Linalool attenuated ischemic injury in PC12 cells through inhibition of caspase-3 and caspase-9 during apoptosis

Numerous studies have indicated the pharmacological properties of linalool, a volatile terpene alcohol found in many flowers and spice plants, including anti-nociceptive, anti-inflammatory, and neuroprotective activities. The aim of this study was to explore the mechanisms of neuroprotection provided by (±) linalool and its enantiomer, (R)-(-) linalool against oxygen, and glucose deprivation/reoxygenation (OGD/R) in PC12 cells. PC12 cells were treated with (±) linalool and (R)-(-) linalool before exposure to OGD/R condition. Cell viability, reactive oxygen species (ROS) production, malondialdehyde (MDA) level, DNA damage, and the levels of proteins related to apoptosis were evaluated using MTT, comet assay, and western blot analysis, respectively. IC₅₀ values for the PC12 cells incubated with (±) linalool and (R)-(-) linalool were 2700 and 2600 μM after 14 h, as well as 5440 and 3040 μM after 18 h, respectively. Survival of the ischemic cells pre-incubated with (±) linalool and (R)-(-) linalool (100 μM of both) increased compared to the cells subjected to the OGD/R alone (p < .001). ROS and MDA formation were also decreased following incubation with (±) linalool and (R)-(-) linalool compared to the OGD/R group (p < .01). In the same way, pre-treatment with (±) linalool and (R)-(-) linalool significantly reduced OGD/R-induced DNA injury compared to that seen in OGD/R group (p < .001). (±) Linalool and (R)-(-) linalool also restored Bax/Bcl-2 ratio and cleaved caspase-3 and caspase-9 (p < .001, p < .01) following ischemic injury. The neuroprotective effect of linalool against ischemic insult might be mediated by alleviation of oxidative stress and apoptosis.

Suppression of miR-130a-3p Attenuates Oxygen-Glucose Deprivation/Reoxygenation-Induced Dendritic Spine Loss by Promoting APP

BACKGROUND

Cerebral stroke induces neuronal dysfunction as a consequence of neuronal morphology changes. Emerging evidence suggests that microRNAs (miRNAs) may play an important role in regulating dysfunction in stroke, yet there are still few studies examining the association between whole blood miRNAs and neuronal morphology. The present study aimed to ascertain the potential roles and mechanisms of action of miR-130a-3p in ischemic stroke.

METHODS

The miRNA datasets of peripheral serum in the GEO database and the mRNA datasets of the human brain after ischemia were analyzed to identify differentially expressed RNAs, and their functions were verified in cultured neurons in vitro. Furthermore, the target gene was validated by dual-luciferase reporter assay, RT-PCR, Western blot, and immunofluorescence experiments. The identified miRNA was further verified by the OGD test to restore neuronal changes after ischemia through APP.

RESULTS

The expression of whole blood miR-130a-3p was found significantly lower in participants with ischemic stroke than in controls by analyzing expression profiling datasets of cerebral ischemia stroke obtained from the Gene Expression Omnibus (GEO) DataSets portal, which was confirmed in the MCAO model in mice. Furthermore, GO analysis showed that miR-130a-3p might directly affect neuronal function. Indeed, we demonstrated that miR-130a-3p played a central role in the inhibition of dendritic morphogenesis and in the growth of dendritic spines in vitro. We also confirmed that miR-130a-3p could regulate the expression of APP by luciferase reporter assay, RT-PCR, Western blot, and immunofluorescence experiments, which were consistent with the bioinformatic analysis. Last but not least, we also demonstrated that reducing miR-130a-3p expression partially rescued neuronal morphological changes after OGD in vitro.

CONCLUSION

miR-130a-3p is a potential biomarker of cerebral stroke, can affect neuronal morphology through APP, and promote the repair of neurons by promoting APP expression after cerebral ischemia.

