Cerebral Injury In Mice Research Articles

CircPTP4A2 Promotes Microglia Polarization in Cerebral Ischemic Stroke via miR-20b-5p/YTHDF1/TIMP2 Axis.

Activated microglia play dual roles in ischemic stroke (IS) according to its polarization states. Herein, we investigated the function of circPTP4A2 in regulating microglia polarization in IS. IS models were established by MACO/R and OGD/R treatment. TTC staining was employed to detect cerebral infarct size. Cell vitality was measured using CCK-8 assay. CD16 and CD206 levels were examined using flow cytometry. The interactions between circPTP4A2, miR-20b-5p, and YTHDF1 were analyzed by dual-luciferase reporter gene, RIP, or RNA pull-down assays. circPTP4A2 was upregulated in IS patients. circPTP4A2 knockdown alleviated MCAO/R-induced cerebral injury in mice. circPTP4A2 knockdown promoted microglia M2 polarization after OGD/R. circPTP4A2 promoted YTHDF1 expression by sponging miR-20b-5p. The promoting effect of circPTP4A2 knockdown on microglia M2 polarization was abrogated by miR-20b-5p inhibition. YTHDF1 activated the NF-κB pathway by increasing TIMP2 mRNA stability and expression. circPTP4A2 downregulation promoted microglia M2 polarization to inhibit IS development by regulating the miR-20b-5p/YTHDF1/TIMP2/NF-κB axis.

Dietary neoagarotetraose extends lifespan and impedes brain aging in mice via regulation of microbiota-gut-brain axis

IntroductionDietary oligosaccharides can impact the gut microbiota and confer tremendous health benefits. ObjectivesThe aim of this study was to determine the impact of a novel functional oligosaccharide, neoagarotetraose (NAT), on aging in mice. Methods8-month-old C57BL/6J mice as the natural aging mice model were orally administered with NAT for 12 months. The preventive effect of NAT in Alzheimer’s disease (AD) mice was further evaluated. Aging related indicators, neuropathology, gut microbiota and short-chain fatty acids (SCFAs) in cecal contents were analyzed. ResultsNAT treatment extended the lifespan of these mice by up to 33.3 %. Furthermore, these mice showed the improved aging characteristics and decreased injuries in cerebral neurons. Dietary NAT significantly delayed DNA damage in the brain, and inhibited reduction of tight junction protein in the colon. A significant increase at gut bacterial genus level (such as Lactobacillus, Butyricimonas, and Akkermansia) accompanied by increasing concentrations of SCFAs in cecal contents was observed after NAT treatment. Functional profiling of gut microbiota composition indicated that NAT treatment regulated the glucolipid and bile acid-related metabolic pathways. Interestingly, NAT treatment ameliorated cognitive impairment, attenuated amyloid-β (Aβ) and Tau pathology, and regulated the gut microbiota composition and SCFAs receptor-related pathway of Alzheimer’s disease (AD) mice. ConclusionNAT mitigated age-associated cerebral injury in mice through gut-brain axis. The findings provide novel evidence for the effect of NAT on anti-aging, and highlight the potential application of NAT as an effective intervention against age-related diseases.

Flavonoids from Citrus paradise cv. Changshan-huyou exerts protective effect on ischemia-induced cerebral injury in mice via inhibiting RhoA-ROCK2 signaling pathway.

