Ethyl pyruvate protects against hypoxic-ischemic brain injury via anti-cell death and anti-inflammatory mechanisms

Ethyl pyruvate alleviates NLRP3/Caspase-1/GSDMD-mediated neuronal pyroptosis in neonatal rats with hypoxic-ischemic brain damage

Pyroptosis is an inflammation-associated programmed cell death, and neuroinflammation is strongly associated with severe neurological deficits in neonatal hypoxic-ischemic encephalopathy (HIE). Ethyl pyruvate (EP), a known anti-inflammatory agent, has shown promise in the treatment of hypoxic-ischemic brain damage (HIBD) rats; nevertheless, the therapeutic mechanism of EP and its capacity to suppress neuronal pyroptosis in HIBD rats remain unclear. In both the neonatal Rice-Vannucci rat model and the OGD/R model, this study examined alterations in the NLRP3/Caspase-1/GSDMD classical pyroptosis pathway in hippocampal neurons during HIE and the potential inhibitory impact of ethyl pyruvate on this pathway. We used HE staining, immunofluorescence double staining, transmission electron microscopy, and western blot to demonstrate that EP effectively inhibited hippocampal neuronal pyroptosis and attenuated the activation of the NLRP3/Caspase-1/GSDMD signaling pathway in HIBD rats, which resulted in a reduction of neuroinflammation and facilitated neural recovery. The results suggest that EP may be a promising neuroprotective agent for treating HIE.

Ethyl pyruvate: A newly discovered compound against ischemia-reperfusion injury in multiple organs

Ischemia-reperfusion injury (IRI) is a process whereby an initial ischemia injury and subsequent recovery of blood flow, which leads to the propagation of an innate immune response and the changes of structural and functional of multiple organs. Therefore, IRI is considered to be a great challenge in clinical treatment such as organ transplantation or coronary angioplasty. In recent years, ethyl pyruvate (EP), a derivative of pyruvate, has received great attention because of its stability and low toxicity. Previous studies have proved that EP has various pharmacological activities, including anti-inflammation, anti-oxidative stress, anti-apoptosis, and anti-fibrosis. Compelling evidence has indicated EP plays a beneficial role in a variety of acute injury models, such as brain IRI, myocardial IRI, renal IRI, and hepatic IRI. Moreover, EP can not only effectively inhibit multiple IRI-induced pathological processes, but also improve the structural and functional lesion of tissues and organs. In this study, we review the recent progress in the research on EP and discuss their implications for a better understanding of multiple organ IRI, and the prospects of targeting the EP for therapeutic intervention.

Tau oligomer induced HMGB1 release contributes to cellular senescence and neuropathology linked to Alzheimer's disease and frontotemporal dementia

Aging, pathological tau oligomers (TauO), and chronic inflammation in the brain play a central role in tauopathies, including Alzheimer's disease (AD) and frontotemporal dementia (FTD). However, the underlying mechanism of TauO-induced aging-related neuroinflammation remains unclear. Here, we show that TauO-associated astrocytes display a senescence-like phenotype in the brains of patients with AD and FTD. TauO exposure triggers astrocyte senescence through high mobility group box 1 (HMGB1) release and inflammatory senescence-associated secretory phenotype (SASP), which mediates paracrine senescence in adjacent cells. HMGB1 release inhibition using ethyl pyruvate (EP) and glycyrrhizic acid (GA) prevents TauO-induced senescence through inhibition of p38-mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB)-the essential signaling pathways for SASP development. Despite the developed tauopathy in 12-month-old hTau mice, EP+GA treatment significantly decreases TauO and senescent cell loads in the brain, reduces neuroinflammation, and thus ameliorates cognitive functions. Collectively, TauO-induced HMGB1 release promotes cellular senescence and neuropathology, which could represent an important common pathomechanism in tauopathies including AD and FTD.

Acetyl-CoA Metabolism and Histone Acetylation in the Regulation of Aging and Lifespan

Acetyl-CoA is a metabolite at the crossroads of central metabolism and the substrate of histone acetyltransferases regulating gene expression. In many tissues fasting or lifespan extending calorie restriction (CR) decreases glucose-derived metabolic flux through ATP-citrate lyase (ACLY) to reduce cytoplasmic acetyl-CoA levels to decrease activity of the p300 histone acetyltransferase (HAT) stimulating pro-longevity autophagy. Because of this, compounds that decrease cytoplasmic acetyl-CoA have been described as CR mimetics. But few authors have highlighted the potential longevity promoting roles of nuclear acetyl-CoA. For example, increasing nuclear acetyl-CoA levels increases histone acetylation and administration of class I histone deacetylase (HDAC) inhibitors increases longevity through increased histone acetylation. Therefore, increased nuclear acetyl-CoA likely plays an important role in promoting longevity. Although cytoplasmic acetyl-CoA synthetase 2 (ACSS2) promotes aging by decreasing autophagy in some peripheral tissues, increased glial AMPK activity or neuronal differentiation can stimulate ACSS2 nuclear translocation and chromatin association. ACSS2 nuclear translocation can result in increased activity of CREB binding protein (CBP), p300/CBP-associated factor (PCAF), and other HATs to increase histone acetylation on the promoter of neuroprotective genes including transcription factor EB (TFEB) target genes resulting in increased lysosomal biogenesis and autophagy. Much of what is known regarding acetyl-CoA metabolism and aging has come from pioneering studies with yeast, fruit flies, and nematodes. These studies have identified evolutionary conserved roles for histone acetylation in promoting longevity. Future studies should focus on the role of nuclear acetyl-CoA and histone acetylation in the control of hypothalamic inflammation, an important driver of organismal aging.

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.

TP53-induced glycolysis and apoptosis regulator alleviates hypoxia/ischemia-induced microglial pyroptosis and ischemic brain damage

Our previous studies have demonstrated that TP53-induced glycolysis and apoptosis regulator (TIGAR) can protect neurons after cerebral ischemia/reperfusion. However, the role of TIGAR in neonatal hypoxic-ischemic brain damage (HIBD) remains unknown. In the present study, 7-day-old Sprague-Dawley rat models of HIBD were established by permanent occlusion of the left common carotid artery followed by 2-hour hypoxia. At 6 days before induction of HIBD, a lentiviral vector containing short hairpin RNA of either TIGAR or gasdermin D (LV-sh_TIGAR or LV-sh_GSDMD) was injected into the left lateral ventricle and striatum. Highly aggressively proliferating immortalized (HAPI) microglial cell models of in vitro HIBD were established by 2-hour oxygen/glucose deprivation followed by 24-hour reoxygenation. Three days before in vitro HIBD induction, HAPI microglial cells were transfected with LV-sh_TIGAR or LV-sh_GSDMD. Our results showed that TIGAR expression was increased in the neonatal rat cortex after HIBD and in HAPI microglial cells after oxygen/glucose deprivation/reoxygenation. Lentivirus-mediated TIGAR knockdown in rats markedly worsened pyroptosis and brain damage after hypoxia/ischemia in vivo and in vitro. Application of exogenous nicotinamide adenine dinucleotide phosphate (NADPH) increased the NADPH level and the glutathione/oxidized glutathione ratio and decreased reactive oxygen species levels in HAPI microglial cells after oxygen/glucose deprivation/reoxygenation. Additionally, exogenous NADPH blocked the effects of TIGAR knockdown in neonatal HIBD in vivo and in vitro. These findings show that TIGAR can inhibit microglial pyroptosis and play a protective role in neonatal HIBD. The study was approved by the Animal Ethics Committee of Soochow University of China (approval No. 2017LW003) in 2017.

Potential therapeutic effects of ethyl pyruvate and N-acetyl cysteine in an experimental rat model of corrosive esophageal

BACKGROUND AND STUDY AIMS

Esophageal burns due to ingestion of corrosive substances are frequently seen in both children and adults. However, there is no standard method of treatment to prevent associated mortality and morbidity. Therefore, this study aimed to evaluate the effects of known antioxidants, namely N-acetyl cysteine and ethyl pyruvate, on esophageal damage due to sodium hydroxide-induced corrosive burns.

