OBJECTIVE： To investigate the relationship of aquaporin 4 （AQP4） and brain edema. DATA SOURCES： Using the terms of ＂aquaporin-4, brain edema＂, we searched PubMed database to identify studies published from Janua...OBJECTIVE： To investigate the relationship of aquaporin 4 （AQP4） and brain edema. DATA SOURCES： Using the terms of ＂aquaporin-4, brain edema＂, we searched PubMed database to identify studies published from January 1997 to April 2006 in the English languages. Meanwhile, we also searched China National Knowledge Infrastructure （CNKI） for related studies. STUDY SELECTION： The collected data were selected firstly. Studies on AQP4 and brain edema were chosen and their full-texts were searched for, and those with repetitive or review studies were excluded. DATA EXTRACTION： Totally 146 related studies were collected, 42 of them were involved and the other 104 studies were used for reading reference data. DATA SYNTHESIS： AQP4 is a selective water permeable integral membrane protein. It is mainly expressed in astrocytes and ependymocyte, and is the important structural basis for water regulation and transportation between glial cells and cerebrospinal fluid or vessels. Phosphorylation is involved in the regulation of AQP4. AQP4 participates in the formation of brain edema caused by various factors. Studies on the structure and pathological changes of AQP4 are still in the initial stage, and the role and mechanism of AQP4 in the formation of brain edema is very unclear. CONCLUSION： AQP4 plays a critical regulating role in the formation of ischemic brain edema, but whether it is regulated by drugs lacks reliable evidence.展开更多
BACKGROUND：Previous studies have demonstrated that aquaporin-4 （AQP4） plays a key role in the formation and resolution of brain edema.However,the molecular mechanisms and role of AQP4 in hypoxia-ischemia-induced br...BACKGROUND：Previous studies have demonstrated that aquaporin-4 （AQP4） plays a key role in the formation and resolution of brain edema.However,the molecular mechanisms and role of AQP4 in hypoxia-ischemia-induced brain edema remain poorly understood.OBJECTIVE：To establish a newborn animal model of astrocytic oxygen-glucose deprivation and reintroduction,to observe the correlation between AQP4 and cellular volume,and to investigate the role of AQP4 in the development of brain edema following oxygen deprivation and reintroduction.DESIGN,TIME AND SETTING：A comparative experiment was performed at the Experimental Center of West China Second University Hospital between October 2007 and April 2009.MATERIALS：Astrocytes were derived from the neocortex of Sprague Dawley rats aged 3 days.METHODS：Astrocytes were incubated in glucose/serum-free Dulbecco＇s modified Eagle＇s medium,followed by 1% oxygen for 6 hours.Finally,oxygen-glucose deprivation and reintroduction models were successfully established.MAIN OUTCOME MEASURES：Real-time polymerase chain reaction and Western blot analysis were used to measure expression of AQP4 mRNA and protein in cultured rat astrocytes following oxygen-glucose deprivation and reintroduction.Astrocytic cellular volume,as determined by [3H]-3-O-methyl-D-glucose,was used to represent the extent of astrocytic swelling.RESULTS：During oxygen-glucose deprivation,AQP4 mRNA and protein expression gradually decreased in astrocytes,whereas cellular volume increased in a time-dependent manner （P〈 0.01）.Following oxygen-glucose reintroduction,AQP4 mRNAand protein expression was upregulated,peaked at day 7,and then gradually decreased,but still higher than normal levels （P 〈 0.05）.However,cellular volume gradually decreased （P 〈 0.01）,and then reached normal levels at day 7.CONCLUSION：AQP4 expression highly correlated with cellular volume changes,suggesting that AQP4 played an important role in modulating brain water transport in an astrocytic oxygen-glucose deprivation and reintroduction model.展开更多