To investigate the protective effect and mechanism of total flavonoids from Citrus paradise cv. Changshan-huyou extracts (TFC) on oxygen-glucose deprivation (OGD) of primary neurons and chronic ischemia-induced cerebral injury in mice. Primary hippocampal neurons of 18-day fetal rats were isolated and cultured for 1 week, then treated with 0.25, 0.50 and 1.00 mg/mL TFC. After oxygen-glucose deprivation for 1 h, cells were reperfused for 6 and 24 h, respectively. The cytoskeleton was observed by phalloidin staining. In animal study, 6-week ICR male mice were randomly divided into sham operation group, model group, low-dose (10 mg/kg), medium-dose (25 mg/kg) and high-dose (50 mg/kg) TFC treatment groups, with 20 mice in each group. After 3 weeks, chronic cerebral ischemia was induced by unilateral common carotid artery ligation in all groups except sham operation group. Mice were treated with different concentrations of TFC in the three TFC treatment groups for 4 weeks. Open field test, novel object recognition test and Morris water maze test were used to evaluate anxiety, learning and memory of these mice. Nissl, HE and Golgi stainings were used to detect neuronal degeneration and dendritic spine changes in the cortex and the hippocampus. The expression levels of Rho-associated kinase (ROCK) 2, LIM kinase (LIMK) 1, cofilin and its phosphorylation, as well as the expression of globular actin (G-actin) and filamentous actin (F-actin) protein in hippocampus of mice were detected by Western blotting. Neurons subjected to OGD showed that neurites displayed shortening and breakage; while treatment with TFC reversed OGD-induced neurite injury, especially in the 0.50 mg/mL TFC group. Compared with the sham operation group, the mice in the model group showed a significant decline in anxiety and cognitive ability (P<0.01), whereas treatment with TFC significantly reversed anxiety and cognitive deficits (P<0.05). Improvement in the medium-dose TFC group was the most obvious. Histopathological analysis indicated that the number of Nissl bodies and dendritic spines in hippocampus and cortex were decreased in the model group (all P<0.01). However, after treatment with medium dose of TFC, the number of Nissl bodies and dendritic spines (all P<0.05) was significantly recovered. Compared with the sham operation group, the phosphorylation level of ROCK2 in the brain tissue of the model group was significantly increased (P<0.05), while the phosphorylation levels of LIMK1 and cofilin were significantly decreased (P<0.05), and the relative content ratio of G-actin/F-actin was significantly increased (P<0.05). After administration of TFC, the phosphorylation level of ROCK2 in brain tissue of each group was significantly decreased (P<0.05), while the phosphorylation levels of LIMK1 and cofilin were significantly up-regulated (P<0.05) and the relative content ratio of G-actin/F-actin was significantly decreased (P<0.05). TFC protects from ischemia-induced cytoskeletal damage, reduces neuronal dendritic spine injury and protects mice against chronic cerebral ischemia through RhoA-ROCK2 signaling pathway, indicating that TFC might be a potential candidate for treatment of chronic ischemic cerebral injury.

Dental pulp stem cell-derived exosomes alleviate cerebral ischaemia-reperfusion injury through suppressing inflammatory response.

ObjectivesThe study aimed to determine whether dental pulp stem cell‐derived exosomes (DPSC‐Exos) exert protective effects against cerebral ischaemia‐reperfusion (I/R) injury and explore its underlying mechanism.Materials and MethodsExosomes were isolated from the culture medium of human DPSC. Adult male C57BL/6 mice were subjected to 2 hours transient middle cerebral artery occlusion (tMCAO) injury followed by 2 hours reperfusion, after which singular injection of DPSC‐Exos via tail vein was administrated. Brain oedema, cerebral infarction and neurological impairment were measured on day 7 after exosomes injection. Then, oxygen‐glucose deprivation–reperfusion (OGD/R) induced BV2 cells were studied to analyse the therapeutic effects of DPSC‐Exos on I/R injury in vitro. Protein levels of TLR4, MyD88, NF‐κB p65, HMGB1, IL‐6, IL‐1β and TNF‐α were determined by western blot or enzyme‐linked immunosorbent assay. The cytoplasmic translocation of HMGB1 was detected by immunofluorescence staining.ResultsDPSC‐Exos alleviated brain oedema, cerebral infarction and neurological impairment in I/R mice. DPSC‐Exos inhibited the I/R‐mediated expression of TLR4, MyD88 and NF‐κB significantly. DPSC‐Exos also reduced the protein expression of IL‐6, IL‐1β and TNF‐α compared with those of the control both in vitro and in vivo. Meanwhile, DPSC‐Exos markedly decreased the HMGB1 cytoplasmic translocation induced by I/R damage.ConclusionsDPSC‐Exos can ameliorate I/R‐induced cerebral injury in mice. Its anti‐inflammatory mechanism might be related with the inhibition of the HMGB1/TLR4/MyD88/NF‐κB pathway.