MATERIALS AND METHODS

Thirty-five female rats were randomly assigned to five equal groups. Group 1 was the sham group, while Group 2 was the control group. Group 3 received N-acetyl cysteine, Group 4 received ethyl pyruvate, and Group 5 received both N-acetyl cysteine and ethyl pyruvate. Rats in the "burn" groups were gavage-fed with 0.2mL of 25% NaOH. All esophagi were extracted on day 4 for histopathological evaluation.

RESULTS

Total histopathological damage scores were evaluated at the end of the study. Groups 3 and 5 were significantly different from the control group in terms of total histopathological scores (p = 0.001), while no significant difference was seen with Group 4. Stenosis index results in groups 3 and 5 were similar to those seen with total histopathological scores (p = 0.004).

CONCLUSION

N-acetyl cysteine, alone or in combination with ethyl pyruvate, may be useful in the treatment of esophageal damage associated with corrosive substances and in achieving histopathological improvement in an experimental setting.

Xanthotoxin and umbelliferone attenuate cognitive dysfunction in a streptozotocin-induced rat model of sporadic Alzheimer's disease: The role of JAK2/STAT3 and Nrf2/HO-1 signalling pathway modulation

The aim of the present study was to assess the neuroprotective effects of xanthotoxin and umbelliferone in streptozotocin (STZ)-induced cognitive dysfunction in rats. Animals were injected intracerebroventricularly (ICV) with STZ (3 mg/kg) once to induce a sporadic Alzheimer's disease (SAD)-like condition. Xanthotoxin or umbelliferone (15 mg/kg, i.p.) were administered 5 hr after ICV-STZ and daily for 20 consecutive days. Xanthotoxin or umbelliferone prevented cognitive deficits in the Morris water maze and object recognition tests. In parallel, xanthotoxin or umbelliferone reduced hippocampal acetylcholinestrase activity and malondialdehyde level. Moreover, xanthotoxin or umbelliferone increased glutathione content. These coumarins also modulated neuronal cell death by reducing the level of proinflammatory cytokines (tumour necrosis factor-alpha and interleukin-6), inhibiting the overexpression of inflammatory markers (nuclear factor κB [NF-κB] and cyclooxygenase II), and upregulating the expression of NF-κB inhibitor (IκB-α). Interestingly, xanthotoxin diminished phosphorylated JAK2 and phosphorylated STAT3 protein expression, while umbelliferone markedly replenished nuclear factor erythroid-derived 2-like 2 (Nrf2) and haem oxygenase-1 (HO-1) levels. The current study provides evidence for the protective effect of xanthotoxin and umbelliferone in STZ-induced cognitive dysfunction in rats. This effect may be attributed, at least in part, to inhibiting acetylcholinestrase and attenuating oxidative stress, neuroinflammation and neuronal loss.

Type III Secretion Effector VopQ of Vibrio parahaemolyticus Modulates Central Carbon Metabolism in Epithelial Cells

The metabolic response of host cells upon infection is pathogen specific, and infection-induced host metabolic reprogramming may have beneficial effects on the proliferation of pathogens. V. parahaemolyticus contains a range of virulence factors to manipulate host signaling pathways and metabolic processes. In this study, we identified that the T3SS1 VopQ effector rewrites host metabolism in conjunction with the inflammation and cell death processes. Understanding how VopQ reprograms host cell metabolism during the infection could help us to identify novel therapeutic strategies to enhance the survival of host cells during V. parahaemolyticus infection.

Vibrio parahaemolyticus is a Gram-negative halophilic pathogen that frequently causes acute gastroenteritis and occasional wound infection. V. parahaemolyticus contains several virulence factors, including type III secretion systems (T3SSs) and thermostable direct hemolysin (TDH). In particular, T3SS1 is a potent cytotoxic inducer, and T3SS2 is essential for causing acute gastroenteritis. Although much is known about manipulation of host signaling transductions by the V. parahaemolyticus effector, little is known about the host metabolomic changes modulated by V. parahaemolyticus. To address this knowledge gap, we performed a metabolomic analysis of the epithelial cells during V. parahaemolyticus infection using capillary electrophoresis-time of flight mass spectrometry (CE-TOF/MS). Our results revealed significant metabolomic perturbations upon V. parahaemolyticus infection. Moreover, we identified that T3SS1’s VopQ effector was responsible for inducing the significant metabolic changes in the infected cells. The VopQ effector dramatically altered the host cell’s glycolytic, tricarboxylic acid cycle (TCA), and amino acid metabolisms. VopQ effector disrupted host cell redox homeostasis by depleting cellular glutathione and subsequently increasing the level of reactive oxygen species (ROS) production.

IMPORTANCE The metabolic response of host cells upon infection is pathogen specific, and infection-induced host metabolic reprogramming may have beneficial effects on the proliferation of pathogens. V. parahaemolyticus contains a range of virulence factors to manipulate host signaling pathways and metabolic processes. In this study, we identified that the T3SS1 VopQ effector rewrites host metabolism in conjunction with the inflammation and cell death processes. Understanding how VopQ reprograms host cell metabolism during the infection could help us to identify novel therapeutic strategies to enhance the survival of host cells during V. parahaemolyticus infection.

Neuroprotective Effects of Ethyl Pyruvate against Aluminum Chloride-Induced Alzheimer's Disease in Rats via Inhibiting Toll-Like Receptor 4

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by the formation of insoluble deposits of β-amyloid (Aβ) plaques within the parenchyma of the brain. The present study aimed to investigate the neuroprotective role of ethyl pyruvate against in vitro and in vivo model of aluminum chloride (AlCl₃)-induced AD. Effect of ethyl pyruvate (5, 10, 20, 40 mM) against AlCl₃ (1250 μM)-induced neurotoxicity in primary neuron-glial mixed cell culture was evaluated using cell viability assays (MTT assay as well as calcein-AM/propidium iodide fluorescent dyes). In vivo model, AlCl₃ (50 mg/kg) were given through intraperitoneal route (i.p.) once daily for 4 weeks in rats and after 2 weeks, ethyl pyruvate (50, 100, 200 mg/kg/day) was co-administered with AlCl₃ once daily via the oral route. The present study, in addition to perform histopathology of the brain, also estimated oxidant and antioxidant parameters as well as memory impairment using pole test, plus maze, and Morris water maze test. The binding mode of ethyl pyruvate in the hMD-2 was also studied. Results of in vitro studies showed that the AlCl₃ administration resulted in neuronal cell death. AlCl₃ administration in rats resulted in memory loss, oxidative stress (increased lipid peroxide and nitric oxide), impairment of antioxidant mechanisms (superoxide dismutase, catalase, and reduced glutathione), and deposition of amyloid plaques in cerebral cortex region of the brain. AlCl₃ also resulted in the overexpression of the TLR4 receptors in the brain tissues. Administration of ethyl pyruvate ameliorated the AlCl₃-induced neurotoxicity in neuron-glial mixed cell culture as well as histopathological, neurochemical, and behavioral consequences of chronic administration of AlCl₃ in the rat. Ethyl pyruvate showed a docking score of 4.048. Thus, ethyl pyruvate is effective against in vitro and in vivo models of AlCl₃-induced AD.

