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.     

Effect of Sargentodoxa cuneata total phenolic acids on focal cerebral ischemia reperfusion injury rats model

Objective

Explore the possible protective effect of Sargentodoxa cuneata total phenolic acids on cerebral ischemia reperfusion injury rats.

Continuous oral administration of atorvastatin ameliorates brain damage after transient focal ischemia in rats

Aims

Pre-treatment with statins is known to ameliorate ischemic brain damage after experimental stroke, and is independent of cholesterol levels. We undertook pre- vs post-ischemic treatment with atorvastatin after focal cerebral ischemia in rats.

Main methods

Male Sprague–Dawley rats underwent transient 90-min middle cerebral artery occlusion (MCAO). Atorvastatin (20 mg/kg/day) or vehicle was administered orally. Rats were divided into vehicle-treated, atorvastatin pre-treatment, atorvastatin post-treatment, and atorvastatin continuous-treatment groups. In the pre-treatment, rats were given atorvastatin or vehicle for 7 days before MCAO. In the post-treatment, rats received atorvastatin or vehicle for 7 days after MCAO. Measurement of infarct volume, as well as neurological and immunohistochemical assessments, were done 24 h and 7 days after reperfusion.

Key findings

Each atorvastatin-treated group demonstrated significant reductions in infarct and edema volumes compared with the vehicle-treated group 24 h after reperfusion. Seven days after reperfusion, infarct volumes in the post-treatment group and continuous-treatment group (but not the pre-treatment group) were significantly smaller than in the vehicle-treated group. Only the continuous-treatment group had significantly improved neurological scores 7 days after reperfusion compared with the vehicle group. Post-treatment and continuous-treatment groups had significantly decreased lipid peroxidation, oxidative DNA damage, microglial activation, expression of tumor necrosis factor-alpha, and neuronal damage in the cortical ischemic boundary area after 7 days of reperfusion.

Significance

These results suggest that continuous oral administration (avoiding withdrawal) with statins after stroke may reduce the extent of post-ischemic brain damage and improve neurological outcome by inhibiting oxidative stress and inflammatory responses.     

Phosphorylation of JNK Increases in the Cortex of Rat Subjected to Diabetic Cerebral Ischemia

Previous studies have demonstrated that the c-Jun N-terminal kinase (JNK) pathway plays an important role in inducing neuronal apoptosis following cerebral ischemic injury. JNK signaling pathway in activated during cerebral ischemic injury. It participates in ischemia-induced neuronal apoptosis. However, whether JNK signaling is involved in the process of neuronal apoptosis of diabetes-induced cerebral ischemia is largely unknown. This study was undertaken to evaluate the influence of cerebral ischemia–reperfusion injury on phosphorylation of JNK in diabetic rats. Twenty-four adult streptozotocin induced diabetic and 24 adult non-diabetic rats were randomly subjected to 15 min of forebrain ischemia followed by reperfusion for 0, 1, 3, and 6 h. Sixteen sham-operated diabetic and non-diabetic rats were used as controls. Apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL). Protein expression of phospho-JNK was examined by immunohistochemistry and Western blot. The numbers of TUNEL-positive cells and phospho-JNK protein expression in the cerebral cortices after 1, 3 and 6 h reperfusion was significantly higher in diabetic rats compared to non-diabetic animals subjected to ischemia and reperfusion (p < 0.05). Western blot analysis showed significantly higher phospho-JNK protein expression in the cerebral cortices of the diabetic rats after 1 and 3 h reperfusion than that was presented in non-diabetic animals subjected to ischemia and reperfusion (p < 0.05). These findings suggest that increased phosphorylation of JNK may be associated with diabetes-enhanced ischemic brain damage.     

