Neuroprotective actions of pterostilbene on hypoxic-ischemic brain damage in neonatal rats through upregulation of heme oxygenase-1

Pterostilbene Potentiates the NGF-TrkA Signaling Pathway, Enhancing Differentiation in PC12 Cells

Pterostilbene, a stilbenoid found in vegetables and natural products, has therapeutic potential due to its multiple pharmacological actions. In the brain, the nerve growth factor (NGF) is a pivotal neurotrophic factor, serving for neuronal survival and differentiation. The decline in NGF levels in aged individuals contributes to the development of neurodegenerative processes and cognitive impairment. Here, we aim to explore the effect of pterostilbene on promoting neuron-like differentiation in PC12 cells, a well-established model to study neuronal differentiation, by potentiating the functions of NGF. Molecular docking and ultrafiltration assays were performed to examine the direct binding of pterostilbene with NGF. The mechanisms underlying the stimulation of PC12 cell differentiation, characterized by enhanced neurite outgrowth and increased neurofilament expression, were determined through TrkA/Akt/CREB signaling pathways. The combined treatment of pterostilbene with a low dose of NGF significantly potentiated the NGF-induced neurite extension and neurofilament expression. Pterostilbene enhanced the effect of NGF on promoting neuron-like differentiation, which was related to increased activation of the TrkA signaling pathway. This upstream event was associated with increased phosphorylation of Akt and CREB. The selective inhibitors of TrkA (K252a) and PI3K/Akt (LY294002) were applied to validate the NGF/TrkA/Akt signaling pathways leading to diminished neurite outgrowth and reduced expression of neurofilaments in cells treated with pterostilbene and NGF. Taken together, the results indicate that pterostilbene could potentiate NGF/TrkA activity, enhancing neuron-like differentiation in PC12 cells under a low concentration of NGF. These findings suggest that the application of pterostilbene could be a promising alternative therapeutic strategy to improve NGF efficacy.

Pretreatment with oleuropein protects the neonatal brain from hypoxia-ischemia by inhibiting apoptosis and neuroinflammation

Hypoxic-ischemic (HI) encephalopathy is a cerebrovascular injury caused by oxygen deprivation to the brain and remains a major cause of neonatal mortality and morbidity worldwide. Therapeutic hypothermia is the current standard of care but it does not provide complete neuroprotection. Our aim was to investigate the neuroprotective effect of oleuropein (Ole) in a neonatal (seven-day-old) mouse model of HI. Ole, a secoiridoid found in olive leaves, has previously shown to reduce damage against cerebral and other ischemia/reperfusion injuries. Here, we administered Ole as a pretreatment prior to HI induction at 20 or 100 mg/kg. A week after HI, Ole significantly reduced the infarct area and the histological damage as well as white matter injury, by preserving myelination, microglial activation and the astroglial reactive response. Twenty-four hours after HI, Ole reduced the overexpression of caspase-3 and the proinflammatory cytokines IL-6 and TNF-α. Moreover, using UPLC-MS/MS we found that maternal supplementation with Ole during pregnancy and/or lactation led to the accumulation of its metabolite hydroxytyrosol in the brains of the offspring. Overall, our results indicate that pretreatment with Ole confers neuroprotection and can prevent HI-induced brain damage by modulating apoptosis and neuroinflammation.

Pterostilbene as a Therapeutic Alternative for Central Nervous System Disorders: A Review of the Current Status and Perspectives

Neurological disorders are diverse, have complex causes, and often result in disability; yet, effective treatments remain scarce. The resveratrol derivative pterostilbene possesses numerous physiological activities that hold promise as a novel therapy for the central nervous system (CNS) disorders. This review aimed to summarize the protective mechanisms of pterostilbene in in vitro and in vivo models of CNS disorders and the pharmacokinetics and safety to assess its possible effects on CNS disorders. Available evidence supports the protective effects of pterostilbene in CNS disorders involving mechanisms such as antioxidant and anti-inflammatory activity, regulation of lipid metabolism and vascular smooth muscle cell proliferation, improvement of synaptic function and neurogenesis, induction of glioma cell cycle arrest, and inhibition of glioma cell migration and invasion. Studies have identified possible molecular targets and pathways for the protective actions of pterostilbene in CNS disorders including the AMPK/STAT3, Akt, NF-κB, MAPK, and ERK signaling pathways. The possible pharmacological effects and molecular pathways of pterostilbene in CNS disorders are critically discussed in this review. Future studies should aim to increase our understanding of pterostilbene in animal models and humans to further evaluate its role in CNS disorders and the detailed mechanisms.

The neuroprotective effect of pterostilbene on oxaliplatin-induced peripheral neuropathy via its anti-inflammatory, anti-oxidative and anti-apoptotic effects: Comparative study with celecoxib

BACKGROUND

Oxaliplatin is one of the first-line drugs in solid tumors treatment. However, neuropathy is a devastating side effect leading to poor compliance and treatment cessation.