Glucosamine Supplementation in Premating Drinking Water Improves Within-Litter Birth Weight Uniformity of Rats Partly through Modulating Hormone Metabolism and Genes Involved in Implantation

Within-litter birth weight variation in multiparous animals has become a big issue due to high incidence of low birth weight neonates, which gives rise to high preweaning mortality and morbidity. Foetus with various birth weights is the outcome of diverse embryos competence which is affected by oocyte quality. Glucosamine (GlcN) has been reported to be involved in oocyte maturation; however, its effect on pregnant outcomes remains unknown. The present study was conducted to investigate the effects of premating GlcN supplementation via drinking water on within-litter birth weight variation and its underlying mechanism. Fifty eight Sprague-Dawley female rats were randomly assigned to one of two groups with normal drinking water or drinking water supplemented with 0.5 mM GlcN from six to eight weeks old. Variation of within-litter birth weight in the GlcN group was 5.55%, significantly lower compared with 8.17% in the control group. Birth weight was significantly increased in the GlcN group (2.27 ± 0.06) compared with the control group (2.08 ± 0.04). Both absolute and relative weights of the ovary at the end of GlcN treatment were higher in the GlcN group than in the control group (P < 0.05). In the GlcN group, there were more successfully implanted blastocysts (13.38 ± 0.63 and 15.75 ± 0.59 in the control and treatment group, respectively) with more uniform distribution along the two uterine horns compared with the control group. Besides, gene expressions of Alk3 and Bmp2 were increased in the implantation sites, while IGF-1 and Mucin-1 were decreased significantly in rats administrated with GlcN. Maternal progesterone, estradiol, and IGF-1 concentrations on D 19.5 were significantly increased, while insulin and total cholesterol levels were significantly decreased in contrast with control dams. In summary, the administration of 0.5 mM GlcN solution before mating reduced within-litter birth weight variation, accompanied with increased fetal weight. Further investigation indicated that the improved outcome of pregnancy results at least partly from the increased ovary weights of the rats, the homogeneous embryo developmental competence, the enhanced receptivity of the uterine environment, and the adjusted maternal hormone levels.

Anti-inflammatory Activity of Ursolic Acid in MPTP-Induced Parkinsonian Mouse Model

Neuroinflammation plays an important role in the progression of Parkinson's disease (PD) and hence may represent a target for treatment. The drugs used currently for PD only provide symptomatic relief and have adverse effects in addition to their inability in preventing degeneration of neurons. Flavonoids show potent antioxidant and anti-inflammatory activities which is very valuable for the health of human beings. Thus, in the present study, we have tried to explore the anti-inflammatory activity of orally given ursolic acid (UA) (25 mg/kg bwt), a pentacyclic triterpenoid in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-intoxicated mouse model. Significant severe oxidative stress and biochemical alterations have been seen in Parkinsonian mice after MPTP intoxication. Whereas, UA administration has significantly rescued the harmful consequence of MPTP intoxication. Ionized calcium-binding adaptor molecule 1 (Iba1), tumor necrosis factor-alpha (TNF-α), and nuclear transcription factor-κB (NF-κB) were seen to be altered in the substantia nigra pars compacta (SNpc) of MPTP-intoxicated mice through immunohistochemical studies. The changes in the expression level of these parameters primarily suggest increased inflammatory responses in MPTP-intoxicated mice as compared with the control. However, UA have significantly reduced these inflammatory parameters (Iba1 and TNF-α) along with transcription factor NF-κB, which regulates these inflammatory parameters and thus have inhibited MPTP-induced neuroinflammation. The immunoreactivity of tyrosine hydroxylase (TH) was considerably increased by UA treatment in the SNpc of Parkinsonian mice. The neuroinflammation and neurodegeneration along with impairments in biochemical and behavioral parameters were found to be reversed on treatment with UA. Thus, UA has shown potent anti-inflammatory activity by preventing the degeneration of dopaminergic neurons from MPTP-induced Parkinsonian mice.

SIRT1-regulated HMGB1 release is partially involved in TLR4 signal transduction: A possible anti-neuroinflammatory mechanism of resveratrol in neonatal hypoxic-ischemic brain injury

Neonatal hypoxic-ischemic brain injury (HIBI) is a knotty disease that lacks appropriate treatment. Inflammation is an important contributor to brain damage, and microglia are responsible for eliciting early and pronounced inflammatory reactions in the immature brain after hypoxic-ischemic (HI) insult. Acetylated HMGB1 can be released from immune cells into the extracellular space, where it acts as a danger-associated molecular pattern molecule to activate TLR4 signalling-mediated inflammatory responses. Resveratrol has neuroprotective and anti-inflammatory effects against HIBI, but whether these effects involve the regulation of the TLR4 signalling pathway and whether HMGB1 participates in this process is still unclear. We investigated the anti-inflammatory effects of resveratrol in HIBI and the molecular mechanisms potentially involved in the effect. The in vivo and in vitro results indicated that the level of cytoplasmic HMGB1 in microglia increased after insult and that treating experimental animals or mouse BV2 microglial cells with resveratrol attenuated HI insult-induced neuroinflammation, which was characterized by improved behavioural defects, reduced microglial activation and TLR4/MyD88/NF-κB signalling, and attenuated primary neuronal damage; this was accompanied by the inhibition of HMGB1 nucleoplasmic transfer and extracellular release. EX527 pretreatment reversed these effects. In addition, co-immunoprecipitation confirmed that SIRT1 was directly involved in the HMGB1 acetylation process in BV2 cells after oxygen glucose deprivation. These data demonstrate that resveratrol plays a neuroprotective role in neonatal HIBI by activating SIRT1 to inhibit HMGB1/TLR4/MyD88/NF-κB signalling and subsequent neuroinflammatory responses.

Enhancement of ATP production ameliorates motor and cognitive impairments in a mouse model of MPTP-induced Parkinson's disease

Approximately 30-40% of patients with Parkinson's disease (PD) exhibit cognitive impairments. However, there are currently no clinically effective drugs for the treatment of cognitive impairment in patients with PD. Previous studies have suggested that mitochondrial dysfunction such as decreased adenosine triphosphate (ATP) production triggers dopaminergic neurodegeneration in patients with PD and that mitochondria represent a potential target for the development of novel treatments for preventing PD. Therefore, in the present study, we investigated the cognition-enhancing effects of ethyl pyruvate (EP) and 1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl) piperazine dihydrochloride (SA4503) in mice with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinsonism. PD model mice were generated via treatment with MPTP (25 mg/kg, i.p.) once a day for 5 consecutive days. Twenty-four hours after the final injection of MPTP, mice were intraperitoneally injected with EP (25, 50, 100 mg/kg) or SA4503 (1 mg/kg) once a day for 4 weeks. Chronic administration of EP (100 mg/kg i.p.) or SA4503 (1 mg/kg, i.p.) improved both motor deficits and cognitive impairments in MPTP-treated mice. Furthermore, treatment with EP or SA4503 attenuated decreases in the levels of ATP and tyrosine hydroxylase (TH) in the substantia nigra pars compacta (SNpc)/ventral tegmental area (VTA), striatum, and hippocampal CA1 region. Administration of EP or SA4503 protected the dopaminergic neurons from MPTP-induce toxicity and restored the dopamine levels in the striatum. Elevated 4-hydroxy-2-nonenal- (4-HNE-) and nitrotyrosine-reactive protein levels induced by MPTP-treatment were suppressed by EP or SA4503 treatment in the SNpc-VTA, striatum, and hippocampal CA1 region. These observations suggest that EP and SA4503 attenuate cognitive impairments and motor dysfunction in mice with MPTP-induced PD.

Quercetin attenuates hypoxia-ischemia induced brain injury in neonatal rats by inhibiting TLR4/NF-κB signaling pathway

Neonatal hypoxic ischemia (HI) is a kind of brain damage that occurs when an infant's brain does not receive enough oxygen and blood. The unrepairable damage leads to newborn death and short/long term brain dysfunctions. Due to the complicated causes and the variety of brain damages, there is no definitive treatment of neonatal HI. In this study, we set up a HI injury model of newborn rat and administrated Quercetin (Que) to treat rat pups before and after HI injury. We performed immunohistochemistry, quantitative PCR and immunoblot experiments to examine whether Que. has a role in attenuating brain injury after HI. We found that Que. treatment could clearly attenuate cortical cell apoptosis, as well as suppress apoptosis marker Bax, and activate anti-apoptosis marker Bcl-2. Moreover, Que. treatment decreased the number of cortical cells microgliosis and astrogliosis induced by HI injury. Furthermore, Que. treatment decreased cortical inflammation. Finally, it is suggested that Que. played a neuroprotective function on HI brain injury via inhibiting the TLR4/NF-κB signaling pathway. From these results, we conclude that Que. treatment may be a used as a therapeutic drug to prevent and decrease the newborn brain damage caused by HI.