Skeletal muscle post-conditioning by diazoxide, anti-oxidative and anti-apoptotic mechanisms

Pretreatment with diazoxide, K_ATP channel opener, increases tissue tolerance against ischemia reperfusion (IR) injury. In clinical settings pretreatment is rarely an option therefore we evaluated the effect of post-ischemic treatment with diazoxide on skeletal muscle IR injury. Rats were treated with either saline, diazoxide (K_ATP opener; 40?mg/kg) or 5-hydroxydecanoate (5-HD; mitochondrial K_ATP inhibitor; 40?mg/kg) after skeletal muscle ischemia (3?h) and reperfusion (6, 24 or 48?h). Tissue contents of malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT) activities, Bax and Bcl-2 protein expression and muscle histology were determined. Apoptosis was examined (24 and 48?h) after ischemia. IR induced severe histological damage, increased MDA content and Bax expression (24 and 48?h; p?<?0.01) and decreased CAT and SOD activities (6 and 24?h, p?<?0.01 and 48?h, p?<?0.05), with no significant effect on Bcl-2 expression. Diazoxide reversed IR effects on MDA (6 and 24?h; p?<?0.05), SOD (6 and 24?h; p?<?0.01) and CAT (6 and 48?h, p?<?0.05 and 24?h p?<?0.01) and tissue damage. Diazoxide also decreased Bax (24 and 48?h; p?<?0.05) and increased Bcl-2 protein expression (24 and 48?h; p?<?0.01). Post-ischemic treatment with 5-HD had no significant effect on IR injury. Number of apoptotic nuclei in IR and 5-HD treated groups significantly increased (p?<?0.001) while diazoxide decreased apoptosis (p?<?0.01). The results suggested that post-ischemic treatment with diazoxide decrease oxidative stress in acute phase which modulates expression of apoptotic proteins in the late phase of reperfusion injury. Involvement of KATP channels in this effect require further evaluations.     

毛蕊异黄酮通过抑制calpain-1的表达发挥抗脑缺血再灌注损伤的研究

目的:探讨毛蕊异黄酮抗脑缺血再灌注损伤的作用是否与抑制calpain-1的表达有关。方法:将SD大鼠随机分为假手术组、模型组以及药物组,采用线栓法建立大鼠大脑中动脉阻断(MCAO)模型,于缺血再灌注前30 min腹腔注射给予20 mg/kg毛蕊异黄酮或等体积的溶剂。再灌注24 h后,行神经功能学评分、脑梗死面积以及神经元凋亡检测;再灌注12 h、24 h时,采用免疫组化和蛋白印迹技术检测大鼠脑皮层calpain-1的表达。结果:与假手术组大鼠比较,MCAO模型组大鼠再灌注24 h后神经功能学评分、梗死面积、神经元凋亡率及calpain-1的表达均明显升高(P0.05),而毛蕊异黄酮能够降低模型组大鼠再灌注24 h后神经功能学评分、梗死面积、神经元凋亡率以及calpain-1的表达(P0.05)。结论:毛蕊异黄酮可能通过抑制calpain-1的表达发挥抗脑缺血再灌注损伤作用。     

Naringin Attenuates Cerebral Ischemia-Reperfusion Injury Through Inhibiting Peroxynitrite-Mediated Mitophagy Activation

Excessive autophagy/mitophagy plays important roles during cerebral ischemia-reperfusion (I/R) injury. Peroxynitrite (ONOO^?), a representative reactive nitrogen species, mediates excessive mitophagy activation and exacerbates cerebral I/R injury. In the present study, we tested the hypothesis that naringin, a natural antioxidant, could inhibit ONOO^?-mediated mitophagy activation and attenuate cerebral I/R injury. Firstly, we demonstrated that naringin possessed strong ONOO^? scavenging capability and also inhibited the production of superoxide and nitric oxide in SH-SY5Y cells exposed to 10 h oxygen-glucose-deprivation plus 14 h of reoxygenation or ONOO^? donor 3-morpholinosydnonimine conditions. Naringin also inhibited the expression of NADPH oxidase subunits and iNOS in rat brains subjected to 2 h ischemia plus 22 h reperfusion. Next, we found that naringin was able to cross the blood-brain barrier, and naringin decreased neurological deficit score, reduced infarct size, and attenuated apoptotic cell death in the ischemia-reperfused rat brains. Furthermore, naringin reduced 3-nitrotyrosine formation, decreased the ratio of LC3-II to LC3-I in mitochondrial fraction, and inhibited the translocation of Parkin to the mitochondria. Taken together, naringin could be a potential therapeutic agent to prevent the brain from I/R injury via attenuating ONOO^?-mediated excessive mitophagy.     

