Transient Cerebral Ischemia In Rats Research Articles

Effect of lipoxin A4 methyl ester from arachidonic acid on JAK2/STAT3 pathway after cerebral ischemia-reperfusion injury

It was determined if lipoxin A4 methyl ester (LXA4 ME) affects JAK2/STAT3 pathway following transient focal cerebral ischemia-reperfusion injury (CIRI) in rats. Adult male SD rats were randomly assigned to sham-operated, CIRI group, DMSO + CIRI, AG490 + CIRI, and LXA4 ME + CIRI. Neurologic deficit was evaluated in rats after 24 h reperfusion. IL-6 levels of brain tissue were determined 6 and 24 h post-reperfusion using an ELISA assay. STAT3 and SOCS3 mRNA levels were analyzed via real-time quantitative PCR. P-JAK2, p-STAT3, and SOCS3 were measured via Western blotting, and localized by fluorescent immunohitochemistry. Transient cerebral ischemia in rats caused a significantly elevated concentration of IL-6, levels of STAT3 and SOCS3 mRNA, phosphorylation of JAK2 and STAT3, and immunoreactive glia of ipsilateral cortex 24 h post-reperfusion versus sham rats. The AG490 intervention downregulated cerebral ischemia-induced JAK2 and STAT3 phosphorylation, and their immunoreactive glia located in the ischemic cortex. LXA4 ME reduced the concentration of IL-6, increased SOCS3 expression, inhibited phosphorylation and immunoreactive glia of JAK2 and STAT3, as well as ameliorated neurologic dysfunction. In conclusions, LXA4 ME inhibited JAK2/STAT3 activation, perhaps via upregulating SOCS3, as well as suppressed IL-6 expression to ameliorate cerebral ischemic injury.

The antioxidant effect of preischemic dexmedetomidine in a rat model: increased expression of Nrf2/HO-1 via the PKC pathway

BackgroundThe precise underlying mechanism of antioxidant effects of dexmedetomidine-induced neuroprotection against cerebral ischemia has not yet been fully elucidated. Activation of Nuclear factor erythroid 2-related factor (Nrf2) and Heme Oxygenase-1 (HO-1) represents a major antioxidant-defense mechanism. Therefore, we determined whether dexmedetomidine increases Nrf2/HO-1 expression after global transient cerebral ischemia and assessed the involvement of Protein Kinase C (PKC) in the dexmedetomidine-related antioxidant mechanism. MethodsThirty-eight rats were randomly assigned to five groups: sham (n...=...6), ischemic (n...=...8), chelerythrine (a PKC inhibitor; 5...mg.kg-1 IV administered 30...min before cerebral ischemia) (n...=...8), dexmedetomidine (100.....g.kg-1 IP administered 30...min before cerebral ischemia (n...=...8), and dexmedetomidine...+...chelerythrine (n...=...8). Global transient cerebral ischemia (10...min) was applied in all groups, except the sham group; histopathologic changes and levels of nuclear Nrf2 and cytoplasmic HO-1 were examined 24...hours after ischemia insult. ResultsWe found fewer necrotic and apoptotic cells in the dexmedetomidine group relative to the ischemic group (p...<...0.01) and significantly higher Nrf2 and HO-1 levels in the dexmedetomidine group than in the ischemic group (p...<...0.01). Additionally, chelerythrine co-administration with dexmedetomidine attenuated the dexmedetomidine-induced increases in Nrf2 and HO-1 levels (p...<...0.05 and p...<...0.01, respectively) and diminished its beneficial neuroprotective effects. ConclusionPreischemic dexmedetomidine administration elicited neuroprotection against global transient cerebral ischemia in rats by increasing Nrf2/HO-1 expression partly via PKC signaling, suggesting that this is the antioxidant mechanism underlying dexmedetomidine-mediated neuroprotection.

