Citrate-coated silver nanoparticles loaded with agomelatine provide neuronal therapy in acute cerebral ischemia/reperfusion of rats by inhibiting the oxidative stress, endoplasmic reticulum stress, and P2X7 receptor-mediated inflammasome

Cerebral ischemia and reperfusion are related to various situations like injuries after various traumas, oxidative stress, increased calcium ion, capillary hypoperfusion, microvascular hyperpermeability, leukocyte infiltration, and blood-brain barrier disruption. An antidepressant Agomelatine which is a melatonin receptor (MT1/MT2) agonist and serotonin receptor (5-HT2C) antagonist has been reported by studies to have antioxidant and anti-inflammatory effects. In our study, we aimed to detect the effects of citrate-coated silver nanoparticle-loaded agomelatine application on neurodegeneration, endoplasmic reticulum stress, autophagic and apoptotic cell death, inflammation, and P2X7R expression in the cerebral ischemia-reperfusion model to facilitate the passage of blood-brain barrier. Forty two Sprague-Dawley rats in total were divided into six equal groups (n:7) and applications were performed. Acute cerebral injury in the ischemia-reperfusion model was created 2 h after internal carotid artery ligation in rats and then at the 2nd hour of reperfusion citrate-coated silver nanoparticles loaded with Agomelatine were applied. Twenty four hours later, neurologic analysis on animals in experimental groups was performed, animals were decapitated and GSH, GPx, SOD, CAT, MDA, IL-1β, and TNF-α parameters were examined after taking blood and the cerebral tissue samples. As a result, it was determined that ischemia-reperfusion caused endoplasmic reticulum stress in the cerebral tissues and thus caused cellular injury.

Neuroprotective Effects of an N-Salicyloyl Tryptamine Derivative against Cerebral Ischemia/Reperfusion Injury

Cerebral ischemia/reperfusion (I/R) injury is a key reason for the poor prognosis of ischemic stroke. As only a few neuroprotective medications for cerebral I/R injury have been applied in the clinic, it is necessary to design a new therapeutic strategy to treat cerebral I/R injury. The N-salicyloyl tryptamine derivative LZWL02003, synthesized from melatonin and salicylic acid, exhibits a wide range of biological properties. In this study, we assessed the neuroprotective capabilities of LZWL02003 in vivo and in vitro and investigated its possible mechanisms. Oxygen-glucose deprivation/reoxygenation was utilized to create an in vitro model of cerebral I/R damage. Middle cerebral artery occlusion/reperfusion was employed to imitate cerebral I/R injury in vivo. Neuronal apoptosis, oxidative stress, mitochondrial dysfunction, and neuroinflammation are associated with the pathogenesis of cerebral I/R injury. Our findings demonstrated that LZWL02003 upregulated the expression of Bcl-2 and downregulated the expression of Bax, thus maintaining the homeostasis of Bcl-2/Bax proteins and preventing apoptosis. LZWL02003 also reduced oxidative stress by reducing malondialdehyde and reactive oxygen species levels, increasing the superoxide dismutase activity, and resolving mitochondrial malfunction. LZWL02003 can lower interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and IL-6 levels, which in turn suppress neuroinflammation. Activation of the nuclear factor-kappa B (NF-κB) pathway is involved in various pathophysiologies, including cerebral I/R injury. We discovered that LZWL02003 suppressed the phosphorylation activation of NF-κB pathway-related proteins and decreased the nuclear translocation of NF-κB p65 subunits. Taken together, our results suggest that LZWL02003 is a neuroprotective drug with pleiotropic effects and may be a candidate for treating cerebral I/R injury.

