Glycine Protects against Hypoxic-Ischemic Brain Injury by Regulating Mitochondria-Mediated Autophagy via the AMPK Pathway

Reduced expression of NUPR1 alleviates epilepsy progression via attenuating ER stress

Epilepsy is a neurological disorder characterized by recurring seizures. It is necessary to further understand the mechanisms of epilepsy in order to develop novel strategies for its prevention and treatment. Abnormal endoplasmic reticulum stress (ERS) activation is related to the pathogenesis of epilepsy. Nuclear protein 1, transcriptional regulator (NUPR1) is involved in ERS and it might play a role in epilepsy progression. In the present study, we generated an epileptic mouse model using pilocarpine induction. After 72 h of pilocarpine treatment, the expression of NUPR1 was increased in epileptic mice. Furthermore, NUPR1 knockdown reduced the number of spontaneous recurrent seizures and alleviated hippocampal damage in these mice. Interestingly, NUPR1 knockdown also reduced the protein expression levels of LC3, PINK1, and Parkin in the mitochondria, and decreased the PINK1 expression in hippocampus. Additionally, the expression of ERS-related proteins-cleaved caspase-12, ATF4, and CHOP-decreased in epileptic mice following NUPR1 knockdown. In vitro experiments showed that the absence of NUPR1 reduced the expression of ATF4, CHOP, and cleaved caspase-12 in hippocampal neurons and inhibited the neuron apoptosis. In all, our study suggested that NUPR1 maybe a potential molecular target for epilepsy therapy.

Berberine inhibits excessive autophagy and protects myocardium against ischemia/reperfusion injury via the RhoE/AMPK pathway

Several studies have shown that berberine (BBR) is effective in protecting against myocardial ischemia‑reperfusion injury (MI/RI). However, the precise molecular mechanism remains elusive. The present study observed the mechanism and the safeguarding effect of BBR against hypoxia/reoxygenation (H/R) myocardial injury in H9c2 cells. BBR pretreatment significantly improved the decrease of cell viability, P62 protein, Rho Family GTPase 3 (RhoE) protein, ubiquinone subunit B8 protein, ubiquinol‑cytochrome c reductase core protein U, the Bcl‑2‑associated X protein/B‑cell lymphoma 2 ratio, glutathione (GSH) and the GSH/glutathione disulphide (GSSG) ratio induced by H/R, while reducing the increase in lactate dehydrogenase, microtubule‑associated protein 1 light 3 protein, caspase‑3 activity, reactive oxygen species, GSSG and malonaldehyde caused by H/R. Transmission electron microscopy and LysoTracker Red DND‑99 staining results showed that BBR pretreatment inhibited H/R‑induced excessive autophagy by mediating RhoE. BBR also inhibited mitochondrial permeability transition, maintained the stability of the mitochondrial membrane potential, reduced the apoptotic rate, and increased the level of caspase‑3. However, the protective effects of BBR were attenuated by pAD/RhoE‑small hairpin RNA, rapamycin (an autophagy activator) and compound C (an AMP‑activated protein kinase inhibitor). These new findings suggested that BBR protects the myocardium from MI/RI by inhibiting excessive autophagy, maintaining mitochondrial function, improving the energy supply and redox homeostasis, and attenuating apoptosis through the RhoE/AMP‑activated protein kinase pathway.

N6-methyladenosine demethylase FTO regulates synaptic and cognitive impairment by destabilizing PTEN mRNA in hypoxic-ischemic neonatal rats

Hypoxic-ischemic brain damage (HIBD) can result in significant global rates of neonatal death or permanent neurological disability. N6-methyladenosine (m6A) modification of RNA influences fundamental aspects of RNA metabolism, and m6A dysregulation is implicated in various neurological diseases. However, the biological roles and clinical significance of m6A in HIBD remain unclear. We currently evaluated the effect of HIBD on cerebral m6A methylation in RNAs in neonatal rats. The m6A dot blot assay showed a global augmentation in RNA m6A methylation post-HI. Herein, we also report on demethylase FTO, which is markedly downregulated in the hippocampus and is the main factor involved with aberrant m6A modification following HI. By conducting a comprehensive analysis of RNA-seq data and m6A microarray results, we found that transcripts with m6A modifications were more highly expressed overall than transcripts without m6A modifications. The overexpression of FTO resulted in the promotion of Akt/mTOR pathway hyperactivation, while simultaneously inhibiting autophagic function. This is carried out by the demethylation activity of FTO, which selectively demethylates transcripts of phosphatase and tensin homolog (PTEN), thus promoting its degradation and reduced protein expression after HI. Moreover, the synaptic and neurocognitive disorders induced by HI were effectively reversed through the overexpression of FTO in the hippocampus. Cumulatively, these findings demonstrate the functional importance of FTO-dependent hippocampal m6A methylome in cognitive function and provides novel mechanistic insights into the therapeutic potentials of FTO in neonatal HIBD.