Neuroprotection by Propofol Post-Conditioning: Focus on PKMζ/KCC2 Pathway Activity

Critical and major operations are often accompanied by brain ischemic complications. Previous studies found that propofol post-conditioning provided neuroprotective functions through upregulating the expression of potassium chloride cotransporter 2 (KCC2) in gamma-aminobutyric acid (GABA) interneurons. Membrane expression and phosphorylation represents KCC2 activity, which were modulated by a protein kinase C (PKC)-dependent mechanism. However, the role of propofol in increasing KCC2 phosphorylation and the involvement of protein kinase Mζ (PKMζ), a major subtype of PKC, in the KCC2 pathway remained unclear. In this study, we established middle cerebral artery occlusion model in rats to evaluate the long-term recovery of brain functions using behavioral experiments. KCC2 and PKMζ were assessed via western blot. We used the selective inhibitor, zeta inhibitory peptide (ZIP), to investigate the relationship between KCC2 and PKMζ. Intracellular chloride concentration in the hippocampal CA1 area was measured to determine KCC2 activity. We found that propofol, infused at a speed of 20 mg kg^?1 h^?1 for 2 h at the onset of reperfusion, improved neurological deficits and cognitive dysfunction following ischemia/reperfusion injury. PKMζ expression was significantly upregulated, which improved KCC2 membrane expression and phosphorylation in the ischemic hippocampal CA1 area, and these effects could last up to 28 days. But ZIP inhibited this process. Ultimately, we showed that propofol increased KCC2 phosphorylation and PKMζ was the upstream of KCC2. Propofol led to long-term recovery of brain functions by upregulating the activity of the PKMζ/KCC2 pathway.     

Tetrandrine Attenuated Cerebral Ischemia/Reperfusion Injury and Induced Differential Proteomic Changes in a MCAO Mice Model Using 2-D DIGE

Ischemic stroke is the most common type of stroke and brings about a big disease burden because of high mortality and disability in China. Tetrandrine, a bisbenzylisoquinoline alkaloid isolated from the Chinese herb Radix Stephania tetrandra, has been demonstrated to possess anti-inflammatory and free radical scavenging effects and even regulate astrocyte activation, but the possible role of tetrandrine in ameliorating cerebral ischemia/reperfusion injury of ischemic stroke remains unknown. The aim of this study was to determine the effects of tetrandrine on neurological injury and differential proteomic changes induced by transient reversible middle cerebral artery occlusion (MCAO) in mice. Male Balb/c mice were divided into sham (n = 30), MCAO + saline as control (n = 30), and MCAO + Tet as tetrandrine-treated (n = 30) groups. Mice in the control and tetrandrine-treated groups underwent 120 min of MCAO following reperfusion. Immediately and 2 h after MCAO, the mice received either normal saline (sham operated and control groups) or tetrandrine (tetrandrine-treated group) intraperitoneally. Neurological defects, brain water content, and infarct volume at 24 h after stoke were used to evaluate neurological injury extent. Treatment with tetrandrine not only mitigated cerebral neurological deficits (P < 0.05) and infarct size (P < 0.01), but also decreased brian edema in the ischemic brain (P < 0.05). Then, fluorescence two-dimensional difference in gel electrophoresis was used to detect our systematic differential profiling of proteomic changes responding to tetrandrine administration. We validated that the expression of GRP78, DJ-1 and HYOU1 was associated with neuroprotective effect of tetrandrine in MCAO model by Western blotting. These findings indicate a potential neuroprotective role of tetrandrine for ischemic stroke and yield insights into cellular and molecular mechanisms of tetrandrine taking place in ischemic stroke.     