Efficacy of exogenous pyruvate in TremblerJ mouse model of Charcot-Marie-Tooth neuropathy

INTRODUCTION

Classic Charcot-Marie-Tooth (CMT) neuropathies including those with Schwann cell genetic defects exhibit a length-dependent process affecting the distal axon. Energy deprivation in the distal axon has been the proposed mechanism accounting for length-dependent distal axonal degeneration. We hypothesized that pyruvate, an intermediate glycolytic product, could restore nerve function, supplying lost energy to the distal axon.

METHODS

To test this possibility, we supplied pyruvate to the drinking water of the Trembler-J (TrJ ) mouse and assessed efficacy based on histology, electrophysiology, and functional outcomes. Pyruvate outcomes were compared with untreated TrJ controls alone or adeno-associated virus mediated NT-3 gene therapy (AAV1.NT-3)/pyruvate combinatorial approach.

RESULTS

Pyruvate supplementation resulted increased myelinated fiber (MF) densities and myelin thickness in sciatic nerves. Combining pyruvate with proven efficacy from AAV1.tMCK.NT-3 gene therapy provided additional benefits showing improved compound muscle action potential amplitudes and nerve conduction velocities compared to pyruvate alone cohort. The end point motor performance of both the pyruvate and the combinatorial therapy cohorts was better than untreated TrJ controls. In a unilateral sciatic nerve crush paradigm, pyruvate supplementation improved myelin-based outcomes in both regenerating and the contralateral uncrushed nerves.

CONCLUSIONS

This proof of principle study demonstrates that exogenous pyruvate alone or as adjunct therapy in TrJ may have clinical implications and is a candidate therapy for CMT neuropathies without known treatment.

Ethyl pyruvate improves skin flap survival after ischaemia reperfusion injury

BACKGROUND & OBJECTIVES

Reperfusion after ischaemia is detrimental to the tissues. The oxidative stress created and cytokines released are mostly responsible in this process. In this study, ethyl pyruvate, a known agent for its anti-inflammatory and antioxidant properties, was used to investigate the effects on ischaemia/reperfusion injury on skin island flaps in rats.

METHODS

Sixty rats were randomly distributed in three groups (non-ischaemic, ischaemic and medication groups). Ethyl pyruvate was administered in the medication group with a dose of 50 mg/kg. After 24 h and one week, the animals were sacrificed, and the flaps were analyzed macroscopically, histopathologically, biochemically (total nitrite, malondialdehyde and myeloperoxidase).

RESULTS

Biochemical markers indicating oxidative stress, were found elevated in ischaemic group, whereas medication with ethyl pyruvate significantly reduced these values. There was a significant reduction (P<0.05) in the levels of these markers between ischaemic and medication groups. Ethyl pyruvate improved all the parameters significantly.

INTERPRETATION & CONCLUSION

Ethyl pyruvate showed strong scavenger activity against reactive oxygen species. It could be a potential candidate to improve the flap viability in reconstructive microsurgery, especially in free tissue transfers. However, more studies are warranted in experimental models to confirm these findings.

Mucuna pruriens Protects against MPTP Intoxicated Neuroinflammation in Parkinson's Disease through NF-κB/pAKT Signaling Pathways

Till date, drugs that have been used to manage Parkinson’s disease (PD) have only shown symptomatic relief with several adverse effects besides their inability to prevent neurodegeneration. Neuroinflammation plays an important role in the advancement of PD and can be targeted for its effective treatment. Researchers have suggested that herbal plants exhibiting the anti-inflammatory and anti-oxidant properties are therefore beneficial to human health. Conventionally, Mucuna pruriens (Mp) seeds are used for maintaining male virility in India. Reportedly, Mp is used as a rejuvenator drug having neuroprotective property. Our study aimed to investigate effects of aqueous extract of Mp (100 mg/kgbwt) on neuroinflammation, orally administered to mice intoxicated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) as well as the molecular mechanism involved in the progression of PD. In this study, we have observed significant behavioral abnormalities beside decreased antioxidant defense in MPTP intoxicated mice. We have also observed significant increase in inflammatory parameters like Glial Fibrillary Acidic Protein, Inducible Nitric Oxide Synthase, Intercellular Cell Adhesion Molecule, and Tumor Necrosis Factor alpha in substantia nigra pars compacta (SNpc) of parkinsonian mice, while Mp treatment has notably reduced these inflammatory parameters. Mp also inhibited the MPTP induced activation of NF-κB and promoted pAkt1 activity which further prevented the apoptosis of the dopaminergic neurons. Moreover, Mp exhibited significant antioxidant defense by inhibiting the lipid peroxidation and nitrite level, and by improving catalase activity and enhancing GSH level in nigrostriatal region of mouse brain. Mp also recovered the behavioral abnormalities in MPTP treated mice. Additionally, Mp treatment considerably increased the immunoreactivity of Tyrosine Hydroxylase and Dopamine Transporter in SNpc of parkinsonian mice. Our high performance liquid chromatography analysis of the Mp seed extract have shown L-DOPA, gallic acid, phytic acid, quercetin, and catechin equivalents as the major components which might cause neuroprotection in PD mice. Our result suggested that Mp extract treatment containing L-DOPA and a mixture of rich novel phytochemicals significantly alleviates the MPTP induced neurotoxicity by NF-κB and pAkt pathway. The findings observed thereby indicate that Mp extract have suggestively ameliorated MPTP induced neuroinflammation, restored the biochemical and behavioral abnormalities in PD mouse and thus provided a scientific basis for its traditional claim.

The Role of Glyoxalase-I (Glo-I), Advanced Glycation Endproducts (AGEs), and Their Receptor (RAGE) in Chronic Liver Disease and Hepatocellular Carcinoma (HCC)

Glyoxalase-I (Glo-I) and glyoxalase-II (Glo-II) comprise the glyoxalase system and are responsible for the detoxification of methylglyoxal (MGO). MGO is formed non-enzymatically as a by-product, mainly in glycolysis, and leads to the formation of advanced glycation endproducts (AGEs). AGEs bind to their receptor, RAGE, and activate intracellular transcription factors, resulting in the production of pro-inflammatory cytokines, oxidative stress, and inflammation. This review will focus on the implication of the Glo-I/AGE/RAGE system in liver injury and hepatocellular carcinoma (HCC). AGEs and RAGE are upregulated in liver fibrosis, and the silencing of RAGE reduced collagen deposition and the tumor growth of HCC. Nevertheless, data relating to Glo-I in fibrosis and cirrhosis are preliminary. Glo-I expression was found to be reduced in early and advanced cirrhosis with a subsequent increase of MGO-levels. On the other hand, pharmacological modulation of Glo-I resulted in the reduced activation of hepatic stellate cells and therefore reduced fibrosis in the CCl₄-model of cirrhosis. Thus, current research highlighted the Glo-I/AGE/RAGE system as an interesting therapeutic target in chronic liver diseases. These findings need further elucidation in preclinical and clinical studies.

Pinocembrin alleviates cognition deficits by inhibiting inflammation in diabetic mice

Diabetic encephalopathy (DE) is one of the most common diabetic complications in diabetes mellitus and is characterized by cognitive impairment and neuroinflammation. It has been reported that hyperglycemia can induce hippocampal and cortical neuronal damage, which can result in severe spatial learning and memory impairment. Pinocembrin (Pino) has been widely used in the therapy of cancer and other diseases due to its anti-inflammatory, anti-allergic, anti-oxidant, anti-carcinogenic, and anti-viral activities. However, the effects of Pino on DE-induced cognition deficits and its precise mechanisms remain largely unknown. Therefore, the aim of this study was to investigate the neuroprotective effects of Pino on cognition and its potential mechanisms in a DE mouse model induced by streptozotocin (STZ, 150mg/kg). Here, we demonstrated that Pino significantly improved the behavior and cognitive deficits of DE mice in open field tasks and the Morris water maze. Pino also markedly increased neuronal survival in the frontal cortex and hippocampal CA3 region. Furthermore, western blotting was performed to measure nuclear translocation of nuclear factor-kappaB (NF-κB) and the expression of tumor necrosis factor-α (TNF-α) in the frontal cortex and hippocampus. The results demonstrated that Pino could suppress the nuclear translocation of NF-κB and decrease TNF-α expression in the cerebral cortex and the hippocampus of DE mice. Taken together, the results suggest that Pino alleviates cognition deficits by protecting neurons from inflammation injury in diabetic mice.