Pseudoginsenoside-F11 promotes functional recovery after transient cerebral ischemia by regulating the microglia/macrophage polarization in rats

The polarization of microglia/macrophages after cerebral ischemia is critical for post-stroke damage/recovery. Previously, we found that pseudoginsenoside-F11 (PF11), an ocotillol-type saponin, has neuroprotective effects on permanent and transient cerebral ischemia in rats. This study aimed to investigate the effects and potential mechanisms of PF11 on microglia/macrophage polarization following transient cerebral ischemia in rats. In vivo data showed that oral administration of PF11 (12 mg/kg) significantly attenuated cognitive deficits and sensorimotor dysfunction, infarct volume and brain edema in transient middle cerebral artery occlusion (tMCAO)-treated rats, as well as reduced the loss of neurons and the over-activation of microglia in penumbra of ipsilateral striatum and cortex. Notably, the proportion of M2 microglia/macrophages in the total activated microglia/macrophages peaked on day 14 after tMCAO in rats, while PF11 promoted its peak advancing to day 3 post-tMCAO, which allowing the damaged brain to enter the repair period more quickly. Furthermore, PF11 increased the expression of anti-inflammatory markers and decreased the expression of pro-inflammatory markers in ipsilateral striatum and cortex. In addition, in vitro data showed that PF11 inhibited the induction of M1 microglia by oxygen glucose deprivation/re-oxygenation (OGD/R)-induced neurons, and promoted the polarization of microglia to M2 phenotype in a Jumonji domain-containing protein 3 (Jmjd3)-dependent manner. Moreover, PF11 promoted the protection of M2 microglia and attenuated the exacerbation of M1 microglia on OGD/R-induced neuronal damage. Taken together, these results indicate that PF11 protects ischemic neurons by promoting M2 microglia/macrophage polarization in a Jmjd3-dependent manner, ultimately facilitating the functional recovery following transient cerebral ischemia.

Pseudoginsenoside-F11 ameliorates ischemic neuron injury by regulating the polarization of neutrophils and macrophages in vitro

Pseudoginsenoside-F11 (PF11), an ocotillol-type saponin, has neuroprotective effects on permanent and transient cerebral ischemia in rats by alleviating autophagic/lysosomal defects and repressing calcium overload, respectively. Ischemic stroke triggers peripheral innate immune cells, mainly neutrophils and macrophages, to infiltrate the damaged brain. The polarization of neutrophils and macrophages after cerebral ischemia is essential for post-stroke damage/recovery. However, it remains elusive whether PF11 ameliorates ischemic neuron injury by regulating the polarization of neutrophils and macrophages. The present study demonstrated for the first time that conditioned media from ischemic neurons induced neutrophils and macrophages to polarize into N1 and M1 phenotypes, respectively. Furthermore, PF11 (30, 100 μM) inhibited the induction of N1 neutrophils by conditioned media from oxygen glucosedeprivation/re-oxygenation (OGD/R)-induced ischemic neurons and promoted the polarization of neutrophils to N2 phenotypes. In addition, PF11 (100 μM) attenuated the exacerbation of N1 neutrophils and facilitated the protection of N2 neutrophils on OGD/R-induced neuronal damage. Similarly, PF11 (100 μM) inhibited the induction of M1 macrophages by conditioned media from ischemic neurons and facilitated the polarization of macrophages to M2 phenotypes. What's more, PF11 (100 μM) attenuated the aggravation of M1 macrophages and promoted the protection of M2 macrophages on OGD/R-induced primary neuron injury. In summary, the present study indicates that PF11 ameliorates ischemic neuron damage by regulating neutrophils and macrophages polarization, suggesting that neutrophils and macrophages may be promising targets for the treatment of cerebral ischemia.

