinson's Disease

Brain-derived neurotrophic factor (BDNF) promotes neuroprotection and neuroregeneration. In animal models of Parkinson’s disease (PD), BDNF enhances the survival of dopaminergic neurons, improves dopaminergic neurotransmission and motor performance. Pharmacological therapies of PD are symptom-targeting, and their effectiveness decreases with the progression of the disease; therefore, new therapeutical approaches are needed. Since, in both PD patients and animal PD models, decreased level of BDNF was found in the nigrostriatal pathway, it has been hypothesized that BDNF may serve as a therapeutic agent. Direct delivery of exogenous BDNF into the patient’s brain did not relieve the symptoms of disease, nor did attempts to enhance BDNF expression with gene therapy. Physical training was neuroprotective in animal models of PD. This effect is mediated, at least partly, by BDNF. Animal studies revealed that physical activity increases BDNF and tropomyosin receptor kinase B (TrkB) expression, leading to inhibition of neurodegeneration through induction of transcription factors and expression of genes related to neuronal proliferation, survival, and inflammatory response. This review focuses on the evidence that increasing BDNF level due to gene modulation or physical exercise has a neuroprotective effect and could be considered as adjunctive therapy in PD.

Positive allosteric modulation of indoleamine 2,3-dioxygenase 1 restrains neuroinflammation

l-tryptophan (Trp), an essential amino acid for mammals, is the precursor of a wide array of immunomodulatory metabolites produced by the kynurenine and serotonin pathways. The kynurenine pathway is a paramount source of several immunoregulatory metabolites, including l-kynurenine (Kyn), the main product of indoleamine 2,3-dioxygenase 1 (IDO1) that catalyzes the rate-limiting step of the pathway. In the serotonin pathway, the metabolite N-acetylserotonin (NAS) has been shown to possess antioxidant, antiinflammatory, and neuroprotective properties in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). However, little is known about the exact mode of action of the serotonin metabolite and the possible interplay between the 2 Trp metabolic pathways. Prompted by the discovery that NAS neuroprotective effects in EAE are abrogated in mice lacking IDO1 expression, we investigated the NAS mode of action in neuroinflammation. We found that NAS directly binds IDO1 and acts as a positive allosteric modulator (PAM) of the IDO1 enzyme in vitro and in vivo. As a result, increased Kyn will activate the ligand-activated transcription factor aryl hydrocarbon receptor and, consequently, antiinflammatory and immunoregulatory effects. Because NAS also increased IDO1 activity in peripheral blood mononuclear cells of a significant proportion of MS patients, our data may set the basis for the development of IDO1 PAMs as first-in-class drugs in autoimmune/neuroinflammatory diseases.

Polysaccharide from Echinacea purpurea reduce the oxidant stress in vitro and in vivo

Echinacea purpurea polysaccharides (EPPS) were extracted through water extract and alcohol precipitate method. Three polysaccharides were purified by DEAE cellulose, named EPPS-1, EPPS-2 and EPPS-3. The antioxidant activities in three polysaccharides were screened by free radical scavenging test and EPPS-3 possessed the best antioxidant function. Then the antioxidant activities of EPPS-3 were further explored in oxidative damage model in vitro and in vivo for the first time. The results showed that the antioxidases and the metabolism content were significantly improved in EPPS-3 group. EPPS-3 could protect hepatic tissue from the injury of CCl₄ compared with the oxidative damage model. The mechanism research demonstrated that EPPS-3 restrained cell apoptosis and promoted Nrf2 cell signal pathway to play an antioxidant impact. Therefore, EPPS-3 an ingredient could be served as amazing gift for food industry and feed additive.

Protective Effects of Chlorogenic Acid on Cerebral Ischemia/Reperfusion Injury Rats by Regulating Oxidative Stress-Related Nrf2 Pathway

Introduction

Cerebral ischemia-reperfusion (CI/R) injury is caused by blood flow recovery after ischemic stroke. Chlorogenic acid (CGA, 5-O-caffeoylquinic acid) is a major polyphenol component of Coffea canephora,Coffea arabica L. and Mate (Ilex paraguariensis A. StHil.). Previous studies have shown that CGA has a significant neuroprotective effect and can improve global CI/R injury. However, the underlying molecular mechanism of CGA in CI/R injury has not been fully revealed.

Materials

In this study, CI/R rat model was constructed. The rats were randomly divided into nine groups with ten in each group: Control, CGA (500 mg·kg-1), CI/R, CI/R + CGA (20 mg·kg-1), CI/R + CGA (100 mg·kg-1), CI/R + CGA (500 mg·kg-1), ML385 (30 mg·kg-1), CI/R + ML385 (30 mg·kg-1), CI/R + CGA + ML385. Cerebral infarction volume was detected by TTC staining. Brain pathological damage was detected by H&E staining. Apoptosis of cortical cells was detected by TUNEL staining. The expression of related proteins was detected by RT-qPCR and Western blotting.