BACKGROUND： Ischemic cerebrovascular disease causes injury to the blood-brain barrier. The occurrence of brain edema is associated with aquaporin expression following cerebral ischemia/reperfusion. OBJECTIVE： To ana...BACKGROUND： Ischemic cerebrovascular disease causes injury to the blood-brain barrier. The occurrence of brain edema is associated with aquaporin expression following cerebral ischemia/reperfusion. OBJECTIVE： To analyze the correlation of aquaporin-4 expression to brain edema and blood-brain barrier permeability in brain tissues of rat models of ischemia/reperfusion. DESIGN, TIME AND SETTING： The randomized control experiment was performed at the Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical College, China from December 2006 to October 2007. MATERIALS： A total of 112 adult, male, Sprague-Dawley rats, weighing 220-250 g, were used to establish rat models of middle cerebral artery occlusion and reperfusion by the suture method. Rabbit anti-aquaporin-4 （Santa Cruz, USA） and Evans blue （Sigma, USA） were used to analyze the tissue. METHODS： The rats were randomized into sham-operated （n = 16） and ischemia/reperfusion （n = 96） groups. There were 6 time points in the ischemia/reperfusion group, comprising 4, 6, 12, 24, 48, and 72 hours after reperfusion, with 16 rats for each time point. Rat models in the sham-operated group at 4 hours after surgery and rat models in the ischemia/reperfusion group at different time points were equally and randomly assigned into 4 different subgroups. MAIN OUTCOME MEASURES： Brain water content on the ischemic side and the control side was measured using the dry-wet weight method. Blood-brain barrier function was determined by Evans Blue. Aquaporin-4 expression surrounding the ischemic focus, as well as the correlation of aquaporin-4 expression with brain water content and Evans blue staining, were measured using immunohistochemistry and Western blot analysis. RESULTS： Brain water content on the ischemic side significantly increased at 12 hours after reperfusion, reached a peak at 48 hours, and was still high at 72 hours. Brain water content was greater on the ischemic hemispheres, compared with the control hemispheres at 6, 12, 24, 48, and 72 hours after reperfusion, as well as both hemispheres in the sham-operated group （P 〈 0.05）. Evans blue content significantly increased on the ischemic side at 4 hours after ischemia/reperfusion, and reached a peak at 48 hours. Evans blue content was greater on the ischemic hemispheres, compared with the control hemispheres at various time points, as well as both hemispheres in the sham-operated group （P 〈 0.05）. Aquaporin-4-positive cells were detected in the cortex and hippocampus, surrounding the ischemic penumbra focus, at 4-6 hours after ischemia/reperfusion. The number of positive cells significantly increased at 12 hours and reached a peak at 48-72 hours. Aquaporin-4 was, however, weakly expressed in the control hemispheres and the sham-operated group. The absorbance ratio of aquaporin-4 to β-actin was greater at 12, 24, 48, and 72 hours following cerebral ischemia/reperfusion, compared with the sham-operated group （P 〈 0.05）. Aquaporin-4 expression positively correlated to brain water content and Evans blue staining following cerebral ischemia/reperfusion （r1 = 0.68, r2 = 0.81, P 〈 0.05）. CONCLUSION： Aquaporin-4 is highly expressed in brain tissues, participates in the occurrence of ischemic brain edema, and is positively correlated to blood-brain barrier permeability following cerebral ischemia/reperfusion.展开更多
Cromakalim,an adenosine triphosphate-sensitive potassium channel opener,exhibits protective effects on cerebral ischemia/reperfusion injury.However,there is controversy as to whether this effect is associated with aqu...Cromakalim,an adenosine triphosphate-sensitive potassium channel opener,exhibits protective effects on cerebral ischemia/reperfusion injury.However,there is controversy as to whether this effect is associated with aquaporin-4 and blood-brain barrier permeability.Immunohistochemistry results show that preventive administration of cromakalim decreased aquaporin-4 and IgG protein expression in rats with ischemia/reperfusion injury;it also reduced blood-brain barrier permeability,and alleviated brain edema,ultimately providing neuroprotection.展开更多
The present results demonstrated that in an adult rat model of permanent middle cerebral artery occlusion （pMCAO）, pretreatment with bilobalide reduced brain water content and infarct area, down-regulated aquaporin ...The present results demonstrated that in an adult rat model of permanent middle cerebral artery occlusion （pMCAO）, pretreatment with bilobalide reduced brain water content and infarct area, down-regulated aquaporin 1, 4 mRNA expression in brain edema tissue, then inhibited their synthesis in the striatum, in particular at the early stage of ischemia （at 8 hours after pMCAO）, inhibited glial fibrillary acidic protein expression, and lightened reactive gliosis. These data sug-gest that bilobalide attenuates brain edema formation due to reduced expression of aquaporins.展开更多
