PD98059 Protects Brain against Cells Death Resulting from ROS/ERK Activation in a Cardiac Arrest Rat Model

S-9-PAHSA's neuroprotective effect mediated by CAIII suppresses apoptosis and oxidative stress in a mouse model of type 2 diabetes

BACKGROUND

With the rapidly increasing prevalence of metabolic diseases such as type 2 diabetes mellitus (T2DM), neuronal complications associated with these diseases have resulted in significant burdens on healthcare systems. Meanwhile, effective therapies have remained insufficient. A novel fatty acid called S-9-PAHSA has been reported to provide metabolic benefits in T2DM by regulating glucose metabolism. However, whether S-9-PAHSA has a neuroprotective effect in mouse models of T2DM remains unclear.

METHODS

This in vivo study in mice fed a high-fat diet (HFD) for 5 months used fasting blood glucose, glucose tolerance, and insulin tolerance tests to examine the effect of S-9-PAHSA on glucose metabolism. The Morris water maze test was also used to assess the impact of S-9-PAHSA on cognition in the mice, while the neuroprotective effect of S-9-PAHSA was evaluated by measuring the expression of proteins related to apoptosis and oxidative stress. In addition, an in vitro study in PC12 cells assessed apoptosis, oxidative stress, and mitochondrial membrane potential with or without CAIII knockdown to determine the role of CAIII in the neuroprotective effect of S-9-PAHSA.

RESULTS

S-9-PAHSA reduced fasting blood glucose levels significantly, increased insulin sensitivity in the HFD mice and also suppressed apoptosis and oxidative stress in the cortex of the mice and PC12 cells in a diabetic setting. By suppressing oxidative stress and apoptosis, S-9-PAHSA protected both neuronal cells and microvascular endothelial cells in in vivo and in vitro diabetic environments. Interestingly, this protective effect of S-9-PAHSA was reduced significantly when CAIII was knocked down in the PC12 cells, suggesting that CAIII has a major role in the neuroprotective effect of S-9-PAHSA. However, overexpression of CAIII did not significantly enhance the protective effect of S-9-PAHSA.

CONCLUSION

S-9-PAHSA mediated by CAIII has the potential to exert a neuroprotective effect by suppressing apoptosis and oxidative stress in neuronal cells exposed to diabetic conditions. Furthermore, S-9-PAHSA has the capability to reduce fasting blood glucose and LDL levels and enhance insulin sensitivity in mice fed with HFD.

Flavonoids in Combination with Stem Cells for the Treatment of Neurological Disorders

Neurological disorders are the leading cause of disability and the world's second leading cause of death. Despite the availability of significant knowledge to reduce the burden of some neurological disorders, various studies are exploring more effective treatment options. While the human body can repair and regenerate damaged tissue through stem cell recruitment, nerve regeneration in case of injury is minimal due to the restriction on the location of nerve stem cells. Recently, different types of stem cells extracted from various tissues have been used in combination with natural stimuli to treat neurologic disorders in neuronal tissue engineering. Flavonoids are polyphenolic compounds that can induce the differentiation of stem cells into neurons and stimulate stem cell proliferation, migration, and survival. They can also increase the secretion of nutritional factors from stem cells. In addition to the effects that flavonoids can have on stem cells, they can also have beneficial therapeutic effects on the nervous system alone. Therefore, the simultaneous use of these compounds and stem cells can multiply the therapeutic effect. In this review, we first introduce flavonoid compounds and provide background information on stem cells. We then compile available reports on the effects of flavonoids on stem cells for the treatment of neurological disorders.

The small molecule Erk1/2 signaling pathway inhibitor PD98059 improves DNA repair in an experimental autoimmune encephalomyelitis SJL/J mouse model of multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disorder in which the myelin sheath covering the central nervous system axons is damaged or lost, disrupting action potential conduction and leading to various neurological complications. The pathogenesis of MS remains unclear, and no effective therapies are currently available. MS is triggered by environmental factors in genetically susceptible individuals. DNA damage and DNA repair failure have been proposed as MS genetic risk factors; however, inconsistent evidence has been found in multiple studies. Therefore, more investigations are needed to ascertain whether DNA damage/repair is altered in this disorder. In this context, therapies that prevent DNA damage or enhance DNA repair could be effective strategies for MS treatment. The overactivation of the extracellular-signal-related kinase 1 and 2 (Erk1/2) pathway can lead to DNA damage and has been linked to MS pathogenesis. In our study, we observed substantially elevated oxidative DNA damage and slower DNA repair rates in an experimentally autoimmune encephalomyelitis animal model of MS (EAE). Moreover, statistical decreases in oxidative DNA strand breaks and faster repair rates were observed in EAE animals injected with the Erk1/2 inhibitor PD98059 (PD). Moreover, the expression of several genes associated with DNA strand breaks and repair changed in EAE mice at both the mRNA and protein levels, as revealed by the RT² Profiler PCR array and verified by RT-PCR and protein analyses. The treatment with PD mitigated these changes and improved DNA repair gene expression. Our results demonstrate clear associations between Erk1/2 activation, DNA damage/repair, and MS pathology, and further suggest that PD therapy may be a promising adjuvant therapeutic strategy.