Results

Step-down test and Y maze test showed that CGA dose-dependently mitigated CI/R-induced brain damage and enhanced learning and spatial memory. Besides, CGA promoted the expression of BDNF and NGF in a dose-dependent manner and alleviated CI/R-induced nerve injury. Moreover, CGA increased the activity of SOD and the level of GSH, as well as decreased production of ROS and LDH and the accumulation of MDA. Notably, CGA attenuated oxidative stress-induced brain injury and apoptosis and inhibited the expression of apoptosis-related proteins (cleaved caspase 3 and caspase 9). Additionally, CGA reversed CI/R induced inactivation of Nrf2 pathway and promoted Nrf2, NQO-1 and HO-1 expression. Nrf2 pathway inhibitor ML385 destroyed this promotion.

Discussion

All the data indicated that CGA had a neuroprotective effect on the CI/R rats by regulating oxidative stress-related Nrf2 pathway.

Global metabolomics analysis of serum from humans at risk of thrombotic stroke

We aimed to determine the serum concentrations of altered compounds to understand the changes in metabolism and pathophysiology that occur prior to thrombotic stroke.

3,3'-Diindolylmethane Promotes BDNF and Antioxidant Enzyme Formation via TrkB/Akt Pathway Activation for Neuroprotection against Oxidative Stress-Induced Apoptosis in Hippocampal Neuronal Cells

3,3'-Diindolylmethane (DIM), a metabolite of indole-3-carbinol present in Brassicaceae vegetables, possesses various health-promoting effects. Nonetheless, the effect of DIM on neurodegenerative diseases has not been elucidated clearly. In this study, we hypothesized DIM may protect neuronal cells against oxidative stress-induced apoptosis by promoting the formation of brain-derived neurotrophic factor (BDNF) and antioxidant enzymes through stabilizing the activation of the tropomyosin-related kinase receptor B (TrkB) cascade and we investigated the effect of DIM on oxidative stress-mediated neurodegenerative models. DIM protected neuronal cells against oxidative stress-induced apoptosis by regulating the expression of apoptosis-related proteins in glutamate-treated HT-22 cells. Additionally, DIM improved the expression of BDNF and antioxidant enzymes, such as heme oxygenase-1, glutamate-cysteine ligase catalytic subunit, and NAD(P)H quinine oxidoreductase-1, by promoting the activation of the TrkB/protein kinase B (Akt) pathway in the cells. Consistent with in vitro studies, DIM attenuated memory impairment by protecting hippocampal neuronal cells against oxidative damage in scopolamine-treated mice. Conclusionally, DIM exerted neuroprotective and antioxidant actions through the activation of both BDNF production and antioxidant enzyme formation in accordance with the TrkB/Akt pathway in neuronal cells. Such an effect of DIM may provide information for the application of DIM in the prevention of and therapy for neurodegenerative diseases.

Obese mice exposed to psychosocial stress display cardiac and hippocampal dysfunction associated with local brain-derived neurotrophic factor depletion

INTRODUCTION

Obesity and psychosocial stress (PS) co-exist in individuals of Western society. Nevertheless, how PS impacts cardiac and hippocampal phenotype in obese subjects is still unknown. Nor is it clear whether changes in local brain-derived neurotrophic factor (BDNF) account, at least in part, for myocardial and behavioral abnormalities in obese experiencing PS.

METHODS

In adult male WT mice, obesity was induced via a high-fat diet (HFD). The resident-intruder paradigm was superimposed to trigger PS. In vivo left ventricular (LV) performance was evaluated by echocardiography and pressure-volume loops. Behaviour was indagated by elevated plus maze (EPM) and Y-maze. LV myocardium was assayed for apoptosis, fibrosis, vessel density and oxidative stress. Hippocampus was analyzed for volume, neurogenesis, GABAergic markers and astrogliosis. Cardiac and hippocampal BDNF and TrkB levels were measured by ELISA and WB. We investigated the pathogenetic role played by BDNF signaling in additional cardiac-selective TrkB (cTrkB) KO mice.

FINDINGS

When combined, obesity and PS jeopardized LV performance, causing prominent apoptosis, fibrosis, oxidative stress and remodeling of the larger coronary branches, along with lower BDNF and TrkB levels. HFD/PS weakened LV function similarly in WT and cTrkB KO mice. The latter exhibited elevated LV ROS emission already at baseline. Obesity/PS augmented anxiety-like behaviour and impaired spatial memory. These changes were coupled to reduced hippocampal volume, neurogenesis, local BDNF and TrkB content and augmented astrogliosis.

INTERPRETATION

PS and obesity synergistically deteriorate myocardial structure and function by depleting cardiac BDNF/TrkB content, leading to augmented oxidative stress. This comorbidity triggers behavioral deficits and induces hippocampal remodeling, potentially via lower BDNF and TrkB levels. FUND: J.A. was in part supported by Rotary Foundation Global Study Scholarship. G.K. was supported by T32 National Institute of Health (NIH) training grant under award number 1T32AG058527. S.C. was funded by American Heart Association Career Development Award (19CDA34760185). G.A.R.C. was funded by NIH (K01HL133368-01). APB was funded by a Grant from the Friuli Venezia Giulia Region entitled: "Heart failure as the Alzheimer disease of the heart; therapeutic and diagnostic opportunities". M.C. was supported by PRONAT project (CNR). N.P. was funded by NIH (R01 HL136918) and by the Magic-That-Matters fund (JHU). V.L. was in part supported by institutional funds from Scuola Superiore Sant'Anna (Pisa, Italy), by the TIM-Telecom Italia (WHITE Lab, Pisa, Italy), by a research grant from Pastificio Attilio Mastromauro Granoro s.r.l. (Corato, Italy) and in part by ETHERNA project (Prog. n. 161/16, Fondazione Pisa, Italy). Funding source had no such involvement in study design, in the collection, analysis, interpretation of data, in the writing of the report; and in the decision to submit the paper for publication.