Metformin treatment after the hypoxia-ischemia attenuates brain injury in newborn rats

Neonatal hypoxic-ischemic (HI) brain injury is a devastating disease that often leads to death and detrimental neurological deficits. The present study was designed to evaluate the ability of metformin to provide neuroprotection in a model of neonatal hypoxic-ischemic brain injury and to study the associated molecular mechanisms behind these protective effects. Here, we found that metformin treatment remarkably attenuated brain infarct volumes and brain edema at 24 h after HI injury, and the neuroprotection of metformin was associated with inhibition of neuronal apoptosis, suppression of the neuroinflammation and amelioration of the blood brain barrier breakdown. Additionally, metformin treatment conferred long-term protective against brain damage at 7 d after HI injury. Our study indicates that metformin treatment protects against neonatal hypoxic-ischemic brain injury and thus has potential as a therapy for this disease.

Effects of environmental enrichment on white matter glial responses in a mouse model of chronic cerebral hypoperfusion

Background

This study was designed to explore the beneficial effects of environmental enrichment (EE) on white matter glial changes in a mouse model of chronic cerebral hypoperfusion induced by bilateral common carotid artery stenosis (BCAS).

Methods

A total of 74 wild-type male C57BL/6J mice underwent BCAS or sham surgery. One week after surgery, the mice were randomly assigned into three different groups having varied amounts of EE—standard housing with no EE conditions (std), limited exposure with 3 h EE a day (3 h) and full-time exposure to EE (full) for 12 weeks. At 16 weeks after BCAS surgery, behavioural and cognitive function were assessed prior to euthanasia. Brain tissues were analysed for the degree of gliosis including morphological changes in astrocytes and microglia.

Results

Chronic cerebral hypoperfusion (or BCAS) increased clasmatodendrocytes (damaged astrocytes) with disruption of aquaporin-4 immunoreactivity and an increased degree of microglial activation/proliferation. BCAS also impaired behavioural and cognitive function. These changes were significantly attenuated, by limited exposure compared to full-time exposure to EE.

Conclusions

Our results suggest that moderate or limited exposure to EE substantially reduced glial damage/activation. Our findings also suggest moderate rather than continuous exposure to EE is beneficial for patients with subcortical ischaemic vascular dementia characterised by white matter disease-related inflammation.

Ethyl Pyruvate Attenuates Early Brain Injury Following Subarachnoid Hemorrhage in the Endovascular Perforation Rabbit Model Possibly Via Anti-inflammation and Inhibition of JNK Signaling Pathway

Early brain injury (EBI) following subarachnoid hemorrhage (SAH) is the main cause to poor outcomes of SAH patients, and early inflammation plays an important role in the acute pathophysiological events. It has been demonstrated that ethyl pyruvate (EP) has anti-inflammatory and neuroprotective effects in various critical diseases, however, the role of EP on EBI following SAH remains to be elucidated. Our study aimed to evaluate the effects of EP on EBI following SAH in the endovascular perforation rabbit model. All rabbits were randomly divided into three groups: sham, SAH + Vehicle (equal volume) and SAH + EP (30 mg/kg/day). MRI was performed to estimate the reliability of the EBI at 24 and 72 h after SAH. Neurological scores were recorded to evaluate the neurological deficit, ELISA kit was used to measure the level of tumor necrosis factor-α (TNF-α), and western blot was used to detect the expression of TNF-α, tJNK, pJNK, bax and bcl-2 at 24 and 72 h after SAH. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and Fluoro-jade B (FJB) staining were used to detect neuronal apoptosis and neurodegeneration respectively, meanwhile hematoxylin and eosin (H&E) staining was used to assess the degree of vasospasm. Our results demonstrated that EP alleviated brain tissue injury (characterized by diffusion weighted imaging and T2 sequence in MRI scan), and significantly improved neurological scores at 72 h after SAH. EP decreased the level of TNF-α and downregulated pJNK/tJNK and bax/bcl-2 in cerebral cortex and hippocampus effectively both at 24 and 72 h after SAH. Furthermore, EP reduced TUNEL and FJB positive cells significantly. In conclusion, the present study supported that EP afforded neuroprotective effects possibly via reducing TNF-α expression and inhibition of the JNK signaling pathway. Therefore, EP may be a potent therapeutic agent to attenuate EBI following SAH.

Metabolic Dysfunctions in Amyotrophic Lateral Sclerosis Pathogenesis and Potential Metabolic Treatments

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease primarily characterized by loss of motor neurons in brain and spinal cord. The death of motor neurons leads to denervation of muscle which in turn causes muscle weakness and paralysis, decreased respiratory function and eventually death. Growing evidence indicates disturbances in energy metabolism in patients with ALS and animal models of ALS, which are likely to contribute to disease progression. Particularly, defects in glucose metabolism and mitochondrial dysfunction limit the availability of ATP to CNS tissues and muscle. Several metabolic approaches improving mitochondrial function have been investigated in vitro and in vivo and showed varying effects in ALS. The effects of metabolic approaches in ALS models encompass delays in onset of motor symptoms, protection of motor neurons and extension of survival, which signifies an important role of metabolism in the pathogenesis of the disease. There is now an urgent need to test metabolic approaches in controlled clinical trials. In addition, more detailed studies to better characterize the abnormalities in energy metabolism in patients with ALS and ALS models are necessary to develop metabolically targeted effective therapies that can slow the progression of the disease and prolong life for patients with ALS.

Neonatal microglia: The cornerstone of brain fate

Microglia, mainly known for their role in innate immunity and modulation of neuroinflammation, play an active role in central nervous system development and homeostasis. Depending on the context and environmental stimuli, microglia adopt a broad spectrum of activation status from pro-inflammatory, associated with neurotoxicity, to anti-inflammatory linked to neuroprotection. Pro-inflammatory microglial activation is a key hallmark of white matter injury in preterm infants and is involved in developmental origin of adult neurological diseases. Characterization of neonatal microglia function in brain development and inflammation has allowed the investigation of promising therapeutic targets with potential long-lasting neuroprotective effects. True prevention of neuro-degenerative diseases might eventually occur as early as the perinatal period.

Cannabinoid Type 2 (CB2) Receptors Activation Protects against Oxidative Stress and Neuroinflammation Associated Dopaminergic Neurodegeneration in Rotenone Model of Parkinson's Disease

The cannabinoid type two receptors (CB₂), an important component of the endocannabinoid system, have recently emerged as neuromodulators and therapeutic targets for neurodegenerative diseases including Parkinson's disease (PD). The downregulation of CB₂ receptors has been reported in the brains of PD patients. Therefore, both the activation and the upregulation of the CB₂ receptors are believed to protect against the neurodegenerative changes in PD. In the present study, we investigated the CB₂ receptor-mediated neuroprotective effect of β-caryophyllene (BCP), a naturally occurring CB₂ receptor agonist, in, a clinically relevant, rotenone (ROT)-induced animal model of PD. ROT (2.5 mg/kg BW) was injected intraperitoneally (i.p.) once daily for 4 weeks to induce PD in male Wistar rats. ROT injections induced a significant loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) and DA striatal fibers, following activation of glial cells (astrocytes and microglia). ROT also caused oxidative injury evidenced by the loss of antioxidant enzymes and increased nitrite levels, and induction of proinflammatory cytokines: IL-1β, IL-6 and TNF-α, as well as inflammatory mediators: NF-κB, COX-2, and iNOS. However, treatment with BCP attenuated induction of proinflammatory cytokines and inflammatory mediators in ROT-challenged rats. BCP supplementation also prevented depletion of glutathione concomitant to reduced lipid peroxidation and augmentation of antioxidant enzymes: SOD and catalase. The results were further supported by tyrosine hydroxylase immunohistochemistry, which illustrated the rescue of the DA neurons and fibers subsequent to reduced activation of glial cells. Interestingly, BCP supplementation demonstrated the potent therapeutic effects against ROT-induced neurodegeneration, which was evidenced by BCP-mediated CB₂ receptor activation and the fact that, prior administration of the CB₂ receptor antagonist AM630 diminished the beneficial effects of BCP. The present study suggests that BCP has the potential therapeutic efficacy to elicit significant neuroprotection by its anti-inflammatory and antioxidant activities mediated by activation of the CB₂ receptors.