Protective mechanisms of quercetin in neonatal rat brain injury induced by hypoxic-ischemic brain damage (HIBD)

Neonatal hypoxic-ischemic brain damage (HIBD) is a leading cause of infant mortality worldwide. This study explored whether quercetin (Que) exerts neuroprotective effects in a rat model of HIBD. A total of 36 seven-day-old Sprague-Dawley rats were divided into control, Que, HI, and HI + Que groups. The Rice method was used to establish HIBD in HI and HI + Que rats, which were treated with hypoxia (oxygen concentration of 8%) for 2 h after ligation of the left common carotid artery. The rats in the HI + Que group were intraperitoneally injected with Que (30 mg/kg) 1 h before hypoxia, and the rats in the Que group were only injected with the same amount of Que. Brain tissues were harvested 24 h postoperation and assessed by hematoxylin and eosin staining, 2,3,5-triphenyltetrazolium chloride staining, and terminal deoxynucleotidyl transferase dUTP nick-end labeling assay; relative gene and protein levels were evaluated by RT-qPCR, IHC, or western blot (WB) assay. Brain tissue morphologies were characterized by transmission electron microscopy (TEM); LC3B protein levels were assessed by immunofluorescence staining. Escape latencies and platform crossing times were significantly improved (p < .05) in HI + Que groups; infarct volume significantly decreased (p < .001), whereas the numbers of autophagic bodies and apoptotic cells increased and decreased, respectively. Meanwhile, NLRX1, ATG7, and Beclin1 expressions were significantly upregulated, and mTOR and TIM23 expressions, LC3B protein level, and LC 3II/LC 3I ratio were significantly downregulated. Que exerted neuroprotective effects in a rat model of HIBD by regulating NLRX1 and autophagy.

Exosomes derived from schwann cells alleviate mitochondrial dysfunction and necroptosis after spinal cord injury via AMPK signaling pathway-mediated mitophagy

Although spinal cord injury (SCI) represents a primary etiology of disability, currently, there are exist limited viable therapies modalities. Acquiring comprehension of the diverse pathways that drive mitochondrial aberration may facilitate the identification of noteworthy targets for ameliorating the deleterious consequences precipitated by SCI. Our objective was to determine the efficiency of exosomes produced from Schwann cells (SCDEs) in protecting against mitochondrial dysfunction. This evaluation was conducted using a rat model of compressed SCI and in vitro experiments involving rat pheochromocytoma cells (PC12) exposed to oxygen-glucose deprivation (OGD). The conducted experiments yielded evidence that SCDEs effectively mitigated oxidative stress (OS) and inflammation subsequent to SCI, while concurrently diminishing necroptosis. Subsequent in vitro inquiry assessed the impact of SCDEs on PC12, with a specific emphasis on mitochondrial functionality, necrotic cell prevalence, and mitophagy. The study findings revealed that SCDEs enhanced mitophagy in PC12 cells, leading to a decrease in the generation of reactive oxygen species (ROS) and inflammatory cytokines (CK) provoked by OGD-induced injury. This, in turn, mitigated mitochondrial dysfunction and necroptosis. Mechanistically, SCDEs facilitated cellular mitophagy through activation of the AMPK signaling pathway. In conclusion, our data strongly support the notion that SCDEs hold considerable promise as a therapeutic approach for managing SCI. Furthermore, our investigation serves to elucidate the pivotal role of AMPK-mediated mitophagy in reducing cell damage, thereby unveiling novel prospects for enhancing neuro-pathological outcomes following SCI.

Piceatannol Protects PC-12 Cells against Oxidative Damage and Mitochondrial Dysfunction by Inhibiting Autophagy via SIRT3 Pathway

Oxidative stress has been identified as a major cause of cellular injury in a variety of neurodegenerative disorders. This study aimed to investigate the cytoprotective effects of piceatannol on hydrogen peroxide (H₂O₂)-induced pheochromocytoma-12 (PC-12) cell damage and explore the underlying mechanisms. Our findings indicated that piceatannol pre-treatment significantly attenuated H₂O₂-induced PC-12 cell death. Furthermore, piceatannol effectively improved mitochondrial content and mitochondrial function, including enhancing mitochondrial reactive oxygen species (ROS) elimination capacity and increasing mitochondrial transcription factor (TFAM), peroxisome-proliferator-activated receptor-γ coactivator-1α (PGC-1α) and mitochondria Complex IV expression. Meanwhile, piceatannol treatment inhibited mitochondria-mediated autophagy as demonstrated by restoring mitochondrial membrane potential, reducing autophagosome formation and light chain 3B II/I (LC3B II/I) and autophagy-related protein 5 (ATG5) expression level. The protein expression level of SIRT3 was significantly increased by piceatannol in a concentration-dependent manner. However, the cytoprotective effect of piceatannol was dramatically abolished by sirtuin 3 (SIRT3) inhibitor, 3-(1H-1,2,3-Triazol-4-yl) pyridine (3-TYP), which led to an exacerbated mitochondrial dysfunction and autophagy in PC-12 cells under oxidative stress. In addition, the autophagy activator (rapamycin) abrogated the protective effects of piceatannol on PC-12 cell death. These findings demonstrated that piceatannol could alleviate PC-12 cell oxidative damage and mitochondrial dysfunction by inhibiting autophagy via the SIRT3 pathway.