N2 neutrophils may participate in spontaneous recovery after transient cerebral ischemia by inhibiting ischemic neuron injury in rats

Neutrophils have been traditionally considered as the major mediators of harmful inflammatory responses in ischemic stroke, whereas accumulating evidence indicates that neutrophils can be polarized into an N2 phenotype. Similar to M2 microglia, N2 neutrophils contribute to resolution of inflammation and may participate in neuroprotection. However, it remains unclear whether N2 neutrophils protect ischemic neurons and whether they are associated with long-term outcomes after transient cerebral ischemia in rats. The present study proved that N2 neutrophils protected against oxygen glucosedeprivation/re-oxygenation (OGD/R)-induced primary cortical neuron injury via brain-derived neurotrophic factor/tropomyosin-related kinase B (BDNF/TrkB) signaling. In addition, in vivo studies revealed that transient middle cerebral artery occlusion (tMCAO)-induced injury exhibited spontaneous recovery over time in rats. Moreover, neutrophils could infiltrate the ipsilateral brain parenchyma from the periphery after transient cerebral ischemia. Pearson’s correlation analysis indicated that the proportion of N2 neutrophils in ipsilateral brain parenchyma was negatively correlated with the number of degenerating neurons, modified Neurological Severity Score (mNSS), brain water content and infarct volume, and positively correlated with the number of surviving neurons and grip strength. In summary, the present study shows that N2 neutrophils likely participate in spontaneous recovery after transient cerebral ischemia by inhibiting ischemic neuron damage in rats, which indicates that N2 neutrophils may represent promising therapeutic target for promoting recovery after ischemic stroke.

Preventive citicoline administration is more effective than therapeutic in model of transient cerebral ischemia in rats

Preventive citicoline administration is more effective than therapeutic in model of transient cerebral ischemia in rats

Immortalized Human Bone Marrow Derived Stromal Cells in Treatment of Transient Cerebral Ischemia in Rats.

Cerebral ischemic stroke may cause a number of adverse neurological complications or behavioral disorders. Moreover, cerebral ischemic stroke is a prevalent disease with limited treatment strategies and may increase chances of developing neurodegenerative diseases, e.g., Alzheimer's disease, in the future. Therefore, alternative strategies are highly needed for improving the therapy for ischemic stroke. Human bone marrow stroma stem cells, also known as mesenchymal stem cells (hMSC), have a demonstrative role in treating transient cerebral ischemia, yet whether immortalized hMSC may have a better effect than hMSC is unknown. Here, we addressed this question. A rat cerebral ischemia reperfusion (IR) model was used to compare the effects of hMSC and an immortalized hMSC by human telomerase reverse transcriptase (hMSC-TERT). We found that both hMSC and hMSC-TERT similarly attenuated the elevation of serum neuron specific enolase levels after IR. Transplantation with hMSC alleviated cerebral infarction, alleviated brain edema, improved neural function, and reduced brain cell apoptosis, in a significantly better degree than transplantation with hMSC. Thus, these data suggest that immortalized hMSC may have an advantage over hMSC in treatment of transient cerebral ischemia.

Experimental Cerebral Ischemia Affects the Expression of Circular RNA Genes of Metabotropic Glutamate Receptors mGluR3 and mGluR5 in Rat Brain

Circular RNAs (circRNAs) are a new RNA type that show predominantly brain-specific expression pattern in mammals. Their individual representatives, acting as competitive endogenous RNAs, can bind microRNAs and contribute to the protection of functional transcripts. In the model of transient cerebral ischemia in rats, we studied the expression of mGluR3 and mGluR5 glutamate metabotropic receptor genes (Grm3 and Grm5). These genes are important participants in the metabolic pathways associated with neurosignaling. In the present study, we found that the rat Grm3 and Grm5 genes, in addition to mRNA, encode circRNAs, which are conserved in humans and rodents. In subcortical brain structures of rats containing a lesion focus, the level of these circRNAs is more stable than that of the corresponding mRNA. Using STarMirDB database analysis, the distribution of the microRNA binding sites along the mRNA molecules of human GRM3 and GRM5 genes which are homologous to the corresponding rat genes was elucidated. It has been revealed that sufficiently large number of binding sites is located within exons, which are also part of conservative circRNAs. The results may indicate the functional role of the circRNAs of the investigated genes as competitive endogenous RNAs in the response of brain cells to ischemia.

Sevoflurane Postconditioning-Induced Anti-Inflammation via Inhibition of the Toll-Like Receptor-4/Nuclear Factor Kappa B Pathway Contributes to Neuroprotection against Transient Global Cerebral Ischemia in Rats.