AIM

The current study explored pterostilbene plausible neuroprotective effects aiming to ascertain the potential mechanisms involved in relieving oxaliplatin-induced peripheral neuropathy (OIPN) and investigating whether pterostilbene and celecoxib combination could show better relief.

MAIN METHODS

Rats were divided into six groups; control, pterostilbene (40 mg/kg/day, p.o. for 5 weeks), oxaliplatin (4 mg/kg, i.p. twice per week for 4.5 weeks), celecoxib (30 mg/kg/day, p.o. for 5 weeks) and combination of pterostilbene and celecoxib. Behavioral tests and histopathological analysis of sciatic nerves were done. MAPKs, cytokines, COX-2, and PGE₂ gene and protein expressions were estimated using qRT-PCR, western, and ELISA techniques. Malondialdehyde (MDA) and total antioxidant capacity (TAC) were assessed by colorimetric assay while apoptotic markers by immunohistochemical analysis and qRT-PCR.

KEY FINDINGS

The study revealed that pterostilbene and celecoxib averted oxaliplatin-induced behavioral and motor impairments along with restoration of histopathological changes. Moreover, pterostilbene and celecoxib have significantly attenuated sciatic nerve: p38 MAPK, JNK, ERK1/2, NF-κB, COX-2, PGE₂, TNF-α, and interleukins levels. Pterostilbene and celecoxib have reduced caspase-3, Bax, and MDA while increasing Bcl-2 level and TAC.

SIGNIFICANCE

Altogether, Pterostilbene mitigates OIPN by interrupting the vicious cycle of inflammation, oxidation, and apoptosis. Furthermore, pterostilbene and celecoxib show comparable attenuation on MAPKs cascades, inflammatory cytokines, oxidative and apoptotic markers. Likewise, co-administration of pterostilbene and celecoxib shows further relief of neuropathic pain.

Plant based food bioactives: A boon or bane for neurological disorders

Neurological disorders are the foremost occurring diseases across the globe resulting in progressive dysfunction, loss of neuronal structure ultimately cell death. Therefore, attention has been drawn toward the natural resources for the search of neuroprotective agents. Plant-based food bioactives have emerged as potential neuroprotective agents for the treatment of neurodegenerative disorders. This comprehensive review primarily focuses on various plant food bioactive, mechanisms, therapeutic targets, in vitro and in vivo studies in the treatment of neurological disorders to explore whether they are boon or bane for neurological disorders. In addition, the clinical perspective of plant food bioactives in neurological disorders are also highlighted. Scientific evidences point toward the enormous therapeutic efficacy of plant food bioactives in the prevention or treatment of neurological disorders. Nevertheless, identification of food bioactive components accountable for the neuroprotective effects, mechanism, clinical trials, and consolidation of information flow are warranted. Plant food bioactives primarily act by mediating through various pathways including oxidative stress, neuroinflammation, apoptosis, excitotoxicity, specific proteins, mitochondrial dysfunction, and reversing neurodegeneration and can be used for the prevention and therapy of neurodegenerative disorders. In conclusion, the plant based food bioactives are boon for neurological disorders.

Mechanistic insights gained from cell and molecular analysis of the neuroprotective potential of bioactive natural compounds in an immortalized hippocampal cell line

Evaluating novel compounds for neuroprotective effects in animal models of traumatic brain injury (TBI) is a protracted, labor-intensive and costly effort. However, the present lack of effective treatment options for TBI, despite decades of research, shows the critical need for alternative methods for screening new drug candidates with neuroprotective properties. Because natural products have been a leading source of new therapeutic agents for human diseases, we used an in vitro model of stretch injury to rapidly assess pro-survival effects of three bioactive compounds, two isolated from natural products (clovanemagnolol [CM], vinaxanthone [VX]) and the third, a dietary compound (pterostilbene [PT]) found in blueberries. The stretch injury experiments were not used to validate drug efficacy in a comprehensive manner but used primarily, as proof-of-principle, to demonstrate that the neuroprotective potential of each bioactive agent can be quickly assessed in an immortalized hippocampal cell line in lieu of comprehensive testing in animal models of TBI. To gain mechanistic insights into potential molecular mechanisms of neuroprotective effects, we performed a pathway-specific PCR array analysis of the effects of CM on the rat hippocampus and microRNA sequencing analysis of the effects of VX and PT on cultured hippocampal progenitor neurons. We show that the neuroprotective properties of these natural compounds are associated with altered expression of several genes or microRNAs that have functional roles in neurodegeneration or cell survival. Our approach could help in quickly assessing multiple natural products for neuroprotective properties and expedite the process of new drug discovery for TBI therapeutics.

