Adiponectin Protects against Glutamate-Induced Excitotoxicity via Activating SIRT1-Dependent PGC-1α Expression in HT22 Hippocampal Neurons

The Therapeutic Effects of Blueberry-Treated Stem Cell-Derived Extracellular Vesicles in Ischemic Stroke

An ischemic stroke, one of the leading causes of morbidity and mortality, is caused by ischemia and hemorrhage resulting in impeded blood supply to the brain. According to many studies, blueberries have been shown to have a therapeutic effect in a variety of diseases. Therefore, in this study, we investigated whether blueberry-treated mesenchymal stem cell (MSC)-derived extracellular vesicles (B-EVs) have therapeutic effects in in vitro and in vivo stroke models. We isolated the extracellular vesicles using cryo-TEM and characterized the particles and concentrations using NTA. MSC-derived extracellular vesicles (A-EVs) and B-EVs were round with a lipid bilayer structure and a diameter of ~150 nm. In addition, A-EVs and B-EVs were shown to affect angiogenesis, cell cycle, differentiation, DNA repair, inflammation, and neurogenesis following KEGG pathway and GO analyses. We investigated the protective effects of A-EVs and B-EVs against neuronal cell death in oxygen-glucose deprivation (OGD) cells and a middle cerebral artery occlusion (MCAo) animal model. The results showed that the cell viability was increased with EV treatment in HT22 cells. In the animal, the size of the cerebral infarction was decreased, and the behavioral assessment was improved with EV injections. The levels of NeuN and neurofilament heavy chain (NFH)-positive cells were also increased with EV treatment yet decreased in the MCAo group. In addition, the number of apoptotic cells was decreased with EV treatment compared with ischemic animals following TUNEL and Bax/Bcl-2 staining. These data suggested that EVs, especially B-EVs, had a therapeutic effect and could reduce apoptotic cell death after ischemic injury.

Electro-Metabolic Coupling of Cumulus-Oocyte Complex

Oocyte-cumulus cell interaction is essential for oocyte maturation and competence. The bidirectional crosstalk network mediated by gap junctions is fundamental for the metabolic cooperation between these cells. As cumulus cells exhibit a more glycolytic phenotype, they can provide metabolic substrates that the oocyte can use to produce ATP via oxidative phosphorylation. The impairment of mitochondrial activity plays a crucial role in ovarian aging and, thus, in fertility, determining the success or failure of assisted reproductive techniques. This review aims to deepen the knowledge about the electro-metabolic coupling of the cumulus-oocyte complex and to hypothesize a putative role of potassium channel modulators in order to improve fertility, promote intracellular Ca2+ influx, and increase the mitochondrial biogenesis and resulting ATP levels in cumulus cells.

The Neuroprotective Effects of BMSC-Derived Exosomes against Glutamate-Induced HT22 Cell Cytotoxicity

Many central nervous system diseases are closely related to nerve damage caused by dysregulation of the endogenous neurotransmitter glutamate. Exosomes derived from bone marrow mesenchymal stem cells (BMSC-Exos) play an important role in improving injury and regeneration functions. However, its mechanism remains unknown. Therefore, the aim of this study is to investigate whether and how BMSC-Exos improve neurotoxicity caused by glutamate and to fill the gap in the literature. In this study, glutamate-treated HT22 cells were first exposed to mouse-derived BMSC-Exos at different concentrations to observe their effects on HT22 apoptosis. Next, we treated glutamate-treated HT22 cells with mouse-derived BMSC-Exos. We then inhibited the PI3K/Akt/mTOR signaling pathways using the PI3K/Akt inhibitor and the mTOR inhibitor, respectively, and observed the protective effect of mouse-derived BMSC-Exos on HT22 cells treated with glutamate. Our results show that BMSC-Exos reduced apoptosis triggered by glutamate stimulation, increased cell vitality, and decreased the levels of proapoptotic proteins while increasing the levels of anti-apoptotic proteins. The protective effect of BMSC-Exos was weakened when PI3K/Akt inhibitor and mTOR inhibitor were added. To sum up, we draw the following conclusions: BMSC-Exos can reduce neuronal apoptosis and apoptosis-related protein expression after glutamate stimulation by regulating the PI3K/Akt/mTOR signaling pathway.

Zhizhu Decoction Alleviates Intestinal Barrier Damage via Regulating SIRT1/FoxO1 Signaling Pathway in Slow Transit Constipation Model Mice

OBJECTIVE

To explore the possible effects and mechanism of Zhizhu Decoction (ZZD) on the pathophysiology of slow transit constipation (STC).

METHODS

A total of 54 C57BL/6 mice was randomly divided into the following 6 groups by a random number table, including control, STC model (model), positive control, and low-, medium- and high-doses ZZD treatment groups (5, 10, 20 g/kg, namely L, M-, and H-ZZD, respectively), 9 mice in each group. Following 2-week treatment, intestinal transport rate (ITR) and fecal water content were determined, and blood and colon tissue samples were collected. Hematoxylin-eosin and periodic acid-Schiff staining were performed to evaluate the morphology of colon tissues and calculate the number of goblet cells. To determine intestinal permeability, serum levels of lipopolysaccharide (LPS), low-density lipoprotein (LDL) and mannose were measured using enzyme-linked immunosorbent assay (ELISA). Western blot analysis was carried out to detect the expression levels of intestinal tight junction proteins zona-occludens-1 (ZO-1), claudin-1, occludin and recombinant mucin 2 (MUC2). The mRNA expression levels of inflammatory cytokines including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-4, IL-10 and IL-22 were determined using reverse transcription-quantitative reverse transcription reaction. Colon indexes of oxidative stress were measured by ELISA, and protein expression levels of colon silent information regulator 1/forkhead box O transcription factor 1 (SIRT1/FoxO1) antioxidant signaling pathway were detected by Western blot.