Anti-inflammatory effect of exendin-4 postconditioning during myocardial ischemia and reperfusion

High mobility group box 1 protein (HMGB1) plays an important role in myocardial ischemia and reperfusion (I/R) injury. Preconditioning of exendin-4 (Ex), a glucagon-like peptide-1 receptor agonist, has been reported to attenuate myocardial I/R injury. The current study investigated whether Ex postconditioning also attenuated myocardial I/R injury and the potential mechanisms. Anesthetized male rats were subjected to ischemia for 30 min and treated with Ex (5 μg/kg, i.v.) 5 min before reperfusion, in the absence and/or presence of exendin (9–39) (an antagonist of glucagon-like peptide-1 receptor, 5 μg/kg, i.v.), followed by reperfusion for 4 h. Lactate dehydrogenase (LDH), creatine kinase (CK), tumor necrosis factor-α, interleukin-6, and infarct size were measured. HMGB1 expression was assessed by immunoblotting. Postconditioning with Ex significantly decreased infarct size and levels of LDH and CK after 4 h reperfusion (all p < 0.05). Ex also significantly inhibited the increase in malondialdehyde level and decreased the level of superoxide dismutase (both p < 0.05). In addition, the increase in HMGB1 expression induced by I/R was significantly attenuated by Ex postconditioning. Administration of exendin (9–39) abolished the protective effect of Ex postconditioning (all p < 0.05). The present study suggests that Ex postconditioning may attenuate myocardial I/R injury, which may in turn be associated with inhibiting inflammation.     

Curcumin Improves Outcomes and Attenuates Focal Cerebral Ischemic Injury via Antiapoptotic Mechanisms in Rats

Curcumin, a member of the curcuminoid family of compounds, is a yellow colored phenolic pigment obtained from the powdered rhizome of C. longa Linn. Recent studies have demonstrated that curcumin has protective effects against cerebral ischemia/reperfusion injury. However, little is known about its mechanism. In the present study, we tested the effects of curcumin in focal cerebral ischemia in rats and the possible mechanisms. Adult male Sprague–Dawley rats were treated with curcumin (100, 300 and 500 mg/kg) administered intraperitoneally after 60 min of occlusion (beginning of reperfusion). Neurological score and infarct volume were assessed at 24 and 72 h. Oxidative stress was evaluated by malondialdehyde assay and the apoptotic mechanisms were studied by Western blotting. Curcumin treatment significantly reduced infarct volume and improved neurological scores at different time points compared with the vehicle-treated group. Curcumin treatment decreased malondialdehyde levels, cytochrome c, and cleaved caspase 3 expression and increased mitochondrial Bcl-2 expression. Inhibition of oxidative stress with curcumin treatment improves outcomes after focal cerebral ischemia. This neuroprotective effect is likely exerted by antiapoptotic mechanisms.     

Propofol Reduces Inflammatory Reaction and Ischemic Brain Damage in Cerebral Ischemia in Rats