Objective:To characterize the expression of aquaporin-4(AQP4),one of the aquaporins(AQPs),in human brainspecimens from patients with traumatic brain injury or brain tumors.Methods:Nineteen hnman brain specimens were o...Objective:To characterize the expression of aquaporin-4(AQP4),one of the aquaporins(AQPs),in human brainspecimens from patients with traumatic brain injury or brain tumors.Methods:Nineteen hnman brain specimens were obtahledfrom the patients with traumatic brain injury,brain tumors,benign meningioma or early stage hemorrhagic stroke.MRI or CTimaging was used to assess brain edema.Hematoxylin and eosm staining were used to evaluate cell damage,Immunohistochem-istry was used to detect the AQP4 expression.Results:AQP4 expression was increased from 15 h to at least 8 d after injury.AQP4immunoreactivity was strong around astrocytomas,ganglioglioma and metastatic adenocarcinoma.However,AQP4 immunore-activity was only found in the centers of astrocytomas and ganglioglioma,but not in metastatic adenocarcinoma derived from lung.Conclusion:AQP4 expression increases in human brains alter traumatic brain injury,within brain-derived tumors,and aroundbrain tumors.展开更多
This study aimed to investigate aquaporin 4 expression and the ultrastructure of the blood-brain barrier at 2-72 hours following cerebral contusion injury, and correlate these changes to the formation of brain edema. ...This study aimed to investigate aquaporin 4 expression and the ultrastructure of the blood-brain barrier at 2-72 hours following cerebral contusion injury, and correlate these changes to the formation of brain edema. Results revealed that at 2 hours after cerebral contusion and laceration injury, aquaporin 4 expression significantly increased, brain water content and blood-brain barrier permeability increased, and the number of pinocytotic vesicles in cerebral microvascular endothelia cells increased. In addition, the mitochondrial accumulation was observed. As contusion and laceration injury became aggravated, aquaporin 4 expression continued to increase, brain water content and blood-brain barrier permeability gradually increased, brain capillary endothelial cells and astrocytes swelled, and capillary basement membrane injury gradually increased. The above changes were most apparent at 12 hours after injury, after which they gradually attenuated. Aquaporin 4 expression positively correlated with brain water content and the blood-brain barrier index. Our experimental findings indicate that increasing aquaporin 4 expression and blood-brain barrier permeability after cerebral contusion and laceration injury in humans is involved in the formation of brain edema.展开更多
To investigate the role of AQP9 in brain edema, the expression of AQP9 in an infectious rat brain edema model induced by the injection of lipopolysaccharide （LPS） was examined. Immuno- histochemistry and reverse tra...To investigate the role of AQP9 in brain edema, the expression of AQP9 in an infectious rat brain edema model induced by the injection of lipopolysaccharide （LPS） was examined. Immuno- histochemistry and reverse transcription-polymerase chain reaction （RT-PCR） analysis demonstrated that the expressions of AQP9 mRNA and protein at all observed intervals were significantly increased in LPS-treated animals in comparison with the control animals. Time-course analysis showed that the first signs of blood-brain barrier disruption and the increase of brain water content in LPS-treated animals were evident 6 h after LPS injection, with maximum value appearing at 12 h, which coincided with the expression profiles of AQP9 mRNA and protein in LPS-treated animals. The further correlation analysis revealed strong positive correlations among the brain water content, the disruption of the blood-brain barrier and the enhanced expressions of AQP9 mRNA and protein in LPS-treated animals. These results suggested that the regulation of AQP9 expression may play im- portant roles in water movement and in brain metabolic homeostasis associated with the pathophysi- ology of brain edema induced by LPS injection.展开更多