Combination treatment with ethyl pyruvate and IGF-I exerts neuroprotective effects against brain injury in a rat model of neonatal hypoxic-ischemic encephalopathy

Neonatal hypoxic-ischemic (HI) brain injury causes severe brain damage in newborns. Following HI injury, rapidly accumulating oxidants injure neurons and interrupt ongoing developmental processes. The antioxidant, sodium pyruvate, has been shown to reduce neuronal injury in neonatal rats under conditions of oxygen glucose deprivation (OGD) and HI injury. In this study, we evaluated the effects of ethyl pyruvate (EP) and insulin-like growth factor-I (IGF-I) alone or in combination in a similar setting. For this purpose, we used an in vitro model involving primary neonatal rat cortical neurons subjected to OGD for 2.5 h and an in vivo model involving unilateral carotid ligation in rats on post-natal day 7 with exposure to 8% hypoxia for 2.5 h. The cultured neurons were examined by lactate dehydrogenase (LDH) and cell viability assays. For the in vivo experiments, behavioral development was evaluated by the foot fault test at 4 weeks of recovery. 2,3,5-Triphenyltetrazolium chloride monohydrate and cresyl violet staining were used to evaluate HI injury. The injured neurons were Fluoro-Jade B-labeled, new neuroprecursors were double labeled with bromodeoxyuridine (BrdU) and doublecortin, new mature neurons were BrdU-labeled and neuronal nuclei were labeled by immunofluorescence. Under conditions of OGD, the LDH levels increased and neuronal viability decreased. Treatment with 0.5 mM EP or 25 ng/ml IGF-I protected the neurons (P<0.05), exerting additive effects. Similarly, either the early administration of EP or delayed treatment with IGF-I protected the neonatal rat brains against HI injury and improved neurological performance and these effects were also additive. This effect may be the result of reduced neuronal injury, and enhanced neurogenesis and maturation. On the whole, our findings demonstrate that the combination of the early administration of EP with delayed treatment with IGF-I exerts neuroprotective effects against HI injury in neonatal rat brains.

Reactivity of pyruvic acid and its derivatives towards reactive oxygen species

Pyruvic acid and its derivatives occurring in most biological systems are known to exhibit several pharmacological properties, such as anti-inflammatory, neuroprotective or anticancer, many of which are suggested to originate from their antioxidant and free radical scavenger activity. The therapeutic potential of these compounds is a matter of particular interest, due to their mechanisms of action, particularly their possible antioxidant behaviour. Here, we report the results of a study of the effect of pyruvic acid (PA), ethyl pyruvate (EP) and sodium pyruvate (SP) on reactions generating reactive oxygen species (ROS), such as superoxide anion radicals, hydroxyl radicals and singlet oxygen, and their total antioxidant capacity. Chemiluminescence (CL) and spectrophotometry techniques were employed. The pyruvate analogues studied were found to inhibit the CL signal arising from superoxide anion radicals in a dose-dependent manner with IC50 = 0.0197 ± 0.002 mM for EP and IC50 = 69.2 ± 5.2 mM for PA. These compounds exhibited a dose-dependent decrease in the CL signal of the luminol + H2O2 system over the range 0.5-10 mM with IC50 values of 1.71 ± 0.12 mM for PA, 3.85 ± 0.21 mM for EP and 22.91 ± 1.21 mM for SP. Furthermore, these compounds also inhibited hydroxyl radical-dependent deoxyribose degradation in a dose-dependent manner over the range 0.5-200 mM, with IC50 values of 33.2 ± 0.3 mM for SP, 116.1 ± 6.2 mM for EP and 168.2 ± 6.2 mM for PA. All the examined compounds also showed antioxidant capacity when estimated using the ferric-ferrozine assay. The results suggest that the antioxidant activities of pyruvate derivatives may reflect a direct effect on scavenging ROS and, in part, be responsible for their pharmacological actions.

Cytosolic HMGB1 controls the cellular autophagy/apoptosis checkpoint during inflammation

The intracellular protein HMGB1 is released from cells and acts as a damage-associated molecular pattern molecule during many diseases, including inflammatory bowel disease (IBD); however, the intracellular function of HMGB1 during inflammation is poorly understood. Here, we demonstrated that cytosolic HMGB1 regulates apoptosis by protecting the autophagy proteins beclin 1 and ATG5 from calpain-mediated cleavage during inflammation. Colitis in mice with an intestinal epithelial cell-specific Hmgb1 deletion and patients with IBD were both characterized by increased calpain activation, beclin 1 and ATG5 cleavage, and intestinal epithelial cell (IEC) death compared with controls. In vitro cleavage assays and studies of enteroids verified that HMGB1 protects beclin 1 and ATG5 from calpain-mediated cleavage events that generate proapoptotic protein fragments. Together, our results indicate that HMGB1 is essential for mitigating the extent and severity of inflammation-associated cellular injury by controlling the switch between the proautophagic and proapoptotic functions of beclin 1 and ATG5 during inflammation. Moreover, these studies demonstrate that HMGB1 is pivotal for reducing tissue injury in IBD and other complex inflammatory disorders.

Ethyl pyruvate protects against blood-brain barrier damage and improves long-term neurological outcomes in a rat model of traumatic brain injury

AIMS

Many traumatic brain injury (TBI) survivors sustain neurological disability and cognitive impairments due to the lack of defined therapies to reduce TBI-induced long-term brain damage. Ethyl pyruvate (EP) has shown neuroprotection in several models of acute brain injury. The present study therefore investigated the potential beneficial effect of EP on long-term outcomes after TBI and the underlying mechanisms.

METHODS

Male adult rats were subjected to unilateral controlled cortical impact injury. EP was injected intraperitoneally 15 min after TBI and again at 12, 24, 36, 48, and 60 h after TBI. Neurological deficits, blood-brain barrier (BBB) integrity, and neuroinflammation were assessed.

RESULTS

Ethyl pyruvate improved sensorimotor and cognitive functions and ameliorated brain tissue damage up to 28 day post-TBI. BBB breach and brain edema were attenuated by EP at 48 h after TBI. EP suppressed matrix metalloproteinase (MMP)-9 production from peripheral neutrophils and reduced the number of MMP-9-overproducing neutrophils in the spleen, and therefore mitigated MMP-9-mediated BBB breakdown. Moreover, EP exerted potent antiinflammatory effects in cultured microglia and inhibited the elevation of inflammatory mediators in the brain after TBI.

CONCLUSION

Ethyl pyruvate confers long-term neuroprotection against TBI, possibly through breaking the vicious cycle among MMP-9-mediated BBB disruption, neuroinflammation, and long-lasting brain damage.

EOP, a newly synthesized ethyl pyruvate derivative, attenuates the production of inflammatory mediators via p38, ERK and NF-κB pathways in lipopolysaccharide-activated BV-2 microglial cells

Microglia-induced neuroinflammation is an important pathological mechanism influencing various neurodegenerative disorders. Excess activation of microglia produces a myriad of proinflammatory mediators that decimate neurons. Hence, therapeutic strategies aimed to suppress the activation of microglia might lead to advancements in the treatment of neurodegenerative diseases. In this study, we synthesized a novel ethyl pyruvate derivative, named EOP (S-ethyl 2-oxopropanethioate) and studied its effects on lipopolysaccharide (LPS)-induced production of nitric oxide (NO) in rat primary microglia and mouse BV-2 microglia. EOP significantly decreased the production of NO, inducible nitric oxide synthase, cyclooxygenase and other proinflammatory cytokines, such as interleukin (IL)-6, IL-1β and tumor necrosis factor-α, in LPS-stimulated BV-2 microglia. The phosphorylation levels of extracellular regulated kinase, p38 mitogen-activated protein kinase, and nuclear translocation of NF-κB were also inhibited by EOP in LPS-activated BV-2 microglial cells. Overall, our observations indicate that EOP might be a promising therapeutic agent to diminish the development of neurodegenerative diseases associated with microglia activation.