RESULTS

Compared with the model group, ITR and fecal moisture were significantly enhanced in STC mice in the M-ZZD and H-ZZD groups (P<0.01). Additionally, ZZD treatment notably increased the thickness of mucosal and muscular tissue, elevated the number of goblet cells in the colon of STC mice, reduced the secretion levels of LPS, LDL and mannose, and upregulated ZO-1, claudin-1, occludin and MUC2 expressions in the colon in a dose-dependent manner, compared with the model group (P<0.05 or P<0.01). In addition, ZZD significantly attenuated intestinal inflammation and oxidative stress and activated the SIRT1/FoxO1 signaling pathway (P<0.05 or P<0.01).

CONCLUSION

ZZD exhibited beneficial effects on the intestinal system of STC mice and alleviated intestinal inflammation and oxidative stress via activating SIRT1/FoxO1 antioxidant signaling pathway in the colon.

New insights into Sirt1: potential therapeutic targets for the treatment of cerebral ischemic stroke

Ischemic stroke is one of the main causes of mortality and disability worldwide. However, the majority of patients are currently unable to benefit from intravenous thrombolysis or intravascular mechanical thrombectomy due to the limited treatment windows and serious complications. Silent mating type information regulation 2 homolog 1 (Sirt1), a nicotine adenine dinucleotide-dependent enzyme, has emerged as a potential therapeutic target for ischemic stroke due to its ability to maintain brain homeostasis and possess neuroprotective properties in a variety of pathological conditions for the central nervous system. Animal and clinical studies have shown that activation of Sirt1 can lessen neurological deficits and reduce the infarcted volume, offering promise for the treatment of ischemic stroke. In this review, we summarized the direct evidence and related mechanisms of Sirt1 providing neuroprotection against cerebral ischemic stroke. Firstly, we introduced the protein structure, catalytic mechanism and specific location of Sirt1 in the central nervous system. Secondly, we list the activators and inhibitors of Sirt1, which are primarily divided into three categories: natural, synthetic and physiological. Finally, we reviewed the neuroprotective effects of Sirt1 in ischemic stroke and discussed the specific mechanisms, including reducing neurological deficits by inhibiting various programmed cell death such as pyroptosis, necroptosis, ferroptosis, and cuproptosis in the acute phase, as well as enhancing neurological repair by promoting angiogenesis and neurogenesis in the later stage. Our review aims to contribute to a deeper understanding of the critical role of Sirt1 in cerebral ischemic stroke and to offer novel therapeutic strategies for this condition.

The Role of LincRNA-EPS/Sirt1/Autophagy Pathway in the Neuroprotection Process by Hydrogen against OGD/R-Induced Hippocampal HT22 Cells Injury

Cerebral ischemia/reperfusion (CI/R) injury causes high disability and mortality. Hydrogen (H2) enhances tolerance to an announced ischemic event; however, the therapeutic targets for the effective treatment of CI/R injury remain uncertain. Long non-coding RNA lincRNA-erythroid prosurvival (EPS) (lincRNA-EPS) regulate various biological processes, but their involvement in the effects of H2 and their associated underlying mechanisms still needs clarification. Herein, we examine the function of the lincRNA-EPS/Sirt1/autophagy pathway in the neuroprotection of H2 against CI/R injury. HT22 cells and an oxygen-glucose deprivation/reoxygenation (OGD/R) model were used to mimic CI/R injury in vitro. H2, 3-MA (an autophagy inhibitor), and RAPA (an autophagy agonist) were then administered, respectively. Autophagy, neuro-proinflammation, and apoptosis were evaluated by Western blot, enzyme-linked immunosorbent assay, immunofluorescence staining, real-time PCR, and flow cytometry. The results demonstrated that H2 attenuated HT22 cell injury, which would be confirmed by the improved cell survival rate and decreased levels of lactate dehydrogenase. Furthermore, H2 remarkably improved cell injury after OGD/R insult via decreasing pro-inflammatory factors, as well as suppressing apoptosis. Intriguingly, the protection of H2 against neuronal OGD/R injury was abolished by rapamycin. Importantly, the ability of H2 to promote lincRNA-EPS and Sirt1 expression and inhibit autophagy were abrogated by the siRNA-lincRNA-EPS. Taken together, the findings proved that neuronal cell injury caused by OGD/R is efficiently prevented by H2 via modulating lincRNA-EPS/Sirt1/autophagy-dependent pathway. It was hinted that lincRNA-EPS might be a potential target for the H2 treatment of CI/R injury.

Natural Compounds for SIRT1-Mediated Oxidative Stress and Neuroinflammation in Stroke: A Potential Therapeutic Target in the Future

Stroke is a fatal cerebral vascular disease with a high mortality rate and substantial economic and social costs. ROS production and neuroinflammation have been implicated in both hemorrhagic and ischemic stroke and have the most critical effects on subsequent brain injury. SIRT1, a member of the sirtuin family, plays a crucial role in modulating a wide range of physiological processes, including apoptosis, DNA repair, inflammatory response, and oxidative stress. Targeting SIRT1 to reduce ROS and neuroinflammation might represent an emerging therapeutic target for stroke. Therefore, we conducted the present review to summarize the mechanisms of SIRT1-mediated oxidative stress and neuroinflammation in stroke. In addition, we provide a comprehensive introduction to the effect of compounds and natural drugs on SIRT1 signaling related to oxidative stress and neuroinflammation in stroke. We believe that our work will be helpful to further understand the critical role of the SIRT1 signaling pathway and will provide novel therapeutic potential for stroke treatment.