Paraoxonase 2 protects against oxygen-glucose deprivation/reoxygenation-induced neuronal injury by enhancing Nrf2 activation via GSK-3β modulation

Paraoxonase 2 (PON2) is a powerful antioxidant that mediates cell survival under oxidative stress; however, its protection neurons against cerebral ischemia-reperfusion injury-induced oxidative stress remains unclear. This study aimed to determine the precise regulating role of PON2 in neuronal survival under oxidative stress. An in vitro model of cerebral ischemia-reperfusion injury was used to assess the effect of PON2 on oxidative stress induced by oxygen-glucose deprivation/reoxygenation (OGD/R). Results showed that PON2 expression in neurons was decreased due to OGD/R exposure. A series of functional experiments revealed that upregulated PON2 improved OGD/R-impaired viability and attenuated OGD/R-induced increases in apoptosis and reactive oxygen species in neurons. Decreased PON2 expression enhanced neuronal sensitivity to OGD/R-induced injury. Overexpressed PON2 markedly enhanced the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) in the nucleus and increased the levels of Nrf2-mediated transcriptional activity. Furthermore, PON2 enhanced the Nrf2 activation by modulating glycogen synthase kinase-3β (GSK-3β). Inhibition of GSK-3β substantially abrogated the PON2 knockdown-mediated suppression of Nrf2 activity. Notably, Nrf2 inhibition partially reversed the neuroprotective effects of PON2 overexpression in OGD/R-exposed neurons. These findings indicate that PON2 alleviates OGD/R-induced apoptosis and oxidative stress in neurons by potentiating Nrf2 activation via GSK-3β modulation. This study highlights the potential neuroprotective function of PON2 against cerebral ischemia-reperfusion injury.

Protective Effects of Astragalus Membranaceus and Ligustrazine on Rat Brain Microvascular Endothelial Cell Injury after Oxygen-Glucose Deprivation/ Reoxygenation by Suppressing the PKCδ/MARCKS Pathway

AIM AND OBJECTIVE

Cell death is a main pathological change in brain ischemia. Astragalus membranaceus (Ast) and ligustrazine (Lig), as traditional Chinese herbs, have a protective effect against ischemia-reperfusion injury. We aim to find whether the underlying protective mechanism of Astragalus membranaceus and ligustrazine against Oxygen-glucose deprivation/reoxygenation (OGD/R) -induced injury in RBMECs is related to PKCδ/MARCKS pathway.

MATERIALS AND METHODS

OGD/R preconditioning was instituted in rat brain microvascular endothelial cells (RBMECs). The survival and apoptosis of RBMECs were detected by a Cell Counting Kit-8 and TUNEL staining; PKCδ/MARCKS and MMP9 expression were examined by immunofluorescence, western blot and quantitative real-time PCR.

RESULTS

OGD/R stimulation significantly increased RBMEC apoptosis, whereas Ast+Lig, Rottlerin or Ast+Lig+Rottlerin treatment evidently reduced cellular apoptosis and increased cell viability (P <0.05). Furthermore, Ast+Lig, Rottlerin or Ast+Lig+Rottlerin treatment significantly reduced mRNA expression levels of PKCδ/MARCKS and MMP9 (P <0.05), compared to OGD/R control group. Moreover, Ast+Lig, Rottlerin or Ast+Lig+Rottlerin treatment evidently reduced protein expression levels of PKCδ, MMP9, and MARCKS (P <0.05), compared to OGD/R control group, detected by western blotting or immunofluorescence.

CONCLUSION

The administration of Astragalus membranaceus and ligustrazine protected RBMECs against OGD/R-induced apoptosis. PKCδ/MARCKS and MMP9 expression were significantly increased after OGD/R stimulation, while Astragalus membranaceus and ligustrazine treatment evidently suppressed. Collectively, Astragalus membranaceus and ligustrazine play protective effects against OGD/R-induced injury in RBMECs through regulating PKCδ/MARCKS pathway to inhibit MMP9 activation.