Protective effect of ethyl pyruvate on ischemia-reperfusion injury in rat ovary: biochemical and histopathological evaluation

BACKGROUND

To investigate the protective effect of ethyl pyruvate (EP), an anti-oxidant agent, against ischemia-reperfusion injury in a rat model of ovarian torsion, considering biochemical and histopathological aspects.

METHODS

Forty Wistar Albino rats were divided into five groups: Group I, sham operation; Group II, ischemia alone, Group III, ischemia-reperfusion; Group IV, ischemia-reperfusion+50 mg/kg EP; and Group V, ischemia-reperfusion+100 mg/kg EP. Through laparotomy, 360° torsion was performed and maintained for 3 h, and detorsion was maintained for a further 3 h. Intraperitoneal EP was given 30 min before the surgical procedure. Ovarian tissues and blood samples were obtained after surgery. Malondialdehyde (MDA) and asymmetric dimethyl arginine (ADMA) levels were measured in both plasma and tissue samples. Tissue sections were evaluated histopatologically. Analysis of variance was used for statistical analyses.

RESULTS

In both serum and tissue samples, ADMA and MDA levels were found to be significantly lower in the EP groups compared with the ischemia alone and ischemia-reperfusion groups (p=0.0001). However, no significant difference was found between groups treated with 50 mg/kg or 100 mg/kg EP. On histopathological evaluation, the total tissue injury score was found to be lower in rats treated with EP. No significant difference was detected between groups treated with 50 mg/kg or 100 mg/kg EP.

CONCLUSION

Ethyl pyruvate may exert positive effects in ischemia-reperfusion injury in cases of ovarian torsion. However, no difference was detected between 50 mg/kg and 100 mg/kg EP.

Ethyl pyruvate ameliorates 3-nitropropionic acid-induced striatal toxicity through anti-neuronal cell death and anti-inflammatory mechanisms

The potential neuroprotective value of ethyl pyruvate (EP) for the treatment of the striatal toxicity is largely unknown. We investigated whether EP promotes the survival of striatal neurons in a 3-nitropropionic acid (3-NP)-induced mouse model of Huntington's disease (HD). EP (5, 10, 20, and 40mg/kg/day, i.p.) was daily injected from 30min before 3-NP intoxication (pretreatment) and from onset/progression/peak point of neurological impairment by 3-NP intoxication. EP produced a neuroprotective effect in dose- and time-dependant manners. EP pretreatment of 40mg/kg/day produced the best neuroprotective effect among other conditions. Pretreatment of EP significantly attenuated neurological impairment and lethality and prevented formation of lesion area and neuronal loss in the striatum after 3-NP intoxication. This neuroprotection afforded by EP was associated with the suppression of succinate dehydrogenase activity, apoptosis, and microglial activation. The suppressive effect of EP corresponded to the down-regulation of mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB) signal pathways, and mRNA expression of inflammatory mediators including tumor necrosis factor-alpha, interleukin (IL)-1β, IL-6, inducible nitric oxide synthase, and cyclooxygenase-2 in the striatum after 3-NP intoxication. Interestingly, the intrathecal introduction of inhibitors MAPKs and NF-κB into control mice decreased the lethality after 3-NP intoxication. Our findings indicate that EP may effectively alleviate 3-NP-induced striatal toxicity by inhibition of the MAPKs and NF-κB pathways in the striatum, and that EP has a wide therapeutic window, suggesting that EP may have therapeutic value in the treatment of aspects of HD's disease related to inflammation.

Impaired cortical mitochondrial function following TBI precedes behavioral changes

Traumatic brain injury (TBI) pathophysiology can be attributed to either the immediate, primary physical injury, or the delayed, secondary injury which begins minutes to hours after the initial injury and can persist for several months or longer. Because these secondary cascades are delayed and last for a significant time period post-TBI, they are primary research targets for new therapeutics. To investigate changes in mitochondrial function after a brain injury, both the cortical impact site and ipsilateral hippocampus of adult male rats 7 and 17 days after a controlled cortical impact (CCI) injury were examined. State 3, state 4, and uncoupler-stimulated rates of oxygen consumption, respiratory control ratios (RCRs) were measured and membrane potential quantified, and all were significantly decreased in 7 day post-TBI cortical mitochondria. By contrast, hippocampal mitochondria at 7 days showed only non-significant decreases in rates of oxygen consumption and membrane potential. NADH oxidase activities measured in disrupted mitochondria were normal in both injured cortex and hippocampus at 7 days post-CCI. Respiratory and phosphorylation capacities at 17 days post-CCI were comparable to naïve animals for both cortical and hippocampus mitochondria. However, unlike oxidative phosphorylation, membrane potential of mitochondria in the cortical lining of the impact site did not recover at 17 days, suggesting that while diminished cortical membrane potential at 17 days does not adversely affect mitochondrial capacity to synthesize ATP, it may negatively impact other membrane potential-sensitive mitochondrial functions. Memory status, as assessed by a passive avoidance paradigm, was not significantly impaired until 17 days after injury. These results indicate pronounced disturbances in cortical mitochondrial function 7 days after CCI which precede the behavioral impairment observed at 17 days.

Neuroinflammation and neuroimmune dysregulation after acute hypoxic-ischemic injury of developing brain

Hypoxic-ischemic (HI) injury to developing brain results from birth asphyxia in neonates and from cardiac arrest in infants and children. It is associated with varying degrees of neurologic sequelae, depending upon the severity and length of HI. Global HI triggers a series of cellular and biochemical pathways that lead to neuronal injury. One of the key cellular pathways of neuronal injury is inflammation. The inflammatory cascade comprises activation and migration of microglia - the so-called "brain macrophages," infiltration of peripheral macrophages into the brain, and release of cytotoxic and proinflammatory cytokines. In this article, we review the inflammatory and immune mechanisms of secondary neuronal injury after global HI injury to developing brain. Specifically, we highlight the current literature on microglial activation in relation to neuronal injury, proinflammatory and anti-inflammatory/restorative pathways, the role of peripheral immune cells, and the potential use of immunomodulators as neuroprotective compounds.

Astrocytes and microglia in acute cerebral injury underlying cerebral palsy associated with preterm birth

Cerebral palsy is one of the most devastating consequences of brain injury around the time of birth, and nearly a third of cases are now associated with premature birth. Compared with term babies, preterm babies have an increased incidence of complications that may increase the risk of disability, such as intraventricular hemorrhage, periventricular leukomalacia, sepsis, and necrotizing enterocolitis. The response to injury is highly dependent on brain maturity, and although cellular vulnerability is well documented, there is now evidence that premyelinating axons are also particularly sensitive to ischemic injury. In this review, we will explore recent evidence highlighting a central role for glia in mediating increased risk of disability in premature infants, including excessive activation of microglia and opening of astrocytic gap junction hemichannels in spreading injury after brain ischemia, in part likely involving release of adenosine triphosphate (ATP) and overactivation of purinergic receptors, particularly in white matter. We propose the hypothesis that inflammation-induced opening of connexin hemichannels is a key regulating event that initiates a vicious circle of excessive ATP release, which in turn propagates activation of purinergic receptors on microglia and astrocytes. This suggests that developing effective neuroprotective strategies for preterm infants requires a detailed understanding of glial responses.