The AMPK pathway in fatty liver disease

Lipid metabolism disorders are the primary causes for the occurrence and progression of various liver diseases, including non-alcoholic fatty liver disease (NAFLD) and alcoholic fatty liver disease (AFLD) caused by a high-fat diet and ethanol. AMPK signaling pathway plays an important role in ameliorating lipid metabolism disorders. Progressive research has clarified that AMPK signal axes are involved in the prevention and reduction of liver injury. Upregulation of AMK can alleviate FLD in mice induced by alcohol or insulin resistance, type 2 diabetes, and obesity, and most natural AMPK agonists can regulate lipid metabolism, inflammation, and oxidative stress in hepatocytes, consequently regulating FLD in mice. In NAFLD and AFLD, increasing the activity of AMPK can inhibit the synthesis of fatty acids and cholesterol by down-regulating the expression of adipogenesis gene (FAS, SREBP-1c, ACC and HMGCR); Simultaneously, by increasing the expression of fatty acid oxidation and lipid decomposition genes (CPT1, PGC1, and HSL, ATGL) involved in fatty acid oxidation and lipid decomposition, the body’s natural lipid balance can be maintained. At present, some AMPK activators are thought to be beneficial during therapeutic treatment. Therefore, activation of AMPK signaling pathway is a potential therapeutic target for disorders of the liver. We summarized the most recent research on the role of the AMPK pathway in FLD in this review. Simultaneously, we performed a detailed description of each signaling axis of the AMPK pathway, as well as a discussion of its mechanism of action and therapeutic significance.

Central Adiponectin Signaling – A Metabolic Regulator in Support of Brain Plasticity

Brain plasticity and metabolism are tightly connected by a constant influx of peripheral glucose to the central nervous system in order to meet the high metabolic demands imposed by neuronal activity. Metabolic disturbances highly affect neuronal plasticity, which underlies the prevalent comorbidity between metabolic disorders, cognitive impairment, and mood dysfunction. Effective pro-cognitive and neuropsychiatric interventions, therefore, should consider the metabolic aspect of brain plasticity to achieve high effectiveness. The adipocyte-secreted hormone, adiponectin, is a metabolic regulator that crosses the blood-brain barrier and modulates neuronal activity in several brain regions, where it exerts neurotrophic and neuroprotective properties. Moreover, adiponectin has been shown to improve neuronal metabolism in different animal models, including obesity, diabetes, and Alzheimer’s disease. Here, we aim at linking the adiponectin’s neurotrophic and neuroprotective properties with its main role as a metabolic regulator and to summarize the possible mechanisms of action on improving brain plasticity via its role in regulating the intracellular energetic activity. Such properties suggest adiponectin signaling as a potential target to counteract the central metabolic disturbances and impaired neuronal plasticity underlying many neuropsychiatric disorders.

Purification, structural characterization and neuroprotective effect of a neutral polysaccharide from Sparassis crispa

In the present study, a purified polysaccharide (named SCP-1, Mw 1.368 × 10⁴ Da) was isolated from Sparassis crispa, and its biological activity was evaluated in an oxidative stress model caused by H₂O₂ in hippocampal neuronal HT22 cells. SCP-1 was a heteropolysaccharide mainly comprising glucose, galactose, fucose, and mannose in a molar ratio of 52.10: 31.10: 15.04: 1.76. The main backbone of SCP-1 was predominantly composed of (1→6)-α-_D-Galp, (1→6)-β-_D-Glcp, (1→3)-β-_D-Glcp, (1→2,6)-α-_D-Galp and (1→3,6)-β-_D-Glcp. The branches, substituted at the O-2 of Gal and O-3 of Glc, contained (1→6)-2-OMe-α-_D-Galp, (1→4)-β-_D-Glcp, (1→3)-β-_D-Glcp, and terminated by T-α-_L-Fucp and T-β-_D-Glcp. Besides, SCP-1 could effectively protect the HT22 cells against H₂O₂-induced oxidative injury via decreasing the intracellular reactive oxygen species levels, modulating antioxidant enzymes, and reducing cell apoptosis. The findings suggested that SCP-1 holds a potential to be a natural antioxidant or as a neuroprotective agent.

Pretreatment with Methylene Blue Protects Against Acute Seizure and Oxidative Stress in a Kainic Acid-Induced Status Epilepticus Model

Background

The aim of the present study was to investigate the potential anticonvulsant effect of methylene blue (MB) in a kainic acid (KA)-induced status epilepticus (SE) model. The effects of MB on levels of oxidative stress and glutamate (Glu) also were explored.

Material/Methods

Sixty C57BL/6 mice were randomly divided into 5 equal-sized groups: (1) controls; (2) KA; (3) MB 0.5 mg/kg+KA; (4) MB 1 mg/kg+KA; and (5) vehicle+KA. The SE model was established by intra-amygdala microinjection of KA. Behavioral observations and simultaneous electroencephalographic records of the seizures in different groups were analyzed to determine the potential anticonvulsant effect of MB. The influences of MB on oxidative stress markers and glutamate were also detected to explore the possible mechanism.

Results

MB afforded clear protection against KA-induced acute seizure, as measured by the delayed latency of onset of generalized seizures and SE, decreased percentage of SE, and increased survival rate in mice with acute epilepsy. MB markedly increased the latency to first onset of epileptiform activity and decreased the average duration of epileptiform events, as well as the percentage of time during which the epileptiform activity occurred. Administration of MB prevented KA-induced deterioration of oxidative stress markers and Glu.

Conclusions

MB is protective against acute seizure in SE. This beneficial effect may be at least partially related to its potent antioxidant ability and influence on Glu level.

Adiponectin improves amyloid-β 31-35-induced circadian rhythm disorder in mice

Adiponectin is an adipocyte‐derived hormone, which is closely associated with the development of Alzheimer's disease (AD) and has potential preventive and therapeutic significance. In the present study, we explored the relationship between adiponectin and circadian rhythm disorder in AD, the effect of adiponectin on the abnormal expression of Bmal1 mRNA/protein induced by amyloid‐β protein 31‐35 (Aβ31‐35), and the underlying mechanism of action. We found that adiponectin‐knockout mice exhibited amyloid‐β deposition, circadian rhythm disorders and abnormal expression of Bmal1. Adiponectin ameliorated the abnormal expression of the Bmal1 mRNA/protein caused by Aβ31‐35 by inhibiting the activity of glycogen synthase kinase 3β (GSK3β). These results suggest that adiponectin deficiency could induce circadian rhythm disorders and abnormal expression of the Bmal1 mRNA/protein, whilst exogenous administration of adiponectin may improve Aβ31‐35‐induced abnormal expression of Bmal1 by inhibiting the activity of GSK3β, thus providing a novel idea for the treatment of AD.

