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Cannabinoid receptor-interacting protein 1a (CRIP1a) binds to the C -terminal domain of cannabinoid 1 receptor (CB1R) and regulates CB1R activities. In this study, we made Tat-CRIP1a fusion proteins to enhance CRIP1a penetration into neurons and brain and to evaluate the function of CRIP1a in neuroprotection following oxidative stress in HT22 hippocampal cells and transient forebrain ischemia in gerbils. Purified exogenous Tat-CRIP1a was penetrated into HT22 cells in a time and concentration-dependent manner and prevented H 2 O 2 -induced reactive oxygen species formation, DNA fragmentation, and cell damage. Tat-CRIP1a fusion protein also ameliorated the reduction of 14-3-3η expression by H 2 O 2 treatment in HT22 cells. Ischemia-reperfusion damage caused motor hyperactivity in the open field test of gerbils; however, the treatment of Tat-CRIP1a significantly reduced hyperactivity 1 day after ischemia. Four days after ischemia, the administration of Tat-CRIP1a restored the loss of pyramidal neurons and decreased reactive astrocytosis and microgliosis induced by ischemic damage in the hippocampal cornu Ammonis (CA)1 region. Ischemic damage decreased 14-3-3η expression in all hippocampal sub-regions 4 days after ischemia; however, the treatment of Tat-CRIP1 ameliorated the reduction of 14-3-3η expression. These results suggest that Tat-CRIP1a attenuates neuronal damage and hyperactivity induced by ischemic damage, and it restores normal expression levels of 14-3-3η protein in the hippocampus.

In the previous study, we demonstrated that adipose-derived stem cells (ASCs) have neuroprotective effects against ischemic damage in the ventral horn of L5-6 levels at 3 days after ischemia/reperfusion. In the present study, we expanded our observations for 3 weeks after ischemia/reperfusion to rule out the possibility of delayed neuronal death in several days after ischemia/reperfusion. Transient spinal cord ischemia was induced by a 15 min aortic artery occlusion in the subrenal region and rabbit ASCs were administered intrathecally into recipient rabbits (2 × 10(5)) immediately after reperfusion. Transplantation of ASCs improved the neurological motor functions of the hindlimb 3 weeks after ischemia/reperfusion. Similarly, the cresyl violet-positive neurons were significantly increased at 3 weeks after ischemia/reperfusion compared to that in the vehicle (artificial cerebrospinal fluid)-treated group. The transplantation of ASCs significantly reduced reactive microglia induced by ischemia at 3 weeks after ischemia/reperfusion. In addition, transplantation of ASCs maintained the brain-derived neurotrophic factor (BDNF) levels 3 weeks after ischemia/reperfusion. These results suggest that the neuroprotective effects of ASCs are maintained 3 weeks after ischemia/reperfusion by modulating microgliosis and BDNF levels in the spinal cord.

A rabbit model of spinal cord ischemia has been introduced as a good model to investigate the pathophysiology of ischemia-reperfusion (I-R)-induced paraplegia. In the present study, we observed the effects of Cu,Zn-superoxide dismutase (SOD1) against ischemic damage in the ventral horn of L(5-6) levels in the rabbit spinal cord. For this study, the expression vector PEP-1 was constructed, and this vector was fused with SOD1 to create a PEP-1-SOD1 fusion protein that easily penetrated the blood-brain barrier. Spinal cord ischemia was induced by transient occlusion of the abdominal aorta for 15 min. PEP-1-SOD1 (0.5 mg/kg) was intraperitoneally administered to rabbits 30 min before ischemic surgery. The administration of PEP-1-SOD1 significantly improved neurological scores compared to those in the PEP-1 (vehicle)-treated ischemia group. Also, in this group, the number of cresyl violet-positive cells at 72 h after I-R was much higher than that in the vehicle-treated ischemia group. Malondialdehyde levels were significantly decreased in the ischemic spinal cord of the PEP-1-SOD1-treated ischemia group compared to those in the vehicle-treated ischemia group. In contrast, the administration of PEP-1-SOD1 significantly ameliorated the ischemia-induced reduction of SOD and catalase levels in the ischemic spinal cord. These results suggest that PEP-1-SOD1 protects neurons from spinal ischemic damage by decreasing lipid peroxidation and maintaining SOD and catalase levels in the ischemic rabbit spinal cord.