Effects of caffeic acid phenethyl ester use and inhibition of p42/44 MAP kinase signal pathway on caveolin 1 gene expression and antioxidant system in chronic renal failure model of rats

Effects of Caffeic acid phenethyl ester (CAPE) and/or PD98059 (PD) on the gene expression of Caveolin-1 (CAV1) and reduced glutathione (GSH), malondialdehyde (MDA), copper-zinc superoxide dismutase (CuZn-SOD), and catalase (CAT) enzyme activities were investigated in an experimental chronic renal failure model in rats. Eighty Wistar rats were divided into eight groups for a 28-day study: Control, CsA (Cyclosporine A), CsA-V (CsA solvent), CsA + PD (CsA + PD98059), CsA + PD + CAPE, CsA + CAPE, CAPE-V (CAPE solvent), and PD-V (PD98059 solvent). Serum blood urea nitrogen and creatinine levels, as well as histopathological findings indicated the development of renal failure in the CsA group. Kidney GSH levels decreased while MDA levels, CuZn-SOD, and CAT activities increased significantly in the CsA group compared to control indicating oxidative stress. CAV1 gene expression significantly decreased in the CsA group compared to the control. PD98059 and CAPE applications made positive improvements in the levels of the parameters investigated. PD98059 and CAPE applications in CsA given animals increased GSH and CAV1 gene expressions and decreased CuZn-SOD and CAT levels compared to the CsA group. In conclusion, it was shown that PD98059 and CAPE could attenuate the effects of chronic renal failure, and CAV1 is suggested as a therapeutic target and the inhibition of the p44/42 MAPK pathway may be a new approach for the treatment of renal degenerations.

Changes of antioxidant enzymes in the kidney after cardiac arrest in the rat model

Globally, cardiac arrest (CA) is a leading cause of death and disability. Asphyxial CA (ACA)-induced kidney damage is a crucial factor in reducing the survival rate. The purpose of this study was to investigate the role of antioxidant enzymes in histopathological renal damage in an ACA rat model at different time points. A total of 88 rats were divided into five groups and exposed to ACA except for the sham group. To evaluate glomerular function and oxidative stress, serum levels of blood urea nitrogen (BUN) and creatinine (Crtn) and malondialdehyde (MDA) levels in renal tissues were measured. To determine histopathological damage, hematoxylin and eosin staining, periodic acid-Schiff staining, and Masson's trichrome staining were performed. Expression levels of antioxidant enzymes including superoxide dismutase-1 (SOD-1), superoxide dismutase-2 (SOD-2), catalase (CAT), and glutathione peroxidase (GPx) were measured by immunohistochemistry (IHC). Survival rate of the experimental rats was reduced to 80% at 6 h, 55% at 12 h, 42.9% at 1 day, and 33% at 2 days after return of spontaneous circulation. Levels of BUN, Crtn, and MDA started to increase significantly in the early period of CA induction. Renal histopathological damage increased markedly from 6 h until two days post-CA. Additionally, expression levels of antioxidant enzymes were significantly decreased at 6 h, 12 h, 1 day, and 2 days after CA. CA-induced oxidative stress and decreased levels of antioxidant enzymes (SOD-1, SOD-2, CAT, GPx) from 6 h to two days could be possible mediators of severe renal tissue damage and increased mortality rate.

PD98059 protects SH-SY5Y cells against oxidative stress in oxygen-glucose deprivation/reperfusion

Mitochondria play a key role in the cerebral ischemia-reperfusion injury. Although the extracellular signal-regulated kinase 1/2 inhibitor PD98059 (PD) is a selective and reversible flavonoid that can protect the mitochondria in a rat model of cardiac arrest/cardiopulmonary resuscitation, its role requires further confirmation. In this study, we investigated whether PD could maintain mitochondrial homeostasis and decrease reactive oxygen species (ROS) production in neuroblastoma (SH-SY5Y) cells exposed to oxygen-glucose deprivation/reperfusion (OGD/R). PD improved the mitochondrial morphology and function, reversed the increase in ROS production and cell apoptosis, and reduced total-superoxide dismutase and Mn-superoxide dismutase activities induced by OGD/R. PD decreases ROS production and improves mitochondrial morphology and function, protecting SH-SY5Y cells against OGD/R-induced injury.