Objective：To determine the relationship between the expression of aquaporin-4（AQP4） after intracerebral hemorrhage and dexamethasone treated. Methods：Collagenase Ⅶ was injected in caudate nucleus in a stereotaxis...Objective：To determine the relationship between the expression of aquaporin-4（AQP4） after intracerebral hemorrhage and dexamethasone treated. Methods：Collagenase Ⅶ was injected in caudate nucleus in a stereotaxis frame to establish the intracerebral hemorrhage（ICH） animal models. The intracerebral hemorrhage（ICH） rats were randomly divided into four groups： the sham group （group A）, the ICH group（group B）, low dose-treated group（group C）, moderate dose group（group D） and high dose group（group E）. The groups were respectively received an intraperitoneal dexamethasone injection with 1 mg/kg, 15 mg/kg, 30 mg/kg, twice a day for three days. The brain water content（BWC）, the permeability of blood-brain barrier（BBB） and the expression of AQP4 were observed. Results：Both the BBB disruption and AQP4 expression decreased in treated groups, and the AQP4 expression had a dose-dependent manner in the dexamethasone treatment. And it seemed that low dose dexamethasone was in favor of brain swelling elimination, but the higher dosage had not similar effect. Conclusion：Dexamethesone may play a critical role on expression of AQP4 in the physiopathology of hemorrhagic edema.展开更多
Recurrent epileptic seizures can lead to brain edema, indicating that water regulation may be perturbed by seizures. We hypothesized that the expression of the brain water channel aquaporin-4 （AQP-4） may be upregula...Recurrent epileptic seizures can lead to brain edema, indicating that water regulation may be perturbed by seizures. We hypothesized that the expression of the brain water channel aquaporin-4 （AQP-4） may be upregulated in the epileptic brain. In the present study, we established the amygdala kindling model of epilepsy, and quantified AQP-4 protein and mRNA levels, using reverse transcription-PCR, immunohistochemistry and western blotting, in epileptic and control rats. We found that AQP-4 was overexpressed in the cerebral cortex of rats with epilepsy compared with controls. These findings show that AQP-4 is highly expressed in the brain of amygdala-kindled rats, suggesting that repeated seizures affect water homeostasis in the brain.展开更多
Aquaporin-4 （AQP-4）, a water-channel protein,is highly expressed in the brain, which is important ele- ments in the formation of brain edema and plays an important role in the rapid transmembrane transport. AQP-4 ex...Aquaporin-4 （AQP-4）, a water-channel protein,is highly expressed in the brain, which is important ele- ments in the formation of brain edema and plays an important role in the rapid transmembrane transport. AQP-4 ex- pression up-regulates after ischemia-reperfusion injury in rats, making the astrocytic endfeet swelling, with the con- sequence of the injury of blood-brain barrier（BBB） , increasing the permeability of BBB, render too much water in the blood flow to the brain parenchyma, which results in cytotoxic edema, disordering the stability of the central nervous system. In addintion, the increased permeability of BBB is one of the important reasons for the cerebral stroke, therefore, it is essential that research the relationship between AQP-4 with BBB further and restore the blood-brain barrier injury be a new strategy for the prevention and treatment of stroke, worthy of further research.展开更多
The aquaporin-4(AQP4)is a highly selective membrane protein.It is important for the body to maintain the water balance between internal and external environment of cells,the studies have found that the abnormal expres...The aquaporin-4(AQP4)is a highly selective membrane protein.It is important for the body to maintain the water balance between internal and external environment of cells,the studies have found that the abnormal expression of AQP4 is related to the occurrence of many diseases.The cerebral edema is the most common and serious complication of brain trauma,and its pathogenesis is closely related to AQP4.The development of multimodal magnetic resonance imaging(M-MRI)could been provided imaging basis for accurate diagnosis of traumatic brain edema.In recent years,the correlation between AQP4 and M-MRI has become a hotspot of research.This paper reviews the research progress on the correlation between AQP4 expression in traumatic cerebral edema and M-MRI.展开更多