• Dendropanax morbifera extract alleviates ischemia-induced hyperlocomotor activity and neuronal death after ischemia. • Dendropanax morbifera extract reduces ischemia-induced oxidative stress in the hippocampus after ischemia. • Dendropanax morbifera extract mitigated the reduction of glutathione redox system after ischemia in the hippocampus. In this study, we investigated the effects of Dendropanax morbifera extract (DME) on neuroprotection against ischemic damage in gerbils. DME (100 or 300 mg/kg) was orally administered to gerbils for three weeks, and 2 h after the last DME treatment, transient forebrain ischemia in the common carotid arteries was induced for 5 min. The forebrain ischemia-related cognitive impairments were assessed by spontaneous motor activity and passive avoidance test one and four days after ischemia, respectively. In addition, surviving and degenerating neurons were morphologically confirmed by neuronal nuclei immunohistochemical staining and Fluoro-Jade C staining, respectively, four days after ischemia. Changes of glial morphology were visualized by immunohistochemical staining for each marker such as glial fibrillary acidic protein and ionized calcium-binding protein. Oxidative stress was determined by measurements of dihydroethidium, O 2 · (formation of formazan) and malondialdehyde two days after ischemia. In addition, glutathione redox system such as reduced glutathione, oxidized glutathione levels, glutathione peroxidase, and glutathione reductase activities were measured two days after ischemia. Spontaneous motor activity monitoring and passive avoidance tests showed that treatment with 300 mg/kg DME, but not 100 mg/kg, significantly alleviated ischemia-induced memory impairments. In addition, approximately 67 % of mature neurons survived and 29.3 % neurons were degenerated in hippocampal CA1 region four days after ischemia, and ischemia-induced morphological changes in astrocytes and microglia were decreased in the CA1 region after 300 mg/kg DME treatment. Furthermore, treatment with 300 mg/kg DME significantly ameliorated ischemia-induced oxidative stress, such as superoxide formation and lipid peroxidation, two days after ischemia. In addition, ischemia-induced reduction of the glutathione redox system in the hippocampus, assessed two days after the ischemia, was ameliorated by treatment with 300 mg/kg DME. These suggest that DME can potentially reduce ischemia-induced neuronal damage through its antioxidant properties. [ABSTRACT FROM AUTHOR]

The neuroprotective effects of two isomers ( Z - and E -) of ajoene, a major compound in oil-macerated garlic products, against ischemic damage were investigated in the gerbil hippocampus. Vehicle (corn oil), Z - or E -ajoenes (25 mg/kg) was orally administered 30 min prior to the induction of transient forebrain ischemia by occlusion of the common carotid arteries for 5 min. One day after ischemia/reperfusion (I/R), I/R-induced hyperactivity significantly reduced in the E - and Z -ajoene-treated groups, compared to that in the vehicle-treated group 5 days after I/R, the number of cresyl violet-positive neurons in the E- and Z- ajoene-treated groups increased, compared to that in the vehicle-treated group. Reactive gliosis in the CA1 region of E - and Z- ajoene-treated groups reduced, compared to that in the vehicle-treated group. These neuroprotective effects were more prominent in animals treated with Z -ajoene, than in those treated with E -ajoene. In addition, Z -ajoene significantly decreased lipid peroxidation, as indicated by 4-hydroxy-2-nonenal levels in hippocampal homogenates, compared to that observed in the vehicle-treated group at a range of time points after I/R. These results suggested that Z -ajoene protected against I/R-induced delayed neuronal death and gliosis by reducing lipid peroxidation in the gerbil hippocampal CA1 region. [ABSTRACT FROM AUTHOR]