Ethyl pyruvate ameliorates hepatic ischemia-reperfusion injury by inhibiting intrinsic pathway of apoptosis and autophagy

Background. Hepatic ischemia-reperfusion (I/R) injury is a pivotal clinical problem occurring in many clinical conditions such as transplantation, trauma, and hepatic failure after hemorrhagic shock. Apoptosis and autophagy have been shown to contribute to cell death in hepatic I/R injury. Ethyl pyruvate, a stable and simple lipophilic ester, has been shown to have anti-inflammatory properties. In this study, the purpose is to explore both the effect of ethyl pyruvate on hepatic I/R injury and regulation of intrinsic pathway of apoptosis and autophagy. Methods. Three doses of ethyl pyruvate (20 mg/kg, 40 mg/kg, and 80 mg/kg) were administered 1 h before a model of segmental (70%) hepatic warm ischemia was established in Balb/c mice. All serum and liver tissues were obtained at three different time points (4 h, 8 h, and 16 h). Results. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), and pathological features were significantly ameliorated by ethyl pyruvate (80 mg/kg). The expression of Bcl-2, Bax, Beclin-1, and LC3, which play an important role in the regulation of intrinsic pathway of apoptosis and autophagy, was also obviously decreased by ethyl pyruvate (80 mg/kg). Furthermore, ethyl pyruvate inhibited the HMGB1/TLR4/ NF-κb axis and the release of cytokines (TNF-α and IL-6). Conclusion. Our results showed that ethyl pyruvate might attenuate to hepatic I/R injury by inhibiting intrinsic pathway of apoptosis and autophagy, mediated partly through downregulation of HMGB1/TLR4/ NF-κb axis and the competitive interaction with Beclin-1 of HMGB1.

Up-down regulation of HO-1 and iNOS gene expressions by ethyl pyruvate via recruiting p300 to Nrf2 and depriving It from p65

Ethyl pyruvate (EP), a simple ester of pyruvic acid, has been shown to exert robust neuroprotection in various neuropathological conditions, such as, cerebral ischemia and KA-induced seizure animal models. The neuroprotective effect of EP is attributable to the anti-inflammatory, anti-oxidative, and anti-apoptotic effects. In the present study, we investigated convergence of anti-inflammatory and anti-oxidative functions of EP and present a novel molecular mechanism underlying anti-inflammatory effects of EP, which is conveyed by p300, a transcriptional co-activator for both Nuclear factor E2-related factor 2 (Nrf2) and p65. In BV2 cells, a microglia cell line, EP induced translocation of Nrf2 from the cytosol to the nucleus and enhanced the expression of hemeoxygenase 1 (HO-1) in a dose-dependent manner and 1h incubation with 10mM EP increased HO-1 to 4.9-fold. Nrf2 was found to translocate from the cytosol to the nucleus beginning 30 min after EP-treatment and binds to the antioxidant response element (ARE) located on HO-1 promoter. Interestingly, LPS-induced inducible NO synthase (iNOS) induction was substantially suppressed in EP-pre-treated BV2 cells and it was reverted by Nrf2 knockdown. We found that EP-induced Nrf2 accumulation in the nucleus recruits p300, a transcriptional co-activator of both Nrf2 and p65, inhibiting p65-p300 interaction. Competition between Nrf2 and p65 for p300 binding was confirmed by glutathione S-transferase (GST) pull down assay and reporter gene analysis. These results demonstrate that EP induced nuclear translocation of Nrf2 which binds to ARE along with p300 and hampers iNOS expression via depleting p300 from p65. This is a novel anti-inflammatory mechanism conveyed by EP, which enhances protective effect by converging anti-inflammatory and anti-oxidative effects and might be applicable to various Nrf2-activating agents, such as phytochemicals.

Unearthing the secrets of mitochondrial ROS and glutathione in bioenergetics

During the cellular oxidation of fuels, electrons are used to power the proton pumps of the mitochondrial electron transport chain (ETC) and ultimately drive ATP synthesis and the reduction of molecular oxygen to water. During these oxidative processes, some electrons can 'spin off' during fuel oxidation and electron transport to univalently reduce O2, forming reactive oxygen species (ROS). In excess, ROS can be detrimental; however, at low concentrations oxyradicals are essential signaling molecules. Mitochondria thus use a battery of systems to finely control types and levels of ROS, including antioxidants. Several antioxidant systems depend on glutathione. Here, we review mitochondrial ROS homeostatic systems, including emerging knowledge about roles of glutathione in redox balance and the control of protein function by post-translational modification.

Mitochondrial dysfunction induced by nuclear poly(ADP-ribose) polymerase-1: a treatable cause of cell death in stroke

Many drugs targeting excitotoxic cell death have demonstrated robust neuroprotective effects in animal models of cerebral ischemia. However, these neuroprotective effects have almost universally required drug administration at relatively short time intervals after ischemia onset. This finding has translated to clinical trial results; interventions targeting excitotoxicity have had no demonstrable efficacy when initiated hours after ischemia onset, but beneficial effects have been reported with more rapid initiation. Consequently, there continues to be a need for interventions with efficacy at later time points after ischemia. Here, we focus on mitochondrial dysfunction as both a relatively late event in ischemic neuronal death and a recognized cause of delayed neuronal death. Activation of poly(ADP-ribose) polymerase-1 (PARP-1) is a primary cause of mitochondrial depolarization and subsequent mitochondria-triggered cell death in ischemia reperfusion. PARP-1 consumes cytosolic NAD(+), thereby blocking both glycolytic ATP production and delivery of glucose carbon to mitochondria for oxidative metabolism. However, ketone bodies such as pyruvate, beta- and gamma-hydroxybutyrate, and 1,4-butanediol can fuel mitochondrial metabolism in cells with depleted cytosolic NAD(+) as long as the mitochondria remain functional. Ketone bodies have repeatedly been shown to be highly effective in preventing cell death in animal models of ischemia, but a rigorous study of the time window of opportunity for this approach remains to be performed.

Omega-3 polyunsaturated fatty acid supplementation improves neurologic recovery and attenuates white matter injury after experimental traumatic brain injury

Dietary supplementation with omega-3 (ω-3) fatty acids is a safe, economical mean of preventive medicine that has shown protection against several neurologic disorders. The present study tested the hypothesis that this method is protective against controlled cortical impact (CCI). Indeed, mice fed with ω-3 polyunsaturated fatty acid (PUFA)-enriched diet for 2 months exhibited attenuated short and long-term behavioral deficits due to CCI. Although ω-3 PUFAs did not decrease cortical lesion volume, these fatty acids did protect against hippocampal neuronal loss after CCI and reduced pro-inflammatory response. Interestingly, ω-3 PUFAs prevented the loss of myelin basic protein (MPB), preserved the integrity of the myelin sheath, and maintained the nerve fiber conductivity in the CCI model. ω-3 PUFAs also directly protected oligodendrocyte cultures from excitotoxicity and blunted the microglial activation-induced death of oligodendrocytes in microglia/oligodendrocyte cocultures. In sum, ω-3 PUFAs elicit multifaceted protection against behavioral dysfunction, hippocampal neuronal loss, inflammation, and loss of myelination and impulse conductivity. The present report is the first demonstration that ω-3 PUFAs protect against white matter injury in vivo and in vitro. The protective impact of ω-3 PUFAs supports the clinical use of this dietary supplement as a prophylaxis against traumatic brain injury and other nervous system disorders.

Ethyl pyruvate ameliorates intracerebral hemorrhage-induced brain injury through anti-cell death and anti-inflammatory mechanisms

Ethyl pyruvate (EP) is a pyruvate derivative and known to be cytoprotective in various pathological conditions through anti-cell death and anti-inflammatory mechanisms. The present study investigated the neuroprotective effect of ethyl pyruvate using a mouse model of collagenase-induced intracerebral hemorrhage (ICH). Our results showed that EP treatment to mice reduced brain edema and improved neurological function after ICH. Delayed treatment with EP until 6h after ICH to mice was still neuroprotective. We further demonstrated that EP protected neurons from hemoglobin-induced cell death in vitro and neuronal cell degeneration in ICH mice. Moreover, EP exerted anti-inflammatory effects by inhibiting microglia activation, nuclear factor-κB (NF-κB) DNA binding activity and subsequent downstream pro-inflammatory cytokines (tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β)) production. Taken together, these results suggest that EP exerts neuroprotective effect via anti-cell death and anti-inflammatory actions. EP is a potential novel treatment for ICH patients and deserves further investigation.