Inhibition of extracellular signal-regulated kinase downregulates endoplasmic reticulum stress-induced apoptosis and decreases brain injury in a cardiac arrest rat model

Cerebral ischemia-reperfusion injury (CIRI) is the predominant cause of neurological disability after cardiac arrest/cardiopulmonary resuscitation (CA/CPR). The endoplasmic reticulum stress (ERs)-induced apoptosis plays an important role in neuronal survival/death in CIRI. Our previous studies reported that the extracellular signal-regulated kinase (ERK) inhibitor, PD98059, alleviates CIRI after CA/CPR. Whether ERs-induced apoptosis is involved in the neuroprotection of PD98059 remains unknown. This study aims to investigate the effects of ERK inhibition by PD98059 on ERs-induced apoptosis after CIRI in the CA/CPR rat model. The baseline characteristics of male adult Sprague-Dawley (SD) rats in all groups were evaluated before CA/CPR. The SD rats that survived from CA/CPR were randomly divided into 3 groups (n=12/group): normal saline group (1 ml/kg), dimethylsulfoxide (DMSO, the solvent of PD98059, 1 ml/kg) group, PD98059 group (0.3 mg/kg). Another 12 SD rats were randomly selected as the Sham group. Twenty-four hours after resuscitation, neural injury was assessed by survival rate, neurological deficit scores (NDS) and Nissl staining; apoptosis of brain cells was detected using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining; mRNA expression and protein levels of ERs-related protein BIP, PERK, ATF4 and CHOP were checked with RT-PCR and Western Blot. The results showed that there were no significant differences in baseline characteristics before CA/CPR among all groups. PD98059 significantly improved survival rate and NDS, increased the Nissl bodies in neurons, reduced apoptosis, downregulated the mRNA transcription and expression levels of BIP, PERK, ATF4 and CHOP at 24 h after CA/CPR. Our results demonstrate that inhibition of ERK by PD98059 alleviates ERs-induced apoptosis via BIP-PERK-ATF4-CHOP signaling pathway and mitigates CIRI in the CA/CPR rat model.

Hydrogen therapy after resuscitation improves myocardial injury involving inhibition of autophagy in an asphyxial rat model of cardiac arrest

Hydrogen (H₂) therapy is a therapeutic strategy using molecular H₂. Due to its ability to regulate cell homeostasis, H₂ therapy has exhibited marked therapeutic effects on a number of oxidative stress-associated diseases. The present study investigated the effectiveness of H₂ therapy in protecting against myocardial injury in a rat model of asphyxial cardiac arrest and cardiopulmonary resuscitation. Rats underwent 10-min asphyxia-induced cardiac arrest (CA) and cardiopulmonary resuscitation (CPR), and were randomly divided into control and H₂ therapy groups. After resuscitation, the H₂ therapy group was administered room air mixed with 2% H₂ gas for respiration. During CA/CPR, the arterial pressure and heart rate were measured every minute. Survival rate, cardiac function, myocardial injury biomarkers creatine kinase-MB and cardiac troponin-T, and histopathological changes were evaluated to determine the protective effects of H₂ therapy in CA/CPR. Immunohistochemistry and western blot analysis were used to determine the expression levels of autophagy-associated proteins. In vitro, H9C2 cells were subjected to hypoxia/reoxygenation and H₂-rich medium was used in H₂ treatment groups. Western blotting and immunofluorescence were used to observe the expression levels of autophagy-associated proteins. Moreover, an adenovirus-monomeric red fluorescent protein-green fluorescent protein-LC3 construct was used to explore the dynamics of autophagy in the H9C2 cells. The results showed that H₂ therapy significantly improved post-resuscitation survival and cardiac function. H₂ therapy also improved mitochondrial mass and decreased autophagosome numbers in cardiomyocytes after resuscitation. The treatment inhibited autophagy activation, with lower expression levels of autophagy-associated proteins and decreased autophagosome formation in vivo and vitro. In conclusion, H₂ gas inhalation after return of spontaneous circulation improved cardiac function via the inhibition of autophagy.

Effect of therapeutic hypothermia against renal injury in a rat model of asphyxial cardiac arrest: Α focus on the survival rate, pathophysiology and antioxidant enzymes

Although multi-organ dysfunction is associated with the survival rate following cardiac arrest (CA), the majority of studies to date have focused on hearts and brains, and few studies have considered renal failure. The objective of the present study, therefore, was to examine the effects of therapeutic hypothermia on the survival rate, pathophysiology and antioxidant enzymes in rat kidneys following asphyxial CA. Rats were sacrificed one day following CA. The survival rate, which was estimated using Kaplan-Meier analysis, was 42.9% one day following CA. However, hypothermia, which was induced following CA, significantly increased the survival rate (71.4%). In normothermia rats with CA, the serum blood urea nitrogen level was significantly increased one day post-CA. In addition, the serum creatinine level was significantly increased one day post-CA. However, in CA rats exposed to hypothermia, the levels of urea nitrogen and creatinine significantly decreased following CA. Histochemical staining revealed a significant temporal increase in renal injury after the normothermia group was subjected to CA. However, renal injury was significantly decreased in the hypothermia group. Immunohistochemical analysis of the kidney revealed a significant decrease in antioxidant enzymes (copper-zinc superoxide dismutase, manganese superoxide dismutase, glutathione peroxidase and catalase) with time in the normothermia group. However, in the hypothermia group, these enzymes were significantly elevated following CA. Collectively, the results revealed that renal dysfunction following asphyxial CA was strongly associated with the early survival rate and therapeutic hypothermia reduced renal injury via effective antioxidant mechanisms.