In the present study, we examined the effects of Cissus verticillata leaf extracts (CVE) against hydrogen peroxide (H2O2)- and ischemia-induced neuronal damage in HT22 cells and gerbil hippocampus. Incubation with CVE produced concentration-dependent toxicity in HT22 cells. Significant cellular toxicity was observed with >75 μg/mL CVE. CVE treatment at 50 μg/mL ameliorated H2O2-induced reactive oxygen species formation, DNA fragmentation, and cell death in HT22 cells. In addition, incubation with CVE significantly mitigated the increase in Bax and decrease in Bcl-2 induced by H2O2 treatment in HT22 cells. In an in vivo study, the administration of CVE to gerbils significantly decreased ischemia-induced motor activity 1 d after ischemia, as well as neuronal death and microglial activation 4 d after ischemia, respectively. CVE treatment reduced the release of interleukin-1β, interleukin-6, and tumor necrosis factor-α 6 h after ischemia. Furthermore, CVE treatment significantly ameliorated ischemia-induced phosphorylation of c-Jun N-terminal kinase, extracellular signal-regulated kinase 1/2, and p38. These results suggest that CVE has the potential to reduce the neuronal damage induced by oxidative and ischemic stress by reducing the inflammatory responses and phosphorylation of MAPKs, suggesting that CVE could be a functional food to prevent neuronal damage induced by ischemia. [ABSTRACT FROM AUTHOR]

The present study explored the effects of endophilin A1 (SH3GL2) against oxidative damage brought about by H2O2 in HT22 cells and ischemic damage induced upon transient forebrain ischemia in gerbils. Tat-SH3GL2 and its control protein (Control-SH3GL2) were synthesized to deliver it to the cells by penetrating the cell membrane and blood–brain barrier. Tat-SH3GL2, but not Control-SH3GL2, could be delivered into HT22 cells in a concentration- and time-dependent manner and the hippocampus 8 h after treatment in gerbils. Tat-SH3GL2 was stably present in HT22 cells and degraded with time, by 36 h post treatment. Pre-incubation with Tat-SH3GL2, but not Control-SH3GL2, significantly ameliorated H2O2-induced cell death, DNA fragmentation, and reactive oxygen species formation. SH3GL2 immunoreactivity was decreased in the gerbil hippocampal CA1 region with time after ischemia, but it was maintained in the other regions after ischemia. Tat-SH3GL2 treatment in gerbils appreciably improved ischemia-induced hyperactivity 1 day after ischemia and the percentage of NeuN-immunoreactive surviving cells increased 4 days after ischemia. In addition, Tat-SH3GL2 treatment in gerbils alleviated the increase in lipid peroxidation as assessed by the levels of malondialdehyde and 8-iso-prostaglandin F2α and in pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin-1β, and interleukin-6; while the reduction of protein levels in markers for synaptic plasticity, such as postsynaptic density 95, synaptophysin, and synaptosome associated protein 25 after transient forebrain ischemia was also observed. These results suggest that Tat-SH3GL2 protects neurons from oxidative and ischemic damage by reducing lipid peroxidation and inflammation and improving synaptic plasticity after ischemia. [ABSTRACT FROM AUTHOR]

Gynura procumbens has been used in Southeast Asia for the treatment of hypertension, hyperglycemia, and skin problems induced by ultraviolet irradiation. Although considerable studies have reported the biological properties of Gynura procumbens root extract (GPE-R), there are no studies on the effects of GPE-R in brain damages, for example following brain ischemia. In the present study, we screened the neuroprotective effects of GPE-R against ischemic damage and neuroinflammation in the hippocampus based on behavioral, morphological, and biological approaches. Gerbils received oral administration of GPE-R (30 and 300 mg/kg) every day for three weeks and 2 h after the last administration, ischemic surgery was done by occlusion of both common carotid arteries for 5 min. Administration of 300 mg/kg GPE-R significantly reduced ischemia-induced locomotor hyperactivity 1 day after ischemia. Significantly more NeuN-positive neurons were observed in the hippocampal CA1 regions of 300 mg/kg GPE-R-treated animals compared to those in the vehicle-treated group 4 days after ischemia. Administration of GPE-R significantly reduced levels of pro-inflammatory cytokines such as interleukin-1β, -6, and tumor necrosis factor-α 6 h after ischemia/reperfusion. In addition, activated microglia were significantly decreased in the 300 mg/kg GPE-R-treated group four days after ischemia/reperfusion compared to the vehicle-treated group. These results suggest that GPE-R may be one of the possible agents to protect neurons from ischemic damage by reducing inflammatory responses. [ABSTRACT FROM AUTHOR]