Neuroprotective Effect of Eco-Sustainably Extracted Grape Polyphenols in Neonatal Hypoxia-Ischemia

Polyphenols are natural compounds with promising prophylactic and therapeutic applications. However, their methods of extraction, using organic solvents, may prove to be unsuitable for daily consumption or for certain medical indications. Here, we describe the neuroprotective effects of grape polyphenols extracted in an eco-sustainable manner in a rat model of neonatal hypoxia-ischemia (NHI). Polyphenols (resveratrol, pterostilben and viniferin) were obtained using a subcritical water extraction technology to avoid organic solvents and heavy metals associated with chemical synthesis processes. A resveratrol or a polyphenol cocktail were administered to pregnant females at a nutritional dose and different time windows, prior to induction of NHI in pups. Reduced brain edema and lesion volumes were observed in rat pups whose mothers were supplemented with polyphenols. Moreover, the preservation of motor and cognitive functions (including learning and memory) was evidenced in the same animals. Our results pave the way to the use of polyphenols to prevent brain lesions and their associated deficits that follow NHI, which is a major cause of neonatal death and disabilities.

The modulation of SIRT1 and SIRT3 by natural compounds as a therapeutic target in doxorubicin-induced cardiotoxicity: A review

Doxorubicin (DOX) is a potent antitumor agent with a broad spectrum of activity; however, irreversible cardiotoxicity resulting from DOX treatment is a major issue that limits its therapeutic use. Sirtuins (SIRTs) play an essential role in several physiological and pathological processes including oxidative stress, apoptosis, and inflammation. It has been reported that SIRT1 and SIRT3 can act as a protective molecular against DOX-induced myocardial injury through targeting numerous signaling pathways. Several natural compounds (NCs), such as resveratrol, sesamin, and berberine, with antioxidative, anti-inflammation, and antiapoptotic effects were evaluated for their potential to suppress the cardiotoxicity induced by DOX via targeting SIRT1 and SIRT3. Numerous NCs exerted their therapeutic effects on DOX-mediated cardiac damage via targeting different signaling pathways, including SIRT1/LKB1/AMPK, SIRT1/PGC-1α, SIRT1/NLRP3, and SIRT3/FoxO. SIRT3 also ameliorates cardiotoxicity by enhancing mitochondrial fusion.

Current Therapies for Neonatal Hypoxic-Ischaemic and Infection-Sensitised Hypoxic-Ischaemic Brain Damage

Neonatal hypoxic-ischaemic brain damage is a leading cause of child mortality and morbidity, including cerebral palsy, epilepsy, and cognitive disabilities. The majority of neonatal hypoxic-ischaemic cases arise as a result of impaired cerebral perfusion to the foetus attributed to uterine, placental, or umbilical cord compromise prior to or during delivery. Bacterial infection is a factor contributing to the damage and is recorded in more than half of preterm births. Exposure to infection exacerbates neuronal hypoxic-ischaemic damage thus leading to a phenomenon called infection-sensitised hypoxic-ischaemic brain injury. Models of neonatal hypoxia-ischaemia (HI) have been developed in different animals. Both human and animal studies show that the developmental stage and the severity of the HI insult affect the selective regional vulnerability of the brain to damage, as well as the subsequent clinical manifestations. Therapeutic hypothermia (TH) is the only clinically approved treatment for neonatal HI. However, the number of HI infants needed to treat with TH for one to be saved from death or disability at age of 18-22 months, is approximately 6-7, which highlights the need for additional or alternative treatments to replace TH or increase its efficiency. In this review we discuss the mechanisms of HI injury to the immature brain and the new experimental treatments studied for neonatal HI and infection-sensitised neonatal HI.

LncRNA TCONS_00041002 improves neurological outcomes in neonatal rats with hypoxic-ischemic encephalopathy by inhibiting apoptosis and promoting neuron survival

It has been reported that Neonatal hypoxic-ischemic encephalopathy (HIE) could induce apoptosis in neonates and result in cognitive and sensory impairments, which are associated with poor developmental outcomes. Despite the improvement in neonatology, there is still no clinically effective treatment for HIE presently. Long non-coding RNAs (lncRNAs) play important roles in cellular homeostasis. Nevertheless, their effects in developing rat brains with HI is little known. Here, we established HIE model in neonate rats and explored the expression and function of lncRNAs in HI, and found the expression of 19 lncRNAs was remarkably changed in the brains of HI rats, compared to the sham group. Among them, three lncRNAs (TCONS_00041002, TCONS_00070547, TCONS_00045572) were enriched in the apoptotic process via gene ontology (GO) and pathway analysis, which were selected for the further qRT-PCR verification. Through lentivirus-mediated overexpression of these three lncRNAs, we found that overexpression of TCONS_00041002 attenuated the cell apoptosis, and increased the vitality of neurons after oxygen-glucose deprivation (OGD), therefore reduced the brain infarction and further promoted the neuron survival as well as improved the neurological disorders in the rats subjected to HIE. What's more, ceRNA network prediction and co-expression verification showed that the expression of TCONS_00041002 was positively associated with Foxe1, Pawr and Nfkbiz. Altogether, this study has exhibited that lncRNA TCONS_00041002 participates in the cell apoptosis and neuronal survival of HIE and represents a potential new target for the treatment of HIE.