Inhibition of PAR-2 Attenuates Neuroinflammation and Improves Short-Term Neurocognitive Functions Via ERK1/2 Signaling Following Asphyxia-Induced Cardiac Arrest in Rats

OBJECTIVE

Global cerebral ischemia-induced neuroinflammation causes neurofunctional impairment following cardiac arrest. Previous studies have demonstrated that the activation of protease-activated receptor-2 (PAR-2) contributes to neuroinflammation. In the present study, we aimed to determine the potential treatment effect of PAR-2 inhibition against neuroinflammation in the setting of asphyxial CA (ACA) in rats.

METHODS

A total of 116 adult, male Sprague-Dawley rats were randomly divided into Sham (n = 18) and ACA (n = 98) groups. Time course, short-term outcome, and mechanism studies were conducted. All drugs were delivered intranasally. The effect of PAR-2 inhibitor FSLLRY-NH2 on neurocognitive functions was assessed by neurologic deficit score, number of seizures, and T-maze test, while hippocampal neuronal degeneration was evaluated by Fluoro-Jade C staining after ACA. Western blotting was performed for the mechanism study at 24 h following ACA. Selective PAR-2 agonist (AC55541) and ERK1/2 inhibitor (PD98059) were used for intervention.

RESULTS

Inhibition of PAR-2 decreased neuroinflammation, reduced the number of degenerating hippocampal neurons and improved neurocognitive functions following ACA. PAR-2 activator alone exerted opposite effects to PAR-2 inhibitor. PAR-2 mediated the augmented brain levels of proinflammatory cytokines by promoting the phosphorylation of ERK1/2.

CONCLUSIONS

PAR-2 inhibition diminished neuroinflammation and thereby reduced hippocampal neuronal degeneration and neurocognitive impairment following ACA. This effect was at least partly mediated via the PAR-2/ERK1/2 signaling.

Pomelo peel oil alleviates cerebral NLRP3 inflammasome activation in a cardiopulmonary resuscitation rat model

The NLR family pyrin domain-containing 3 (NLRP3) inflammasome, which is composed of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC) and pro-caspase-1 protein complexes, is activated by the reactive oxygen species (ROS) that are associated with ischemia-reperfusion (I/R) and are involved in brain damage. Pomelo peel oil (PPO) exhibits antioxidant activity. However, it is unclear whether PPO is able to attenuate NLRP3 inflammasome-induced inflammation and pyroptosis. Healthy male Sprague-Dawley rats were subjected to 7 min of cardiac arrest via trans-esophageal electrical stimulation, followed by cardiopulmonary resuscitation (CPR). The rats were then treated with PPO prior to reperfusion for 24 h. Hematoxylin and eosin staining was used to evaluate brain tissue and cell damage. In the brain tissues, reactive oxygen species (ROS) were assayed, immunofluorescence was used to analyze the expression of NLRP3 and western blotting was performed to determine the expression levels of neuroenolase (NSE), NF-κB, interleukin-1β (IL-1β), gasdermin D (GSDMD) and the NLRP3 inflammasome. Treatment of the rats with PPO significantly decreased the pathological damage of the brain tissue and reduced the expression of NSE, production of ROS and secretion of NF-κB, NLRP3, IL-1β and GSDMD. In conclusion, these results demonstrate the ability of PPO to protect the brain against I/R injury in rats after CPR by a mechanism involving inhibition of the inflammation and pyroptosis mediated by NLRP3 inflammasome activation.

The MAP kinase inhibitor PD98059 reduces chromosomal instability in the autoimmune encephalomyelitis SJL/J-mouse model of multiple sclerosis

Multiple sclerosis (MS), a disease in which the immune system attacks nerve cells, has been associated with both genetic and environmental risk factors. We observed increased micronucleus (MN) formation in SJL/J mouse experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Most of these MN were due to chromosomal loss. Increased activation of MAP kinases, which leads to disruption of the mitotic spindle and improper segregation of chromosomes, is associated with MS. MAP kinase inhibitors, such as PD98059, may therefore be beneficial for MS. In the EAE model, PD98059 treatment reduced adverse effects, including MN formation, lipid peroxidation, and GSH oxidation. Interventions that mitigate chromosomal instability may have therapeutic value in MS.

A novel biscoumarin derivative dephosphorylates ERK and alleviates apoptosis induced by mitochondrial oxidative damage in ischemic stroke mice

AIM

We previously reported the protective effects of biscoumarin derivatives against oxidative stress, but effects of the derivative on mitochondrial oxidative damage induced apoptosis in ischemic stroke remains unknown.