Indole-3-carbinol ameliorated the neurodevelopmental deficits in neonatal anoxic injury in rats

Neonatal anoxia is linked to long-lasting neurodevelopmental deficits. Due to the lack of pharmacological intervention to treat neonatal anoxia, there is interest in finding new molecules for its treatment. Indole-3-carbinol (I3C) has shown neuroprotective effects in some disease conditions. However, the neuroprotective role of I3C in neonatal anoxia has not been explored. Consequently, we have investigated the effect of I3C on neonatal anoxia-induced brain injury and neurodevelopmental deficits. Rat pups after 30 h of birth were subjected to two episodes of anoxia (10 min in each) at a time interval of 24 h by flowing 100% nitrogen. I3C was administered within 30 min of the second episode of anoxia on a postnatal day (PND) 3 and continued for PND 9. Neurodevelopmental deficits, cortical mitochondrial membrane potential (MMP), opening of mitochondrial permeability transition pore (MPTP), electron transport chain (ETC) enzyme activities, oxidative stress, hypoxia-inducible factor-1α (HIF-1α) levels, histopathological changes, and apoptosis were measured. I3C treatment dose-dependently ameliorated the neurodevelopmental deficits and somatic growth in anoxic pups. I3C improved mitochondrial function by enhancing the MMP, mitochondrial ETC enzymes, and antioxidants. It blocked the MPTP opening and release of cytochrome C in anoxic pups. Further, I3C reduced the elevated cortical HIF-1α in neonatal anoxic pups. Furthermore, I3C ameliorated histopathological abnormalities and mitochondrial-mediated apoptotic indicators Cyt C, caspase-9, and caspase-3. Our study concludes that I3C improved neuronal development in anoxic pups by enhancing mitochondrial function, reducing HIF-1α, and mitigating apoptosis.

Ketogenic Diet and Ketone Bodies against Ischemic Injury: Targets, Mechanisms, and Therapeutic Potential

The ketogenic diet (KD) has been used as a treatment for epilepsy since the 1920s, and its role in the prevention of many other diseases is now being considered. In recent years, there has been an intensive investigation on using the KD as a therapeutic approach to treat acute pathologies, including ischemic ones. However, contradictory data are observed for the effects of the KD on various organs after ischemic injury. In this review, we provide the first systematic analysis of studies conducted from 1980 to 2022 investigating the effects and main mechanisms of the KD and its mimetics on ischemia-reperfusion injury of the brain, heart, kidneys, liver, gut, and eyes. Our analysis demonstrated a high diversity of both the composition of the used KD and the protocols for the treatment of animals, which could be the reason for contradictory effects in different studies. It can be concluded that a true KD or its mimetics, such as β-hydroxybutyrate, can be considered as positive exposure, protecting the organ from ischemia and its negative consequences, whereas the shift to a rather similar high-calorie or high-fat diet leads to the opposite effect.

Up-Regulation of miR-9-5p Inhibits Hypoxia-Ischemia Brain Damage Through the DDIT4-Mediated Autophagy Pathways in Neonatal Mice

Introduction

Hypoxia-ischemia (HI) remains the leading cause of cerebral palsy and long-term neurological sequelae in infants. Despite intensive research and many therapeutic approaches, there are limited neuroprotective strategies against HI insults. Herein, we reported that HI insult significantly down-regulated microRNA-9-5p (miR-9-5p) level in the ipsilateral cortex of neonatal mice.

Methods

The biological function and expression patterns of protein in the ischemic hemispheres were evaluated by qRT-PCR, Western Blotting analysis, Immunofluorescence and Immunohistochemistry. Open field test and Y-maze test were applied to detect locomotor activity and exploratory behavior and working memory.

Results

Overexpression of miR-9-5p effectively alleviated brain injury and improved neurological behaviors following HI insult, accompanying with suppressed neuroinflammation and apoptosis. MiR-9-5p directly bound to the 3' untranslated region of DNA damage-inducible transcript 4 (DDIT4) and negatively regulated its expression. Furthermore, miR-9-5p mimics treatment down-regulated light chain 3 II/light chain 3 I (LC3 II/LC3 I) ratio and Beclin-1 expression and decreased LC3B accumulation in the ipsilateral cortex. Further analysis showed that DDIT4 knockdown conspicuously inhibited the HI-up-regulated LC3 II/ LC3 I ratio and Beclin-1 expression, associating with attenuated brain damage.

Conclusion

The study indicates that miR-9-5p-mediated HI injury is regulated by DDIT4-mediated autophagy pathway and up-regulation of miR-9-5p level may provide a potential therapeutic effect on HI brain damage.

Role of Endogenous Lipopolysaccharides in Neurological Disorders

Lipopolysaccharide (LPS) is a cell-wall immunostimulatory endotoxin component of Gram-negative bacteria. A growing body of evidence reveals that alterations in the bacterial composition of the intestinal microbiota (gut dysbiosis) disrupt host immune homeostasis and the intestinal barrier function. Microbial dysbiosis leads to a proinflammatory milieu and systemic endotoxemia, which contribute to the development of neurodegenerative diseases and metabolic disorders. Two important pathophysiological hallmarks of neurodegenerative diseases (NDDs) are oxidative/nitrative stress and inflammation, which can be initiated by elevated intestinal permeability, with increased abundance of pathobionts. These changes lead to excessive release of LPS and other bacterial products into blood, which in turn induce chronic systemic inflammation, which damages the blood-brain barrier (BBB). An impaired BBB allows the translocation of potentially harmful bacterial products, including LPS, and activated neutrophils/leucocytes into the brain, which results in neuroinflammation and apoptosis. Chronic neuroinflammation causes neuronal damage and synaptic loss, leading to memory impairment. LPS-induced inflammation causes inappropriate activation of microglia, astrocytes, and dendritic cells. Consequently, these alterations negatively affect mitochondrial function and lead to increases in oxidative/nitrative stress and neuronal senescence. These cellular changes in the brain give rise to specific clinical symptoms, such as impairment of locomotor function, muscle weakness, paralysis, learning deficits, and dementia. This review summarizes the contributing role of LPS in the development of neuroinflammation and neuronal cell death in various neurodegenerative diseases.