The anti-inflammatory actions of sevoflurane postconditioning are suggested as an important mechanism of sevoflurane postconditioning-induced neuroprotection against cerebral ischemia. Here, we determined whether the anti-inflammatory effects of sevoflurane postconditioning were mediated via inhibition of the toll-like receptor (TLR)-4/nuclear factor kappa B (NF-κB) pathway after global transient cerebral ischemia in rats. Forty-five rats were randomly assigned to five groups as follows: (1) control (10 min of ischemia, n = 10); (2) sevoflurane postconditioning (two periods of sevoflurane inhalation after ischemia for 10 min with a wash period of 10 min, n = 10); (3) resatorvid (intraperitoneal injection of a selective TLR-4 antagonist (3 mg/kg) 30 min before ischemia, n = 10); (4) sevoflurane postconditioning plus resatorvid (n = 10), and sham (n = 5). The numbers of necrotic and apoptotic cells in the hippocampal CA1 region, the expression levels of TLR-4, NF-κB, cleaved caspase-3, and tumor necrosis factor alpha (TNF-α) in the anterior part of each brain, and the serum levels of TNF-α, interleukin 6 (IL-6), and interleukin 1 beta (IL-1β) were assessed 1 day after ischemia. The necrotic cell counts and expression levels of TLR-4, NF-κB, caspase-3, and TNF-α in brain tissue as well as serum levels of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) were significantly higher in the control group than in the other groups. Our findings suggest that the anti-inflammatory actions of sevoflurane postconditioning via inactivation of the TLR-4/NF-κB pathway and subsequent reduction in pro-inflammatory cytokine production, in part, contribute to sevoflurane postconditioning-induced neuroprotection after global transient cerebral ischemia in rats.

Reduced Severity of Outcome of Recurrent Ipsilateral Transient Cerebral Ischemia Compared with Contralateral Transient Cerebral Ischemia in Rats

To investigate whether prior transient ischemic attack (TIA) had a preconditioning effect on subsequent cerebral infarction in a rat model using middle cerebral artery occlusion (MCAO). Thirty-six adult male Sprague-Dawley rats were divided into 3 groups: those with transient (5 minutes) left MCAO (left TIA) (n = 15), those with transient right MCAO (right TIA) (n = 15), and a sham operation group (n = 6). Seven days after the initial transient MCAO, rats in all groups underwent permanent left MCAO. After 24 hours, all rats underwent motor function measurement (the Garcia score and tilting plane test), magnetic resonance imaging, postmortem brain examination, and biomarkers of stroke. Following permanent MCAO, the Garcia score, the brain edema area of T2-weighted images, brain infarction volume, and the level of tumor necrosis factor α mRNA of the ipsilateral and contralateral TIA groups showed no significant difference. The angle of sliding off in the tilting plane test, the mean intensity of the brain edema area of T2-weighted images, levels of matrix metalloproteinase 9, interleukin-1β, inducible nitric oxide synthase mRNA, and apoptosis-related proteins, BAX, and phosphorylated-p38, were lower in the ipsilateral TIA group compared with the contralateral TIA group. The main finding of this study was that a transient, mild, unilateral focus of cerebral ischemia (or TIA) in either the left or right hemisphere, which is then followed by a second unilateral severe and focal ischemic event, results in brain injury. The severity of the brain injury following this second ischemic event will be alleviated when the second insult is ipsilateral to the first TIA.

Intraarterial route increases the risk of cerebral lesions after mesenchymal cell administration in animal model of ischemia

Mesenchymal stem cells (MSCs) are a promising clinical therapy for ischemic stroke. However, critical parameters, such as the most effective administration route, remain unclear. Intravenous (i.v.) and intraarterial (i.a.) delivery routes have yielded varied outcomes across studies, potentially due to the unknown MSCs distribution. We investigated whether MSCs reached the brain following i.a. or i.v. administration after transient cerebral ischemia in rats, and evaluated the therapeutic effects of both routes. MSCs were labeled with dextran-coated superparamagnetic nanoparticles for magnetic resonance imaging (MRI) cell tracking, transmission electron microscopy and immunohistological analysis. MSCs were found in the brain following i.a. but not i.v. administration. However, the i.a. route increased the risk of cerebral lesions and did not improve functional recovery. The i.v. delivery is safe but MCS do not reach the brain tissue, implying that treatment benefits observed for this route are not attributable to brain MCS engrafting after stroke.