The present study evaluated the effect of dl-3-n-butylphthalide(NBP) ,a novel brain protective agent, on brain edema in rats following focal ischemia. Edema was induced by occluding the right middle cerebral artery (M...The present study evaluated the effect of dl-3-n-butylphthalide(NBP) ,a novel brain protective agent, on brain edema in rats following focal ischemia. Edema was induced by occluding the right middle cerebral artery (MCAO).producing permanent focal ischemia in the right cerebral hemisphere,which developed ip-silateral brain edema reproducibly. Edema was assessed 24 h after MCA occlusion by determining the brain water content from wet and dry weight measurements,and the sodium,potassium concentrations with ion-selective electrodes. In this model,NBP at the dose of 80,160 and 240 mg/kg po 15 min after MCAO prevented from brain edema in a dose-dependent manner. A significant reduction of sodium content and an increase in potassium level were observed in all drug-treated groups. It showed that NBP strongly attenuated brain water entry,sodium accumulation and potassium loss. Nimodipine treatment(5mg/kg sc) also reduced brain edema (P<0. 05). The results suggest that a strong anti-edema activity of NBP may play an important role to contribute to the treatment of ischemic damage.展开更多
BACKGROUND： Several studies have demonstrated that propofol exhibits protective effects in the central nervous system. OBJECTIVE： To observe the effects of propofol on neuronal apoptosis and aquaporin-4 （AQP-4） ex...BACKGROUND： Several studies have demonstrated that propofol exhibits protective effects in the central nervous system. OBJECTIVE： To observe the effects of propofol on neuronal apoptosis and aquaporin-4 （AQP-4） expression in a rat model of traumatic brain injury and to further investigate the mechanisms of action. DESIGN, TIME AND SETTING： The present neuronal, pathomorphological experiment was performed at the Institute of Cerebrovascular Disease, Qingdao University Medical College between April 2007 and March 2008. MATERIALS： Traumatic brain injury was induced by free falling objects in 150 healthy, male, Wistar rats. Propofol was produced by AstraZeneca, China. Rabbit anti-rat AQP-4 polyclonal antibody, SABC immunohistochemistry kit, and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick-end labeling （TUNEL） kit were purchased from Wuhan Boster Bioengineering Co., Ltd., China. METHODS： All 150 rats were randomly and evenly divided into lesion-only and propofol-treated groups. One hour after traumatic brain injury, propofol-treated animals received 1% propofol （10 mg/kg） through the caudal vein, followed by a sustained perfusion of 30 mg/kg propofol per hour for 2 hours, while the lesion-only group received equal volumes of physiological saline in parallel. MAIN OUTCOME MEASURES： At 6, 12, 24, 48, and 72 hours after traumatic brain injury, morphological changes in the peritraumatic and adjacent brain areas were analyzed in all rats by hematoxylin-eosin （HE） staining. In addition, cellular apoptosis was detected by TUNEL assay and the number of AQP-4-positive cells was determined by immunohistochemistry techniques. Brain water content was calculated as the ratio of dry to wet tissue weight. RESULTS： HE staining results demonstrated that, in the lesion-only group, the peritraumatic area exhibited neuronal and glial cell necrosis and disintegration. The adjacent area displayed swollen neuronal perikarya and vascular endothelial ceils, cellular edema, and a small amount of proliferating glial ceils. In contrast, these pathological changes were noticeably alleviated in the peritraumatic and adjacent areas of propofol-treated animals. Compared with the lesion-only group, the number of apoptotic cells was significantly decreased in the propofol-treated group at each time point after traumatic brain injury, in particular at 24 and 48 hours （P 〈 0.05-0.01）. In the lesion-only group, AQP-4 expression began to increase at 6 hours after traumatic brain injury, reached a peak level at 24-48 hours, and began to decrease by 72 hours. In the propofol-treated group, the number of AQP-4 positive cells was significantly less than the lesion-only group. This was the case at all time points, in particular at 12 and 24 hours （P 〈 0.01-0.05）. CONCLUSION： Propofol can dowuregulate neuronal apoptosis and AQP-4 expression in rats following traumatic brain injury, in particular at 24-48 hours.展开更多