Glycine protects the male reproductive system against lead toxicity via alleviating oxidative stress, preventing sperm mitochondrial impairment, improving kinematics of sperm, and blunting the downregulation of enzymes involved in the steroidogenesis

Lead (Pb) is a highly toxic heavy metal widely dispersed in the environment because of human industrial activities. Many studies revealed that Pb could adversely affect several organs, including the male reproductive system. Pb-induced reproductive toxicity could lead to infertility. Thus, finding safe and clinically applicable protective agents against this complication is important. It has been found that oxidative stress plays a fundamental role in the pathogenesis of Pb-induced reprotoxicity. Glycine is the simplest amino acid with a wide range of pharmacological activities. It has been found that glycine could attenuate oxidative stress and mitochondrial impairment in various experimental models. The current study was designed to evaluate the role of glycine in Pb-induced reproductive toxicity in male mice. Male BALB/c mice received Pb (20 mg/kg/day; gavage; 35 consecutive days) and treated with glycine (250 and 500 mg/kg/day; gavage; 35 consecutive days). Then, reproductive system weight indices, biomarkers of oxidative stress in the testis and isolated sperm, sperm kinetic, sperm mitochondrial indices, and testis histopathological alterations were monitored. A significant change in testis, epididymis, and Vas deferens weight was evident in Pb-treated animals. Markers of oxidative stress were also significantly increased in the testis and isolated sperm of the Pb-treated group. A significant disruption in sperm kinetic was also evident when mice received Pb. Moreover, Pb exposure caused significant deterioration in sperm mitochondrial indices. Tubular injury, tubular desquamation, and decreased spermatogenic index were histopathological alterations detected in Pb-treated mice. It was found that glycine significantly blunted oxidative stress markers in testis and sperm, improved sperm mitochondrial parameters, causing considerable higher velocity-related indices (VSL, VCL, and VAP) and percentages of progressively motile sperm, and decreased testis histopathological changes in Pb-exposed animals. These data suggest glycine as a potential protective agent against Pb-induced reproductive toxicity. The effects of glycine on oxidative stress markers and mitochondrial function play a key role in its protective mechanism.

The Influence of Gut Dysbiosis in the Pathogenesis and Management of Ischemic Stroke

Recent research on the gut microbiome has revealed the influence of gut microbiota (GM) on ischemic stroke pathogenesis and treatment outcomes. Alterations in the diversity, abundance, and functions of the gut microbiome, termed gut dysbiosis, results in dysregulated gut–brain signaling, which induces intestinal barrier changes, endotoxemia, systemic inflammation, and infection, affecting post-stroke outcomes. Gut–brain interactions are bidirectional, and the signals from the gut to the brain are mediated by microbially derived metabolites, such as trimethylamine N-oxide (TMAO) and short-chain fatty acids (SCFAs); bacterial components, such as lipopolysaccharide (LPS); immune cells, such as T helper cells; and bacterial translocation via hormonal, immune, and neural pathways. Ischemic stroke affects gut microbial composition via neural and hypothalamic–pituitary–adrenal (HPA) pathways, which can contribute to post-stroke outcomes. Experimental and clinical studies have demonstrated that the restoration of the gut microbiome usually improves stroke treatment outcomes by regulating metabolic, immune, and inflammatory responses via the gut–brain axis (GBA). Therefore, restoring healthy microbial ecology in the gut may be a key therapeutic target for the effective management and treatment of ischemic stroke.

Emerging Roles for the Orphan GPCRs, GPR37 and GPR37 L1, in Stroke Pathophysiology

Recent studies have shed light on the diverse and complex roles of G-protein coupled receptors (GPCRs) in the pathophysiology of stroke. These receptors constitute a large family of seven transmembrane-spanning proteins that play an intricate role in cellular communication mechanisms which drive both tissue injury and repair following ischemic stroke. Orphan GPCRs represent a unique sub-class of GPCRs for which no natural ligands have been found. Interestingly, the majority of these receptors are expressed within the central nervous system where they represent a largely untapped resource for the treatment of neurological diseases. The focus of this review will thus be on the emerging roles of two brain-expressed orphan GPCRs, GPR37 and GPR37 L1, in regulating various cellular and molecular processes underlying ischemic stroke.

Role of Mitophagy in the Pathogenesis of Stroke: From Mechanism to Therapy

Mitochondria can supply adenosine triphosphate (ATP) to the tissue, which can regulate metabolism during the pathologic process and is also involved in the pathophysiology of neuronal injury after stroke. Recent studies have suggested that selective autophagy could play important roles in the pathophysiological process of stroke, especially mitophagy. It is usually mediated by the PINK1/Parkin-independent pathway or PINK1/Parkin-dependent pathway. Moreover, mitophagy may be a potential target in the therapy of stroke because the control of mitophagy is neuroprotective in stroke in vitro and in vivo. In this review, we briefly summarize recent researches in mitophagy, introduce the role of mitophagy in the pathogenesis of stroke, then highlight the strategies targeting mitophagy in the treatment of stroke, and finally propose several issues in the treatment of stroke by targeting mitophagy.