Pre-Treatment of Pterostilbene Enhances H2O2-induced Cell Apoptosis Through Caspase-dependent Pathway in Human Keratinocyte Cells

BACKGROUND/AIM

Hydrogen peroxide (H₂O₂) is one of the reactive oxygen species (ROS), which can induce apoptotic cell death in numerous cancer cells. Pterostilbene (PTE), a natural polyphenolic compound, induces cell apoptosis in many human cancer cells.

MATERIALS AND METHODS

We investigated whether PTE could enhance H₂O₂-induced cell apoptosis in human keratinocyte HaCaT cells in vitro. The morphological change of HaCaT cells was observed and photographed under a contrast-phase microscope. The percentage of cell viability was measured by propidium iodide exclusion assay. Cell apoptosis was performed by Annexin V/PI double staining and assayed by flow cytometer. DNA condensation was measured by DAPI staining. The protein expression was determined by western blotting. ROS production-associated proteins were also assayed by confocal laser scanning microscopy.

RESULTS

PTE pre-treatment enhanced H₂O₂ (600 μM)-induced cell morphological changes and reduced the total cell number (cell viability). The decreased cell viability in HaCaT cells was through induction of apoptotic cell death, which was confirmed by Annexin V/PI double staining and DAPI staining. Western blotting studies indicated that HaCaT cells which were pre-treated with PTE (100 μM) and then co-treated with H₂O₂ (600 μM) for 12 h showed significantly increased levels of SOD (Cu/Zn), SOD (Mn), Bax, caspase-3, caspase-8, caspase-9, PARP, p53, p-p53, and p-H2A.X but decreased levels Bcl-2 and catalase. Results also showed that HaCaT cells pre-treated with PTE and then co-treated with H₂O₂ had increased expression of SOD (Cu/Zn) and glutathione but decreased catalase.

CONCLUSION

These observations suggest that PTE pre-treatment can enhance the H₂O₂-induced apoptotic cell death in keratinocyte cells and may be an effective candidate for the treatment of proliferative keratinocytes.

Multitarget neuroprotection by quercetin: Changes in gene expression in two perinatal asphyxia models

Hypoxic-ischemic encephalopathy (HIE) causes mortality and long-term neurologic morbidities in newborns, affecting pathways related to energy failure, excitotoxicity and oxidative stress that often lead to cell death. The whole process of HIE injury is coupled to changes in the expression of a great array of proteins. A nanoliposomal preparation of the flavonoid quercetin has been shown to exert neuroprotective effects in perinatal asphyxia models. This study aimed to identify neonatal HIE markers and explore the effect of quercetin administration in two perinatal asphyxia models: newborn rats and piglets. In the rat model, nanoliposomal quercetin administration reduced mortality after asphyxia. In the piglet model, quercetin partially overrode the reduction of HIF-1α mRNA levels in the cortex induced by asphyxia. Quercetin administration also reduced increased level of HO-1 mRNA in asphyctic piglets. These results suggest that quercetin neuroprotection might be involved in the regulation of HIF-1α, HO-1 and their targets. A proteomic approach revealed that the glycolytic pathway is strongly regulated by quercetin in both species. We also identified a set of proteins differentially expressed that could be further considered as markers. In piglets, this set includes Acidic Leucine-rich nuclear phosphoprotein 32 (ANP32A), associated with nervous system differentiation, proteins related with death pathways and alpha-enolase which can be converted to neuron-specific enolase, a glycolytic enzyme that may promote neuroprotection. In newborn rats, other promising proteins associated with neurogenesis and neuroprotection emerged, such as dihydropyrimidinase-related proteins, catalytic and regulatory subunits of phosphatases and heterogeneous nuclear ribonucleoprotein K (hnRNPK). Our results show that a nanoliposomal preparation of quercetin, with protective effect in two HIE mammal models, modulates the expression of proteins involved in energy metabolism and other putative neuroprotective signals in the cortex. Identification of these signals could reveal potential molecular pathways involved in disease onset and the novel quercetin neuroprotective strategy.

