Pretreatment with 2-(4-methoxyphenyl)ethyl-2-acetamido-2-deoxy-β-D-pyranoside attenuates cerebral ischemia/reperfusion-induced injury in vitro and in vivo

MiR-29c Inhibits TNF-α-Induced ROS Production and Apoptosis in Mouse Hippocampal HT22 Cell Line

Recent reports have suggested that abnormal miR-29c expression in hippocampus have been implicated in the pathophysiology of some neurodegenerative and neuropsychiatric diseases. However, the underlying effect of miR-29c in regulating hippocampal neuronal function is not clear. In this study, HT22 cells were infected with lentivirus containing miR-29c or miR-29c sponge. Cell counting kit-8 (CCK8) and lactate dehydrogenase (LDH) assay kit were applied to evaluate cell viability and toxicity before and after TNF-α administration. Reactive oxygen species (ROS) generation and mitochondrial membrane potential (MMP) were measured with fluorescent probes. Hoechst 33258 staining and TUNEL assay were used to evaluate cell apoptosis. The expression of key mRNA/proteins (TNFR1, Bcl-2, Bax, TRADD, FADD, caspase-3, -8 and -9) in the apoptosis pathway was detected by PCR or WB. In addition, the protein expression of microtubule-associated protein-2 (MAP-2), nerve growth-associated protein 43 (GAP-43) and synapsin-1 (SYN-1) was detected by WB. As a result, we found that miR-29c overexpression could improve cell viability, attenuate LDH release, reduce ROS production and inhibit MMP depolarization in TNF-α-treated HT22 cells. Furthermore, miR-29c overexpression was found to decrease apoptotic rate, along with decreased expression of Bax, cleaved caspase-3, cleaved caspase-9, and increased expression of Bcl-2 in TNF-α-treated HT22 cells. However, miR-29c sponge exhibited an opposite effects. In addition, in TNF-α-treated HT22 cells, miR-29c overexpression could decrease the expressions of TNFR1, TRADD, FADD and cleaved caspase-8. However, in HT22 cells transfected with miR-29c sponge, TNF-α-induced the expressions of TNFR1, TRADD, FADD and cleaved caspase-8 was significantly exacerbated. At last, TNF-α-induced the decreased expression of MAP-2, GAP-43 and SYN-1 was reversed by miR-29c but exacerbated by miR-29c sponge. Overall, our study demonstrated that miR-29c protects against TNF-α-induced HT22 cells injury through alleviating ROS production and reduce neuronal apoptosis. Therefore, miR-29c might be a potential therapeutic agent for TNF-α accumulation and toxicity-related brain diseases.

Activation of the Akt/FoxO3 signaling pathway enhances oxidative stress-induced autophagy and alleviates brain damage in a rat model of ischemic stroke

Autophagy has been implicated in stroke. Our previous study showed that the FoxO3 transcription factor promotes autophagy after transient cerebral ischemia/reperfusion (I/R). However, whether the Akt/FoxO3 signaling pathway plays a regulatory role in autophagy in cerebral I/R-induced oxidative stress injury is still unclear. The present study aims to investigate the effects of the Akt/FoxO3 signaling pathway on autophagy activation and neuronal injury in vitro and in vivo. By employing LY294002 or insulin to regulate the Akt/FoxO3 signaling pathway, we found that insulin pretreatment increased cell viability, decreased reactive oxygen species production, and enhanced the expression of antiapoptotic and autophagy-related proteins following H₂O₂ injury in HT22 cells. In addition, insulin significantly decreased neurological deficit scores and infarct volume and increased the expression of antiapoptotic and autophagy-related proteins following I/R injury in rats. However, LY294002 showed the opposite effects under these conditions. Altogether, these results indicate that Akt/FoxO3 signaling pathway activation inhibited oxidative stress-mediated cell death through activation of autophagy. Our study supports a critical role for the Akt/FoxO3 signaling pathway in autophagy activation in stroke.