MAR1 suppresses inflammatory response in LPS-induced RAW 264.7 macrophages and human primary peripheral blood mononuclear cells via the SIRT1/PGC-1α/PPAR-γ pathway

Background

Sepsis is a complex syndrome characterized by a dysregulated inflammatory response to systemic infection and leads to shock, multiple organ failure and death especially if not recognized early and treated promptly. Previous studies have suggested Maresin 1 (MAR1) can alleviate systemic inflammation in sepsis, but its mechanism has not been clarified.

Methods

RAW 264.7 cells and human primary peripheral blood mononuclear cells (hPBMCs) were pretreated with LPS and MAR1. The mRNA expression and supernatant levels of pro-inflammatory cytokines, tumor necrosis factor (TNF-α), interleukin (IL)-1β and IL-6 were evaluated by RT-qPCR and ELISA, respectively. The expression levels of Sirtuin 1 (SIRT1), peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), and Peroxisome proliferator-activated receptor gamma (PPAR-γ) were determined by RT-qPCR and Western blot analysis, respectively.

Results

Our results show that LPS-induced inflammation increased the expression and secretion of proinflammatory cytokines TNF-α, IL-1β and IL-6 and induced suppression of SIRT1, PGC-1α, and PPAR-γ expression, which could be reversed by MAR1. And the effect of MAR1 was eliminated by repression of SIRT1/PPAR-γ and enhanced by PGC-1α overexpression.

Conclusions

MAR1 suppressed inflammatory response in LPS-induced RAW 264.7 macrophages and hPBMCs via the SIRT1/PGC-1α/PPAR-γ pathway.

Antioxidant, antimicrobial and neuroprotective effects of Octaviania asterosperma in vitro

Octaviania asterosperma (hypogeous Basidiomycota) We investigated the phenolic composition, and antioxidant, antimicrobial and antigenotoxic effects of methanol extracts of fruiting bodies from Octaviania asterosperma. The total phenolic content (ppm) of O. asterosperma was found to be catechin (54.73 ± 4.68), epicatechin (123.90 ± 8.52), caffeic acid (4.23 ± 0.97), p-hydroxybenzoic acid (37.72 ± 3.84), cinnamic acid (58.07 ± 5.40), gallic acid (56.64 ± 6.39), clorogenic acid (80.76 ± 4.92) and coumaric acid (2.45 ± 0.15). The total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI) were 3.410 ± 0.099 mmol/L, 7.548 ± 0.147 μmol/L and 0.221 ± 0.005 respectively. O. asterosperma showed some promising antimicrobial activity. The extract showed no genotoxic potential and attenuated hydrogen peroxide (H2O2)-induced oxidative DNA damage in neurons. Pre-treatment with O. asterosperma maintained mitochondrial function, reduced expression levels of cleaved-caspase-3 and apoptosis-inducing factor (AIF) when HT22 cells were exposed to pathophysiological concentrations of GLU (25 mM) and modulated protein kinase B (Akt), the mammalian target of rapamycin (mTOR), and the phosphotase and tensin homolog on chromosome ten (PTEN). O. asterosperma is an important food for the treatment or management of neurodegenerative disorders due to its phenolic content and potent antioxidant and anti-excitotoxic effects.

Loganetin and 5-fluorouracil synergistically inhibit the carcinogenesis of gastric cancer cells via down-regulation of the Wnt/β-catenin pathway

Although most gastrointestinal tumours are sensitive to 5-fluorouracil (5FU), drug resistance is commonly occurred after 5FU therapy in gastric cancer (GC). Loganetin is the primary active compound in Cornus officinali. However, the synergetic effects of loganetin and 5FU on GC remain unknown. Here, we investigated the synergetic effects and the underlying mechanism of loganetin and 5FU on proliferation, stem-like properties, migration, and invasion of GC both in vitro and in vivo. We found that loganetin alone inhibited the proliferation, stem-like properties, migration and invasion of GC cells in vitro. Importantly, the loganetin remarkably enhanced the anti-cancer effect of 5FU on GC cells and the Wnt/β-catenin pathway might be involved in this process. Animal experiments further confirmed the synergistic effects of 5FU and loganetin on inhibiting cell growth and metastasis of GC. These results suggested that loganetin could synergistically increase the effect of 5FU against GC, which sheds light on effective combinational drug strategies for GC treatment.

Adiponectin: The Potential Regulator and Therapeutic Target of Obesity and Alzheimer's Disease

Animal and human mechanistic studies have consistently shown an association between obesity and Alzheimer’s disease (AD). AD, a degenerative brain disease, is the most common cause of dementia and is characterized by the presence of extracellular amyloid beta (Aβ) plaques and intracellular neurofibrillary tangles disposition. Some studies have recently demonstrated that Aβ and tau cannot fully explain the pathophysiological development of AD and that metabolic disease factors, such as insulin, adiponectin, and antioxidants, are important for the sporadic onset of nongenetic AD. Obesity prevention and treatment can be an efficacious and safe approach to AD prevention. Adiponectin is a benign adipokine that sensitizes the insulin receptor signaling pathway and suppresses inflammation. It has been shown to be inversely correlated with adipose tissue dysfunction and may enhance the risk of AD because a range of neuroprotection adiponectin mechanisms is related to AD pathology alleviation. In this study, we summarize the recent progress that addresses the beneficial effects and potential mechanisms of adiponectin in AD. Furthermore, we review recent studies on the diverse medications of adiponectin that could possibly be related to AD treatment, with a focus on their association with adiponectin. A better understanding of the neuroprotection roles of adiponectin will help clarify the precise underlying mechanism of AD development and progression.