Nutraceuticals in the Prevention of Neonatal Hypoxia-Ischemia: A Comprehensive Review of their Neuroprotective Properties, Mechanisms of Action and Future Directions

Neonatal hypoxia-ischemia (HI) is a brain injury caused by oxygen deprivation to the brain due to birth asphyxia or reduced cerebral blood perfusion, and it often leads to lifelong limiting sequelae such as cerebral palsy, seizures, or mental retardation. HI remains one of the leading causes of neonatal mortality and morbidity worldwide, and current therapies are limited. Hypothermia has been successful in reducing mortality and some disabilities, but it is only applied to a subset of newborns that meet strict inclusion criteria. Given the unpredictable nature of the obstetric complications that contribute to neonatal HI, prophylactic treatments that prevent, rather than rescue, HI brain injury are emerging as a therapeutic alternative. Nutraceuticals are natural compounds present in the diet or used as dietary supplements that have antioxidant, anti-inflammatory, or antiapoptotic properties. This review summarizes the preclinical in vivo studies, mostly conducted on rodent models, that have investigated the neuroprotective properties of nutraceuticals in preventing and reducing HI-induced brain damage and cognitive impairments. The natural products reviewed include polyphenols, omega-3 fatty acids, vitamins, plant-derived compounds (tanshinones, sulforaphane, and capsaicin), and endogenous compounds (melatonin, carnitine, creatine, and lactate). These nutraceuticals were administered before the damage occurred, either to the mothers as a dietary supplement during pregnancy and/or lactation or to the pups prior to HI induction. To date, very few of these nutritional interventions have been investigated in humans, but we refer to those that have been successful in reducing ischemic stroke in adults. Overall, there is a robust body of preclinical evidence that supports the neuroprotective properties of nutraceuticals, and these may represent a safe and inexpensive nutritional strategy for the prevention of neonatal HI encephalopathy.

A Review of Plant Extracts and Plant-Derived Natural Compounds in the Prevention/Treatment of Neonatal Hypoxic-Ischemic Brain Injury

Neonatal hypoxic-ischemic (HI) brain injury is one of the major drawbacks of mortality and causes significant short/long-term neurological dysfunction in newborn infants worldwide. To date, due to multifunctional complex mechanisms of brain injury, there is no well-established effective strategy to completely provide neuroprotection. Although therapeutic hypothermia is the proven treatment for hypoxic-ischemic encephalopathy (HIE), it does not completely chang outcomes in severe forms of HIE. Therefore, there is a critical need for reviewing the effective therapeutic strategies to explore the protective agents and methods. In recent years, it is widely believed that there are neuroprotective possibilities of natural compounds extracted from plants against HIE. These natural agents with the anti-inflammatory, anti-oxidative, anti-apoptotic, and neurofunctional regulatory properties exhibit preventive or therapeutic effects against experimental neonatal HI brain damage. In this study, it was aimed to review the literature in scientific databases that investigate the neuroprotective effects of plant extracts/plant-derived compounds in experimental animal models of neonatal HI brain damage and their possible underlying molecular mechanisms of action.

Lycopene Exerts Neuroprotective Effects After Hypoxic-Ischemic Brain Injury in Neonatal Rats via the Nuclear Factor Erythroid-2 Related Factor 2/Nuclear Factor-κ-Gene Binding Pathway

Neonatal hypoxic-ischemic encephalopathy (HIE) is a brain injury caused by perinatal asphyxia and is the main cause of neonatal death and chronic neurological diseases. Protection of neuron after hypoxic-ischemic (HI) brain injury is considered as a potential therapeutic target of HI brain injury. To date, there are no effective medicines for neonatal HI brain injury. Lycopene (Lyc), a member of the carotenoids family, has been reported to have anti-oxidative and anti-inflammatory effects. However, its effects and potential mechanisms in HI brain injury have not yet to be systematically evaluated. In this study, we investigated whether Lyc could ameliorate HI brain injury and explored the associated mechanism both in vivo and in vitro experiments. In vivo study, Lyc significantly reduced infarct volume and ameliorated cerebral edema, decreased inflammatory response, promoted the recovery of tissue structure, and improved prognosis following HI brain injury. In vitro study, results showed that Lyc reduced expression of apoptosis mediators in oxygen-glucose deprivation (OGD)-induced primary cortical neurons. Mechanistically, we found that Lyc-induced Nrf2/NF-κB pathway could partially reversed by Brusatol (an Nrf2 inhibitor), indicated that the Nrf2/NF-κB pathway was involved in the therapy of Lyc. In summary, our findings indicate that Lyc can attenuated HI brain injury in vivo and OGD-induced apoptosis of primary cortical neurons in vitro through the Nrf2/NF-κB signaling pathway.