This study used electroacupuncture at Renzhong （DU26） and Baihui （DU20） in a rat model of cerebral ischemia/reperfusion injury. Neurological deficit scores, western blotting, and reverse transcription-PCR results ...This study used electroacupuncture at Renzhong （DU26） and Baihui （DU20） in a rat model of cerebral ischemia/reperfusion injury. Neurological deficit scores, western blotting, and reverse transcription-PCR results demonstrated that electroacupuncture markedly reduced neurological deficits, decreased corpus striatum aquaporin-4 protein and mRNA expression, and relieved damage to the blood-brain barrier in a rat model of cerebral ischemia/reperfusion injury. These results suggest that electroacupuncture most likely protects the blood-brain barrier by regulating aquaporin-4 expression following cerebral ischemia/reperfusion injury.展开更多
Puerarin, a traditional Chinese medicine, exerts a powerful neuroprotective effect in cerebral ischemia/reperfusion injury, but its mechanism is unknown. Here, we established rat models of middle cerebral artery ische...Puerarin, a traditional Chinese medicine, exerts a powerful neuroprotective effect in cerebral ischemia/reperfusion injury, but its mechanism is unknown. Here, we established rat models of middle cerebral artery ischemia/reperfusion injury using the suture method. Puerarin （100 mg/kg） was administered intraperitoneally 30 minutes before middle cerebral artery occlusion and 8 hours after reperfusion. Twenty-four hours after reperfusion, we found that puerarin significantly improved neurological deficit, reduced infarct size and brain water content, and notably diminished the expression of Toll-like receptor-4, myeloid differentiation factor 88, nuclear factor kappa B and tumor necrosis factor-α in the ischemic region. These data indicate that puerarin exerts an anti-inflammatory protective effect on brain tissue with ischemia/reperfusion damage by downregulating the expression of multiple inflammatory factors.展开更多
Autophagy has been suggested to participate in the pathology of hypoxic-ischemic brain damage（HIBD）.However,its regulatory role in HIBD remains unclear and was thus examined here using a rat model.To induce HIBD,the...Autophagy has been suggested to participate in the pathology of hypoxic-ischemic brain damage（HIBD）.However,its regulatory role in HIBD remains unclear and was thus examined here using a rat model.To induce HIBD,the left common carotid artery was ligated in neonatal rats,and the rats were subjected to hypoxia for 2 hours.Some of these rats were intraperitoneally pretreated with the autophagy inhibitor 3-methyladenine（10 m M in 10 μL） or the autophagy stimulator rapamycin（1 g/kg） 1 hour before artery ligation.Our findings demonstrated that hypoxia-ischemia-induced hippocampal injury in neonatal rats was accompanied by increased expression levels of the autophagy-related proteins light chain 3 and Beclin-1 as well as of the AMPA receptor subunit GluR 1,but by reduced expression of GluR 2.Pretreatment with the autophagy inhibitor 3-methyladenine blocked hypoxia-ischemia-induced hippocampal injury,whereas pretreatment with the autophagy stimulator rapamycin significantly augmented hippocampal injury.Additionally,3-methyladenine pretreatment blocked the hypoxia-ischemia-induced upregulation of Glu R1 and downregulation of GluR2 in the hippocampus.By contrast,rapamycin further elevated hippocampal Glu R1 levels and exacerbated decreased GluR2 expression levels in neonates with HIBD.Our results indicate that autophagy inhibition favors the prevention of HIBD in neonatal rats,at least in part,through normalizing Glu R1 and GluR2 expression.展开更多
Neuroinflammation is a well-recognized consequence of subarachnoid hemorrhage（SAH）, and Toll-like receptor（TLR） 4 may be an important therapeutic target for post-SAH neuroinflammation. Of the TLR family members, T...Neuroinflammation is a well-recognized consequence of subarachnoid hemorrhage（SAH）, and Toll-like receptor（TLR） 4 may be an important therapeutic target for post-SAH neuroinflammation. Of the TLR family members, TLR4 is expressed in various cell types in the central nervous system, and is unique in that it can signal through both the myeloid differentiation primary-response protein 88-dependent and the toll receptor associated activator of interferon-dependent cascades to coordinate the maximal inflammatory response. TLR4 can be activated by many endogenous ligands having damage-associated molecular patterns including heme and fibrinogen at the rupture of an intracranial aneurysm, and the resultant inflammatory reaction and thereby tissue damages may furthermore activate TLR4. It is widely accepted that the excreted products of TLR4 signaling alter neuronal functions. Previous studies have focused on the pathway