Saponins of Panax japonicus Confer Neuroprotection against Brain Aging through Mitochondrial Related Oxidative Stress and Autophagy in Rats

BACKGROUND

Oxidative stress and mitochondrial dysfunction play a vital role in the pathogenesis of brain aging. Saponins from Panax japonicus (SPJ) have attracted much attention for their potential to attenuate age-related oxidative stress as the main ingredient in rhizomes of Panax japonicus.

OBJECTIVE

This study aimed to investigate the neuroprotective effects of SPJ on natural aging rats as well as the underlying mechanisms regarding oxidative stress and mitochondrial pathway.

METHODS

Sprague-Dawley rats were divided into control groups (3-, 9-, 15- and 24-month old groups) and SPJ-treated groups. For SPJ-treated groups, SPJ were orally administrated to 18-month old rats at doses of 10 mg/kg, 30 mg/kg and 60 mg/kg once daily. Control groups were given the same volume of saline. After the treatment with SPJ or saline for six months, the cortex and hippocampus were rapidly harvested and deposited at -80°C after the rats were decapitated under anesthesia. The neuroprotective effects of SPJ were estimated by histopathological observation, TUNEL detection, biochemical determination and western blotting.

RESULTS

SPJ improved pathomorphological changes in neuronal cells and decreased apoptosis in the cortex and hippocampus of aging rats, increased the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), Na+/K+-ATPase, Ca2+-ATPase and Ca2+/Mg2+-ATPase whereas, decreased malondialdehyde (MDA) contents in the cortex of aging rats. Furthermore, the SPJ increased silent mating type information regulation 2 homolog-1 (SIRT1) protein expression, decreased acetylated level of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) in the cortex and hippocampus of aging rats, and reversed the aging-induced decline of Forkhead box O3 (Foxo3a), Superoxide Dismutase 2 (SOD2), microtubule-associated protein light chain 3 (LC3II) and Beclin1 levels in the cortex and hippocampus.

CONCLUSION

Our data showed that SPJ conferred neuroprotection partly through the regulation of oxidative stress and mitochondria-related pathways in aging rats.

Salvianolic acid B protects against sepsis-induced liver injury via activation of SIRT1/PGC-1α signaling

Liver injury occurs frequently during sepsis, which leads to high mortality and morbidity. A previous study has suggested that salvianolic acid B (SalB) is protective against sepsis-induced lung injury. However, whether SalB is able to protect against sepsis-induced liver injury remains unclear. The present study aimed to investigate the effects of SalB on sepsis-induced liver injury and its potential underlying mechanisms. Sepsis was induced in mice using a cecal ligation and puncture (CLP) method. The mice were treated with SalB (30 mg/kg intraperitoneally) at 0.5, 2 and 8 h after CLP induction. Pathological alterations of the liver were assessed using hematoxylin and eosin staining. The serum levels of alanine transaminase (ALT), aspartate aminotransferase (AST), tumor necrosis factor (TNF)-α and interleukin (IL)-6 were measured. The hepatic mRNA levels of TNF-α, IL-6, Bax and Bcl-2 were also detected. The results suggested that treatment with SalB ameliorated sepsis-induced liver injury in the mice, as supported by the mitigated pathologic changes and lowered serum aminotransferase levels. SalB also decreased the levels of the inflammatory cytokines TNF-α and IL-6 in the serum and the liver of the CLP model mice. In addition, SalB significantly downregulated Bax expression and upregulated Bcl-2 expression, and upregulated the expression levels of SIRT1 and PGC-1α. However, when sirtuin 1 (SIRT1) small interfering RNA was co-administered with SalB, the protective effects of SalB were attenuated and the expression levels of SIRT1 and PGC-1α were reduced. In summary, these results indicate that SalB mitigates sepsis-induced liver injury via reduction of the inflammatory response and hepatic apoptosis, and the underlying mechanism may be associated with the activation of SIRT1/PGC-1α signaling.

Adiponectin inhibits cardiac arrest/cardiopulmonary resuscitation‑induced apoptosis in brain by increasing autophagy involved in AdipoR1‑AMPK signaling

Emerging evidence suggests that both apoptosis and autophagy contribute to global cerebral ischemia‑reperfusion (GCIR)‑induced neuronal death, which results from cardiac arrest (CA). However, the mechanism of how GCIR may affect the balance between apoptosis and autophagy resulting from CA remains to be elucidated. Additionally, the role of adiponectin (APN) in reversing the apoptosis and autophagy induced by GCIR following cardiac arrest‑cardiopulmonary resuscitation (CA‑CPR) is unclear. Thus, the aim of the present study was to investigate how GCIR affect the apoptosis and autophagy in response to CA and to clarify whether APN may alter the apoptosis and autophagy of neuronal death in GCIR‑injured brain post‑CA‑CPR. Using normal controls (Sham group) and two experimental groups [CA‑CPR‑induced GCIR injury (PCAS) group and exogenous treatment with adiponectin post‑CA‑CPR (APN group)], it was demonstrated that both apoptosis and autophagy were observed simultaneously in the brain subjected to GCIR, but apoptosis appeared to be more apparent. Exogenous administration of APN significantly reduced the formation of malondialdehyde, a marker of oxidative stress and increased the expression of superoxide dismutase, an anti‑oxidative enzyme, resulting in the stimulation of autophagy, inhibition of apoptosis and reduced brain tissue injury (P<0.05 vs. PCAS). APN treatment increased the expression of APN receptor 1 (AdipR1) and the phosphorylation of AMP‑activated protein kinase (AMPK; Ser182) in brain tissues. In conclusion, GCIR induced apoptosis and inhibited autophagy, contributing to brain injury in CA‑CPR. By contrast, APN reduced the brain injury by reversing the changes of neuronal autophagy and apoptosis induced by GCIR. The possible mechanism might owe to its effects on the activation of AMPK after combining with AdipR1 on neurons, which suggests a novel intervention against GCIR injury in CA‑CPR conditions.