FoxO3 transcription factor promotes autophagy after oxidative stress injury in HT22 cells

Autophagy has been implicated in neurodegenerative diseases. Forkhead box O3 (FoxO3) transcription factors promote autophagy in heart and inhibit oxidative damage. Here we investigate the role of FoxO3 transcription factors in regulating autophagy after oxidative stress injury in immortalized mouse hippocampal cell line (HT22). The present study confirms that hydrogen peroxide (H2O2) injury could induce autophagy and FoxO3 activation in HT22 cells. In addition, overexpression of FoxO3 enhanced H2O2-induced autophagy activation and suppressed neuronal cell damage, while knockdown of FoxO3 reduced H2O2-induced autophagy activation and exacerbated neuronal cell injury. Inhibition of autophagy by 3-methyladenine (3-MA) resulted in reduced cell viability, increased production of reactive oxygen species (ROS), promoted nuclear condensation, and decreased expression of antiapoptotic and autophagy-related proteins, indicating that autophagy may have protective effects on H2O2-induced injury in HT22 cells. Moreover, overexpression of FoxO3 prevented exacerbation of brain damage induced by 3-MA. Taken together, these results show that activation of FoxO3 could induce autophagy and inhibit H2O2-induced damage in HT22 cells. Our study demonstrates the critical role of FoxO3 in regulating autophagy in brain.

Mustard Leaf Extract Suppresses Psychological Stress in Chronic Restraint Stress-Subjected Mice by Regulation of Stress Hormone, Neurotransmitters, and Apoptosis

Mustard leaf (Brassica juncea var. crispifolia L. H. Bailey) has been reported to have psychological properties such as anti-depressant activities. However, studies on chronic stress and depression caused by restraint have not been conducted. Therefore, this study aimed to evaluate the effects of a mustard leaf (ML) extract on chronic restraint stress (CRS) in mice. Male mice were subjected to a CRS protocol for a period of four weeks to induce stress. The results showed that the ML extract (100 and 500 mg/kg/perorally administered for four weeks) significantly decreased corticosterone levels and increased neurotransmitters levels in stressed mice. Apoptosis by CRS exposure was induced by Bcl-2 and Bax expression regulation and was suppressed by reducing caspase-3 and poly (ADP-ribose) polymerase expression after treatment with the ML extract. Our results confirmed that apoptosis was regulated by increased expression of brain-derived neurotrophic factor (BDNF). Additionally, cytokine levels were regulated by the ML extract. In conclusion, our results showed that the ML extract relieved stress effects by regulating hormones and neurotransmitters in CRS mice, BDNF expression, and apoptosis in the brain. Thus, it can be suggested that the studied ML extract is an agonist that can help relieve stress and depression.

Antioxidant Effects of Salidroside in the Cardiovascular System

Cardiovascular disease is one of the main human health risks, and the incidence is increasing. Salidroside is an important bioactive component of Rhodiola rosea L., which is used to treat Alzheimer's disease, tumor, depression, and other diseases. Recent studies have shown that salidroside has therapeutic effects, to some degree, in cardiovascular diseases via an antioxidative mechanism. However, evidence-based clinical data supporting the effectiveness of salidroside in the treatment of cardiovascular diseases are limited. In this review, we discuss the effects of salidroside on cardiovascular risk factors and cardiovascular diseases and highlight potential antioxidant therapeutic strategies.

FoxO3 transcription factor promotes autophagy after transient cerebral ischemia/reperfusion