Macamide B Pretreatment Attenuates Neonatal Hypoxic-Ischemic Brain Damage of Mice Induced Apoptosis and Regulates Autophagy via the PI3K/AKT Signaling Pathway

Lepidium meyenii (maca) is an annual or biennial herb from South America that is a member of the genus Lepidium L. in the family Cruciferae. This herb possesses antioxidant and antiapoptotic activities, enhances autophagy functions, prevents cell death, and protects neurons from ischemic damage. Macamide B, an effective active ingredient of maca, exerts a neuroprotective effect on neonatal hypoxic-ischemic brain damage (HIBD), but the mechanism underlying its neuroprotective effect is not yet known. The purpose of this study was to explore the effect of macamide B on HIBD-induced autophagy and apoptosis and its potential neuroprotective mechanism. The modified Rice-Vannucci method was used to induce HIBD in 7-day-old (P7) macamide B- and vehicle-pretreated pups. TTC staining was performed to evaluate the cerebral infarct volume in pups, the brain water content was measured to evaluate the neurological function of pups, neurobehavioural testing was conducted to assess functional recovery after HIBD, TUNEL and FJC staining was performed to detect cellular autophagy and apoptosis, and Western blot analysis was used to detect the levels of proteins in the pro-survival phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) signaling pathway and autophagy and apoptosis-related proteins. Macamide B pretreatment significantly decreases brain damage and improves the recovery of neural function after HIBD. At the same time, macamide B pretreatment activates the PI3K/AKT signaling pathway after HIBD, enhances autophagy, and reduces hypoxic-ischemic (HI)-induced apoptosis. In addition, 3-methyladenine (3-MA), an inhibitor of the PI3K/AKT signaling pathway, significantly inhibits the increase in autophagy levels, aggravates HI-induced apoptosis, and reverses the neuroprotective effect of macamide B on HIBD. Our data indicate that a macamide B pretreatment might regulate autophagy through the PI3K/AKT signaling pathway, thereby reducing HIBD-induced apoptosis and exerting neuroprotective effects on neonatal HIBD. Macamide B may become a new drug for the prevention and treatment of HIBD.

Mitophagy in neurological disorders

Selective autophagy is an evolutionarily conserved mechanism that removes excess protein aggregates and damaged intracellular components. Most eukaryotic cells, including neurons, rely on proficient mitophagy responses to fine-tune the mitochondrial number and preserve energy metabolism. In some circumstances (such as the presence of pathogenic protein oligopolymers and protein mutations), dysfunctional mitophagy leads to nerve degeneration, with age-dependent intracellular accumulation of protein aggregates and dysfunctional organelles, leading to neurodegenerative disease. However, when pathogenic protein oligopolymers, protein mutations, stress, or injury are present, mitophagy prevents the accumulation of damaged mitochondria. Accordingly, mitophagy mediates neuroprotective effects in some forms of neurodegenerative disease (e.g., Alzheimer's disease, Parkinson’s disease, Huntington's disease, and Amyotrophic lateral sclerosis) and acute brain damage (e.g., stroke, hypoxic–ischemic brain injury, epilepsy, and traumatic brain injury). The complex interplay between mitophagy and neurological disorders suggests that targeting mitophagy might be applicable for the treatment of neurodegenerative diseases and acute brain injury. However, due to the complexity of the mitophagy mechanism, mitophagy can be both harmful and beneficial, and future efforts should focus on maximizing its benefits. Here, we discuss the impact of mitophagy on neurological disorders, emphasizing the contrast between the positive and negative effects of mitophagy.

Rescuing mitochondria in traumatic brain injury and intracerebral hemorrhages - A potential therapeutic approach

Mitochondria are dynamic organelles responsible for cellular energy production. Besides, regulating energy homeostasis, mitochondria are responsible for calcium homeostasis, signal transmission, and the fate of cellular survival in case of injury and pathologies. Accumulating reports have suggested multiple roles of mitochondria in neuropathologies, neurodegeneration, and immune activation under physiological and pathological conditions. Mitochondrial dysfunction, which occurs at the initial phase of brain injury, involves oxidative stress, inflammation, deficits in mitochondrial bioenergetics, biogenesis, transport, and autophagy. Thus, development of targeted therapeutics to protect mitochondria may improve functional outcomes following traumatic brain injury (TBI) and intracerebral hemorrhages (ICH). In this review, we summarize mitochondrial dysfunction related to TBI and ICH, including the mechanisms involved, and discuss therapeutic approaches with special emphasis on past and current clinical trials.

Cerebrolysin restores balance between excitatory and inhibitory amino acids in brain following concussive head injury. Superior neuroprotective effects of TiO2 nanowired drug delivery

Concussive head injury (CHI) often associated with military personnel, soccer players and related sports personnel leads to serious clinical situation causing lifetime disabilities. About 3-4k head injury per 100k populations are recorded in the United States since 2000-2014. The annual incidence of concussion has now reached to 1.2% of population in recent years. Thus, CHI inflicts a huge financial burden on the society for rehabilitation. Thus, new efforts are needed to explore novel therapeutic strategies to treat CHI cases to enhance quality of life of the victims. CHI is well known to alter endogenous balance of excitatory and inhibitory amino acid neurotransmitters in the central nervous system (CNS) leading to brain pathology. Thus, a possibility exists that restoring the balance of amino acids in the CNS following CHI using therapeutic measures may benefit the victims in improving their quality of life. In this investigation, we used a multimodal drug Cerebrolysin (Ever NeuroPharma, Austria) that is a well-balanced composition of several neurotrophic factors and active peptide fragments in exploring its effects on CHI induced alterations in key excitatory (Glutamate, Aspartate) and inhibitory (GABA, Glycine) amino acids in the CNS in relation brain pathology in dose and time-dependent manner. CHI was produced in anesthetized rats by dropping a weight of 114.6g over the right exposed parietal skull from a distance of 20cm height (0.224N impact) and blood-brain barrier (BBB), brain edema, neuronal injuries and behavioral dysfunctions were measured 8, 24, 48 and 72h after injury. Cerebrolysin (CBL) was administered (2.5, 5 or 10mL/kg, i.v.) after 4-72h following injury. Our observations show that repeated CBL induced a dose-dependent neuroprotection in CHI (5-10mL/kg) and also improved behavioral functions. Interestingly when CBL is delivered through TiO₂ nanowires superior neuroprotective effects were observed in CHI even at a lower doses (2.5-5mL/kg). These observations are the first to demonstrate that CBL is effectively capable to attenuate CHI induced brain pathology and behavioral disturbances in a dose dependent manner, not reported earlier.