Soursop fruit extract mitigates scopolamine-induced amnesia and oxidative stress via activating cholinergic and Nrf2/HO-1 pathways

Current therapeutic interventions for memory loss are inadequate and are associated with numerous adverse effects. There is an urgent need for new alternative agents for the treatment of memory loss and related disorders. Here, we investigated the potential neuroprotective role of soursop fruit extract (SSFE) in scopolamine (SCO)-induced amnesia and oxidative damage in the hippocampus of rats. Thirty-five rats were randomly allocated into 5 groups: control, SCO, SSFE, SCO, SSFE+SCO and N-acetylcysteine (NAC) + SCO. SCO-treatment increased acetylcholine esterase activity and decreased hippocampal levels of acetylcholine, serotonin, dopamine, norepinephrine, and histamine. The level of ATP increased. SCO-treated rats showed a disturbance in oxidative status, which was evident through the increase in malondialdehyde, and nitrites/nitrates and a decrease in cellular antioxidant molecules including glutathione, superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase. A disturbance was also observed via downregulation of the nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 defense pathways. SCO-treatment enhances a neuroinflammatory state, as indicated by the release of tumor necrosis factor- α and interleukin-1β and increased inducible nitric oxide synthase and mRNA expression. SCO-treatment decreased the expression of the anti-apoptotic protein, B cell lymphoma 2 and increased the expression of the pro-apoptotic protein, Bcl-2 associated X protein, caspase-3 and cytochrome c in hippocampal neurons. SSFE pretreatment markedly ameliorated hippocampal changes. Our findings revealed that SSFE exerts its potential anti-amnestic effect mainly through the activation of the cholinergic system and Nrf2/HO-1 pathway.

Cognitive-enhancing and ameliorative effects of acanthoside B in a scopolamine-induced amnesic mouse model through regulation of oxidative/inflammatory/cholinergic systems and activation of the TrkB/CREB/BDNF pathway

Recently, our research team reported the anti-amnesic potential of desalted-hydroethanolic extracts of Salicornia europaea L. (SE-EE). In this study, we performed bioactivity-guided isolation and identification of Acanthoside B (Aca.B), from SE-EE, as the potential bioactive candidate and examined anti-amnesic activity with its potential mechanism of action using an in vivo model. S7-L3-3 purified from SE-EE showed enhanced in vitro acetylcholinesterase (AChE) inhibitory activity. The isolated S7-L3-3 was identified and characterized as Aca.B using varied spectral analyses, i.e., Nuclear magnetic resonance (NMR), Ultraviolet-visible (UV-Vis), and Electrospray ionization-mass spectrometry (ESI-MS). In the in vitro studies, Aca.B exhibited negligible toxicity and showed a dose-dependent nitric oxide inhibitory potential in Lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. In the in vivo studies, the oral administration of Aca.B to mice showed enhanced bioavailability and dose-dependent repression of the behavioral/cognitive impairment by regulating the cholinergic function, restoring the antioxidant status, attenuating the inflammatory cytokines/mediators and actively enriching neurotropic proteins in the hippocampal regions of the scopolamine-administered mice.

Arsenic modifies serotonin metabolism through glucuronidation in pancreatic β-cells

In arsenic-endemic regions of the world, arsenic exposure correlates with diabetes mellitus. Multiple animal models of inorganic arsenic (iAs, as As³⁺) exposure have revealed that iAs-induced glucose intolerance manifests as a result of pancreatic β-cell dysfunction. To define the mechanisms responsible for this β-cell defect, the MIN6-K8 mouse β-cell line was exposed to environmentally relevant doses of iAs. Exposure to 0.1-1 µM iAs for 3 days significantly decreased glucose-induced insulin secretion (GIIS). Serotonin and its precursor, 5-hydroxytryptophan (5-HTP), were both decreased. Supplementation with 5-HTP, which loads the system with bioavailable 5-HTP and serotonin, rescued GIIS, suggesting that recovery of this pathway was sufficient to restore function. Exposure to iAs was accompanied by an increase in mRNA expression of UDP-glucuronosyltransferase 1 family, polypeptide a6a (Ugt1a6a), a phase-II detoxification enzyme that facilitates the disposal of cyclic amines, including serotonin, via glucuronidation. Elevated Ugt1a6a and UGT1A6 expression levels were observed in mouse and human islets, respectively, following 3 days of iAs exposure. Consistent with this finding, the enzymatic rate of serotonin glucuronidation was increased in iAs-exposed cells. Knockdown by siRNA of Ugt1a6a during iAs exposure restored GIIS in MIN6-K8 cells. This effect was prevented by blockade of serotonin biosynthesis, suggesting that the observed iAs-induced increase in Ugt1a6a affects GIIS by targeting serotonin or serotonin-related metabolites. Although it is not yet clear exactly which element(s) of the serotonin pathway is/are most responsible for iAs-induced GIIS dysfunction, this study provides evidence that UGT1A6A, acting on the serotonin pathway, regulates GIIS under both normal and pathological conditions.