Aim: Autophagy was activated after cerebral ischemia reperfusion (I/R) injury. However, the molecular mechanisms underlying regulation of autophagy in cerebral I/R injury were not completely understood. Studies reported that Forked-box class O (FoxO) transcription factors involved in autophagy and might be the regulator of autophagy in multiple cells. In this study, we investigated the effects of FoxO3 on regulating autophagy after cerebral I/R injury. Materials and methods: Rats were subjected to MCAO for 2 h and reperfusion for different times, western blot was used to examine the expression of p-FoxO3, FoxO3 and the autophagic marker LC3 and Beclin-1 in penumbral region. Then rats were injected with WT-FoxO3 or TM-FoxO3 adenovirus by lateral cerebral ventricle to increase the function of FoxO3, western blot was used to examine the expression of LC3 and Beclin-1 in penumbral region. TTC and HE staining were used to evaluate the effects of increased FoxO3 activation on I/R induced brain damage. Results: Our studies showed that I/R injury resulted in induction of autophagy in penumbral brain tissue with concomitant dephosphorylation of FoxO3, consistent with increased activity of nuclear FoxO3 transcription factor. Increased FoxO3 activation led to autophagy significantly increased and had a protective effects on I/R injury. Conclusion: These data revealed an important role of FoxO3 in regulating autophagy in brain, and provided a new approach for further prevention and treatment of cerebral ischemia.

Salidroside attenuates hypoxia/reoxygenation-induced human brain vascular smooth muscle cell injury by activating the SIRT1/FOXO3α pathway

It has been reported that salidroside (SAL), a natural dietary isothiocyanate, exhibits neuroprotective roles in cerebral ischemia-reperfusion injury. However, to the best of our knowledge, its underlying protective mechanism remains unknown. Sirtuin 1 (SIRT1) is a class III histone deacetylase involved in a variety of cellular functions. SIRT1 has been identified as a mediator of cerebral ischemia and may induce neuroprotection by activating various intracellular downstream targets, such as forkhead box protein O3α (FOXO3α). Therefore, the present study aimed to investigate whether SAL protects human brain vascular smooth muscle cells (HBVSMC) against hypoxia/reoxygenation (H/R) injury, which is a cell model of cerebral ischemia-reperfusion injury, through regulating the SIRT1-activited signaling pathway. The present study revealed that H/R treatment significantly reduced the expression of SIRT1 protein in HBVSMCs. Additionally, pretreatment with SAL reversed the H/R-induced decrease in cellular viability, increased caspase-3 activity, the appearance of apoptotic cells and the apoptosis rate in HBVSMCs. SAL attenuated the H/R-induced decrease in the expression of SIRT1 and phosphorylated FOXO3α protein in HBVSMCs, suggesting that the protective role of SAL in H/R injury occurs via the SIRT1/FOXO3α pathway. Furthermore, sirtinol, a SIRT1-specific inhibitor, suppressed the inhibitory effects of SAL on H/R-induced cytotoxicity and apoptosis as indicated by the downregulation of cell viability and upregulation of caspase-3 activity and apoptosis rate induced by sirtinol treatment in HBVSMCs. The reversal effects of SAL on H/R-induced alternation of B-cell lymphoma (Bcl-2) and Bcl-2 associated X protein expression were also attenuated by sirtinol. These results suggest that SAL exhibits neuroprotective effects against H/R injury by activating the SIRT1/FOXO3α pathway, which may become a novel potential therapeutic target for the treatment of cerebral ischemic disease.

Neuron-autonomous transcriptome changes upon ischemia/reperfusion injury

Ischemic stroke and the following reperfusion, an acute therapeutic intervention, can cause irreversible brain damages. However, the underlying pathological mechanisms are still under investigation. To obtain a comprehensive, real-time view of the cell-autonomous mechanisms involved in ischemic stroke and reperfusion, we applied the next-generation sequencing (NGS) technology to characterize the temporal changes in gene expression profiles using primarily cultured hippocampal neurons under an oxygen-glucose deprivation/reperfusion (OGD/R) condition. We first identified the differentially expressed genes (DEGs) between normal cultured neurons, neurons with OGD, and neurons with OGD followed by reperfusion for 6 h, 12 h, and 18 h, respectively. We then performed bioinformatics analyses, including gene ontological (GO) and pathway analysis and co-expression network analysis to screen for novel key pathways and genes involved in the pathology of OGD/R. After we confirmed the changes of selected key genes in hippocampal cultures with OGD/R, we further validated their expression changes in an in vivo ischemic stroke model (MCAO). Finally, we demonstrated that prevention of the up-regulation of a key gene (Itga5) associated with OGD/R promoted hippocampal neuronal survival. Our research thereby provided novel insights into the molecular mechanisms in ischemic stroke pathophysiology and potential targets for therapeutic intervention after ischemic stroke.