Protective effect of α-terpineol against impairment of hippocampal synaptic plasticity and spatial memory following transient cerebral ischemia in rats.

Cerebral ischemia is often associated with cognitive impairment. Oxidative stress has a crucial role in the memory deficit following ischemia/reperfusion injury. α-Terpineol is a monoterpenoid with anti-inflammatory and antioxidant effects. This study was carried out to investigate the effect of α-terpineol against memory impairment following cerebral ischemia in rats. Cerebral ischemia was induced by transient bilateral common carotid artery occlusion in male Wistar rats. The rats were allocated to sham, ischemia, and α-terpineol-treated groups. α-Terpineol was given at doses of 50, 100, and 200 mg/kg, IP once daily for 7 days post ischemia. Morris water maze (MWM) test was used to assess spatial memory and in vivo extracellular recording of long-term potentiation (LTP) in the hippocampal dentate gyrus was carried out to evaluate synaptic plasticity. Malondialdehyde (MDA) was measured to assess the extent of lipid peroxidation in the hippocampus. In MWM test, α-terpineol (100 mg/kg, IP) significantly decreased the escape latency during training trials (P<0.01). In addition, α-terpineol increased the number of crossings over the platform location and decreased average proximity to the target in probe trial (P<0.05). In electrophysiological recording, α-terpineol (100 mg/kg) facilitated the induction of LTP in the hippocampus which was persistent over 2 hr. α-Terpineol (100 and 200 mg/kg) also significantly lowered hippocampal MDA levels in rats subjected to cerebral ischemia. These findings indicate that α-terpineol improves cerebral ischemia-related memory impairment in rats through the facilitation of LTP and suppression of lipid peroxidation in the hippocampus.

Neuroprotective Effect of Dracocephalum moldavica L. Total Flavonoids in Transient Cerebral Ischemia in Rats

Aims: The aim of the present study was to investigate the potential neuroprotective effects of Dracocephalum moldavica L. total flavonoids (DMTF) on cerebral oxidative stress and damage as well as apoptosis induced by transient cerebral ischemia in rats. Methodology: Wistar rats were randomly divided into five groups: model group, sham group, DMTF high, middle, low dose groups (50, 25, 12.5 mg/kg). Focal cerebral ischemia/reperfusion was induced by middle cerebral artery occlusion (MCAO) for 2 h, followed by 22 h reperfusion. The reduced glutathione/ oxidized glutathione (GSH/GSSG) ratio, antioxidant enzyme activities, malondialdehyde (MDA), protein carbonyl and 8hydroxy-deoxyguanosine (8-OHdG) contents were determined. The neuron apoptosis was measured by TdT-mediated dUTP nick end labeling (TUNEL) assay. At last, the Original Research Article Annual Research & Review in Biology, 4(12): 1915-1926, 2014 1916 neurological deficit was observed. Results: Transient cerebral ischemia led to significant depress in GSH/GSSG ratio, depletion in antioxidant enzyme activities, rise in MDA, protein carbonyl, 8-OHdG contents, neuron apoptosis and neurological deficit scores. Pre-treatment with DMTF obviously attenuated the brain oxidative stress and damage, apoptosis and neurological deficits. Conclusion: These findings suggested that DMTF has neuroprotective effect on cerebral ischemia/reperfusion injury which might be related to its antioxidant and anti-apoptosis activity.

Ionizing radiation as preconditioning against transient cerebral ischemia in rats.