Tenacissoside H promotes neurological recovery of cerebral ischaemia/reperfusion injury in mice by modulating inflammation and oxidative stress via TrkB pathway.

Cerebral ischaemia/reperfusion (I/R)-induced acute brain injury remains a troublesome condition in clinical practice. The present study aimed to investigate the protective effect of tenacissoside H (TH) on I/R-induced cerebral injury in mice. Here, a mouse model of middle cerebral artery occlusion (MCAO) was established by an improved Longa-Zea method. TH was given by intraperitoneal injection once a day within 1week before establishing the mouse MCAO model. The neurological functions of mice were evaluated and the apoptosis of neurons was also detected by the TUNEL method and Nissl's staining. ELISA and western blot were used to detect the expression of inflammatory factors, oxidation factors and proteins in the cerebral ischaemic cortex. The results revealed that TH dose-dependently reduced neurological impairment, neuron apoptosis and brain oedema induced by MCAO. Furthermore, TH attenuated the expression of pro-inflammatory cytokines (including interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α), iNOS and nuclear factor (NF)-κB while increased production of anti-inflammatory cytokines (IL-4, IL-10 and BDNF) and proteins of tropomyosin-related kinase receptor B (TrkB) and PPARγ. Nevertheless, after the addition of TrkB inhibitor, the effects of TH above were mostly restrained. In conclusion, TH can protect mice against I/R-induced neurological impairments via modulating inflammation and oxidative stress through TrkB signalling.

Isolation and characterization of components responsible for neuroprotective effects of Allium cepa outer scale extract against ischemia reperfusion induced cerebral injury in mice.

The antioxidant-mediated neuroprotective effect of Allium cepa outer scale extract (ACE) in mice with cerebral ischemia-reperfusion (I-R) injury was demonstrated in our earlier work. The current investigation aimed at establishing the bioactive component(s) responsible for this activity. Thus ACE was fractionated into ethyl acetate (EF) and aqueous (AF) fractions. These fractions were evaluated against cerebral I-R injury in mice. I-R injury in mice was induced by bilateral common carotid artery occlusion followed by 24 hr reperfusion. Memory, sensorimotor functions, cerebral infarct size, and oxidative stress were measured to address the neuroprotective mechanism of test substances. EF showed marked improvement of memory and sensorimotor functions by reducing brain oxidative stress and infarct size in mice after I-R injury. The bioactive EF was subjected to chromatographic (HPLC-PDA, HPLC-MS, preparative HPLC) and spectroscopic studies to isolate and identify the neuroprotective compounds. This lead to separation of three components, namely quercetin, quercetin 4'-O-glucoside, and the remaining fraction, from EF. The separated components were biologically evaluated. These components showed improvement in mice with I-R injury. But, EF displayed more marked neuroprotective effects as compared to the isolated components. The distinct neuroprotective outcome of EF may be credited to the synergistic action of compounds present in EF. Further studies such as evaluation of neurotoxic effects and other possible neuroprotective mechanisms are required to develop EF as a neuroprotective drug.

Caspase-1 inhibition mediates neuroprotection in experimental stroke by polarizing M2 microglia/macrophage and suppressing NF-κB activation