p27Kip1 (p27), a well-known cell regulator, is involved in the regulation of cell death and survival. In the present study, we observed the effects of p27 against oxidative stress induced by H2O2 in HT22 cells and transient ischemia in gerbils. Tat (trans-acting activator of transcription) peptide and p27 fusion proteins were prepared to facilitate delivery into cells and across the blood-brain barrier. The tat-p27 fusion protein, rather than its control protein Control-p27, was delivered intracellularly in a concentration and incubation time-dependent manner and showed its activity in HT22 cells. The localization of the delivered Tat-p27 protein was also confirmted in the HT22 cells and hippocampus in gerbils. In addition, the optimal concentration (5 μM) of Tat-p27 was determined to protect neurons from cell death induced by 1 mM H2O2. Treatment with 5 μM Tat-p27 significantly ameliorated H2O2-induced DNA fragmentation and the formation of reactive oxygen species (ROS) in HT22 cells. Tat-p27 significantly mitigated the increase in locomotor activity a day after ischemia and neuronal damage in the hippocampal CA1 region. It also reduced the ischemia-induced membrane phospholipids and ROS formation. In addition, Tat-p27 significantly increased microtubule-associated protein 1A/1B light chain 3A/3B expression and ameliorated the H2O2 or ischemia-induced increases of p62 and decreases of beclin-1 in the HT22 cells and hippocampus. These results suggest that Tat-p27 protects neurons from oxidative or ischemic damage by reducing ROS-induced damage and by facilitating the formation of autophagosomes in hippocampal cells. [ABSTRACT FROM AUTHOR]

Phosphoglycerate mutase 1 (PGAM1) is a glycolytic enzyme that increases glycolytic flux in the brain. In the present study, we examined the effects of PGAM1 in conditions of oxidative stress and ischemic damage in motor neuron-like (NSC34) cells and the rabbit spinal cord. A Tat-PGAM1 fusion protein was prepared to allow easy crossing of the blood-brain barrier, and Control-PGAM1 was synthesized without the Tat peptide protein transduction domain. Intracellular delivery of Tat-PGAM1, not Control-PGAM1, was achieved in a time- and concentration-dependent manner. Immunofluorescent staining confirmed the intracellular expression of Tat-PGAM1 in NSC34 cells. Tat-PGAM1, but not Control-PGAM1, significantly alleviated H2O2-induced oxidative stress, neuronal death, mitogen-activated protein kinase, and apoptosis-inducing factor expression in NSC34 cells. After ischemia induction in the spinal cord, Tat-PGAM1 treatment significantly improved ischemia-induced neurological impairments and ameliorated neuronal cell death in the ventral horn of the spinal cord 72 h after ischemia. Tat-PGAM1 treatment significantly mitigated the ischemia-induced increase in malondialdehyde and 8-iso-prostaglandin F2α production in the spinal cord. In addition, Tat-PGAM1, but not Control-PGAM1, significantly decreased microglial activation and secretion of pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α induced by ischemia in the ventral horn of the spinal cord. These results suggest that Tat-PGAM1 can be used as a therapeutic agent to reduce spinal cord ischemia-induced neuronal damage by lowering the oxidative stress, microglial activation, and secretion of pro-inflammatory cytokines, such as IL-1β, IL-6, and TNF-α. [ABSTRACT FROM AUTHOR]