Discovery of arylbenzylamines as PDE4 inhibitors with potential neuroprotective effect

Growing evidence confirms the potential of PDE4 inhibitors for the treatment of Parkinson's disease. Our reported PDE4 inhibitors FCPR16 and FCPR03 have displayed neuroprotective effects in SH-SY5Y cells, but have very low oral bioavailability. To access analogues with improved bioavailability, a new series of arylbenzylamine derivatives were designed and synthesized. Preliminary screening results of the series showed that arylbenzylamine derivatives bearing a pyridin-3-amine side chain displayed good inhibitory activities against human PDE4B1 and PDE4D7 isoforms. Moreover, kinetic studies revealed that the most potent compounds 11r and 11s with mid-nanomolar IC₅₀ values partially bind to PDE4B1 (I_max = 93% and 90% respectively). Molecular docking results revealed the possible interactions of compounds 11r and 11s with upstream conserved region 2 (UCR2) of PDE4B1, which illuminate possible reasons for their partial inhibition against PDE4. Using a cell-based model of PD, compounds 11r and 11s were found to alleviate cellular apoptosis in SH-SY5Y cells induced by MPP⁺ (1-methyl-4-phenylpyridinium), with this neuroprotective effect being greater than PDE4 inhibitor rolipram. Furthermore, compound 11r displayed nearly sevenfold oral bioavailability (8.20%) than FCPR03 (1.23%).

A new oxidative stress indicator: Effect of 5-hydroxytryptophan on thiol-disulfide homeostasis in exercise

OBJECTIVES

The aim of the present study was to evaluate the relationship between exercise and both 5-hydroxytryptophan and oxidative stress using thiol-disulfide homeostasis via what is likely a novel biomarker.

METHODS

Male albino Wistar rats (n = 32) were randomly divided into four groups as follows: control, exercise group, 5-hydroxytryptophan group (5H), and 5-HTP + exercise group (5Hex). Exercise and 5-HTP administration (25mg/kg per d) were performed 5d/wk for 10 wk. After completion of the experimental protocol, to determine oxidative stress parameters, serum total thiol and native thiol concentrations were measured. Dynamic disulfide status, reduced thiol, oxidized thiol (OT), and thiol oxidation reduction percentage ratios were compared between the groups. The methods used in the present study to measure dynamic thiol-disulfide homeostasis as calorimetric and duplex quantities were developed in 2014. These new methods are simple, reliable, and sensitive, with both high linearity and repeatability.

RESULTS

Compared with the control group, serum dynamic disulfide levels were significantly lower in the 5H group and highest in the control group. The lowest OT and the highest reduced thiol rates were determined to be in the 5H group. The highest OT value was found in the 5Hex group. Thiol oxidation reduction values were found to be highest in the 5H group and lowest in the 5Hex group.

CONCLUSIONS

Both 5-HTP and moderate exercise seem to be significantly effective in inhibiting oxidative damage. In addition, the new oxidative stress measurement method used in this study is a promising practical and useful method to evaluate and improve the performance of athletes.

N-Acetyl Serotonin Protects Neural Progenitor Cells Against Oxidative Stress-Induced Apoptosis and Improves Neurogenesis in Adult Mouse Hippocampus Following Traumatic Brain Injury

In this study, with primary mouse neural progenitor cells (NPCs), we investigated the neuroprotective effect of a tropomyosin-related kinase receptor B (TrkB) agonist, N-acetyl serotonin (NAS), against hydrogen peroxide (H₂O₂)-induced toxicity. We found that pre-incubation with NAS not only ameliorates H₂O₂-induced cell viability loss, lactate dehydrogenase (LDH) release, and proliferative and migratory capacity impairments, but counteracts H₂O₂-triggered production of nitric oxide (NO), reactive oxygen species (ROS), malondialdehyde (MDA), and 8-hydroxy-deoxyguanosine (8-OHdG) in a dose-dependent manner. Additionally, pre-treatment with NAS was able to attenuate H₂O₂-induced apoptosis in NPCs, evidenced by the decreased percentage of apoptotic cells and altered expression of apoptosis-related factors. Furthermore, in differentiated NPCs, NAS improves H₂O₂-induced reduction in neurite growth. Mechanistic studies revealed that the protective effects of NAS in NPCs may be mediated by the TrkB/PI3K/Akt/ cAMP response element binding protein (CREB) signaling cascades. In a mouse traumatic brain injury (TBI) model, we found that systemic administration of 30 mg/kg NAS could improve hippocampal neurogenesis, manifested by the increased number of SOX-2-positive cells and increased expression of phosphorylated CREB in the dentate gyrus (DG) area. Treatment with NAS also ameliorates cognitive impairments caused by TBI, as assessed by Y-maze and contextual and cued fear conditioning tests. Taken together, these results provide valuable insights into the neuroprotective and neuroregenerative effects of NAS, suggesting it may have therapeutic potential for the treatment of TBI.