Asialo-rhuEPO as a Potential Neuroprotectant for Ischemic Stroke Treatment

Neuroprotective drugs to protect the brain against cerebral ischemia and reperfusion (I/R) injury are urgently needed. Mammalian cell-produced recombinant human erythropoietin (rhuEPOM) has been demonstrated to have excellent neuroprotective functions in preclinical studies, but its neuroprotective properties could not be consistently translated in clinical trials. The clinical failure of rhuEPOM was thought to be mainly due to its erythropoietic activity-associated side effects. To exploit its tissue-protective property, various EPO derivatives with tissue-protective function only have been developed. Among them, asialo-rhuEPO, lacking terminal sialic acid residues, was shown to be neuroprotective but non-erythropoietic. Asialo-rhuEPO can be prepared by enzymatic removal of sialic acid residues from rhuEPOM (asialo-rhuEPOE) or by expressing human EPO gene in glycoengineered transgenic plants (asialo-rhuEPOP). Both types of asialo-rhuEPO, like rhuEPOM, displayed excellent neuroprotective effects by regulating multiple cellular pathways in cerebral I/R animal models. In this review, we describe the structure and properties of EPO and asialo-rhuEPO, summarize the progress on neuroprotective studies of asialo-rhuEPO and rhuEPOM, discuss potential reasons for the clinical failure of rhuEPOM with acute ischemic stroke patients, and advocate future studies needed to develop asialo-rhuEPO as a multimodal neuroprotectant for ischemic stroke treatment.

14,15-EET Reduced Brain Injury from Cerebral Ischemia and Reperfusion via Suppressing Neuronal Parthanatos

To investigate the effect of 14,15-EET on the parthanatos in neurons induced by cerebral ischemia and reperfusion, middle cerebral artery occlusion and reperfusion (MCAO/R) and oxygen glucose deprivation/reoxygenation (OGD/R) were used to simulate cerebral ischemia reperfusion in vivo and in vitro, respectively. TTC staining and the Tunel method were used to detect cerebral infarct volume and neuronal apoptosis. Western blot and immunofluorescence were used to detect poly (ADP-ribose) polymerase-1 (PARP-1) activation and AIF nuclear translocation. The production of reactive oxygen species (ROS) and the expression of antioxidant genes were detected by Mito SOX, DCFH-DA and qPCR methods. MCAO/R increased cerebral infarct volume and neuronal apoptosis in mice, while 14,15-EET pretreatment increased cerebral infarct volume and neuronal apoptosis. OGD/R induced reactive oxygen species generation, PARP-1 cleavage, and AIF nuclear translocation in cortical neurons. 14,15-EET pretreatment could enhance the antioxidant gene expression of glutathione peroxidase (GSH-Px), heme oxygenase-1 (HO-1) and superoxide dismutase (SOD) in cortical neurons after ischemia and reperfusion. 14,15-EET inhibits the neuronal parthanatos induced by MCAO/R through upregulation of the expression of antioxidant genes and by reducing the generation of reactive oxygen species. This study advances the EET neuroprotection theory and provides a scientific basis for targeted clinical drugs that reduce neuronal parthanatos following cerebral ischemia and reperfusion.

Transient cerebral ischemia/reperfusion-induced acute lung injury in rats associated with protein kinase C alpha expression

OBJECTIVE

The pathogenesis and development timing of acute lung injury (ALI) following cerebral ischemia/reperfusion (I/R) are not fully understood. In this study, the development timing of ALI induced by transient global cerebral I/R as well as the underlying mechanisms of action were investigated.

METHODS

A cerebral I/R-induced ALI model in Wistar rats was established by electrocoagulation of bilateral vertebral arteries combined with ligation of the transient bilateral common carotid arteries. Rats were randomly divided into control and cerebral I/R groups. The latter was subdivided into 3 h, 24 h, 48 h and 72 h post reperfusion. Lung injury was assessed by histological examination. The mRNA and protein expression of protein kinase C alpha (PKCα) were determined using qRT-PCR and immunofluorescence analysis, respectively.