METHODS

Primary neurons were subjected to oxygen and glucose deprivation (OGD) for the in vitro simulation of ischemic stroke, and an ischemic stroke model was established in mice by operation of middle cerebral artery occlusion (MCAO).

RESULTS

The results indicated that the nontoxic concentration range of biscoumarin derivative Comp. B in neurons was from 0 to 30 μg/ml and the optimal protective concentration was 20 μg/ml. Treatment with Comp. B increased the cell survival rate and alleviated mitochondrial oxidative damage and apoptosis in OGD-treated neurons. Comp. B reduced the ratio of Bax/Bcl-2, inhibited the phosphorylation of ERK, and thus alleviated apoptosis in OGD-treated neurons. Further research demonstrated that the dephosphorylation effect on ERK of Comp. B is a key factor in alleviating apoptosis in neurons induced by OGD injury. Furthermore, Comp. B reduced the infarct volume, improved neurobehavioural score, and alleviated morphological changes and brain apoptosis in MCAO mice.

CONCLUSION

The novel biscoumarin derivative Comp. B alleviates mitochondrial oxidative damage and apoptosis in ischemic stroke mice. These findings might provide new insights that will aid in elucidating the effect of biscoumarin derivative against cerebral ischemic reperfusion injury and support the new development of Comp. B as a potential treatment for ischemic stroke.

Heat shock protein 90 inhibitor AUY922 attenuates platelet-derived growth factor-BB-induced migration and proliferation of vascular smooth muscle cells

Luminespib (AUY922), a heat shock proteins 90 inhibitor, has anti-neoplastic and antitumor effects. However, it is not clear whether AUY922 affects events in vascular diseases. We investigated the effects of AUY922 on the platelet-derived growth factor (PDGF)-BB-stimulated proliferation and migration of vascular smooth muscle cells (VSMC). VSMC viability was detected using the XTT (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) reagent. To detect the attenuating effects of AUY922 on PDGF-BB-induced VSMCs migration in vitro, we performed the Boyden chamber and scratch wound healing assays. To identify AUY922-mediated changes in the signaling pathway, the phosphorylation of protein kinase B (Akt) and extracellular signal-regulated kinase (ERK) 1/2 was analyzed by immunoblotting. The inhibitory effects of AUY922 on migration and proliferation ex vivo were tested using an aortic ring assay. AUY922 was not cytotoxic at concentrations up to 5 nM. PDGF-BB-induced VSMC proliferation, migration, and sprout outgrowth were significantly decreased by AUY922 in a dose-dependent manner. AUY922 significantly reduced the PDGF-BB-stimulated phosphorylation of Akt and ERK1/2. Furthermore, PD98059 (a selective ERK1/2 inhibitor) and LY294002 (a selective Akt inhibitor) decreased VSMC migration and proliferation by inhibiting phosphorylation of Akt and ERK1/2. Greater attenuation of PDGF-BB-induced cell viability and migration was observed upon treatment with PD98059 or LY294002 in combination with AUY922. AUY922 showed anti-proliferation and anti-migration effects towards PDGF-BBinduced VSMCs by regulating the phosphorylation of ERK1/2 and Akt. Thus, AUY922 is a candidate for the treatment of atherosclerosis and restenosis.

PD98059 Protects Cerebral Cortex Mitochondrial Structure and Function at 48 h Post-Resuscitation in a Rat Model of Cardiac Arrest

Background

Mitochondria play a critical role as effectors and targets of brain injury in the post-resuscitation period. Although we found previously that the extracellular signal-regulated kinase (ERK)1/2 inhibitor PD98059 (PD) protects the brain against mitochondrial-mediated cell death at 24 h post-resuscitation in rats subjected to cardiac arrest/cardiopulmonary resuscitation (CA/CPR), it is not clear whether PD also exerts mitochondrial protective effect for a lasting time. Therefore, we examined the effect of PD on brain mitochondria at 48 h post-resuscitation to evaluate the time-effect of PD in the current study.

Methods

Experimental rats were divided randomly into 5 groups: Sham, CA, dimethylsulfoxide (DMSO), 0.15mg/kg PD and 0.3mg/kg PD. Rats except for sham group were subjected to CA for 6 min followed by CPR. We detected survival rates and neurologic deficit scores, cerebral cortex mitochondrial function by evaluating adenosine triphosphate (ATP) levels, mitochondrial permeability transition pore (MPTP) opening, and the expression of mitofusin2 (Mfn2) and observing the ultrastructure by electron microscopy at 48 h post-resuscitation in a 6-min CA rat model.

Results

PD improved survival rates and neurologic deficit scores, alleviated cerebral cortex mitochondrial damage by reducing MPTP opening and increasing Mfn2 production at 48 h post-resuscitation in a 6-min CA rat model.