Intracellular ion and protein nanoparticle-induced osmotic pressure modify astrocyte swelling and brain edema in response to glutamate stimuli

Intracellular tension activity plays a crucial role in cytotoxic brain edema and astrocyte swelling. Here, a few genetically encoded FRET-based tension probes were designed to detect cytoskeletal structural tension optically, including their magnitude and vectors. The astrocyte swelling resulted in GFAP tension increment, which is associated with the antagonistic effect of inward microfilaments (MFs) and microtubules (MTs) forces. In glutamate-induced astrocyte swelling, GFAP tension rise resulted from outward ion and protein nanoparticle-induced osmotic pressure (PN-OP) increases, where PN-OP could be elicited by MF and MT depolymerization, protein nanoparticle production, and activation of cofilin and stathmin-1. Attenuation of both ion osmotic pressure and PN-OP by drug combinations, together with free-radical scavenger, relieved cerebral edema in vivo. The study suggests that intracellular osmotic pressure (especially PN-OP) has a pivotal role in glutamate-induced astrocyte swelling and brain edema. Recovery of cytoplasmic potential is a promising target to develop new drugs and cure brain edema.

cAMP Response Element-Binding Protein (CREB): A Possible Signaling Molecule Link in the Pathophysiology of Schizophrenia

Dopamine is a brain neurotransmitter involved in the pathology of schizophrenia. The dopamine hypothesis states that, in schizophrenia, dopaminergic signal transduction is hyperactive. The cAMP-response element binding protein (CREB) is an intracellular protein that regulates the expression of genes that are important in dopaminergic neurons. Dopamine affects the phosphorylation of CREB via G protein-coupled receptors. Neurotrophins, such as brain derived growth factor (BDNF), are critical regulators during neurodevelopment and synaptic plasticity. The CREB is one of the major regulators of neurotrophin responses since phosphorylated CREB binds to a specific sequence in the promoter of BDNF and regulates its transcription. Moreover, susceptibility genes associated with schizophrenia also target and stimulate the activity of CREB. Abnormalities of CREB expression is observed in the brain of individuals suffering from schizophrenia, and two variants (-933T to C and -413G to A) were found only in schizophrenic patients. The CREB was also involved in the therapy of animal models of schizophrenia. Collectively, these findings suggest a link between CREB and the pathophysiology of schizophrenia. This review provides an overview of CREB structure, expression, and biological functions in the brain and its interaction with dopamine signaling, neurotrophins, and susceptibility genes for schizophrenia. Animal models in which CREB function is modulated, by either overexpression of the protein or knocked down through gene deletion/mutation, implicating CREB in schizophrenia and antipsychotic drugs efficacy are also discussed. Targeting research and drug development on CREB could potentially accelerate the development of novel medications against schizophrenia.

A Proteomic Approach to Uncover Neuroprotective Mechanisms of Oleocanthal against Oxidative Stress

Neurodegenerative diseases represent a heterogeneous group of disorders that share common features like abnormal protein aggregation, perturbed Ca2+ homeostasis, excitotoxicity, impairment of mitochondrial functions, apoptosis, inflammation, and oxidative stress. Despite recent advances in the research of biomarkers, early diagnosis, and pharmacotherapy, there are no treatments that can halt the progression of these age-associated neurodegenerative diseases. Numerous epidemiological studies indicate that long-term intake of a Mediterranean diet, characterized by a high consumption of extra virgin olive oil, correlates with better cognition in aged populations. Olive oil phenolic compounds have been demonstrated to have different biological activities like antioxidant, antithrombotic, and anti-inflammatory activities. Oleocanthal, a phenolic component of extra virgin olive oil, is getting more and more scientific attention due to its interesting biological activities. The aim of this research was to characterize the neuroprotective effects of oleocanthal against H₂O₂-induced oxidative stress in neuron-like SH-SY5Y cells. Moreover, protein expression profiling, combined with pathways analyses, was used to investigate the molecular events related to the protective effects. Oleocanthal was demonstrated to counteract oxidative stress, increasing cell viability, reducing reactive oxygen species (ROS) production, and increasing reduced glutathione (GSH) intracellular level. Proteomic analysis revealed that oleocanthal significantly modulates 19 proteins in the presence of H₂O₂. In particular, oleocanthal up-regulated proteins related to the proteasome, the chaperone heat shock protein 90, the glycolytic enzyme pyruvate kinase, and the antioxidant enzyme peroxiredoxin 1. Moreover, oleocanthal protection seems to be mediated by Akt activation. These data offer new insights into the molecular mechanisms behind oleocanthal protection against oxidative stress.