Stroke is a life-threatening neurological disease with limited therapeutic options. Inflammation is believed to be involved in the pathogenesis of ischemic stroke and contribute to the degree of brain injury. Vx-765 is a potent, selective, small-molecule caspase-1 inhibitor. Current studies have shown the anti-inflammatory properties of vx-765 in various disease; however, the impact of vx-765 on the ischemic stroke is still unclear. In the present study, we determine the neuroprotective effect of vx-765 in mice subjected to transient middle cerebral artery occlusion (MCAO). We found that caspase-1 inhibition by administration of vx-765 ameliorated cerebral injury in mice after ischemic stroke by reducing infarct volume and ameliorating the neurological deficits. Mechanistically, we showed that the contribution of vx-765 to ischemic injuries may be associated with reducing microglial activation, and downregulating the production of associated pro inflammatory cytokines including IL-1β, TNF-α, and iNOS, as well as upregulating anti-inflammatory cytokines such as TGF-β and YM-1. Additionally, vx-765 altered the phenotype of microglia via switching the microglia polarization toward M2 phenotype, as demonstrably related to inhibition of the NF-κB activation. Our findings indicate that vx-765 protects against MCAO injury and attenuated microglia mediated neuroinflammation primarily by shifting microglia polarization from M1 phenotype toward M2 phenotype. Vx-765 might be a potential therapeutic drug for ameliorating ischemic stroke.

Amelioration of ischaemia reperfusion-induced cerebral injury in mice by liposomes containing Allium cepa fraction administered intranasally

Neuroprotection in ischaemic stroke prevents neuronal injury and subsequent death. Our earlier work revealed the neuroprotective effect of ethylacetate fraction (EF) obtained from Allium cepa outer scales in a mouse model of cerebral ischaemia–reperfusion (I–R) injury. The present study was designed to develop and optimize a liposomal delivery system for EF, along with its biological assessment. Thin film hydration method was used for the preparation of liposomal formulation. The prepared liposomes were optimized with respect to particle size, size distribution and encapsulation efficiency (EE) and characterised on the basis of zeta potential, in vitro release, morphology (TEM) and physical stability. The biological activity of the optimized liposomal formulation (EF-L; 8.5 mg/kg, intra-nasal) was evaluated after induction of cerebral injury in the experimental animals. Neuroprotective effects were assessed in terms of improvement of cognitive/sensorimotor functions and reduction of cerebral infarct size and brain oxidative stress. EF-L (particle size of 204.93 ± 7.96 nm; EE of 88.02 ± 2.09%; zeta potential of –20.8 ± 1.24 mV) showed controlled release pattern; spherical shape and were physically stable for 60 days at 4 °C. Intra-nasal administration of EF-L produced significant neuroprotection in mice at 1/10th the oral dose. Thus, EF-L may be developed as a neuroprotective formulation.

Antioxidant-mediated neuroprotection by Allium schoenoprasum L. leaf extract against ischemia reperfusion-induced cerebral injury in mice

Background Oxidative stress is strongly implicated in ischemia reperfusion (IR)-mediated functional and neuronal impairment. Therefore, strategies employing antioxidants to reverse the damage due to IR are being investigated. Allium schoenoprasum L. is a culinary medicine whose antioxidant properties are well documented but whose neuroprotective potential has not been examined. Hence, the present study was designed to evaluate the effect of A. schoenoprasum leaf extract (ASLE) on functional deficit against IR-induced cerebral injury in mice. Methods Acute toxicity studies of ASLE were performed following the Organisation for Economic Co-operation and Development Guideline 423. IR injury was induced by bilateral common carotid artery occlusion (BCCAO) for 15 min followed by 24-h reperfusion. Animals were treated for 7 days with ASLE (200 and 400 mg/kg, p.o. once daily) after IR injury. Functional outcomes (memory and sensorimotor functions) were measured using Morris water maze and neurological severity score, respectively. Cerebral infarct size and oxidative stress (thiobarbituric acid reactive species (TBARS), reduced glutathione (GSH), and superoxide dismutase (SOD) activity) were measured in order to elucidate the neuroprotective mechanism of ASLE. Results No toxic effects of ASLE were observed in mice. Oral treatment with ASLE for 7 days significantly attenuated IR-mediated memory and sensorimotor function deficit in the animals. The extract also reduced the cerebral infarct size and rise in brain TBARS levels, and restored the GSH levels and SOD activity. Conclusions The results of the present study suggest that ASLE is safe and effective in improving functional outcomes. It demonstrates neuroprotective effect by enhancing the antioxidant defence against IR injury.