RESULTS

Lung histological injury could be detected as early as 3 h after global cerebral I/R, and was significant between groups at 48 h and 72 h. Compared with the control group, mRNA expression of PKCα in the lung was enhanced in rats in the cerebral I/R groups (P<0.001), and the highest expression was observed at 48 h (P<0.001). The intensity of PKCα reactivity gradually increased starting at 3 h, and peaked at 72 h after cerebral I/R (P<0.05).

CONCLUSIONS

The lung is very susceptible to transient global cerebral I/R injury in vivo. Lung histological injury occurred within hours of cerebral I/R induction and aggregated in a very short period after cerebral I/R. Moreover, PKCα expression was implicated in the pathogenesis of cerebral I/R-induced ALI.

Lycium Barbarum Polysaccharides Decrease Hyperglycemia-Aggravated Ischemic Brain Injury through Maintaining Mitochondrial Fission and Fusion Balance

Although it has been reported that polysaccharides found in Lycium barbarum possess neuroprotective effects, little is known of their ability to ameliorate hyperglycemia-aggravated ischemia/reperfusion brain injury. In this study, normoglycemic (NG) and hyperglycemic (HG) rats were compared after 30 minutes of middle cerebral artery occlusion (MCAO), followed by 24 or 27 hours of reperfusion, with HG rats pretreated with lyceum barbarum polysaccharides (LBP) or insulin. In each group, the neurological deficit, infarct volume, pathohistology, and expression of proteins, Opa1 and Drp1, were assessed to determine the efficacy of LBP in alleviating hyperglycemia-aggravated ischemia/reperfusion brain injury. Our results show that, compared to the NG group, the HG group had increases in neurological deficits, infarct volume, and evidence of neuronal pyknosis at 24- and/or 72-h of reperfusion (P<0.05) and that pre-treatment with LBP decreased these effects (P<0.05). In addition, immunohistochemistry revealed an increase of Drp1 and a decrease of Opa1 positive neurons in the HG group after 24 and 72 hours of reperfusion when compared to the NG group. LBP treatment prevented the HG-induced alterations in Drp-1 and Opa1 expression. Western blots further confirmed these findings showing that HG caused an increase in phospho-Drp1 and a decrease in Opa1 which were subsequently reversed by LBP addition. These results suggest that hyperglycemia-aggravated ischemic brain damage is associated with an alteration of mitochondrial dynamics and that pre-treatment with LBP ameliorates the hyperglycemia-enhanced ischemic brain damage through maintaining mitochondrial dynamic balance.

Neuroprotective effects of Aceglutamide on motor function in a rat model of cerebral ischemia and reperfusion

PURPOSE

To investigate the effect and underlying mechanism of Aceglutamide on motor dysfunction in rats after cerebral ischemia-reperfusion.

METHODS

Adult male Sprague-Dawley rats were subjected to 2 h transient middle cerebral artery occlusion (MCAO). Aceglutamide or vehicle was intraperitoneally given to rats at 24 h after reperfusion and lasted for 14 days. Subsequently functional recovery was assessed and number of tyrosine hydroxylase (TH)-positive neurons in substantia nigra (SN) was analyzed. Tumor necrosis factor receptor-associated factor 1(TRAF1), P-Akt and Bcl-2/Bax were determined in mesencephalic tissue by Western blot method. PC12 cells and primary cultured mesencephalic neurons were employed to further investigate the mechanism of Aceglutamide.

RESULTS

Aceglutamide treatment improved behavioral functions, reduced the infarction volume, and elevated the number of TH-positive neurons in the SN. Moreover, Aceglutamide significantly attenuated neuronal apoptosis in the SN. Meanwhile Aceglutamide treatment significantly inhibited the expression of TRAF1 and up-regulated the expression of P-Akt and Bcl-2/Bax ratio both in vitro and in vivo.

CONCLUSIONS

Aceglutamide ameliorated motor dysfunction and delayed neuronal death in the SN after ischemia, which involved the inhibition of pro-apoptotic factor TRAF1 and activation of Akt/Bcl-2 signaling pathway. These data provided experimental information for applying Aceglutamide to ischemic stroke treatment.