The transplantation of human urine stem cells combined with chondroitinase ABC promotes brain-derived neurotrophic factor and nerve growth factor following spinal cord injury in rats

Cells based on therapies are currently gaining momentum in neural tissue engineering to treat spinal cord injury (SCI). The present study aimed to evaluate the effects of the concomitant use of human urine stem cells (hUSCs) and chondroitinase ABC (ChABC) on functional improvement and to explore the expressions of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). The SCI model was induced by a falling heavy object. hUSCs were cultured and transplanted into the impaired spinal cord with ChABC administration. The Basso, Beattie and Bresnahan (BBB) scores were valued, and real time PCR, immunofluorescence and Western blot were used to detect the expression of BDNF and NGF. We found that rats receiving both hUSCs and ChABC treatment demonstrated the best functional recovery. In addition, the mRNA and protein expressions of the BDNF and NGF expressions were found to be effectively higher in the combined treatment group than these in the other groups. In conclusion, hUSCs transplantation combined with ChABC administration promotes motor functional recovery in SCI rats, which may be associated with BDNF and NGF regulation.

Trilobatin Protects Against Oxidative Injury in Neuronal PC12 Cells Through Regulating Mitochondrial ROS Homeostasis Mediated by AMPK/Nrf2/Sirt3 Signaling Pathway

Oxidative stress-induced neuronal cell damage is a crucial factor in the pathogenesis of mitochondria-associated neurological diseases. Therefore, elimination of overproduction of mitochondrial reactive oxygen species (mtROS) may be a potential strategy for prevention and treatment of neurological diseases. In the present study, the neuroprotective effects of trilobatin (TLB), a novel small molecule monomer derived from Lithocarpus polystachyus Rehd, and its underlying mechanisms were investigated in vitro using hydrogen peroxide (H₂O₂)-induced oxidative stress model in a neuron-like PC12 cell. The findings revealed that pre-treatment with TLB dramatically concentration-dependently suppressed H₂O₂-induced PC12 cells damage by enhancing cell viability, repressed reduction of mitochondrial membrane potential (MMP) and decreased mtROS overgeneration, thereby deferring cell apoptosis. Further study demonstrated that TLB not only increased the enzymatic activities of glutathione peroxidase (GPx), isocitrate dehydrogenase 2 (IDH2),superoxide dismutase 2 (SOD2) and deacetylation of SOD2, but also activated silent mating-type information regulation 2 homolog 3 (Sirt3) within the mitochondria and thereby upregulating forkheadboxO3a (FoxO3a), which regulated mitochondrial DNA genes, then led to improving complex I activity and adenosine triphosphate (ATP) synthesis. What’s more, TLB up-regulated p-adenosine monophosphate-activated protein kinase (AMPK) level, the expression of peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α), and ERRα. Intriguingly, TLB failed to mitigate H₂O₂-induced PC12 injury in the presence of the AMPK inhibitor (Compound C), indicating that the beneficial effects of TLB on the regulation of mtROS homeostasis were reliance on AMPK -Sirt3 signaling pathway. Moreover, TLB also facilitated nuclear factor erythroid 2-related factor 2 (Nrf2) and promoted antioxidant gene expression in turn, and knockdown of Nrf2 by siRNA dramatically reduced the neuroprotective effects of TLB. Notably, AMPK inhibitor abolished the activation of Nrf2 and Sirt3, whereas, knockdown of Nrf2 blocked the upregulation of Sirt3, but it did not affect p-AMPK level. In conclusion, our findings demonstrate that TLB protects against oxidative injury in neuronal PC12 cells through regulating mtROS homeostasis in the first time, which is, at least partly, mediated through the AMPK/Nrf2/Sirt3 signaling pathway.

Supraphysiological Levels of Oxygen Exposure During the Neonatal Period Impairs Signaling Pathways Required for Learning and Memory

Preterm infants often require prolonged oxygen supplementation and are at high risk of neurodevelopmental impairment. We recently reported that adult mice exposed to neonatal hyperoxia (postnatal day [P] 2 to 14) had spatial navigation memory deficits associated with hippocampal shrinkage. The mechanisms by which early oxidative stress impair neurodevelopment are not known. Our objective was to identify early hyperoxia-induced alterations in hippocampal receptors and signaling pathways necessary for memory formation. We evaluated C57BL/6 mouse pups at P14, exposed to either 85% oxygen or air from P2 to 14. We performed targeted analysis of hippocampal ligand-gated ion channels and proteins necessary for memory formation, and global bioinformatic analysis of differentially expressed hippocampal genes and proteins. Hyperoxia decreased hippocampal mGLU7, TrkB, AKT, ERK2, mTORC1, RPS6, and EIF4E and increased α3, α5, and ɤ2 subunits of GABA_A receptor and PTEN proteins, although changes in gene expression were not always concordant. Bioinformatic analysis indicated dysfunction in mitochondria and global protein synthesis and translational processes. In conclusion, supraphysiological oxygen exposure reduced proteins necessary for hippocampus-dependent memory formation and may adversely impact hippocampal mitochondrial function and global protein synthesis. These early hippocampal changes may account for memory deficits seen in preterm survivors following prolonged oxygen supplementation.