Pinocembrin attenuates hemorrhagic transformation after delayed t-PA treatment in thromboembolic stroke rats by regulating endogenous metabolites

Hemorrhagic transformation (HT) is a common serious complication of stroke after thrombolysis treatment, which limits the clinical use of tissue plasminogen activator (t-PA). Since early diagnosis and treatment for HT is important to improve the prognosis of stroke patients, it is urgent to discover the potential biomarkers and therapeutic drugs. Recent evidence shows that pinocembrin, a natural flavonoid compound, exerts anti-cerebral ischemia effect and expands the time window of t-PA. In this study, we investigated the effect of pinocembrin on t-PA-induced HT and the potential biomarkers for HT after t-PA thrombolysis, thereby improving the prognosis of stroke. Electrocoagulation-induced thrombotic focal ischemic rats received intravenous infusion of t-PA (10 mg/kg) 6 h after ischemia. Administration of pinocembrin (10 mg/kg, iv) prior t-PA infusion significantly decreased the infarct volume, ameliorated t-PA-induced HT, and protected blood-brain barrier. Metabolomics analysis revealed that 5 differential metabolites in the cerebral cortex and 16 differential metabolites in serum involved in amino acid metabolism and energy metabolism were significantly changed after t-PA thrombolysis, whereas pinocembrin administration exerted significant intervention effects on these metabolites. Linear regression analysis showed that lactic acid was highly correlated to the occurrence of HT. Further experiments confirmed that t-PA treatment significantly increased the content of lactic acid and the activity of lactate dehydrogenase in the cerebral cortex and serum, and the expression of monocarboxylate transporter 1 (MCT 1) in the cerebral cortex; pinocembrin reversed these changes, which was consistent with the result of metabolomics. These results demonstrate that pinocembrin attenuates HT after t-PA thrombolysis, which may be associated with the regulation of endogenous metabolites. Lactic acid may be a potential biomarker for HT prediction and treatment.

Hypoxia-inducible factor-1: Regulatory mechanisms and drug development in stroke

Stroke is an acute cerebrovascular disease caused by sudden rupture of blood vessels in the brain or blockage of blood vessels, which has now become one of the main causes of adult death. During stroke, hypoxia-inducible factor-1 (HIF-1), as an important regulator under hypoxia conditions, is involved in the pathological process of stroke by regulating multi-pathways, such as glucose metabolism, angiogenesis, erythropoiesis, cell survival. However, the roles of HIF-1 in stroke are still controversial, which are related with ischemic time and degree of ischemia. The regulatory mechanisms of HIF-1 in stroke include inflammation, autophagy, oxidative stress, apoptosis and energy metabolism. The potential drugs targeting HIF-1 have attracted more attention, such as HIF-1 inhibitors, HIF-1 stabilizers and natural products. Based on the role of HIF-1 in stroke, HIF-1 is expected to be a potential target for stroke treatment. Resolving when and what interventions for HIF-1 to take during stroke will provide novel strategies for stroke treatment.

Tortoise Plastron and Deer Antler Gelatin Prevents Against Neuronal Mitochondrial Dysfunction In Vitro: Implication for a Potential Therapy of Alzheimer's Disease

Mitochondrial dysfunction with oxidative damage plays the fundamental roles in the pathogenesis of Alzheimer's disease. In traditional Chinese medicine (TCM) practice, animal tissue-derived gelatins are often used as nootropic agents to treat cognitive deterioration and senile dementia. Tortoise plastron gelatin (TPG) and deer antler gelatin (DAG) are the two most commonly used gelatins for this purpose. This study sought to examine the effects of the two gelatins in preventing neuronal mitochondria from oxidative damage. PC12 cells, a cell line derived from rat pheochromocytoma, exposed to the neurotoxin Aβ_25-35 served as an in vitro model of Alzheimer's disease. The cells were separately pre-treated with TPG and DAG at various concentrations ranging from 6.26 µg/ml-200 µg/ml, followed by co-incubation with 20 μM Aβ_25-35 for different duration. Cell viability, mitochondrial membrane potential (MMP) and ultrastructure, intracellular ATP, reactive oxygen species (ROS) and calcium (Ca²⁺) level, the expression of mitochondrial dynamic proteins and biomarkers of apoptosis were measured. Pretreatment with TPG and DAG reversed the Aβ-induced reduction of cell viability in a dose-dependent manner. Both TPG and DAG significantly increased MMP and ATP, alleviated the accumulation of damaged mitochondrial fragments, and normalized the aberrant expression of multiple mitochondrial dynamic proteins of the Aβ-exposed cells. Both gelatins also suppressed intracellular ROS overproduction and Ca²⁺ overload, overexpression of cytochrome c and pro-apoptosis biomarkers induced by the Aβ exposure. These results suggest that TPG and DAG may have the anti-dementia potential by preventing neuronal mitochondria from oxidative damage.