Conclusion

A single dose of PD improved 48 h post-resuscitation outcome and mitochondrial function, indicating the potential of the use of ERK inhibitors for the treatment of brain injury resulting from CA in the future.

Green Tea Polyphenols Modulated Cerebral SOD Expression and Endoplasmic Reticulum Stress in Cardiac Arrest/Cardiopulmonary Resuscitation Rats

BACKGROUND

Reducing cerebral ischemia-reperfusion injury is crucial for improving survival and neurologic outcomes after cardiac arrest/cardiopulmonary resuscitation (CA/CPR). The purpose of this study is to investigate the neuroprotective effects of green tea polyphenols (GTPs) concern with the modulation of endogenous antioxidation and endoplasmic reticulum stress.

METHODS

After subjecting to CA/CPR, rats were randomized into the saline group (NS, n = 40) and the GTPs group (GTPs, n = 40) and the GTPs group (GTPs, n = 40) and the GTPs group (GTPs.

RESULTS

Comparing with that in NS group, GTPs increased the expression of SOD1 and SOD2 at 12 h, 24 h, 48 h, 72 h, and the expression of GRP78 at 24 h and 48 h (p < 0.05) butdecreased caspase-12, CHOP, caspase-3 level, and apoptotic number of neurons (p < 0.05) butdecreased caspase-12, CHOP, caspase-3 level, and apoptotic number of neurons (.

CONCLUSION

GTPs exert neuroprotective effects via mechanisms that may be related to the enhancement of endogenous antioxidant capacity and inhibition of endoplasmic reticulum stress in CA/CPR rat models.

Edaravone Ameliorates Renal Warm Ischemia-Reperfusion Injury by Downregulating Endoplasmic Reticulum Stress in a Rat Resuscitation Model

Background

This study was conducted to explore whether the effect of edaravone (5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol3-one, EDR) can ameliorate renal warm ischemia-reperfusion injury (IRI) by modulating endoplasmic reticulum stress (ERS) and its downstream effector after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) in a rat model.

Methods

The rats (n=10) experienced anaesthesia and intubation followed by no CA inducement were defined as the Sham group. Transoesophageal alternating current stimulation was employed to establish 8 min of CA followed by conventional CPR for a resuscitation model. The rats with successful restoration of spontaneous circulation (ROSC) randomly received EDR (3 mg/kg, EDR group, n=10) or equal volume normal saline solution (the NS group, n=10). At 24 hr after ROSC, serum creatinine (SCR), blood urea nitrogen (BUN) levels, and cystatin-C (Cys-C) levels were determined and the protein level of glucose-regulated protein (GRP78), C/EBP homologous protein (CHOP), extracellular signal-regulated kinase (ERK), phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2), Bax/Bcl-2, and caspase-3 were detected by Western blot method.

Results

At 24 hrs after ROSC, SCR, BUN and Cys-C were obviously increased and the proteins expression, including GRP78, CHOP and p-ERK1/2, cleaved-caspase 3 Bax/Bcl-2 ratio, were significantly upregulated in the NS group compared with the Sham group (p<0.05). The remarkable improvement of these adverse outcomes was observed in the EDR group (p<0.05).

Conclusion

In conclusion, we found that EDR ameliorates renal warm IRI by downregulating ERS and its downstream effectors in a rat AKI model evoked by CA/CPR. These data may provide evidence for future therapeutic benefits of EDR against AKI induced by CA/CPR.

The protective effect of inosine against rotenone-induced Parkinson's disease in mice; role of oxido-nitrosative stress, ERK phosphorylation, and A2AR expression

Parkinson's disease (PD) is a severe disabling syndrome in which neuroinflammation and various signaling pathways are believed to mediate dopaminergic neurodegeneration. Here, the possible disease-modifying effects of the purine nucleoside inosine were examined against rotenone-induced PD. Mice were allocated into six groups, namely, a normal control group receiving dimethylsulfoxide, a PD control group receiving rotenone, a standard treatment group receiving L-dopa/carbidopa together with rotenone, and three treatment groups receiving inosine in low, medium, and high doses together with rotenone. At the end of the experimental protocol, three behavioral tests were performed to assess PD motor manifestations, namely, wire-hanging test, wood-walking test, and stair test. After performing the behavioral study, mice striata were isolated for the colorimetric assay of hypoxanthine, the enzyme-linked immunosorbent assay of dopamine, tumor necrosis factor-α, interleukin-6 and nitrite, the Western blot estimation of total and phosphorylated extracellular signal-regulated kinase (tERK and pERK), the polymerase chain reaction estimation of adenosine A_2A receptor (A2AR) expression, as well as the histopathological examination of substantia nigra and striatal tissue. Inosine protected against PD progression in a dose-dependent manner, with the effect comparable to the standard treatment L-dopa/carbidopa, evidenced by behavioral, biochemical, and histologic findings. The beneficial antiparkinsonian effect of inosine could be attributed to the ability of the drug to ameliorate neuroinflammation and oxido-nitrosative stress, together with suppression of ERK phosphorylation and down-regulation of A2AR expression. Inosine could therefore be considered as a disease-modifying agent against PD, but further studies are claimed to confirm such effects clinically.