Induction of ischemic tolerance (IT), the ability of an organism to survive an otherwise lethal ischemia, is the most effective known approach to preventing postischemic damage. IT can be induced by exposing animals to a broad range of stimuli. In this study we tried to induce IT of brain neurons using ionizing radiation (IR). A preconditioning (pre-C) dose of 10, 20, 30 or 50 Gy of gamma rays was used 2 days before an 8 min ischemia in adult male rats. Ischemia alone caused the degeneration of almost one half of neurons in CA1 region of hippocampus. However, a significant decrease of the number of degenerating neurons was observed after higher doses of radiation (30 and 50 Gy). Moreover, ischemia significantly impaired the spatial memory of rats as tested in Morris's water maze. In rats with a 50 Gy pre-C dose, the latency times were reduced to values close to the control level. Our study is the first to reveal that IR applied in sufficient doses can induce IT and thus allow pyramidal CA1 neurons to survive ischemia. In addition, we show that the beneficial effect of IR pre-C is proportional to the radiation dose.

Effect of Propofol Post-treatment on Blood–Brain Barrier Integrity and Cerebral Edema After Transient Cerebral Ischemia in Rats

Although propofol has been reported to offer neuroprotection against cerebral ischemia injury, its impact on cerebral edema following ischemia is not clear. The objective of this investigation is to evaluate the effects of propofol post-treatment on blood-brain barrier (BBB) integrity and cerebral edema after transient cerebral ischemia and its mechanism of action, focusing on modulation of aquaporins (AQPs), matrix metalloproteinases (MMPs), and hypoxia inducible factor (HIF)-1α. Cerebral ischemia was induced in male Sprague-Dawley rats (n = 78) by occlusion of the right middle cerebral artery for 1 h. For post-treatment with propofol, 1 mg kg(-1) min(-1) of propofol was administered for 1 h from the start of reperfusion. Nineteen rats undergoing sham surgery were also included in the investigation. Edema and BBB integrity were assessed by quantification of cerebral water content and extravasation of Evans blue, respectively, following 24 h of reperfusion. In addition, the expression of AQP-1, AQP-4, MMP-2, and MMP-9 was determined 24 h after reperfusion and the expression of HIF-1α was determined 8 h after reperfusion. Propofol post-treatment significantly reduced cerebral edema (P < 0.05) and BBB disruption (P < 0.05) compared with the saline-treated control. The expression of AQP-1, AQP-4, MMP-2, and MMP-9 at 24 h and of HIF-1α at 8 h following ischemia/reperfusion was significantly suppressed in the propofol post-treatment group (P < 0.05). Propofol post-treatment attenuated cerebral edema after transient cerebral ischemia, in association with reduced expression of AQP-1, AQP-4, MMP-2, and MMP-9. The decreased expression of AQPs and MMPs after propofol post-treatment might result from suppression of HIF-1α expression.

MiR-15b Suppression of Bcl-2 Contributes to Cerebral Ischemic Injury and is Reversed by Sevoflurane Preconditioning

Ischemic neuroprotection afforded by sevoflurane preconditioning has been previously demonstrated, yet the underlying mechanism is poorly understood and likely affects a wide range of cellular activities. Several individual microRNAs have been implicated in both the pathogenesis of cerebral ischemia and cellular survival, and are capable of affecting a range of target mRNA. Conceivably, sevoflurane preconditioning may lead to alterations in ischemia-induced microRNA expression that may subsequently exert neuroprotective effects. We first examined the microRNA expression profile following transient cerebral ischemia in rats and the impact of sevoflurane preconditioning. Microarray analysis revealed that 3 microRNAs were up-regulated (>2.0 fold) and 9 were down-regulated (< 0.5 fold) following middle cerebral artery occlusion (MCAO) compared to sham controls. In particular, miR-15b was expressed at significantly high levels after MCAO. Preconditioning with sevoflurane significantly attenuated the upregulation of miR-15b at 72h after reperfusion. Bcl-2, an anti-apoptotic gene involved in the pathogenesis of cerebral ischemia, has been identified as a direct target of miR-15b. Consistent with the observed downregulation of miR-15b in sevoflurane-preconditioned brain, postischemic Bcl-2 expression was significantly increased by sevoflurane preconditioning. We identified the 3'-UTR of Bcl-2 as the target for miR-15b. Molecular inhibition of miR-15b was capable of mimicking the neuroprotective effect of sevoflurane preconditioning, suggesting that the suppression of miR-15b due to sevoflurane contributes to its ischemic neuroprotection. Thus, sevoflurane preconditioning may exert its anti-apoptotic effects by reducing the elevated expression of miR-15b following ischemic injury, allowing its target proteins, including Bcl-2, to be translated and expressed at the protein level.