Mitochondrial dysfunction and mitochondrion-targeted therapeutics in liver diseases

The liver is a vital metabolic and detoxifying organ and suffers diverse endogenous or exogenous damage. Hepatocyte mitochondria experience various structural and functional defects from liver injury, bearing oxidative stress, metabolic dysregulation, and the disturbance of mitochondrial quality control (MQC) mechanisms. Mitochondrial malfunction initiates the mitochondria-mediated apoptotic pathways and the release of damage signals, aggravating liver damage and disease progression via inflammation and reparative fibrogenesis. Removal of mitochondrial impairment or the improvement of MQC mechanisms restore mitochondrial homeostasis and benefit liver health. This review discusses the association of mitochondrial disorders with hepatic pathophysiological processes and the resultant potential of mitochondrion-targeting therapeutics for hepatic disorders. The recent advances in the MQC mechanisms and the mitochondrial-derived damage-associated molecular patterns (DAMPs) in the pathology and treatment of liver disease are particularly focussed.

Glycine alleviates fluoride-induced oxidative stress, apoptosis and senescence in a porcine testicular Sertoli cell line

Glycine is a well-known free radical scavenger in the cellular antioxidant system that prevents oxidative damage and apoptosis. Excessive fluoride exposure is associated with multiple types of cellular damage in humans and animals. The objective of the present study was to investigate the protective effects of glycine on sodium fluoride (NaF) exposure and the possible underlying mechanisms in a porcine testicular Sertoli cell line model. Cellular viability and proliferation were examined following NaF exposure and glycine supplementation, and glycine dramatically ameliorated the decreases in NaF-induced porcine testicular Sertoli cell viability and proliferation. Further investigations revealed that glycine decreased NaF-induced intracellular reactive oxygen species production, DNA fragment accumulation and the apoptosis incidence in the porcine testicular Sertoli cell line; in addition, glycine improved mitochondrial function and ATP production. Notably, results of the SPiDER-β-Gal analysis suggested that glycine alleviated NaF-induced cellular senescence and downregulated P53, P21, HMGA2 and P16INK4a gene expression in the porcine testicular Sertoli cell line. Collectively, the beneficial effects of glycine alleviate NaF-induced oxidative stress, apoptosis and senescence, and together with our previous findings, support the hypothesis that glycine plays an important role in protecting against NaF exposure-induced impairments in the porcine testicular Sertoli cell line.

Surgical procedures suppress autophagic flux in the kidney

Many surgical models are used to study kidney and other diseases in mice, yet the effects of the surgical procedure itself on the kidney and other tissues have not been elucidated. In the present study, we found that both sham surgery and unilateral nephrectomy (UNX), which is used as a model of renal compensatory hypertrophy, in mice resulted in increased mammalian target of rapamycin complex 1/2 (mTORC1/2) in the remaining kidney. mTORC1 is known to regulate lysosomal biogenesis and autophagy. Genes associated with lysosomal biogenesis and function were decreased in sham surgery and UNX kidneys. In both sham surgery and UNX, there was suppressed autophagic flux in the kidney as indicated by the lack of an increase in LC3-II or autophagosomes seen on immunoblot, IF and EM after bafilomycin A1 administration and a concomitant increase in p62, a marker of autophagic cargo. There was a massive increase in pro-inflammatory cytokines, which are known to activate ERK1/2, in the serum after sham surgery and UNX. There was a large increase in ERK1/2 in sham surgery and UNX kidneys, which was blocked by the MEK1/2 inhibitor, trametinib. Trametinib also resulted in a significant decrease in p62. In summary, there was an intense systemic inflammatory response, an ERK-mediated increase in p62 and suppressed autophagic flux in the kidney after sham surgery and UNX. It is important that researchers are aware that changes in systemic pro-inflammatory cytokines, ERK1/2 and autophagy can be caused by sham surgery as well as the kidney injury/disease itself.

The Role of Mitophagy in Ischemic Stroke

Mitochondria are important places for eukaryotes to carry out energy metabolism and participate in the processes of cell differentiation, cell information transmission, and cell apoptosis. Autophagy is a programmed intracellular degradation process. Mitophagy, as a selective autophagy, is an evolutionarily conserved cellular process to eliminate dysfunctional or redundant mitochondria, thereby fine-tuning the number of mitochondria and maintaining energy metabolism. Many stimuli could activate mitophagy to regulate related physiological processes, which could ultimately reduce or aggravate the damage caused by stimulation. Stroke is a common disease that seriously affects the health and lives of people around the world, and ischemic stroke, which is caused by cerebral vascular stenosis or obstruction, accounts for the vast majority of stroke. Abnormal mitophagy is closely related to the occurrence, development and pathological mechanism of ischemic stroke. However, the exact mechanism of mitophagy involved in ischemic stroke has not been fully elucidated. In this review, we discuss the process and signal pathways of mitophagy, the potential role of mitophagy in ischemic stroke and the possible signal transduction pathways. It will help deepen the understanding of mitophagy and provide new ideas for the treatment of ischemic stroke.

Glycine Improves Ischemic Stroke Through miR-19a-3p/AMPK/GSK-3β/HO-1 Pathway

Purpose

To explore the molecular mechanism of glycine in improving ischemic stroke.