Ellagic acid protects mice against sleep deprivation-induced memory impairment and anxiety by inhibiting TLR4 and activating Nrf2

Sleep disorder has become a prevalent issue in current society and is connected with the deterioration of neurobehaviors such as mood, cognition and memory. Ellagic acid (EA) is a phenolic phytoconstituent extracted from grains and fruits that has potent neuroprotective properties. This research aimed to study the alleviative effect and mechanism of EA on memory impairment and anxiety caused by sleep deprivation (SD). EA ameliorated behavioral abnormalities in SD mice, associated with increased dendritic spine density, and reduced shrinkage and loss of hippocampal neurons. EA reduced the inflammatory response and oxidative stress injury caused by SD, which may be related to activation of the Nrf2/HO-1 pathway and mitigation of the TLR4-induced inflammatory response. In addition, EA significantly reduced the mortality and ROS levels in glutamate (Glu)-induced hippocampal neuron injury, and these effects of EA were enhanced in TLR4 siRNA-transfected neurons. However, knockdown of Nrf2 dramatically restrained the protective impact of EA on Glu-induced toxicity. Taken together, EA alleviated memory impairment and anxiety in sleep-deprived mice potentially by inhibiting TLR4 and activating Nrf2. Our findings suggested that EA may be a promising nutraceutical ingredient to prevent cognitive impairment and anxiety caused by sleep loss.

Resveratrol protects mitochondrial quantity by activating SIRT1/PGC-1α expression during ovarian hypoxia

PURPOSE

Resveratrol is a well-known potent activator of sirtuin-1 (SIRT1). We investigated the direct effects of hypoxia and resveratrol on SIRT1/ peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α) pathways, vascular endothelial growth factor (VEGF), hypoxia-inducible factor (HIF)-1α, and mitochondrial quantity in a steroidogenic human ovarian granulosa-like tumor cell line (KGN) cells.

METHODS

KGN cells were cultured with cobalt chloride (CoCl2; a hypoxia-mimicking agent) and/or resveratrol. The mRNA and protein levels, protein secretion, and intracellular localization were assessed by real-time PCR, Western blot analysis, ELISA, and immunofluorescence staining, respectively. Mitochondrial quantity was measured based on the mitochondrial DNA (mtDNA) copy number.

RESULTS

CoCl2 simultaneously attenuated the levels of SIRT1 and mtDNA expression, and induced the levels of VEGF protein production. In contrast, resveratrol significantly increased the levels of SIRT1 and mtDNA copy number, but reduced VEGF production in normoxia. Resveratrol could recover CoCl2-suppressed SIRT1 and mtDNA expression and antagonize CoCl2-induced VEGF production. CoCl2 treatment resulted in a downregulation of PGC-1α expression, and this effect was recovered by resveratrol. Resveratrol significantly suppressed the production of the CoCl2-induced HIF-1α and VEGF proteins.

CONCLUSION

These results suggest that resveratrol improves mitochondrial quantity by activating the SIRT1/PGC-1α pathway and inhibits VEGF induction through HIF-1α under hypoxic conditions.

Effect of atorvastatin on Aβ1-42 -induced alteration of SESN2, SIRT1, LC3II and TPP1 protein expressions in neuronal cell cultures

OBJECTIVES

Sestrins (SESNs) and sirtuins (SIRTs) are antioxidant and antiapoptotic genes and crucial mediators for lysosomal autophagy regulation that play a pivotal role in the Alzheimer's disease (AD). Recently, statins have been linked to the reduced prevalence of AD in statin-prescribed populations yet molecular basis for the neuroprotective action of statins is still under debate.

METHODS

This study was undertaken whether Aβ-induced changes of SESN2 and SIRT1 protein expression, autophagy marker LC3II and lysosomal enzyme TPP1 affected by atorvastatin (Western blot) and its possible role in Aβ neurotoxicity (ELISA).

KEY FINDINGS/RESULTS

We showed that SESN2 and LC3II expressions were elevated, whereas SIRT1 and TPP1 expressions were decreased in the Aβ_1-42 -exposed human neuroblastoma cells (SH-SY5Y). Co-administration of atorvastatin with Aβ_1-42 compensates SESN2 increase and recovers SIRT1 decline by reducing oxidative stress, decreasing SESN2 expression and increasing SIRT1 expression by its neuroprotective action. Atorvastatin induced LC3II but not TPP1 level in the Aβ_1-42 -exposed cells suggested that atorvastatin is effective in the formation of autophagosome but not on the expression of the specific lysosomal enzyme TPP1.

DISCUSSION AND CONCLUSION

Together, these results indicate that atorvastatin induced SESN2, SIRT1 and LC3II levels play a protective role against Aβ_1-42 neurotoxicity.

Calycosin-7-O-β-D-glucoside Attenuates OGD/R-Induced Damage by Preventing Oxidative Stress and Neuronal Apoptosis via the SIRT1/FOXO1/PGC-1α Pathway in HT22 Cells

Neuronal apoptosis induced by oxidative stress is a major pathological process that occurs after cerebral ischemia-reperfusion. Calycosin-7-O-β-D-glucoside (CG) is a representative component of isoflavones in Radix Astragali (RA). Previous studies have shown that CG has potential neuroprotective effects. However, whether CG alleviates neuronal apoptosis through antioxidant stress after ischemia-reperfusion remains unknown. To investigate the positive effects of CG on oxidative stress and apoptosis of neurons, we simulated the ischemia-reperfusion process in vitro using an immortalized hippocampal neuron cell line (HT22) and oxygen-glucose deprivation/reperfusion (OGD/R) model. CG significantly improved cell viability and reduced oxidative stress and neuronal apoptosis. In addition, CG treatment upregulated the expression of SIRT1, FOXO1, PGC-1α, and Bcl-2 and downregulated the expression of Bax. In summary, our findings indicate that CG alleviates OGD/R-induced damage via the SIRT1/FOXO1/PGC-1α signaling pathway. Thus, CG maybe a promising therapeutic candidate for brain injury associated with ischemic stroke.