The incidence of acute kidney injury following cardiac arrest and cardiopulmonary resuscitation in a rat model

OBJECTIVE

In the current study, we investigated the incidence of acute kidney injury (AKI) induced by cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) and whether such an AKI can recover spontaneously in rats.

METHODS

We used transesophageal alternating current stimulation to establish 7 min of CA rat model followed by conventional CPR. The experimental rats were randomly divided into three groups (n = 20 per group) according to the different time points after restoration spontaneous circulation (ROSC): the ROSC 24 h, ROSC 48 h, and ROSC 72 h group. The diagnosis of rat AKI refers to the 2012 KDIGO adult AKI diagnostic criteria. The severity of AKI quantified by the serum creatinine (SCR), blood urea nitrogen (BUN) levels and histological features of renal tissue.

RESULTS

The incidence rates of AKI in ROSC 24 h, ROSC 48 h, and ROSC 72 h group were 65%, 45%, and 42.9%. Moreover, the values of SCR and BUN were highest at ROSC 24 h, and then gradually decreased with the time of ROSC. The histological changes of the renal tissues such as glomerular collapse, renal tubular cell swelling, and inflammatory cell infiltration had also observed.

CONCLUSION

The incidence of AKI in rats was high after suffering from CA and CPR, but renal function improved with the prolongation of ROSC time, indicating the ability of the kidney to self-repair.

Cerebral protection of epigallocatechin gallate (EGCG) via preservation of mitochondrial function and ERK inhibition in a rat resuscitation model

Background

Various and opposite roles of epigallocatechin gallate (EGCG) have been reported in different studies. We aimed to investigate how EGCG affects the cerebral injury in a cardiac arrest/cardiopulmonary resuscitation (CA/CPR) model of rat.

Methods

The rats which were subjected to CA/CPR randomly received low dose of EGCG (3 mg/kg, Low-EGCG group, n=16), high dose of EGCG (9 mg/kg, High-EGCG group, n=16) and equal volume of 0.9% saline solution (NS group, n=16) at the first minute after return of spontaneous circulation (ROSC). The rats underwent anesthesia and intubation were defined as Sham group (n=16). Twenty-four hours after ROSC, neural defect score (NDS), ROS fluorescence intensity, degree of mitochondrial permeability transition pore (mPTP) opening, ATP contents and mitochondrial ATP synthase expression were evaluated in the four groups. The expression of extracellular signal-regulated kinase (ERK) activity and cleaved-caspase 3 were also detected by Western blot.

Results

CA/CPR induced severe ischemia-reperfusion injury (IRI), resulted in mitochondrial dysfunction and upregulated phosphorylation of ERK. EGCG dose-dependently alleviated the IRI after CA/CPR, inhibited ERK activity and restored mitochondrial function and, as indicated by improved NDS, reduced ROS level, decreased mPTP opening, elevated ATP content, increased ATPase expression and downregulated cleaved-caspase 3 level.

Conclusion

EGCG alleviated global cerebral IRI by restoring mitochondrial dysfunction and ERK modulation in a rat CA/CPR model, which might make it a potential candidate agent against IRI after CA/CPR in the future. Further study is needed to determine whether higher dosage of EGCG might aggravate cerebral IRI post-CA/CPR.

PD98059 protects the brain against mitochondrial-mediated apoptosis and autophagy in a cardiac arrest rat model

AIMS

Mitochondrial dysfunction has been regarded as one of the hallmarks of cerebral ischemia-reperfusion injury. In previous studies, we have provided evidence that the extracellular signaling pathway (ERK) 1/2 inhibitor PD98059 improved the neurological deficits by modulating antioxidant and anti-apoptotic activities in rats subjected to cardiac arrest/cardiopulmonary resuscitation (CA/CPR). Since oxidative stress can activate mitochondria-dependent apoptosis and autophagy, we further explored the effects of PD98059 on mitochondria involved with apoptosis and autophagy in rat CA model.

MATERIALS AND METHODS

We disposed PD98059 in CA/CPR rats, tested the mitochondrial-mediated apoptosis pathway in brain tissues at 24 h post-resuscitation by mitochondrial permeability transition pores (MPTP), cytochrome c (CytC), BCL-2, BAX, caspase-3, as well as autophagy by LC3, Beclin-1, and p62. Furthermore, we explored the relationship of dynamin-related protein 1 (Drp1) with apoptosis and autophagy.