Improvement of memory and neurological deficit with Ocimum basilicum L. extract after ischemia reperfusion induced cerebral injury in mice.

Oxidative stress is strongly implicated in the pathogenesis of stroke. Strategies using antioxidants to improve neurological functions after stroke have, thus, gained significant attention. Ocimum basilicum L. is used traditionally to treat CNS disorders. Its antioxidant capacity is well established. Our laboratory has reported protective effects of pre-treatment with O. basilicum in experimental stroke, but its curative (post-treatment) effects in ischemic stroke have not been documented. Hence, the present study was aimed to evaluate the effect of O. basilicum leaf extract (OBLE) on functional outcomes following cerebral injury in mice. Cerebral injury was induced in the experimental animals by bilateral common carotid artery occlusion (BCCAO) followed by reperfusion. OBLE treatment (200 and 400mg/kg; orally, once daily) was given for 7days after BCCAO. Cognitive outcomes and sensorimotor disturbances were evaluated with Morris Water Maze, Elevated Plus Maze and neurological severity score, respectively. TTC (2,3,5-triphenyltetrazolium chloride) staining was used to measure cerebral infarct size. Thiobarbituric acid reactive substances, reduced glutathione levels and superoxide dismutase activity in mice brain homogenate were estimated to elucidate the neuroprotective mechanism of OBLE. Treatment with OBLE resulted in marked improvement in memory and motor coordination. OBLE also decreased cerebral infarct size and oxidative stress in mice. The extract was standardised with respect to total phenol content; an HPLC-PDA analysis showed the presence of eight phenolic acids in OBLE. It is concluded that treatment with OBLE improves functional outcomes after ischemic stroke and this may be developed as a neuroprotective drug.

Neuroprotective effects of ocimum kilimandscharicum leaf extract against ischemia-reperfusion induced cerebral injury in mice

Neuroprotective effects of ocimum kilimandscharicum leaf extract against ischemia-reperfusion induced cerebral injury in mice

NLRP3 Deficiency Ameliorates Neurovascular Damage in Experimental Ischemic Stroke

Although the innate immune response to induce postischemic inflammation is considered as an essential step in the progression of cerebral ischemia injury, the role of innate immunity mediator NLRP3 in the pathogenesis of ischemic stroke is unknown. In this study, focal ischemia was induced by middle cerebral artery occlusion in NLRP3(-/-), NOX2(-/-), or wild-type (WT) mice. By magnetic resonance imaging (MRI), Evans blue permeability, and electron microscopic analyses, we found that NLRP3 deficiency ameliorated cerebral injury in mice after ischemic stroke by reducing infarcts and blood-brain barrier (BBB) damage. We further showed that the contribution of NLRP3 to neurovascular damage was associated with an autocrine/paracrine pattern of NLRP3-mediated interleukin-1β (IL-1β) release as evidenced by increased brain microvessel endothelial cell permeability and microglia-mediated neurotoxicity. Finally, we found that NOX2 deficiency improved outcomes after ischemic stroke by mediating NLRP3 signaling. This study for the first time shows the contribution of NLRP3 to neurovascular damage and provides direct evidence that NLRP3 as an important target molecule links NOX2-mediated oxidative stress to neurovascular damage in ischemic stroke. Pharmacological targeting of NLRP3-mediated inflammatory response at multiple levels may help design a new approach to develop therapeutic strategies for prevention of deterioration of cerebral function and for the treatment of stroke.

Pharmacological evidence for connection of nitric oxide-mediated pathways in neuroprotective mechanism of ischemic postconditioning in mice.