Recent Advances in Synthesis, Bioactivity, and Pharmacokinetics of Pterostilbene, an Important Analog of Resveratrol

Pterostilbene is a natural 3,5-dimethoxy analog of resveratrol. This stilbene compound has a strong bioactivity and exists widely in Dalbergia and Vaccinium spp. Besides natural extraction, pterostilbene can be obtained by biosynthesis. Pterostilbene has become popular because of its remarkable pharmacological activities, such as anti-tumor, anti-oxidation, anti-inflammation, and neuroprotection. Pterostilbene can be rapidly absorbed and is widely distributed in tissues, but it does not seriously accumulate in the body. Pterostilbene can easily pass through the blood-brain barrier because of its low molecular weight and good liposolubility. In this review, the studies performed in the last three years on resources, synthesis, bioactivity, and pharmacokinetics of pterostilbene are summarized. This review focuses on the effects of pterostilbene on certain diseases to explore its targets, explain the possible mechanism, and look for potential therapeutic applications.

C/EBPα-mediated transcriptional activation of miR-134-5p entails KPNA3 inhibition and modulates focal hypoxic-ischemic brain damage in neonatal rats

Hypoxic-ischemic brain damage (HIBD) is a frequent cause of mortality and neurological handicaps in infants and children worldwide. To understand better the pathogenesis and management of HIBD, we established a HIBD model by common carotid artery ligation followed by systemic hypoxia in neonatal rats, and in other studies induced neuronal death in rat pheochromocytoma (PC12) cells by 12 h of oxygen-glucose deprivation (OGD). The level of KPNA3 declined in rats following experimental HIBD and in PC12 cells following OGD. KPNA3 overexpression protected neonatal rats against HIBD and PC12 cells against OGD-induced cell death. KPNA3 demonstrated to be the target of miR-134-5p could be activated by the transcriptional factor CCAAT/enhancer binding protein alpha (C/EBPα). The expression of miR-134-5p and C/EBPα was elevated in rats following experimental HIBD and in PC12 cells following OGD. In the parallel experiments, C/EBPα knockdown and miR-134 inhibition protected against HIBD pathology in neonatal rats and against OGD-induced neuronal death in PC12 cells. These findings reveal that the C/EBPα/miR-134-5p/KPNA3 axis mediates hypoxic-ischemic brain damage and neuronal death, thus presenting a potential therapeutic target for the treatment of human newborns at risk for HIBD.

Antioxidant Alternatives in the Treatment of Amyotrophic Lateral Sclerosis: A Comprehensive Review

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that produces a selective loss of the motor neurons of the spinal cord, brain stem and motor cortex. Oxidative stress (OS) associated with mitochondrial dysfunction and the deterioration of the electron transport chain has been shown to be a factor that contributes to neurodegeneration and plays a potential role in the pathogenesis of ALS. The regions of the central nervous system affected have high levels of reactive oxygen species (ROS) and reduced antioxidant defenses. Scientific studies propose treatment with antioxidants to combat the characteristic OS and the regeneration of nicotinamide adenine dinucleotide (NAD+) levels by the use of precursors. This review examines the possible roles of nicotinamide riboside and pterostilbene as therapeutic strategies in ALS.

Characterization of Effectiveness in Concerted Ih Inhibition and IK(Ca) Stimulation by Pterostilbene (Trans-3,5-dimethoxy-4'-hydroxystilbene), a Stilbenoid

Pterostilbene (PTER), a natural dimethylated analog of resveratrol, has been demonstrated to produce anti-neoplastic or neuroprotective actions. However, how and whether this compound can entail any perturbations on ionic currents in electrically excitable cells remains unknown. In whole-cell current recordings, addition of PTER decreased the amplitude of macroscopic I_h during long-lasting hyperpolarization in GH₃ cells in a concentration-dependent manner, with an effective IC₅₀ value of 0.84 μM. Its presence also shifted the activation curve of I_h along the voltage axis to a more hyperpolarized potential, by 11 mV. PTER at a concentration greater than 10 μM could also suppress l-type Ca²⁺ and transient outward K⁺ currents in GH₃ cells. With the addition of PTER, I_K(Ca) amplitude was increased, with an EC₅₀ value of 2.23 μM. This increase in I_K(Ca) amplitude was attenuated by further addition of verruculogen, but not by tolbutamide or TRAM-39. Neither atropine nor nicotine, in the continued presence of PTER, modified the PTER-stimulated I_K(Ca). PTER (10 μM) slightly suppressed the amplitude of l-type Ca²⁺ current and transient outward K⁺ current. The presence of PTER (3 μM) was also effective at increasing the open-state probability of large-conductance Ca²⁺-activated K⁺ (BK_Ca) channels identified in hippocampal mHippoE-14 neurons; however, its inability to alter single-channel conductance was detected. Our study highlights evidence to show that PTER has the propensity to perturb ionic currents (e.g., I_h and I_K(Ca)), thereby influencing the functional activities of neurons, and neuroendocrine or endocrine cells.