Patients and Methods

The serum samples of patients with ischemic stroke and healthy people were compared. The ischemic stroke model of PC12 cells was established by oxygen-glucose deprivation (OGD). qPCR quantified miR-19a-3p and AMPK mRNA, and protein expression was detected by Western blot. MTT was used to detect cell activity. Flow cytometry was used to detect cells. Glucose metabolism kit was used to detect glucose intake and formation amount of lactic acid.

Results

Compared with the control group, OGD group (OGDG) showed lower cell activity and increased cell apoptosis. TNF-α, IL-1βI, L-6, Caspase 3, Caspase 9 and Bax were up-regulated, and Glut1, HK2, LDHA, PDK1, PKM2 and Bcl2 were down-regulated. At the same time, glucose intake, formation amount of lactic acid and cell apoptosis rate were reduced, and AMPK/GSK-3β/HO-1 pathway activity was down-regulated. Glycine could counteract the above phenomena in OGDG. miR-19a-3p and AMPK decreased and increased, respectively, during glycine therapy. AMPK was the target gene of miR-19a-3p. Rescue experiments demonstrated that glycine improved cell apoptosis, inflammatory response and glucose metabolism disorder of ischemic stroke through miR-19a-3p/AMPK/GSK-3β/HO-1 pathway.

Conclusion

Glycine improves ischemic stroke through miR-19a-3p/AMPK/GSK-3β/HO-1 pathway.

ApoE deficiency promotes non-alcoholic fatty liver disease in mice via impeding AMPK/mTOR mediated autophagy

AIM

This work was to investigate the relationship between ApoE and autophagy regulated by AMPK/mTOR pathway in the pathological process of NAFLD.

MAIN METHODS

Both WT and ApoE^-/- mice were divided into two groups and allocated into either a normal chow (ND) or a high-fat diet (HFD) for 8 weeks. After that, we detected the indicators of lipid accumulation, hepatic injury, mitochondrial function hallmark, autophagy, apoptosis, inflammation, and oxidative stress by commercially available kits, immunohistochemistry, immunofluorescent staining, and western blot.

KEY FINDING

We found the lipid levels of serum and liver, and hepatic injury were significantly increased in the ApoE^-/--HFD group compared to other groups. ApoE^-/- mice exhibited increased deposition of fat in liver tissue. The PGC1α, NRF1, ATP, p-AMPK, AMPK, Beclin1, and LC3 levels were downregulated and ROS, p-mTOR, and mTOR were increased in the ApoE^-/--HFD group compared to WT-HFD group. When treated with AMPK and autophagy activators, AICAR and rapamycin, these pathologies and protein levels can be rescued. The expression levels of apoptosis-related proteins, inflammation, and oxidative stress were increased in the ApoE^-/--HFD group compared to the WT-HFD group.

SIGNIFICANCE

Our results indicated that ApoE deficiency can regulate AMPK/mTOR pathway, which leads to NAFLD most likely by modulating hepatic mitochondrial function.

Activation of AMPK under Hypoxia: Many Roads Leading to Rome

AMP-activated protein kinase (AMPK) is known as a pivotal cellular energy sensor, mediating the adaptation to low energy levels by deactivating anabolic processes and activating catabolic processes in order to restore the cellular ATP supply when the cellular AMP/ATP ratio is increased. Besides this well-known role, it has also been shown to exert protective effects under hypoxia. While an insufficient supply with oxygen might easily deplete cellular energy levels, i.e., ATP concentration, manifold other mechanisms have been suggested and are heavily disputed regarding the activation of AMPK under hypoxia independently from cellular AMP concentrations. However, an activation of AMPK preceding energy depletion could induce a timely adaptation reaction preventing more serious damage. A connection between AMPK and the master regulator of hypoxic adaptation via gene transcription, hypoxia-inducible factor (HIF), has also been taken into account, orchestrating their concerted protective action. This review will summarize the current knowledge on mechanisms of AMPK activation under hypoxia and its interrelationship with HIF.

Autophagy and inflammation in ischemic stroke

Appropriate autophagy has protective effects on ischemic nerve tissue, while excessive autophagy may cause cell death. The inflammatory response plays an important role in the survival of nerve cells and the recovery of neural tissue after ischemia. Many studies have found an interaction between autophagy and inflammation in the pathogenesis of ischemic stroke. This study outlines recent advances regarding the role of autophagy in the post-stroke inflammatory response as follows. (1) Autophagy inhibits inflammatory responses caused by ischemic stimulation through mTOR, the AMPK pathway, and inhibition of inflammasome activation. (2) Activation of inflammation triggers the formation of autophagosomes, and the upregulation of autophagy levels is marked by a significant increase in the autophagy-forming markers LC3-II and Beclin-1. Lipopolysaccharide stimulates microglia and inhibits ULK1 activity by direct phosphorylation of p38 MAPK, reducing the flux and autophagy level, thereby inducing inflammatory activity. (3) By blocking the activation of autophagy, the activation of inflammasomes can alleviate cerebral ischemic injury. Autophagy can also regulate the phenotypic alternation of microglia through the nuclear factor-κB pathway, which is beneficial to the recovery of neural tissue after ischemia. Studies have shown that some drugs such as resveratrol can exert neuroprotective effects by regulating the autophagy-inflammatory pathway. These studies suggest that the autophagy-inflammatory pathway may provide a new direction for the treatment of ischemic stroke.