Introduction:Postconditioning (PoCo) is an adaptive phenomenon whereby brief repetitive cycles of ischemia with intermittent reperfusion instituted immediately after prolonged ischemia at the onset of prolonged reperfusion elicit tissue protection. PoCo is noted to exert a protective effect in various organs like heart, liver, kidney and brain. Various triggers, mediators and end effectors are suggested to contribute to the protective effect of PoCo. However, the neuroprotective mechanism of PoCo is poorly understood.Objectives:The present study has been designed to investigate the role of nitric oxide pathway in the neuroprotective mechanism of ischemic postconditioning (iPoCo) employing a mouse model of global cerebral ischemia and reperfusion-induced injury.Materials and Methods:Bilateral carotid artery occlusion (BCAO) of 12 min followed by reperfusion for 24 h was employed to produce ischemia and reperfusion (I/R)-induced cerebral injury in mice. Cerebral injury was assessed in the terms of cerebral infarct, memory impairment and motor in-coordination. Brain nitrite/nitrate; acetylcholinesterase activity, thiobarbituric acid reactive species (TBARS) and glutathione level were also estimated.Results:BCAO followed by reperfusion produced a significant rise in cerebral infarct size, memory impairment and motor incoordination. Further a rise in acetylcholinesterase activity and TBARS level along with fall in brain nitrite/nitrate and glutathione levels was also noted. iPoCo consisting of three episodes of 10 s carotid artery occlusion and reperfusion (instituted immediately after BCAO) significantly attenuated infarct size, memory impairment, motor incoordination as well as altered biochemicals. iPoCo-induced neuroprotective effects were significantly abolished by pretreatment of L-NAME, a nonselective NOS inhibitor.Conclusion:It may be concluded that the nitric oxide pathway probably plays a vital role in the neuroprotective mechanism of iPoCo.

Effect of delayed preconditioning with morphine on ischemic cerebral injury in mice and the role of classical protein kinase C

Objective To evaluate the effect of delayed preconditioning with morphine on ischemic cerebral injury in mice and the role of classical protein kinase C (cPKC).Methods Forty male BALB/C mice,weighing 20-22 g,were randomly divided into 4 groups (n =10 each):sham operation group (group S),ischemic cerebral injury group (group ICI),morphine preconditioning group (group MP) and cPKC inhibitor Go6983 group (group G).Ischemia was induced by middle cerebral artery occlusion (MCAO).In S group,the middle cerebralartery was only exposed but not occluded.In MP group,morphine 10 mg/kg was injected intraperitoneally 24 h before MCAO.In G group,morphine 10 mg/kg was injected intraperitoneally 24 h before MCAO and 5 μl Go6983 (6nmol) was injected into the left lateral cerebral ventricle immediately before MCAO.The neurologic deficit was evaluated and scored according to neurological disability status scale in a blind nanner 6 h after MCAO.The animals were sacrificed and brains were immediately removed for measurement of the brain edema and infarct volume.Apoptotic rate was calculated.Results Compared with S group,the neurologic deficit scores,infarct volume,brain edema and apoptotic rate were significantly increased in ICI,MP and G groups (P ＜ 0.01).Compared with group ICI,the neurologic deficit scores,infarct volume,brain edema and apoptotic rate were significantly decreased in group MP (P ＜ 0.01),and no significant change was found in the parameters mentioned above in group G (P ＞ 0.05).Conclusion Delayed preconditioning with morphine can reduce ischemic cerebral injury in mice and activation of classical cPKC signaling pathway is involved in the mechanism. Key words: Morphine; Ischemic pretreatment; Brain ischemia; Protein kinase C

MFGE8 inhibits inflammasome-induced IL-1β production and limits postischemic cerebral injury

Milk fat globule-EGF 8 (MFGE8) plays important, nonredundant roles in several biological processes, including apoptotic cell clearance, angiogenesis, and adaptive immunity. Several recent studies have reported a potential role for MFGE8 in regulation of the innate immune response; however, the precise mechanisms underlying this role are poorly understood. Here, we show that MFGE8 is an endogenous inhibitor of inflammasome-induced IL-1β production. MFGE8 inhibited necrotic cell-induced and ATP-dependent IL-1β production by macrophages through mediation of integrin β(3) and P2X7 receptor interactions in primed cells. Itgb3 deficiency in macrophages abrogated the inhibitory effect of MFGE8 on ATP-induced IL-1β production. In a setting of postischemic cerebral injury in mice, MFGE8 deficiency was associated with enhanced IL-1β production and larger infarct size; the latter was abolished after treatment with IL-1 receptor antagonist. MFGE8 supplementation significantly dampened caspase-1 activation and IL-1β production and reduced infarct size in wild-type mice, but did not limit cerebral necrosis in Il1b-, Itgb3-, or P2rx7-deficient animals. In conclusion, we demonstrated that MFGE8 regulates innate immunity through inhibition of inflammasome-induced IL-1β production.