Pioglitazone Attenuates Lipopolysaccharide-Induced Oxidative Stress, Dopaminergic Neuronal Loss and Neurobehavioral Impairment by Activating Nrf2/ARE/HO-1

The aim of the present study was to examine the neuroprotective potential of pioglitazone via activation of Nrf2/ARE-dependent HO-1 signaling pathway in chronic neuroinflammation and progressive neurodegeneration mouse model induced by lipopolysaccharide (LPS). After assessing spatial memory, anxiety and motor-coordination, TH+ neurons in substantia nigra (SN) were counted. The oxidative stress marker carbonyl protein levels and HO-1 enzyme activity were also evaluated. RT-qPCR was conducted to detect HO-1, Nrf2 and NF-κp65 mRNA expression levels and Nrf2 transcriptional activation of antioxidant response element (ARE) of HO-1 was investigated. Pioglitazone ameliorated LPS-induced dopaminergic neuronal loss, as well as mitigated neurobehavioral impairments. It enhanced Nrf2 mRNA expression, and augmented Nrf2/ARE-dependent HO-1 pathway activation by amplifying HO-1 mRNA expression. Moreover, it induced a significant decrease in NF-κB p65 mRNA expression, while reducing carbonyl protein levels and restoring the HO-1 enzyme activity. Interestingly, LPS induced Nrf2/antioxidant response element (ARE) of HO-1 activation, ultimately resulting in slight enhanced HO-1 mRNA expression. However, LPS elicited decrease in HO-1 enzyme activity. Zinc protoporphyrin-IX (ZnPPIX) administrated with pioglitazone abolished its effects in the LPS mouse model. The study results demonstrate that coordinated activation of Nrf2/ARE-dependent HO-1 pathway defense mechanism by the PPARγ agonist pioglitazone mediated its neuroprotective effects.

Anticonvulsant Activity of Pterostilbene in Zebrafish and Mouse Acute Seizure Tests

Pterostilbene (PTE), a natural dimethylated analog of resveratrol, possesses numerous health-beneficial properties. The ability of PTE to cross the blood–brain barrier raised the possibility that this compound may modulate central nervous system functions, including seizure activity. The aim of our study was to investigate the activity of PTE in the larval zebrafish pentylenetetrazole (PTZ) seizure assay and three acute seizure tests in mice, i.e., in the maximal electroshock seizure threshold (MEST), 6 Hz-induced psychomotor seizure threshold and intravenous (iv) PTZ tests. Additionally, potential antidepressant activity of PTE was estimated in the forced swim test in mice. The chimney test was used to determine the influence of PTE on motor coordination in mice, while its influence on neuromuscular strength was assessed in the grip strength test in mice. Locomotor activity was determined to verify the results from the forced swim test. PTE revealed an evident anticonvulsant effect both in zebrafish larvae (10 µM; 2 h-incubation) and mice (at doses of 100 and 200 mg/kg, intraperitoneally) but it did not exhibit antidepressant potential in the forced swim test. Furthermore, it did not cause any statistically significant changes in motor coordination, neuromuscular strength and locomotor activity in mice. In conclusion, our present findings demonstrate for the first time the anticonvulsant potential of PTE. The aforementioned results suggest that it might be employed in epilepsy treatment, however, further precise studies are required to verify its activity in other experimental seizure and epilepsy models and its precise mechanism of action should be determined.

Neurointegrity and neurophysiology: astrocyte, glutamate, and carbon monoxide interactions

Astrocyte contributions to brain function and prevention of neuropathologies are as extensive as that of neurons. Astroglial regulation of glutamate, a primary neurotransmitter, is through uptake, release through vesicular and non-vesicular pathways, and catabolism to intermediates. Homeostasis by astrocytes is considered to be of primary importance in determining normal central nervous system health and central nervous system physiology - glutamate is central to dynamic physiologic changes and central nervous system stability. Gasotransmitters may affect diverse glutamate interactions positively or negatively. The effect of carbon monoxide, an intrinsic central nervous system gasotransmitter, in the complex astrocyte homeostasis of glutamate may offer insights to normal brain development, protection, and its use as a neuromodulator and neurotherapeutic. In this article, we will review the effects of carbon monoxide on astrocyte homeostasis of glutamate.

Heme Oxygenase 1 in the Nervous System: Does It Favor Neuronal Cell Survival or Induce Neurodegeneration?

Heme oxygenase 1 (HO-1) up-regulation is recognized as a pivotal mechanism of cell adaptation to stress. Under control of different transcription factors but with a prominent role played by Nrf2, HO-1 induction is crucial also in nervous system response to damage. However, several lines of evidence have highlighted that HO-1 expression is associated to neuronal damage and neurodegeneration especially in Alzheimer’s and Parkinson’s diseases. In this review, we summarize the current literature regarding the role of HO-1 in nervous system pointing out different molecular mechanisms possibly responsible for HO-1 up-regulation in nervous system homeostasis and neurodegeneration.