Therapeutic Modulation of Brain Temperature: Relevance of Hypothermia to Inflammatory Changes following Transient Cerebral Ischemia in Rats

Background : In stroke, the ischemic crisis activates a series of events, including the inflammatory reactions that are potentiated by reperfusion, eventually leading to neuronal damage. Mild hypothermia has been considered to have a protective effect during ischemic neuronal cell death. The chief aim in this study was to investigate whether changing temperature during and after ischemia could minimize this damage by reducing the inflammatory injury.&#x0D; Material and Methods: The effect of moderate whole body hypothermia (300 C) on transient focal cerebral ischemia induced inflammatory injury was investigated. Experimental stroke (transient focal cerebral ischemia) was induced by a 2-hour middle cerebral artery occlusion (MCAO) with the use of a suture inserting into the lumen of the internal carotid artery (ICA) in male Wistar rats. Histopathological evaluation was performed 96 h after reperfusion.&#x0D; Results: MCAO induced inflammatory injury, involving the ipsilateral cortex and basal ganglia with massive infiltration of neutrophils, macrophages and microvascular proliferation, was exhibited in all normothermic rats. However, hypothermic MCAO rats showed minimal inflammatory response.&#x0D; Conclusion: The present study provides experimental evidence for the beneficial role of mild hypothermia using reversible MCAO in rats. Our results indicate that moderate hypothermia has a significant protective effect on the inflammatory injury induced by transient focal cerebral ischemia. Perhaps, the therapeutic effect was related to a reduction in releasing of cytotoxic products and improvement of the cerebral microcirculation.&#x0D; Bangladesh Journal of Neuroscience 2013; Vol. 29 (1) : 18-23

Methylprednisolone improves the survival of new neurons following transient cerebral ischemia in rats.

Cerebral ischemia induced the proliferation and differentiation of neural stem cells in discrete regions of brain. However, only a small fraction of the neural stem/progenitor cells survives. In this report, the effects of methylprednisolone (MP) on proliferation, differentiation and survival of neural progenitor cells were explored through early MP administration after occlusion of the middle cerebral artery (MCAo). Transient cerebral ischemia was induced by middle cerebral artery occlusion in Sprague Dawley male rats. One hour, 1 day, 3 days, 14 days, and 28 days after MCAo, neurological examination was performed to evaluate the neurological deficit. MCAo rats were randomly divided into two groups, MP-group was injected MP (30 mg/kg, i.p.) at 3 h, 12 h, and 24 h after MCAo, and vehicle group was injected equal saline (i.p.). Animals were sacrificed at 3 days, 14 days, and 28 days after MCAo. MP was found to decrease apoptosis and TNF-alpha and IL-6 expression at 3 days after MCAo in the ipsilateral striatum. Moreover, MP significantly increased the migrated new neurons (BrdU+/ DCX+) and immature neurons (BrdU+/Tuj1+) at day 14 after MCAo in the ipsilateral striatum. Likewise, MP increased the number of mature neurons (BrdU+/MAP2+) at 28 days after MCAo. However, MP did not affect the progenitor cell proliferation (BrdU+ and Nestin+) at day 3 after MCAo in the subventricular zone (SVZ), but improved the neurological deficit at day 1 and day 3 after MCAo. These results indicate that early MP administration can improve the neurological deficit and enhance the survival of new neurons in the ipsilateral striatum by inhibiting apoptosis and downregulation of inflammatory response after transient cerebral ischemia in rats.