The Neuroprotective Effect of the Adiponectin Receptor Agonist AdipoRon on Glutamate-Induced Cell Death in Rat Primary Retinal Ganglion Cells

Purpose: To determine whether the adiponectin receptor (AdipoR) agonist AdipoRon inhibits glutamate-induced neuronal cell death and to investigate the neuroprotective mechanism of AdipoRon in rat primary retinal ganglion cells (RGCs). Methods: The expression pattern of AdipoR1 and AdipoR2 in rat retina and primary RGCs was examined by immunostaining. The neuroprotective effect of AdipoRon on glutamate-induced cell death was evaluated in rat primary RGCs. Cellular levels of reactive oxygen species (ROS) were also measured. Peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), estrogen-related receptor-α (Esrra), mitochondrial transcription factor A (TFAM), peroxisome proliferator-activated receptor α (PPARα), and catalase mRNA levels were examined. Results: The expression of AdipoR1 and AdipoR2 was confirmed in rat retina and primary RGCs. AdipoRon significantly increased the survival rate of glutamate-induced cell death and decreased ROS production. Additionally, the mRNA levels of PGC-1α, Esrra, and TFAM were upregulated by AdipoRon. Conclusions: These results suggest that AdipoRon has a neuroprotective effect by inhibiting ROS production via upregulation of PGC-1α, Esrra, and TFAM against glutamate-induced RGC death.

Peroxisome Proliferator-Activated Receptor-γ Coactivator-1α Inhibits Vascular Calcification Through Sirtuin 3-Mediated Reduction of Mitochondrial Oxidative Stress

Aims: Vascular calcification is associated with cardiovascular death in patients with chronic kidney disease (CKD). Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) plays an important role in various cardiovascular diseases. However, its role in vascular calcification remains unknown. Results: Adenine-induced rat CKD model was used to induce arterial medial calcification. The level of PGC-1α decreased in abdominal aorta of CKD rats. Overexpression of PGC-1α significantly ameliorated calcium deposition in rat abdominal aorta, isolated carotid rings, and cultured vascular smooth muscle cells (VSMCs). Mitochondrial reactive oxygen species (mtROS) increased in calcifying aorta and VSMCs. Upregulation of PGC-1α inhibited, whereas PGC-1α depletion promoted β-glycerophosphate-induced mtROS production and calcium deposition. Moreover, PGC-1α increased superoxide dismutase 1 (SOD1) and SOD2 contents in vivo and in vitro, whereas SOD2 deletion eliminated PGC-1α-mediated mtROS change and promoted calcium deposition. Mechanistically, sirtuin 3 (SIRT3) expression declined in calcifying aorta and VSMCs, while PGC-1α overexpression restored SIRT3 expression. Inhibition of SIRT3 by 3-TYP or siRNA (small interfering RNA) reduced PGC-1α-induced upregulation of SOD1 and SOD2, and abolished the protective effect of PGC-1α on calcification of VSMCs. Importantly, PGC-1α was reduced in calcified femoral arteries in CKD patients. In phosphate-induced human umbilical arterial calcification, upregulation of PGC-1α attenuated calcium nodule formation, while this protective effect was abolished by SIRT3 inhibitor. Innovation: We showed for the first time that PGC-1α is an important endogenous regulator against vascular calcification. Induction of PGC-1α could be a potential strategy to treat vascular calcification in CKD patients. Conclusions: PGC-1α protected against vascular calcification by SIRT3-mediated mtROS reduction.

Adiponectin Protects Against Cerebral Ischemic Injury Through AdipoR1/AMPK Pathways

Excitotoxicity induced by excessive N-methyl-D-aspartate (NMDA) receptor activation underlies the pathology of ischemic injury. Adiponectin (APN) is an adipocyte-derived protein hormone that modulates a number of metabolic processes. APN exerts a wide range of biological functions in the central nervous system. However, the role of APN and its receptors in cerebral ischemia/reperfusion (I/R)-induced injury and the related mechanisms remain to be clarified. Here, we found that APN and APN receptor agonist AdipoRon (APR) were protective against excitotoxicity induced by oxygen and glucose deprivation/reperfusion (OGD/R) and NMDA in primary neurons. Adiponectin receptor 1 (AdipoR1) knockdown reversed the protection conferred by either APN or APR. Moreover, the protective effects offered by both APN and APR were compromised by compound C, an inhibitor of amp-activated protein kinase (AMPK) phosphorylation. Both APN and APR protected the dissipation of the ΔΨm caused by OGD/R. They also up-regulated the PGC-1α expression, which was reversed by compound C. Furthermore, both APN and APR ameliorated but APN knockout aggravated the infarct volume and neurological deficient induced by transient middle cerebral artery occlusion (tMCAO) in vivo. Taken together, these findings show that APN and APR protect against ischemic injury in vitro and in vivo. The protective mechanism is mainly related to AdipoR1-dependent AMPK phosphorylation and PGC-1α up-regulation.

Administration of rCTRP9 Attenuates Neuronal Apoptosis Through AdipoR1/PI3K/Akt Signaling Pathway after ICH in Mice

Targeting neuronal apoptosis after intracerebral hemorrhage (ICH) may be an important therapeutic strategy for ICH patients. Emerging evidence indicates that C1q/TNF-Related Protein 9 (CTRP9), a newly discovered adiponectin receptor agonist, exerts neuroprotection in cerebrovascular disease. The aim of this study was to investigate the anti-apoptotic role of CTRP9 after experimental ICH and to explore the underlying molecular mechanisms. ICH was induced in mice via intrastriatal injection of bacterial collagenase. Recombinant CTRP9 (rCTRP9) was administrated intranasally at 1 h after ICH. To elucidate the underlying mechanisms, adiponectin receptor1 small interfering ribonucleic acid (AdipoR1 siRNA) and selective PI3 K inhibitor LY294002 were administered prior to rCTRP9 treatment. Western blots, neurofunctional assessments, immunofluorescence staining, and Fluoro-Jade C (FJC) staining experiments were performed. Administration of rCTRP9 significantly improved both short- and long-term neurofunctional behavior after ICH. RCTRP9 treatment significantly increased the expression of AdipoR1, PI3 K, p-Akt, and Bcl-2, while at the same time was found to decrease the expression of Bax in the brain, which was reversed by inhibition of AdipoR1 and PI3 K. The neuroprotective effect of rCTRP9 after ICH was mediated by attenuation of neuronal apoptosis via the AdipoR1/PI3K/Akt signaling pathway; therefore, rCTRP9 should be further evaluated as a potential therapeutic agent for ICH patients.