Our previous studies demonstrated that inflammatory reaction and neuronal apoptosis are the most important pathological mechanisms in ischemia-induced brain damage. Propofol has been shown to attenuate ischemic brain damage via inhibiting neuronal apoptosis. The present study was performed to evaluate the effect of propofol on brain damage and inflammatory reaction in rats of focal cerebral ischemia. Sprague–Dawley rats underwent permanent middle cerebral artery occlusion, then received treatment with propofol (10 or 50 mg/kg) or vehicle after 2 h of ischemia. Neurological deficit scores, cerebral infarct size and morphological characteristic were measured 24 h after cerebral ischemia. The enzymatic activity of myeloperoxidase (MPO) was assessed 24 h after cerebral ischemia. Nuclear factor-kappa B (NF-κB) p65 expression in ischemic rat brain was detected by western blot. Cyclooxygenase-2 (COX-2) expression in ischemic rat brain was determined by immunohistochemistry. ELISA was performed to detect the serum concentration of tumor necrosis factor-α (TNF-α). Neurological deficit scores, cerebral infarct size and MPO activity were significantly reduced by propofol administration. Furthermore, expression of NF-κB, COX-2 and TNF-α were attenuated by propofol administration. Our results demonstrated that propofol (10 and 50 mg/kg) reduces inflammatory reaction and brain damage in focal cerebral ischemia in rats. Propofol exerts neuroprotection against ischemic brain damage, which might be associated with the attenuation of inflammatory reaction and the inhibition of inflammatory genes.     

Nicotine-Induced Neuroprotection Against Ischemic Injury Involves Activation of Endocannabinoid System in Rats

Nicotine has been reported to exert certain protective effect in the Parkinson’s and Alzheimer’s diseases. Whether it has a similar action in focal cerebral ischemia was unclear. In the present study, rats received either an injection of (?)-nicotine hydrogen tartrate salt (1.2 mg/kg, i.p.) or the vehicle 2 h before the 120 min middle cerebral artery occlusion. Neurological deficits and histological injury were assessed at 24 h after reperfusion. The content of endocannabinoids and the expression of cannabinoid receptor CB1 in brain tissues were determined at different time points after nicotine administration. Results showed that nicotine administration ameliorated neurological deficits and reduced infarct volume induced by cerebral ischemia in the rats. The neuroprotective effect was partially reversed by CB1 blockage. The content of the endocannabinoids N-arachidonylethanolamine and 2-arachidonoylglycerol, as well as the expression of cannabinoid receptor CB1 were up-regulated in brain tissues after nicotine delivery. These results suggest that endogenous cannabinoid system is involved in the nicotine-induced neuroprotection against transient focal cerebral ischemia.     

Irisin Peptide Protects Brain Against Ischemic Injury Through Reducing Apoptosis and Enhancing BDNF in a Rodent Model of Stroke

Evidence has shown therapeutic potential of irisin in cerebral stroke. The present study aimed to assess the effects of recombinant irisin on the infarct size, neurological outcomes, blood–brain barrier (BBB) permeability, apoptosis and brain-derived neurotrophic factor (BDNF) expression in a mouse model of stroke. Transient focal cerebral ischemia was established by middle cerebral artery occlusion (MCAO) for 45 min and followed reperfusion for 23 h in mice. Recombinant irisin was administrated at doses of 0.1, 0.5, 2.5, 7.5, and 15 µg/kg, intracerebroventricularly (ICV), on the MCAO beginning. Neurological outcomes, infarct size, brain edema and BBB permeability were evaluated by modified neurological severity score (mNSS), 2,3,5-triphenyltetrazolium chloride (TTC) staining and Evans blue (EB) extravasation methods, respectively, at 24 h after ischemia. Apoptotic cells and BDNF protein were detected by TUNEL assay and immunohistochemistry techniques. The levels of Bcl-2, Bax and caspase-3 proteins were measured by immunoblotting technique. ICV irisin administration at doses of 0.5, 2.5, 7.5 and 15 µg/kg, significantly reduced infarct size, whereas only in 7.5 and 15 µg/kg improved neurological outcome (P?<?0.001). Treatment with irisin (7.5 µg/kg) reduced brain edema (P?<?0.001) without changing BBB permeability (P?>?0.05). Additionally, irisin (7.5 µg/kg) significantly diminished apoptotic cells and increased BDNF immunoreactivity in the ischemic brain cortex (P?<?0.004). Irisin administration significantly downregulated the Bax and caspase-3 expression and upregulated the Bcl-2 protein. The present study indicated that irisin attenuates brain damage via reducing apoptosis and increasing BDNF protein of brain cortex in the experimental model of stroke in mice.     