A Comparative Study of Neuroprotective Effect of Single and Combined Blockade of AT1 Receptor and PARP-1 in Focal Cerebral Ischaemia in Rat

Cerebral ischaemia results in enhanced expression of type 1 angiotensin receptor and oxidative stress. Free radicals due to oxidative stress lead to excessive DNA damage causing overactivation of poly (ADP-ribose) polymerase-1 resulting in neuronal death. Activation of both type 1 angiotensin receptors and poly (ADP-ribose) polymerase-1 following cerebral ischaemia takes place simultaneously, but until now, no study has explored the effect of combined blockade of both angiotensin type 1 angiotensin receptor and poly (ADP-ribose) polymerase-1 in cerebral ischaemia. Our purpose was to compare the effect of single and combined treatment with angiotensin type 1 angiotensin receptor blocker, candesartan, and the poly (ADP-ribose) polymerase-1 inhibitor, 1, 5 isoquinolinediol, on brain damage and oxidative stress in transient focal cerebral ischaemia in rats. Transient focal cerebral ischaemia was induced in Sprague-Dawley rats by an intraluminal technique for two-hours following 48 h of reperfusion. Candesartan (0·05 mg/kg) was administered just after initiation of ischaemia followed by a repeat administration at 24 h while 1, 5 isoquinolinediol (0·1 mg/kg) was given one-hour after of ischaemia. After 24 h of reperfusion, neurological deficit was evaluated in the different treatment groups. After 48 h of reperfusion, the rats were sacrificed and the brain was isolated. Ischaemic brain damage by 2,3,5 triphenyl tetrazolium chloride staining, oxidative stress markers, and levels of reactive oxygen species were determined biochemically. Single treatment with candesartan and 1, 5 isoquinolinediol significantly reduced neurological deficit, infarct, and oedema volume as compared to ischaemic control and different vehicle groups for each of the drugs. However, treatment with candesartan + 1, 5 isoquinolinediol offered greater reduction in neurological deficit, cerebral infarct volume, and oedema as compared to single-drug treatments. Furthermore, treatment with candesartan + 1, 5 isoquinolinediol significantly decreased oxidative stress as compared to single treatments with each drug. The study suggests that blockade of either type 1 angiotensin receptor or poly (ADP-ribose) polymerase-1 alone provides neuroprotection, but the better result was achieved when both type 1 angiotensin receptor and poly (ADP-ribose) polymerase-1 were blocked together by the combined use of their pharmacological inhibitor in transient cerebral ischaemia in rat.

S-Nitrosylation of Mixed Lineage Kinase 3 Contributes to Its Activation after Cerebral Ischemia

Previous studies in our laboratory have shown that mixed lineage kinase 3 (MLK3) can be activated following global ischemia. In addition, other laboratories have reported that the activation of MLK3 may be linked to the accumulation of free radicals. However, the mechanism of MLK3 activation remains incompletely understood. We report here that MLK3, overexpressed in HEK293 cells, is S-nitrosylated (forming SNO-MLK3) via a reaction with S-nitrosoglutathione, an exogenous nitric oxide (NO) donor, at one critical cysteine residue (Cys-688). We further show that the S-nitrosylation of MLK3 contributes to its dimerization and activation. We also investigated whether the activation of MLK3 is associated with S-nitrosylation following rat brain ischemia/reperfusion. Our results show that the administration of 7-nitroindazole, an inhibitor of neuronal NO synthase (nNOS), or nNOS antisense oligodeoxynucleotides diminished the S-nitrosylation of MLK3 and inhibited its activation induced by cerebral ischemia/reperfusion. In contrast, 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (an inhibitor of inducible NO synthase) or nNOS missense oligodeoxynucleotides did not affect the S-nitrosylation of MLK3. In addition, treatment with sodium nitroprusside (an exogenous NO donor) and S-nitrosoglutathione or MK801, an antagonist of the N-methyl-D-aspartate receptor, also diminished the S-nitrosylation and activation of MLK3 induced by cerebral ischemia/reperfusion. The activation of MLK3 facilitated its downstream protein kinase kinase 4/7 (MKK4/7)-JNK signaling module and both nuclear and non-nuclear apoptosis pathways. These data suggest that the activation of MLK3 during the early stages of ischemia/reperfusion is modulated by S-nitrosylation and provides a potential new approach for stroke therapy whereby the post-translational modification machinery is targeted.