We investigated the effects of pyridoxine deficiency on ischemic neuronal death in the hippocampus of gerbil (n = 5 per group). Serum pyridoxal 5′-phosphate levels were significantly decreased in Pyridoxine-deficient diet (PDD)-fed gerbils, while homocysteine levels were significantly increased in sham- and ischemia-operated gerbils. PDD-fed gerbil showed a reduction in neuronal nuclei (NeuN)-immunoreactive neurons in the medial part of the hippocampal CA1 region three days after. Reactive astrocytosis and microgliosis were found in PDD-fed gerbils, and transient ischemia caused the aggregation of activated microglia in the stratum pyramidale three days after ischemia. Lipid peroxidation was prominently increased in the hippocampus and was significantly higher in PDD-fed gerbils than in Control diet (CD)-fed gerbils after ischemia. In contrast, pyridoxine deficiency decreased the proliferating cells and neuroblasts in the dentate gyrus in sham- and ischemia-operated gerbils. Nuclear factor erythroid-2-related factor 2 (Nrf2) and brain-derived neurotrophic factor (BDNF) levels also significantly decreased in PDD-fed gerbils sham 24 h after ischemia. These results suggest that pyridoxine deficiency accelerates neuronal death by increasing serum homocysteine levels and lipid peroxidation, and by decreasing Nrf2 levels in the hippocampus. Additionally, it reduces the regenerated potentials in hippocampus by decreasing BDNF levels. Collectively, pyridoxine is an essential element in modulating cell death and hippocampal neurogenesis after ischemia. [ABSTRACT FROM AUTHOR]

In the present study, we investigated the effects of cuprizone on cell death, glial activation, and neuronal plasticity induced by hypothermia after ischemia in gerbils. Food was supplemented with cuprizone at 0.2% ad libitum for eight weeks. At six weeks after diet feeing, gerbils received transient forebrain ischemia with or without hypothermic preconditioning. Cuprizone treatment for 8 weeks increased the number of astrocytes, microglia, and pro-inflammatory cytokine levels in the hippocampus. In addition, cuprizone treatment significantly decreased the number of proliferating cells and neuroblasts in the dentate gyrus. Brain ischemia caused cell death, disruption of myelin basic proteins, and reactive gliosis in CA1. In addition, ischemia significantly increased pro-inflammatory cytokines and the number of proliferating cells and differentiating neuroblasts in the dentate gyrus. In contrast, hypothermic conditioning attenuated these changes in CA1 and the dentate gyrus. However, cuprizone treatment decreased cell survival induced by hypothermic preconditioning after ischemia and increased the number of reactive microglia and astrocytes in CA1 as well as that of macrophages in the subcallosal zone. These changes occurred because the protective effect of hypothermia in ischemic damage was disrupted by cuprizone administration. Furthermore, cuprizone decreased ischemia-induced proliferating cells and neuroblasts in the dentate gyrus. [ABSTRACT FROM AUTHOR]

In a previous study, we observed the effect of phosphoglycerate mutase 1 (PGAM1) on proliferating cells and neuroblasts in the subgranular zone of mouse dentate gyrus. In the present study, we examined the roles of PGAM1 in the HT22 hippocampal cell line and in gerbil hippocampus after H 2 O 2 -induced oxidative stress and after ischemia/reperfusion, respectively. Control-PGAM1 and Tat-PGAM1 proteins were synthesized using Tat-1 expression vector since Tat-1 fusion proteins can easily cross the blood-brain barrier and cell membranes. We found that transduction of Tat-PGAM1 protein into HT22 cells was dose- and time-dependent. Delivery of the protein to the cytoplasm was confirmed by western blotting and immunocytochemistry. Treatment of HT22 cells with Tat-PGAM1 protein showed a concentration-dependent reduction in cell damage and decreased formation of reactive oxygen species after H 2 O 2 exposure. Tat-PGAM1 administration significantly ameliorated the ischemia-induced hyperactivity in gerbils at 1 day after ischemia/reperfusion. Additionally, a pronounced decrease in neuronal damage and reactive gliosis were observed in the hippocampal CA1 region of the Tat-PGAM1-treated group at 4 days after ischemia/reperfusion compared to that in the vehicle (Tat peptide) or control-PGAM1-treated groups. Administration of Tat-PGAM1 mitigated the changes in ATP content, succinate dehydrogenase activity, pH, and 4-hydroxynonenal levels in the hippocampus at 4 and 7 days after ischemia/reperfusion compared to that in the vehicle-treated group. In addition, administration of Tat-PGAM1 significantly ameliorated the ischemia-induced increases of lactate levels in the hippocampus at 15 min and 6 h after ischemia/reperfusion than in the vehicle or control-PGAM1-treated groups. These results suggest that Tat-PGAM1 can be used as a therapeutic agent to prevent neuronal damage from oxidative stress or ischemia. •Tat-PGAM1 is efficiently delivered to HT22 cells. •Tat-PGAM1 ameliorates the H 2 O 2 -induced oxidative stress and cell death in HT22 cells. •Tat-PGAM1 prevents neuronal damage in the hippocampus by modulating the energy metabolism and lipid peroxidation. [ABSTRACT FROM AUTHOR]