Neuroprotective Effects of Inhibiting Fyn S-Nitrosylation on Cerebral Ischemia/Reperfusion-Induced Damage to CA1 Hippocampal Neurons

Nitric oxide (NO) can regulate signaling pathways via S-nitrosylation. Fyn can be post-translationally modified in many biological processes. In the present study, using a rat four-vessel-occlusion ischemic model, we aimed to assess whether Fyn could be S-nitrosylated and to evaluate the effects of Fyn S-nitrosylation on brain damage. In vitro, Fyn could be S-nitrosylated by S-nitrosoglutathione (GSNO, an exogenous NO donor), and in vivo, endogenous NO synthesized by NO synthases (NOS) could enhance Fyn S-nitrosylation. Application of GSNO, 7-nitroindazole (7-NI, an inhibitor of neuronal NOS) and hydrogen maleate (MK-801, the N-methyl-d-aspartate receptor (NMDAR) antagonist) could decrease the S-nitrosylation and phosphorylation of Fyn induced by cerebral ischemia/reperfusion (I/R). Cresyl violet staining validated that these compounds exerted neuroprotective effects against the cerebral I/R-induced damage to hippocampal CA1 neurons. Taken together, in this study, we demonstrated that Fyn can be S-nitrosylated both in vitro and in vivo and that inhibiting S-nitrosylation can exert neuroprotective effects against cerebral I/R injury, potentially via NMDAR-mediated mechanisms. These findings may lead to a new field of inquiry to investigate the underlying pathogenesis of stroke and the development of novel treatment strategies.

Neuroprotective effects of salidroside on focal cerebral ischemia/reperfusion injury involve the nuclear erythroid 2-related factor 2 pathway

Salidroside, the main active ingredient extracted from Rhodiola crenulata, has been shown to be neuroprotective in ischemic cerebral injury, but the underlying mechanism for this neuroprotection is poorly understood. In the current study, the neuroprotective effect of salidroside on cerebral ischemia-induced oxidative stress and the role of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway was investigated in a rat model of middle cerebral artery occlusion. Salidroside (30 mg/kg) reduced infarct size, improved neurological function and histological changes, increased activity of superoxide dismutase and glutathione-S-transferase, and reduced malon-dialdehyde levels after cerebral ischemia and reperfusion. Furthermore, salidroside apparently increased Nrf2 and heme oxygenase-1 expression. These results suggest that salidroside exerts its neuroprotective effect against cerebral ischemia through anti-oxidant mechanisms and that activation of the Nrf2 pathway is involved. The Nrf2/antioxidant response element pathway may become a new therapeutic target for the treatment of ischemic stroke.

Expression of netrin-1 and its receptors, deleted in colorectal cancer and uncoordinated locomotion-5 homolog B, in rat brain following focal cerebral ischemia reperfusion injury

Netrin-1 is currently one of the most highly studied axon guidance factors. Netrin-1 is widely expressed in the embryonic central nervous system, and together with the deleted in colorectal cancer and uncoordinated locomotion-5 homolog B receptors, netrin-1 plays a guiding role in the construction of neural conduction pathways and the directional migration of neuronal cells. In this study, we established a rat middle cerebral artery ischemia reperfusion model using the intraluminal thread technique. Immunofluorescence microscopy showed that the expression of netrin-1 and deleted in colorectal cancer in the ischemic penumbra was upregulated at 1 day after reperfusion, reached a peak at 14 days, and decreased at 21 days. There was no obvious change in the expression of uncoordinated locomotion-5 homolog B during this time period. Double immunofluorescence labeling revealed that netrin-1 was expressed in neuronal cells and around small vessels, but not in astrocytes and microglia, while deleted in colorectal cancer was localized in the cell membranes and protrusions of neurons and astrocytes. Our experimental findings indicate that netrin-1 may be involved in post-ischemic repair and neuronal protection via deleted in colorectal cancer receptors.