Effect of Neurosteroid Modulation on Global Ischaemia-Reperfusion-Induced Cerebral Injury in Mice

The present study was designed to investigate the putative effect of neurosteroid modulation on global ischaemia-reperfusion-induced cerebral injury in mice. Bilateral carotid artery occlusion followed by reperfusion, produced a significant rise in cerebral infarct size along with impairment of grip strength and motor coordination in Swiss albino mice. Administration of carbamazepine (16 mg/kg, i.p.) before global cerebral ischaemia significantly attenuated cerebral infarct size and improved the motor performance. However, administration of indomethacin (100 mg/kg, i.p.) attenuated the neuroprotective effect of carbamazepine. Mexiletine (50 mg/kg, i.p.) did not produce significant neuroprotective effect. It may be concluded that the neuroprotective effect of carbamazepine may be due to increase in synthesis of neurosteroids perhaps by activating enzyme (3α HSD) as indomethacin attenuated the neuroprotective effect of carbamazepine. The sodium channel blocking effect of carbamazepine may not be involved in neuroprotection as mexiletine, a sodium channel blocker, did not produce significant neuroprotective effect.

Involvement of CCR-2 chemokine receptor activation in ischemic preconditioning and postconditioning of brain in mice

The present study has been designed to investigate the potential role of CCR-2 chemokine receptor in ischemic preconditioning as well as postconditioning induced reversal of ischemia–reperfusion injury in mouse brain. Bilateral carotid artery occlusion of 17min followed by reperfusion for 24h was employed in present study to produce ischemia and reperfusion induced cerebral injury in mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was evaluated using elevated plus-maze test and Morris water maze test. Rota rod test was employed to assess motor incoordination. Bilateral carotid artery occlusion followed by reperfusion produced cerebral infarction and impaired memory and motor co-ordination. Three preceding episodes of bilateral carotid artery occlusion for 1min and reperfusion of 1min were employed to elicit ischemic preconditioning of brain, while three episodes of bilateral carotid artery occlusion for 10s and reperfusion of 10s immediately after the completion of were employed to elicit ischemic postconditioning of brain. Both prior ischemic preconditioning as well as ischemic postconditioning immediately after global cerebral ischemia prevented markedly ischemia–reperfusion-induced cerebral injury as measured in terms of infarct size, loss of memory and motor coordination. RS 102895, a selective CCR-2 chemokine receptor antagonist, attenuated the neuroprotective effect of both the ischemic preconditioning as well as postconditioning. It is concluded that the neuroprotective effect of both ischemic preconditioning as well as ischemic postconditioning may involve the activation of CCR-2 chemokine receptors.

Involvement of src-kinase activation in ischemic preconditioning induced protection of mouse brain

AimsTo investigate the role of src-kinase in ischemic preconditioning induced reversal of ischemia and reperfusion induced cerebral injury in mice. Main methodsBilateral carotid artery occlusion of 17min followed by reperfusion for 24h was employed to produce ischemia and reperfusion induced cerebral injury in mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining using both by volume and by weight methods differently. Memory was evaluated using elevated plus maze test. Rota rod test was employed to assess motor incoordination. Key findingsBilateral carotid artery occlusion followed by reperfusion produced cerebral infarction and impaired memory and motor co-ordination. Three preceding episodes of bilateral carotid artery occlusion for 1min and reperfusion of 1min (ischemic preconditioning) prevented markedly ischemia–reperfusion-induced cerebral injury measured in terms of infarct size (38.5±1.3% and 38.5±2.9% mean infarct of control animals was reduced to 24.3±1.2% and 23.5±1.8% of the preconditioning groups respectively), loss of memory (72.2±3.6 mean transfer latency time of control animals was reduced to 25.6±5.2 of the preconditioning group respectively) and motor coordination (78.3±17.6s mean falling down latency time of control animals was increased to a mean value of 180.9±6.5s of the preconditioning groups respectively). SU6656 (2mg/kg, ip) and PP1 (0.1mg/kg, ip), highly selective src-kinase inhibitors, attenuated this neuroprotective effect of ischemic preconditioning. SignificanceTherefore, neuroprotective effect of ischemic preconditioning may be due to src-kinase linked mechanism.