Tert-butylhydroquinone post-treatment attenuates neonatal hypoxic-ischemic brain damage in rats

Hypoxic-ischemic (HI) encephalopathy is a leading cause of dire mortality and morbidity in neonates. Unfortunately, no effective therapies have been developed as of yet. Oxidative stress plays a critical role in pathogenesis and progression of neonatal HI. Previously, as a Nrf2 activator, tert-butylhydroquinone (TBHQ) has been demonstrated to exert neuroprotection on brain trauma and ischemic stroke models, as well as oxidative stress-induced cytotoxicity in neurons. It is, however, still unknown whether TBHQ administration can protect against oxidative stress in neonatal HI brain injury. This study was undertaken to determine the neuroprotective effects and mechanisms of TBHQ post-treatment on neonatal HI brain damage. Using a neonatal HI rat model, we demonstrated that TBHQ markedly abated oxidative stress compared to the HI group, as evidenced by decreased oxidative stress indexes, enhanced Nrf2 nuclear accumulation and DNA binding activity, and up-regulated expression of Nrf2 downstream antioxidative genes. Administration of TBHQ likewise significantly suppressed reactive gliosis and release of inflammatory cytokines, and inhibited apoptosis and neuronal degeneration in the neonatal rat cerebral cortex. In addition, infarct size and neuronal damage were attenuated distinctly. These beneficial effects were accompanied by improved neurological reflex and motor coordination as well as amelioration of spatial learning and memory deficits. Overall, our results provide the first documentation of the beneficial effects of TBHQ in neonatal HI model, in part conferred by activation of Nrf2 mediated antioxidative signaling pathways.

Pterostilbene inhibits reactive oxygen species production and apoptosis in primary spinal cord neurons by activating autophagy via the mechanistic target of rapamycin signaling pathway

Autophagy is an important self-adaptive mechanism that is involved in inhibiting reactive oxygen species (ROS) in spinal cord neurons. Pterostilbene, a natural plant extract, has been demonstrated to possess antioxidant effects; however, it has not yet been investigated whether pterostilbene could activate autophagy and protect spinal cord neurons from oxidative stress. In the present study, primary spinal cord neurons of Sprague Dawley rats were cultured. Cell counting kit‑8 analysis was used to detect cytotoxicity of pterostilbene. Cells were treated with various doses of pterostilbene for 24 and 48 h, respectively, and H2O2 was used to induce ROS production. Western blot analysis was performed to assess the protein expression of microtubule‑associated protein 1 light chain 3 (LC3)‑II, Beclin‑1, p62, p‑p70S6K and p‑mechanistic target of rapamycin (mTOR). Furthermore, the green fluorescent protein (GFP)‑LC3 assay was used to detect the level of autophagy level and activation mechanism. 2',7'‑Dichlorofluorescin diacetate and MitoSOX Red staining were used to detect ROS production, and Terminal deoxynucleotidyl‑transferase‑mediated dUTP nick end labelling assay was used to analyze apoptosis percentage. ATG5 small interfering (si)RNA transfection was used to analyze the involvement of autophagy. A dose‑dependent increase in the expression of LC3‑II and Beclin‑1, as well as the p62 decline, were observed in the pterostilbene‑treated neurons; however, p‑p70S6K and p‑mTOR expression was inhibited by pterostilbene. Pterostilbene increased the expression of LC3‑II in H2O2‑treated cells, and GFP‑LC3 analysis demonstrated an increased number of autophagosomes. Furthermore, pterostilbene significantly inhibited the ROS production and apoptosis induced by H2O2; however, ATG5 siRNA transfection significantly reversed the protection of pterostilbene. These results indicate that pterostilbene may inhibit the ROS production and apoptosis in spinal cord neurons by activating autophagy via the mTOR signaling pathway.

Effect of resveratrol and pterostilbene on aging and longevity

Over the past years, several studies have found that foods rich in polyphenols protect against age-related disease, such as atherosclerosis, cardiovascular disease, cancer, arthritis, cataracts, osteoporosis, type 2 diabetes (T2D), hypertension and Alzheimer's disease. Resveratrol and pterostilbene, the polyphenol found in grape and blueberries, have beneficial effects as anti-aging compounds through modulating the hallmarks of aging, including oxidative damage, inflammation, telomere attrition and cell senescence. In this review, we discuss the relationship between resveratrol and pterostilbene and possible aging biomarker, including oxidative stress, inflammation, and high-calorie diets. Moreover, we also discuss the positive effect of resveratrol and pterostilbene on lifespan, aged-related disease, and health maintenance. Furthermore, we summarize a variety of important mechanisms modulated by resveratrol and pterostilbene possibly involved in attenuating age-associated disorders. Overall, we describe resveratrol and pterostilbene potential for prevention or treatment of several age-related diseases by modulating age-related mechanisms. © 2017 BioFactors, 44(1):69-82, 2018.