Protective Effect of Aliskiren in Experimental Ischemic Stroke: Up-Regulated p-PI3K,p-AKT,Bcl-2 Expression,Attenuated Bax Expression

Aliskiren (ALK), a pharmacological renin inhibitor, is an effective antihypertensive drug and has potent anti-apoptotic activity, but it is currently unknown whether ALK is able to attenuate brain damage caused by acute cerebral ischemia independent of its blood pressure-lowering effects. This study aimed to investigate the role of ALK and its potential mechanism in cerebral ischemia. C57/BL6 mice were subjected to transient middle cerebral artery occlusion (tMCAO) and treated for 5 days with Vehicle or ALK (10 or 25 mg/kg per day via intragastric administration), whereas Sham-operated animals served as controls. Treatment with ALK significantly improved neurological deficits, infarct volume, brain water content and Nissl bodies after stroke (P < 0.05), which did not affect systemic blood pressure. Furthermore, the protection of ALK was also related to decreased levels of apoptosis in mice by enhanced activation of phosphatidylinositol 3-kinase (PI3K)/AKT pathway, increased level of Bcl-2 and reduced Bax expression (P < 0.05). In addition, ALK’s effects were reversed by PI3K inhibitors LY294002 (P < 0.05). Our data indicated that ALK protected the brain from reperfusion injuries without affecting blood pressure, and this effect may be through PI3K/AKT signaling pathway.     

Ischemic post-conditioning reduces infarct size of the in vivo rat heart: role of PI3-K, mTOR, GSK-3β, and apoptosis

Post-conditioning by repetitive cycles of reperfusion/ischemia after prolonged ischemia protects the heart from infarction. The objectives of this study were: Are kinases (PI3-kinase, mTOR, and GSK-3β) involved in the signaling pathway of post-conditioning? Does post-conditioning result in a diminished necrosis or apoptosis? In open chest rats the infarct size was determined after 30 min of regional ischemia and 30 min of reperfusion using propidium iodide and microspheres. Post-conditioning was performed by three cycles of 30 s reperfusion and reocclusion each, immediately upon reperfusion. PI3-kinase and mTOR were blocked using wortmannin (0.6 mg/kg) or rapamycin (0.25 mg/kg), respectively. The phosphorylation of GSK-3β and p70S6K was determined with phospho-specific antibodies. TUNEL staining and detection of apoptosis-inducing factor (AIF) were used for the determination of apoptosis. Control hearts had an infarct size of 49 ± 3%, while post-conditioning significantly reduced it to 29 ± 3% (P < 0.01). Wortmannin as well as rapamycin completely blocked the infarct size reduction of post-conditioning (51 ± 2% and 54 ± 5%, respectively). Western blot analysis revealed that post-conditioning increased the phosphorylation of GSK-3β by 2.3 times (P < 0.01), and this increase could be blocked by wortmannin, a PI3-kinase inhibitor. Although rapamycin blocked the infarct size reduction, phosphorylation of p70S6K was not increased in post-conditioned hearts. After 2 h of reperfusion, the post-conditioned hearts had significantly fewer TUNEL-positive nuclei (35 %) compared to control hearts (53%; P < 0.001). AIF was equally reduced in post-conditioned rat hearts (P < 0.05 vs. control). Infarct size reduction by ischemic post-conditioning of the in vivo rat heart is PI3-kinase dependent and involves mTOR. Furthermore, GSK-3β, which is thought to be a regulator of the mPTP, is part of the signaling pathway of post-conditioning. Finally, apoptosis was inhibited by post-conditioning, which was shown by two independent methods. The role of apoptosis and/or autophagy in post-conditioning has to be further elucidated to find therapeutic targets to protect the heart from the consequences of acute myocardial infarction.     