Evaluation of Antioxidant and Cerebroprotective Effect of Medicago sativa Linn. against Ischemia and Reperfusion Insult

Antioxidants have been the focus of studies for developing neuroprotective agents to be used in the therapy for stroke, which is an acute and progressive neurodegenerative disorder. Medicago sativa (MS) has a long tradition of use as ayurvedic and homoeopathic medicine in central nervous system disorders. The plant has been reported to have antioxidant, anti-inflammatory and antidiabetic effects. Therefore, the present study was designed to investigate the neuroprotective effect of methanol extract of MS on ischemia and reperfusion-induced cerebral injury in mice. Bilateral carotid artery occlusion (BCAO) for 15 min followed by 24-h reperfusion, resulted in significant elevation in infarct size, xanthine oxidase (XO) activity, superoxide anion (O•− 2) production and thiobarbituric acid-reactive substance (TBARS) levels, and significant depletion in endogenous antioxidant [reduced glutathione (GSH), superoxide dismutase (SOD) and total tissue sulfhydryl (T-SH) groups] systems in mice brain. Further, BCAO led to impairment in short-term memory and motor coordination. Pre-treatment with MS (100 or 200 mg kg−1, p.o.) markedly reduced cerebral infarct size, XO, O•− 2 and TBARS levels, significantly restored GSH, SOD and T-SH levels and attenuated impairment in short-term memory and motor coordination. In addition, MS directly scavenged free radicals generated against a stable radical 1,1-diphenyl-2-picrylhydrazyl and O•− 2 generated in phenazine methosulphate-nicotinamide adenine dinucleotide systems, and also inhibited XD/XO conversion and resultant O•− 2 production. The data from this study suggest that treatment with MS enhances the antioxidant defense against BCAO-induced global cerebral ischemia and exhibits neuroprotective activity.

Possible Involvement of Ubiquitin Proteasome System and Other Proteases in Acute and Delayed Aspects of Ischemic Preconditioning of Brain in Mice

The present study has been designed to investigate the potential role of ubiquitin proteasome system and other proteases in acute as well as delayed aspects of ischemic preconditioning induced reversal of ischemia-reperfusion injury in mouse brain. Bilateral carotid artery occlusion of 17 min followed by reperfusion for 24 h was employed in present study to produce ischemia and reperfusion induced cerebral injury in mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was evaluated using elevated plus-maze test. Rota rod test was employed to assess motor incoordination. Bilateral carotid artery occlusion followed by reperfusion produced cerebral infarction and impaired memory and motor co-ordination. Three preceding episodes of bilateral carotid artery occlusion for 1 min and reperfusion of 1 min (ischemic preconditioning) both immediately before (for acute preconditioning) and 24 h before (for delayed preconditioning) global cerebral ischemia prevented markedly ischemia-reperfusion-induced cerebral injury as measured in terms of infarct size, loss of memory and motor coordination. Z-Leu-Leu-Phe-Chinese hamster ovary (CHO) (2 mg/kg, intraperitoneally (i.p.)), an inhibitor of ubiquitin proteasome system and other proteases attenuated the neuroprotective effect of both the acute as well as delayed ischemic preconditioning. It is concluded that the neuroprotective effect of both the acute as well as delayed phases of ischemic preconditioning may be due to the activation of ubiquitin proteasome system and other proteases.