Adiponectin Attenuates Oxygen-Glucose Deprivation-Induced Mitochondrial Oxidative Injury and Apoptosis in Hippocampal HT22 Cells via the JAK2/STAT3 Pathway

Ischemic stroke is among the leading causes of morbidity and mortality worldwide. Improving the tolerance of neurons to ischemia and reperfusion injury could be a feasible strategy against ischemia. Adiponectin (APN) is a major adipokine that regulates glucose and lipid metabolism and plays an important role in the protection of the cerebral nervous system. We aimed to investigate the effects of APN on oxygen and glucose deprivation (OGD)-induced neuronal injury in hippocampal neuronal HT22 cells. APN displayed neuroprotective effects against OGD, evidenced by increased cell viability and decreased lactate dehydrogenase release and apoptotic rate. Additionally, APN also maintained mitochondrial ultrastructure and transmembrane potential, attenuated reactive oxygen species and malondialdehyde, and increased superoxide dismutase and glutathione peroxidase activity. Moreover, APN promoted Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) phosphorylation, enhanced STAT3 nuclear translocation, increased the Bcl-2/Bax ratio, and decreased cleaved caspase-3. The aforementioned APN-induced effects were almost reversed by a JAK2 inhibitor, AG490. APN may attenuate OGD-induced hippocampal HT22 neuronal impairment by protecting cells against mitochondrial oxidative stress and apoptosis, mediated by JAK2/STAT3 signaling.

Adiponectin attenuates neuronal apoptosis induced by hypoxia-ischemia via the activation of AdipoR1/APPL1/LKB1/AMPK pathway in neonatal rats

Adiponectin is an important adipocyte-derived plasma protein that has beneficial effects on cardio- and cerebrovascular diseases. A low level of plasma Adiponectin is associated with increased mortality post ischemic stroke; however, little is known about the causal role of Adiponectin as well as its molecular mechanisms in neonatal hypoxia ischemia (HI). In the present study, ten-day-old rat pups were subjected to right common carotid artery ligation followed by 2.5 h hypoxia. Recombinant human Adiponectin (rh-Adiponectin) was administered intranasally 1 h post HI. Adiponectin Receptor 1 (AdipoR1) siRNA, APPL1 siRNA, LKB1 siRNA were administered through intracerebroventricular injection 48 h before HI. Brain infarct area measurement, neurological function test, western blot, Fluoro Jade C (FJC), TUNEL, and immunofluorescence staining were conducted. Results revealed that endogenous Adiponectin, AdipoR1 and APPL1 were increased in a time dependent manner after HI. Administration of rh-Adiponectin reduced brain infarct area, neuronal apoptosis, brain atrophy and improved neurological function at 24 h and 4 weeks post HI. Furthermore, rh-Adiponectin treatment increased Adiponectin, AdipoR1, APPL1, cytosolic LKB1, p-AMPK expression levels and thereby attenuated apoptosis as shown by the decreased expression of the pro-apoptotic marker, Cleaved Caspase 3 (C-Cas3), as well as the number of FJC and TUNEL positively stained neurons. AdipoR1, APPL1 and LKB1 siRNAs abolished the anti-apoptotic effects of rh-Adiponectin at 24 h after HI. Collectively, the data provided evidence that intranasal administration of rh-Adiponectin attenuated neuronal apoptosis at least in part via activating AdipoR1/APPL1/LKB1/AMPK signaling pathway. Adiponectin could represent a therapeutic target for treatment of neonatal hypoxic ischemic encephalopathy.

Adiponectin Attenuates Streptozotocin-Induced Tau Hyperphosphorylation and Cognitive Deficits by Rescuing PI3K/Akt/GSK-3β Pathway

Clinical studies have demonstrated that decreased adiponectin is associated with the development of Type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD). We focused on determining the neuroprotective effect offered by adiponectin against streptozotocin-induced brain damage in ICV-STZ rat model. We found that adiponectin supplements significantly restored the cognitive deficits in ICV-STZ rat model including shorter escape latency, more crossing times and increased time spent in the target quadrant. Adiponectin supplements also increased number of dendritic branches and mushroom percentage. In addition, adiponectin supplements attenuated tau hyperphosphorylation at multiple AD-related sites through activation of protein Ser9-phosphorylated glycogen synthase kinase-3β (Ser9-GSK-3β) with increased the Akt and PI3K activity. Our data suggest that adiponectin supplements have neuroprotective effects on the ICV-STZ rat model, which may be mediated by the activation of the PI3K/Akt/GSK-3β signaling pathway.

Overexpression of selenoprotein H prevents mitochondrial dynamic imbalance induced by glutamate exposure

Selenium and selenoproteins play important roles in neuroprotection against glutamate‑induced cell damage, in which mitochondrial dysfunction is considered a major pathogenic feature. Recent studies have revealed that mitochondrial fission could activates mitochondrial initiated cell death pathway. The objectives of the study are to determine whether glutamate induced cell death is mediated through mitochondrial initiated cell death pathway and activation of autophagy, and whether overexpression of selenoprotein H can protect cells from glutamate toxicity by preserving mitochondrial morphology and suppressing autophagy. Vector- or human selenoprotein H (SelH)-transfected HT22 cells (V-HT22 and SelH-HT22, respectively) were exposed to glutamate. The results showed that glutamate-induced cytotoxicity was associated with increased ROS production and imbalance in mitochondrial dynamics and autophagy. These alterations were reversed and cellular integrity restored by overexpression of SelH in HT22 cells.