Neuroprotective effect of zolpidem against glutamate-induced toxicity is mediated via the PI3K/Akt pathway and inhibited by PK11195

Excitotoxicity is a pathological process in which neuronal dysfunction and death are induced by excessive glutamate stimulation, the major fast excitatory neurotransmitter in the mammalian brain. Excitotoxicity-induced neurodegeneration is a contributing factor in ischemia-induced brain damage, traumatic brain injury, and various neurodegenerative diseases. It is triggered by calcium overload due to prolonged over-activation of ionotropic N-methyl-d-aspartate (NMDA) receptors. Enhanced Ca²⁺ release results in neuronal vulnerability through several intertwined mechanisms, including activation of proteolytic enzymes, increased production of reactive oxygen species (ROS), mitochondrial dysfunction and modulation of intracellular signalling pathways. We investigated the neuroprotective effect of hypnotic zolpidem, a drug that exerts its central effects at the GABA_A receptor complex, against glutamate-induced toxicity in P19 neurons. Zolpidem prevented death of P19 neurons exposed to glutamate, and abolished the glutamate-induced increase in ROS production, p53 and Bax expression, and caspase-3/7 activity. Zolpidem effects were mediated by marked over-activation of Akt kinase. The pro-survival effect, as well as the pAkt induction, were prevented in the presence of wortmannin, an inhibitor of phosphatidylinositol-3-kinase (PI3K) that functions upstream of Akt. The beneficial effect of zolpidem on neuronal survival was not prevented by flumazenil, a GABA_A receptor antagonist. PK11195, a drug that modulates the mitochondrial translocator protein 18 kDa (TSPO) and F₀F₁-ATPase, prevented the beneficial effect of zolpidem, indicating that the mechanism of zolpidem action involves preservation of mitochondrial function and integrity. Zolpidem effects were further mediated by prevention of glutamate-induced increase in the expression of the NR2B subunit of NMDA receptor. The obtained results suggest the promising therapeutic potential of zolpidem against excitotoxic insults and highlight the importance of mitochondria and the Akt pathway as valuable targets for therapeutic interventions in glutamate-mediated neuropathological conditions.

Lanthionine ketimine-5-ethyl ester provides neuroprotection in a zebrafish model of okadaic acid-induced Alzheimer's disease

Okadaic acid (OKA) is a protein phosphatase 2A inhibitor that is used to induce neurodegeneration and study disease states such as Alzheimer's disease (AD). Lanthionine ketimine-5-ethyl ester (LKE) is a bioavailable derivative of the naturally occurring brain sulfur metabolite, lanthionine ketimine (LK). In previously conducted studies, LKE exhibited neuroprotective and neurotrophic properties in murine models but its mechanism of action remains to be clarified. In this study, a recently established zebrafish OKA-induced AD model was utilized to further elucidate the neuroprotective and neurotrophic properties of LKE in the context of an AD-like condition. The fish were divided into 3 groups containing 8 fish per group. Group #1 = negative control, Group #2 = 100 nM OKA, Group #3 = 100 nM OKA +500 μM LKE. OKA caused severe cognitive impairments in the zebrafish, but concomitant treatment with LKE protected against cognitive impairments. Further, LKE significantly and substantially reduced the number of apoptotic brain cells, increased brain-derived neurotrophic factor (BDNF), and increased phospho-activation of the pro-survival factors pAkt (Ser 473) and pCREB (Ser133). These findings clarify the neuroprotective and neurotrophic effects of LKE by highlighting particular survival pathways that are bolstered by the experimental therapeutic LKE.

Ripk3 promotes ER stress-induced necroptosis in cardiac IR injury: A mechanism involving calcium overload/XO/ROS/mPTP pathway

Receptor-interacting protein 3 (Ripk3)-mediated necroptosis contributes to cardiac ischaemia-reperfusion (IR) injury through poorly defined mechanisms. Our results demonstrated that Ripk3 was strongly upregulated in murine hearts subjected to IR injury and cardiomyocytes treated with LPS and H₂O₂. The higher level of Ripk3 was positively correlated to the infarction area expansion, cardiac dysfunction and augmented cardiomyocytes necroptosis. Function study further illustrated that upregulated Ripk3 evoked the endoplasmic reticulum (ER) stress, which was accompanied with an increase in intracellular Ca²⁺ level ([Ca²⁺]c) and xanthine oxidase (XO) expression. Activated XO raised cellular reactive oxygen species (ROS) that mediated the mitochondrial permeability transition pore (mPTP) opening and cardiomyocytes necroptosis. By comparison, genetic ablation of Ripk3 abrogated the ER stress and thus blocked the [Ca²⁺]c overload-XO-ROS-mPTP pathways, favouring a pro-survival state that ultimately resulted in the inhibition of cardiomyocytes necroptosis in the setting of cardiac IR injury. In summary, the present study helps to elucidate how necroptosis is mediated by ER stress, via the calcium overload /XO/ROS/mPTP opening axis.

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ER stress is activated by Ripk3 in cardiac IR injury.

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ER stress induces calcium overload which triggers XO-dependent ROS overproduction.