Propofol Protects Against Focal Cerebral Ischemia via Inhibition of Microglia-Mediated Proinflammatory Cytokines in a Rat Model of Experimental Stroke

Ischemic stroke induces microglial activation and release of proinflammatory cytokines, contributing to the expansion of brain injury and poor clinical outcome. Propofol has been shown to ameliorate neuronal injury in a number of experimental studies, but the precise mechanisms involved in its neuroprotective effects remain unclear. We tested the hypothesis that propofol confers neuroprotection against focal ischemia by inhibiting microglia-mediated inflammatory response in a rat model of ischemic stroke. Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) for 2 h followed by 24 h of reperfusion. Propofol (50 mg/kg/h) or vehicle was infused intravenously at the onset of reperfusion for 30 minutes. In vehicle-treated rats, MCAO resulted in significant cerebral infarction, higher neurological deficit scores and decreased time on the rotarod compared with sham-operated rats. Propofol treatment reduced infarct volume and improved the neurological functions. In addition, molecular studies demonstrated that mRNA expression of microglial marker Cd68 and Emr1 was significantly increased, and mRNA and protein expressions of proinflammatory cytokines tumor necrosis factor-α, interleukin-1β and interleukin-6 were augmented in the peri-infarct cortical regions of vehicle-treated rats 24 h after MCAO. Immunohistochemical study revealed that number of total microglia and proportion of activated microglia in the peri-infarct cortical regions were markedly elevated. All of these findings were ameliorated in propofol-treated rats. Furthermore, vehicle-treated rats had higher plasma levels of interleukin-6 and C-reactive protein 24 h after MCAO, which were decreased after treatment with propofol. These results suggest that propofol protects against focal cerebral ischemia via inhibition of microglia-mediated proinflammatory cytokines. Propofol may be a promising therapeutic agent for the treatment of ischemic stroke and other neurodegenerative diseases associated with microglial activation.     

Effect of repeated allogeneic bone marrow mononuclear cell transplantation on brain injury following transient focal cerebral ischemia in rats

Aims

Transplantation of bone marrow mononuclear cells (BMMCs) exerts neuroprotection against cerebral ischemia. We examined the therapeutic timepoint of allogeneic BMMC transplantation in a rat model of focal cerebral ischemia, and determined the effects of repeated transplantation outside the therapeutic window.

Main methods

Male Sprague–Dawley rats were subjected to 90 minute focal cerebral ischemia, followed by intravenous administration of 1 × 10⁷ allogeneic BMMCs or vehicle at 0, 3 or 6 h after reperfusion or 2 × 10⁷ BMMCs 6 h after reperfusion. Other rats administered 1 × 10⁷ BMMCs at 6 h after reperfusion received additional BMMC transplantation or vehicle 9 h after reperfusion. Infarct volumes, neurological deficit scores and immunohistochemistry were evaluated 24 or 72 h after reperfusion.

Key findings

Infarct volumes at 24 h were significantly decreased in transplantation rats at 0 and 3 h, but not at 6 h, after reperfusion, compared to vehicle-treatment. Even high dose BMMC transplantation at 6 h after reperfusion was ineffective. Repeated BMMC transplantation at 6 and 9 h after reperfusion reduced infarct volumes and significantly improved neurological deficit scores at 24 and 72 h. Immunohistochemistry showed repeated BMMC transplantation reduced ionized calcium-binding adapter molecule 1, 4-hydroxy-2-nonenal and 8-hydroxydeoxyguanosine expression at 24 and 72 h after reperfusion.

Significance

Intravenous allogeneic BMMCs were neuroprotective following transient focal cerebral ischemia, and the therapeutic time window of BMMC transplantation was > 3 h and < 6 h after reperfusion in this model. Repeated transplantation at 6 and 9 h after reperfusion suppressed inflammation and oxidative stress in ischemic brains, resulting in improved neuroprotection.