In a previous study, we utilized a proteomic approach and found a significant reduction in phosphatidylethanolamine-binding protein 1 (PEBP1) protein level in the spinal cord at 3 h after ischemia. In the present study, we investigated the role of PEBP1 against oxidative stress in NSC34 cells in vitro, and ischemic damage in the rabbit spinal cord in vivo. We generated a PEP-1-PEBP1 fusion protein to facilitate the penetration of blood-brain barrier and intracellular delivery of PEBP1 protein. Treatment with PEP-1-PEBP1 significantly decreased cell death and the induction of oxidative stress in NSC34 cells. Furthermore, administering PEP-1-PEBP1 did not show any significant side effects immediately before and after ischemia/reperfusion. Administration of PEP-PEBP1 improved the Tarlov's neurological score at 24 and 72 h after ischemia, and significantly improved neuronal survival at 72 h after ischemia based on neuronal nuclei (NeuN) immunohistochemistry, Flouro-Jade B staining, and western blot study for cleaved caspase 3. PEP-1-PEBP1 administration decreased oxidative stress based on malondialdehyde level, advanced oxidation protein products, and 8-iso-prostaglandin F2α in the spinal cord. In addition, inflammation based on myeloperoxidase level, tumor necrosis factor-α level, and high mobility group box 1 level was decreased by PEP-1-PEBP1 treatment at 72 h after ischemia. Thus, PEP-1-PEBP1 treatment, which decreases oxidative stress, inflammatory cytokines, and neuronal death, may be an effective therapeutic strategy for spinal cord ischemia. [ABSTRACT FROM AUTHOR]

Phosphoglycerate mutase 5 (PGAM5), a glycolytic enzyme, plays an important role in cell death and regulation of mitochondrial dynamics. In this study, we investigated the effects of PGAM5 on oxidative stress in HT22 hippocampal cells and ischemic damage in the gerbil hippocampus to elucidate the role of PGAM5 in oxidative and ischemic stress. Constructs were designed with a PEP-1 expression vector to facilitate the intracellular delivery of PGAM5 proteins. We observed time- and concentration-dependent increases in the intracellular delivery of the PEP-1-PGAM5 protein, but not its control protein (PGAM5), in HT22 cells, and morphologically demonstrated the localization of the transduced protein, which was stably expressed in the cytoplasm after 12 h of PEP-1-PGAM5 treatment. PEP-1-PGAM5 treatment significantly ameliorated cell death, reactive oxygen species formation, DNA fragmentation, and the reduction of cell proliferation induced by H 2 O 2 treatment in HT22 cells. In addition, PEP-1-PGAM5 was effectively delivered to the gerbil hippocampus 8 h after treatment, and ischemia-induced hyperlocomotion and neuronal death in the hippocampal CA1 region were significantly alleviated 1 and 4 days after ischemia, respectively. Ischemia-induced microglial activation was also mitigated by treatment with 1.0 mg/kg PEP-1-PGAM5. At 3 h after ischemia, PEP-1-PGAM5 treatment significantly ameliorated the increase in lipid peroxidation, as assessed by malondialdehyde and hydroperoxide levels, and decreased glutathione levels (increases in glutathione disulfide, the oxidized form of glutathione) in the hippocampus. Two days after ischemia, treatment with PEP-1-PGAM5 significantly alleviated the ischemia-induced reduction in glutathione peroxidase activity and further increased superoxide dismutase activity in the hippocampus. The neuroprotective effects of PEP-1-PGAM5 are partially mediated by a reduction in oxidative stress, such as the formation of reactive oxygen species, and increases in the activity of antioxidants such as glutathione peroxidase and superoxide dismutase. • PEP-1-PGAM5 is delivered into HT22 cells with time- and concentration-dependent manner. • PEP-1-PGAM5 alleviates H 2 O 2 -induced ROS formation, DNA fragmentation, and cell death in HT22 cells. • PEP-1-PGAM5 ameliorates ischemic neuronal death in the hippocampus by reducing lipid peroxidation and increasing glutathione. [ABSTRACT FROM AUTHOR]