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ROS outburst promotes mPTP opening that accounts for the necroptosis.

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Inhibiting ER stress favors cardiomyocytes survival and protects cardiac function.

Inhibition of phosphodiesterase 4 by FCPR16 protects SH-SY5Y cells against MPP+-induced decline of mitochondrial membrane potential and oxidative stress

Phosphodiesterase 4 (PDE4) is a promising target for the treatment of Parkinson's disease (PD). However, the underlying mechanism has not yet been well elucidated. Additionally, most of current PDE4 inhibitors produce severe nausea and vomiting response in patients, which limit their clinical application. FCPR16 is a novel PDE4 inhibitor with little emetic potential. In the present study, the neuroprotective effect and underlying mechanism of FCPR16 against cellular apoptosis induced by 1-methyl-4-phenylpyridinium (MPP⁺) were examined in SH-SY5Y cells. FCPR16 (12.5–50 μM) dose-dependently reduced MPP⁺-induced loss of cell viability, accompanied by reductions in nuclear condensation and lactate dehydrogenase release. The level of cleaved caspase 3 and the ratio of Bax/Bcl-2 were also decreased after treatment with FCPR16 in MPP⁺-treated cells. Furthermore, FCPR16 (25 μM) significantly suppressed the accumulation of reactive oxygen species (ROS), prevented the decline of mitochondrial membrane potential (Δψm) and attenuated the expression of malonaldehyde level. Further studies disclosed that FCPR16 enhanced the levels of cAMP and the exchange protein directly activated by cAMP (Epac) in SH-SY5Y cells. Western blotting analysis revealed that FCPR16 increased the phosphorylation of cAMP response element-binding protein (CREB) and protein kinase B (Akt) down-regulated by MPP⁺ in SH-SY5Y cells. Moreover, the inhibitory effects of FCPR16 on the production of ROS and Δψm loss could be blocked by PKA inhibitor H-89 and Akt inhibitor KRX-0401. Collectively, these results suggest that FCPR16 attenuates MPP⁺-induced dopaminergic degeneration via lowering ROS and preventing the loss of Δψm in SH-SY5Y cells. Mechanistically, cAMP/PKA/CREB and Epac/Akt signaling pathways are involved in these processes. Our findings indicate that FCPR16 is a promising pre-clinical candidate for the treatment of PD and possibly other oxidative stress-related neuronal diseases.

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FCPR16 protected SH-SY5Y cells against MPP⁺-induced apoptosis.

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FCPR16 attenuated Δψm loss and ROS generation in SH-SY5Y cells treated with MPP⁺.

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FCPR16 activated cAMP/PKA/CREB and Epac/Akt signaling pathways in SH-SY5Y cells.

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Blocking cAMP/PKA/CREB or Epac/Akt pathways canceled the protective role of FCPR16.

IGF-II promotes neuroprotection and neuroplasticity recovery in a long-lasting model of oxidative damage induced by glucocorticoids

Insulin-like growth factor-II (IGF-II) is a naturally occurring hormone that exerts neurotrophic and neuroprotective properties in a wide range of neurodegenerative diseases and ageing. Accumulating evidence suggests that the effects of IGF-II in the brain may be explained by its binding to the specific transmembrane receptor, IGFII/M6P receptor (IGF-IIR). However, relatively little is known regarding the role of IGF-II through IGF-IIR in neuroprotection. Here, using adult cortical neuronal cultures, we investigated whether IGF-II exhibits long-term antioxidant effects and neuroprotection at the synaptic level after oxidative damage induced by high and transient levels of corticosterone (CORT). Furthermore, the involvement of the IGF-IIR was also studied to elucidate its role in the neuroprotective actions of IGF-II. We found that neurons treated with IGF-II after CORT incubation showed reduced oxidative stress damage and recovered antioxidant status (normalized total antioxidant status, lipid hydroperoxides and NAD(P) H:quinone oxidoreductase activity). Similar results were obtained when mitochondria function was analysed (cytochrome c oxidase activity, mitochondrial membrane potential and subcellular mitochondrial distribution). Furthermore, neuronal impairment and degeneration were also assessed (synaptophysin and PSD-95 expression, presynaptic function and FluoroJade B® stain). IGF-II was also able to recover the long-lasting neuronal cell damage. Finally, the effects of IGF-II were not blocked by an IGF-IR antagonist, suggesting the involvement of IGF-IIR. Altogether these results suggest that, in or model, IGF-II through IGF-IIR is able to revert the oxidative damage induced by CORT. In accordance with the neuroprotective role of the IGF-II/IGF-IIR reported in our study, pharmacotherapy approaches targeting this pathway may be useful for the treatment of diseases associated with cognitive deficits (i.e., neurodegenerative disorders, depression, etc.).

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First evidence that IGF-II reverts oxidative synaptic damage produced by corticoids.

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IGF-II recovers mitochondrial function in synapses after oxidative damage.

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IGF-II restores mitochondrial distribution in neurons after oxidative damage.

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Evidence of the involvement of IGF-II receptor in the recovery of synaptic function.

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IGF-II reverts neurodegeneration induced by oxidative damage produced by corticoids.