The Proliferation Enhancing Effects of Salidroside on Schwann Cells In Vitro

Derived from Rhodiola rosea L., which is a popular plant in Eastern Europe and Asia, salidroside has pharmacological properties including antiviral, anticancer, hepatoprotective, antidiabetic, and antioxidative effects. Recent studies show that salidroside has neurotrophic and neuroprotective effects. However, the effect of salidroside on Schwann cells (SCs) and the underlying mechanisms of the salidroside-induced neurotrophin secretion have seldom been studied. In this study, the effect of salidroside on the survival, proliferation, and gene expression of Schwann cells lineage (RSC96) was studied through the examinations of the cell viability, proliferation, morphology, and expression of neurotrophic factor related genes including BDNF, GDNF, and CDNF at 2, 4, and 6 days, respectively. These results showed that salidroside significantly enhanced survival and proliferation of SCs. The underlying mechanism might involve that salidroside affected SCs growth through the modulation of several neurotrophic factors including BDNF, GDNF, and CDNF. As for the concentration, 0.4 mM, 0.2 mM, and 0.1 mM of salidroside were recommended, especially 0.2 mM. This investigation indicates that salidroside is capable of enhancing SCs survival and function in vitro, which highlights the possibility that salidroside as a drug agent to promote nerve regeneration in cellular nerve scaffold through salidroside-induced neurotrophin secretion in SCs.

Cannabidiol attenuates OGD/R-induced damage by enhancing mitochondrial bioenergetics and modulating glucose metabolism via pentose-phosphate pathway in hippocampal neurons

Deficient bioenergetics and diminished redox conservation have been implicated in the development of cerebral ischemia/reperfusion injury. In this study, the mechanisms underlying the neuroprotective effects of cannabidiol (CBD), a nonpsychotropic compound derived from Cannabis sativa with FDA-approved antiepilepsy properties, were studied in vitro using an oxygen-glucose-deprivation/reperfusion (OGD/R) model in a mouse hippocampal neuronal cell line. CBD supplementation during reperfusion rescued OGD/R-induced cell death, attenuated intracellular ROS generation and lipid peroxidation, and simultaneously reversed the abnormal changes in antioxidant biomarkers. Using the Seahorse XFe24 Extracellular Flux Analyzer, we found that CBD significantly improved basal respiration, ATP-linked oxygen consumption rate, and the spare respiratory capacity, and augmented glucose consumption in OGD/R-injured neurons. The activation of glucose 6-phosphate dehydrogenase and the preservation of the NADPH/NADP+ ratio implies that the pentose-phosphate pathway is stimulated by CBD, thus protecting hippocampal neurons from OGD/R injury. This study is the first to document the neuroprotective effects of CBD against OGD/R insult, which depend in part on attenuating oxidative stress, enhancing mitochondrial bioenergetics, and modulating glucose metabolism via the pentose-phosphate pathway, thus preserving both energy and the redox balance.

Salidroside protects against kainic acid-induced status epilepticus via suppressing oxidative stress