Abstract Ischemia causes oxidative stress in the endoplasmic reticulum (ER), accelerates the accumulation of unfolded and misfolded proteins, and may ultimately lead to neuronal cell apoptosis. In the present study, we investigated the effects of protein disulfide-isomerase A3 (PDIA3), an ER-resident chaperone that catalyzes disulfide-bond formation in a subset of glycoproteins, against oxidative damage in the hypoxic HT22 cell line and against ischemic damage in the gerbil hippocampus. We also confirmed the neuroprotective effects of PDIA3 by using PDIA3-knockout HAP1 cells. The HT22 and HAP1 cell lines showed effective (dose-dependent and time-dependent) penetration and stable expression of the Tat-PDIA3 fusion protein 24 h after Tat-PDIA3 treatment compared to that in the control-PDIA3-treated group. We observed that the fluorescence for both 2′,7′-dichlorofluorescein diacetate (DCF-DA) and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL), which are markers for the formation of hydrogen peroxide (H 2 O 2)-induced reactive oxygen species and apoptosis, respectively, was higher in HAP1 cells than in HT22 cells. The administration of Tat-PDIA3 significantly reduced the (1) DCF-DA and TUNEL fluorescence in HT22 and HAP1 cells, (2) ischemia-induced hyperactivity that was observed 1 day after ischemia/reperfusion, (3) ischemia-induced neuronal damage and glial (astrocytes and microglia) activation that was observed in the hippocampal CA1 region 4 days after ischemia/reperfusion, and (4) lipid peroxidation and nitric oxide generation in the hippocampal homogenates 3–12 h after ischemia/reperfusion. Transient forebrain ischemia significantly elevated the immunoglobulin-binding protein (BiP) and C/EBP-homologous protein (CHOP) mRNA levels in the hippocampus at 12 h and 4 days after ischemia, relative to those in the time-matched sham-operated group. Administration of Tat-PDIA3 ameliorated the ischemia-induced upregulation of BiP mRNA levels versus the Tat peptide- or control-PDIA3-treated groups, and significantly reduced the induction of CHOP mRNA levels, at 12 h or 4 days after ischemia. Collectively, these results suggest that Tat-PDIA3 acts as a neuroprotective agent against ischemia by attenuating oxidative damage and blocking the apoptotic pathway that is related to the unfolded protein response in the ER. Highlights • Tat-PDIA3 can efficiently transduce into the hippocampal cells and is stably expressed within the cells. • Tat-PDIA3 strongly ameliorates H 2 O 2 -induced neuronal death and reactive oxygen species formation in the hippocampal cells. • Tat-PDIA3 protects neurons from ischemic damage in the gerbil hippocampus by reducing the lipid peroxidation, nitric oxide generation, and CHOP expression. [ABSTRACT FROM AUTHOR]