Ginsenosides Rb1 and Rg1 Protect Primary Cultured Astrocytes against Oxygen-Glucose Deprivation/Reoxygenation-Induced Injury via Improving Mitochondrial Function

This study aimed to evaluate whether ginsenosides Rb1 (20-S-protopanaxadiol aglycon) and Rg1 (20-S-protopanaxatriol aglycon) have mitochondrial protective effects against oxygen-glucose deprivation/reoxygenation (OGD/R)-induced injury in primary mouse astrocytes and to explore the mechanisms involved. The OGD/R model was used to mimic the pathological process of cerebral ischemia-reperfusion in vitro. Astrocytes were treated with normal conditions, OGD/R, OGD/R plus Rb1, or OGD/R plus Rg1. Cell viability was measured to evaluate the cytotoxicity of Rb1 and Rg1. Intracellular reactive oxygen species (ROS) and catalase (CAT) were detected to evaluate oxidative stress. The mitochondrial DNA (mtDNA) copy number and mitochondrial membrane potential (MMP) were measured to evaluate mitochondrial function. The activities of the mitochondrial respiratory chain (MRC) complexes I–V and the level of cellular adenosine triphosphate (ATP) were measured to evaluate oxidative phosphorylation (OXPHOS) levels. Cell viability was significantly decreased in the OGD/R group compared to the control group. Rb1 or Rg1 administration significantly increased cell viability. Moreover, OGD/R caused a significant increase in ROS formation and, subsequently, it decreased the activity of CAT and the mtDNA copy number. At the same time, treatment with OGD/R depolarized the MMP in the astrocytes. Rb1 or Rg1 administration reduced ROS production, increased CAT activity, elevated the mtDNA content, and attenuated the MMP depolarization. In addition, Rb1 or Rg1 administration increased the activities of complexes I, II, III, and V and elevated the level of ATP, compared to those in the OGD/R groups. Rb1 and Rg1 have different chemical structures, but exert similar protective effects against astrocyte damage induced by OGD/R. The mechanism may be related to improved efficiency of mitochondrial oxidative phosphorylation and the reduction in ROS production in cultured astrocytes.

Sodium hydrosulfide attenuates cerebral ischemia/reperfusion injury by suppressing overactivated autophagy in rats

Ischemic stroke is a leading cause of death and disability worldwide, and autophagy may be involved in the pathological process of cerebral ischemia/reperfusion injury. Hydrogen sulfide (H₂S) is an endogenous gasotransmitter with protective effects against multiple diseases. Here, we tested the effect of H₂S on cerebral ischemia/reperfusion injury in rats. Sodium hydrosulfide (NaHS), an H₂S donor, improved neurological function and reduced the size of the infarcts induced by transient middle cerebral artery occlusion (MCAO) followed by reperfusion in rats. NaHS treatment reduced the lactate dehydrogenase (LDH) activity in the serum (a marker of cellular membrane integrity) and the expression of cleaved caspase-3 (a marker for apoptosis) in the brains of MCAO rats. We also found that autophagy was overactivated in the brains of MCAO rats, as indicated by an increased ratio of LC3 II to I, decreased expression of p62, and transmission electron microscope detection. NaHS treatment significantly inhibited the autophagic activity in the brains of MCAO rats. Furthermore, PC12 cells were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) to mimic MCAO in vitro. We found that NaHS treatment reduced cellular injury and suppressed overactivated autophagy induced by OGD/R in PC12 cells. An autophagy stimulator (rapamycin) eliminated the protective effect of NaHS against LDH release and caspase-3 activity induced by OGD/R in PC12 cells. An autophagy inhibitor (3-methyladenine, 3-MA) also reduced the cellular injury induced by OGD/R in PC12 cells. In conclusion, the results indicate that overactivated autophagy accelerates cellular injury after MCAO in rats and that exogenous H₂S attenuates cerebral ischemia/reperfusion injury via suppressing overactivated autophagy in rats.