KEY FINDINGS

Our study showed that PD98059 decreased the openings of MPTP, CytC release, caspase3 activation, apoptotic indices, LC3-II, Beclin-1and increased P62. PD98059 also inhibited mitochondria-dependent apoptosis and the activity of autophagy in a dose-dependent manner in rat cerebral cortices at 24 h post-resuscitation. The generation of phosphorylated Drp1-616 was down-regulated accompanied by a decrease of TUNEL-positive cells and LC3 in dual immunostaining after PD98059 inhibited activation of ERK signaling pathway in a dose-dependent manner in rat cerebral cortices at 24 h post-resuscitation.

SIGNIFICANCE

PD98059 protects the brain against mitochondrial-mediated apoptosis and autophagy at 24 h post-resuscitation in rats subjected to CA/CPR, which is linked with the downregulation of Drp1 expression.

Dibutyl phthalate-induced activation of ROS and ERK1/2 causes hepatic and renal damage in Kunming mice

Dibutyl phthalate (DBP), a ubiquitous environmental contaminant, has been reported to be involved in hepatic and renal tissue damage. However, the role of DBP in oxidative stress and in extracellular signal-regulated kinase (ERK1/2) pathways remains unclear. To investigate the underlying mechanism, Kunming (KM) mice received daily doses of combinations of 50 mg/kg DBP, 50 mg/kg vitamin E (VitE), and 1 mg/kg PD98059 for 28 consecutive days. Any changes in reactive oxygen species (ROS) and malondialdehyde (MDA) levels, as well as any histopathological alterations in tissues, were observed to assess oxidative stress. In addition, the levels of alanine aminotransferase, aspartate aminotransferase, and albumin in serum were used to evaluate liver function. The levels of creatinine and urea nitrogen in serum were measured to evaluate kidney function. We found that DBP significantly increased oxidative damage and the expression of phosphorylated ERK1/2. Furthermore, pretreatment with the ERK inhibitor PD98059 followed by the antioxidant VitE attenuated the levels of ROS, MDA, ERK1/2 phosphorylation, and DBP-mediated disorders, indicating that the oxidative stress and the ERK1/2 pathways are associated with DBP-induced hepatic and renal dysfunction in KM mice.

Neuroprotective effects of orientin on oxygen-glucose deprivation/reperfusion-induced cell injury in primary culture of rat cortical neurons

Orientin (luteolin-8-C-glucoside) is a phenolic compound found abundantly in millet, juice, and peel of passion fruit and has been shown to have antioxidant properties. In the present study, we explored the effects of orientin on oxygen-glucose deprivation/reperfusion (OGD/RP)-induced cell injury in primary culture of rat cortical neurons using an in vitro model of neonatal ischemic brain injury. The reduced cell viability and elevated lactate dehydrogenase leakage were observed after OGD/RP exposure, which were then reversed by orientin (10, 20, and 30 µM) pretreatment in a dose-dependent manner. Additionally, OGD/RP treatment resulted in significant oxidative stress, accompanied by enhanced intracellular reactive oxygen species (ROS) generation, and obvious depletion in the activities of intracellular Mn-superoxide dismutase, catalase, and glutathione peroxidase antioxidases. However, these effects were dose dependently restored by orientin pretreatment. We also found that orientin pretreatment dose dependently suppressed [Ca²⁺]_i increase and mitochondrial membrane potential dissipation caused by OGD/RP in primary culture of rat cortical neurons. Western blot analysis showed that OGD/RP exposure induced a distinct decrease of Bcl-2 protein and a marked elevation of Bax, caspase-3, and cleaved caspase-3 proteins; whereas these effects were dose dependently reversed by orientin incubation. Both the caspase-3 activity and the apoptosis rate were increased under OGD/RP treatment, but was then dose dependently down-regulated by orientin (10, 20, and 30 µM) incubation. Moreover, orientin pretreatment dose dependently inhibited OGD/RP-induced phosphorylation of JNK and ERK1/2. Notably, JNK inhibitor SP600125 and ERK1/2 inhibitor PD98059 also dramatically attenuated OGD/RP-induced cell viability loss and ROS generation, and further, orientin failed to protect cortical neurons with the interference of JNK activator anisomycin or ERK1/2 activator FGF-2. Taken together, these results demonstrated that orientin has significant neuroprotective effects against OGD/RP-induced cell injury via JNK and ERK1/2 signaling pathways in primary culture of rat cortical neurons. Impact statement Orientin has been used in traditional eastern medicine and reported to possess antioxidant properties. However, the effects of orientin on neonatal ischemic brain injury and the underlying mechanisms involved have not been studied. Our results showed that orientin exerts significant neuroprotective effects on cell injury caused by oxygen-glucose deprivation/reperfusion via the JNK and ERK1/2 signaling pathways in primary culture of rat cortical neurons, implying the potential therapeutic application of orientin via the suppression of oxidative stress and cell apoptosis. This research suggested that orientin may be used as a therapeutic and preventive option for newborn cerebral ischemia/reperfusion injury.