There are numerous mechanisms by which the brain generates seizures. It is well known that oxidative stress plays a pivotal role in status epilepticus (SE). Salidroside (SDS) extracted from Rhodiola rosea L. shows multiple bioactive properties, such as neuroprotection and antioxidant activity in vitro and in vivo. This study explored the role of SDS in kainic acid (KA)-induced SE and investigated the underlying mechanism. Latency to SE increased in the SDS-pretreated mice compared to the KA group, while the percentage of incidence of SE was significantly reduced. These results suggested that pretreatment with SDS not only delayed SE, but it also decreased the incidence of SE induced by KA. KA increased MDA level and reduced the production of SOD and GSH at multiple timepoints after KA administration. SDS inhibited the change of MDA, SOD and GSH induced by KA prior to SE onset, indicating that SDS protects against KA-induced SE via suppressing oxidative stress. Based on these results, we investigated the possible molecular mechanism of SDS. Pretreatment with SDS reversed the KA-induced decrease in AMP-activated protein kinase (AMPK); increased the sirtuin 1 (SIRT1) deacetylase activity in KA-treated mice, which had no demonstrable effect on SIRT1 mRNA and protein; and suppressed the KA-induced increase in Ace-FoxO1. These results showed that AMPK/SIRT1/FoxO1 signaling is possibly the molecular mechanism of neuroprotection by SDS.

The protective effect of dopamine against OGD/R injury-induced cell death in HT22 mouse hippocampal cells

Previous studies have shown that levo-dopamine (L-dopa) can improve the consciousness of certain patients with prolonged coma after cerebral ischemia-reperfusion injury, and promote cell growth in vivo. This study aimed to investigate whether L-dopa, which is used clinically to treat Parkinson's disease, might also ameliorate ischemia-reperfusion injury-induced cell death. The oxygen-glucose deprivation and re-oxygenation (OGD/R) model was used to mimic the ischemia-reperfusion pathological process in vitro. HT22 cells were treated with dopamine hydrochloride at different times (i.e., 2 h prior to OGD, during the period of OGD, during the period of R, and throughout the period of OGD/R) and at different concentrations (i.e., 25 μM, 50 μM, 100 μM). Lactate dehydrogenase (LDH) release, flow cytometry-annexin V, and propidium iodide staining with light microscopy showed that dopamine hydrochloride (added during re-oxygenation) promoted cell proliferation and facilitated maintenance of normal cell morphology. However, when present during oxygen-glucose deprivation for 18 h and present throughout OGD/R, dopamine hydrochloride increased cell damage as manifested by shrinkage, rounding up, and reduced viability. In conclusion, dopamine protected HT22 cells from OGD/R injury-induced cell death only at a particular point in time, suggesting that it may be useful for treating severe ischemia-reperfusion brain injury.

Pretreatment with baicalin attenuates hypoxia and glucose deprivation-induced injury in SH-SY5Y cells

OBJECTIVE

To explore the neuroprotective effects of baicalin against hypoxia and glucose deprivation-reperfusion (OGD/RO)-induced injury in SH-SY5Y cells.

METHODS

SH-SY5Y cells were divided into a control group, a OGD/RO group, which was subject to OGD/RO induction; and 3 baicalin groups subject to baicalin (1, 5, 25 μmol/L) for 2 h before induction of OGD/RO (low-, medium-, and high-dose baicalin groups). Cell viability was detected by thiazolyl blue tetrazolium bromide (MTT) assay and flow cytometric analysis was used to detect cell apoptosis. Real-time polymerase chain reaction was performed to determine the mRNA expression of caspase-3 gene. Western blot analysis was conducted to determine the expression of nuclear factor (NF)-κB and N-methyl-daspartic acid receptor-1 (NMDAR1).

RESULTS

Baicalin could significantly attenuate OGD/RO mediated apoptotic cell death in SH-SY5Y cells; the apoptosis rates in the low-, medium- and high-dose groups were 12.1%, 7.9%, and 5.4%, respectively. Western blot and real-time PCR analysis revealed that significant decrease in caspase-3 expression in the baicalin group compared with the OGD/RO group (P<0.01). Additionally, down-regulation of NF-κB and NMDAR1 was observed in the baicalin group compared with those obtained from the OGD/RO group. Compared with the low-dose baicalin group, remarkable decrease was noted in the medium- and high-dose groups (P<0.01).

CONCLUSION

Baicalin pre-treatment attenuates brain ischemia reperfusion injury by suppressing cellular apoptosis.