through nuclear factor（NF）-κΒ signaling among TLR4 signaling pathways as to the development of early brain injury（EBI） such as neuronal apoptosis and blood-brain barrier disruption, and cerebral vasospasm. However, many findings suggest that both pathways via NF-κΒ and mitogen-activated protein kinases may be involved in EBI and cerebral vasospasm development. To overcome EBI and cerebral vasospasm is important to improve outcomes after SAH, because both EBI and vasopasm are responsible for delayed brain injuries or delayed cerebral ischemia, the most important preventable cause of poor outcomes after SAH. Increasing evidence has shown that TLR4 signaling plays an important role in SAH-induced brain injuries. Better understanding of the roles of TLR4 signaling in SAH will facilitate development of new treatments.展开更多
BACKGROUND： Aquaporin-4 （AQP-4）, which is able to rapidly transport water within the brain, is highly expressed in brain tissue. It also plays an important role in the formation of cerebral edema following brain in...BACKGROUND： Aquaporin-4 （AQP-4）, which is able to rapidly transport water within the brain, is highly expressed in brain tissue. It also plays an important role in the formation of cerebral edema following brain injury. However, the role of AQP-4 in the formation of cerebral edema following severe bums remains unknown. OBJECTIVE： To study changes in AQP-4 protein and mRNA expression during formation of cerebral edema following severe burns, and to explore the correlation between AQP-4 protein and mRNA expression with plasma levels of arginine vasopressin （AVP）. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the Research Center of Neuroscience, Chongqing Medical University from 2007 to 2008. MATERIALS： Biotin-labeled goat anti-rabbit antibody was provided by Beijing Zhongshan Biotechnology, China; in situ hybridization kit was provided by Wuhan Boster Biotechnology, China; rabbit anti-AQP-4 polyclonal antibody and horseradish peroxidase-labeled goat anti-rabbit IgG were provided by Chemicon, USA; AVP radioimmunoassay kit was provided by the Research Department of Neurobiology, the Second Military Medical University of Shanghai, China. METHODS： A total of 180 adult, healthy, Wistar rats were randomly assigned to control and burn groups with 30 rats in each group. The burn group was observed at five different time points： 2, 6, 12, 24, and 48 hours after burn. Hair on the mouse back was removed to expose skin on the back. After 1 day, skin with the hair removed was dipped into 100℃ water for 15 seconds to induce grade III bum injury that measures 30% of total bum surface area. MAIN OUTCOME MEASURES： Brain water content was measured using the dry-wet weight method. AQP-4 protein and mRNA expressions were detected using immunohistochemistry, in situ hybridization, Western blot, and reverse transcription-polymerase chain reaction; dynamic changes in plasma AVP were detected using radioimmunoassay. RESULTS： Brain water content gradually increased following severe burn injury. AQP-4 protein and mRNA expressions were upregulated in the supraoptic nucleus, suprachiasmatic nucleus, paraventricular nucleus, hippocampus, choroid plexus, and cerebral cortex. Plasma AVP levels increased following burn injury. AQP-4 protein and mRNA expressions positively correlated with brain water content and AVP levels during formation of cerebral edema （r= 0.870, 0.848, P 〈 0.01）. CONCLUSION： AQP-4 participated in the formation of cerebral edema following burn injury. Plasma AVP upregulated AQP-4 expression in brain tissue, thereby promoting formation of cerebral edema.展开更多
文摘OBJECTIVE： To investigate the relationship of aquaporin 4 （AQP4） and brain edema. DATA SOURCES： Using the terms of ＂aquaporin-4, brain edema＂, we searched PubMed database to identify studies published from January 1997 to April 2006 in the English languages. Meanwhile, we also searched China National Knowledge Infrastructure （CNKI） for related studies. STUDY SELECTION： The collected data were selected firstly. Studies on AQP4 and brain edema were chosen and their full-texts were searched for, and those with repetitive or review studies were excluded. DATA EXTRACTION： Totally 146 related studies were collected, 42 of them were involved and the other 104 studies were used for reading reference data. DATA SYNTHESIS： AQP4 is a selective water permeable integral membrane protein. It is mainly expressed in astrocytes and ependymocyte, and is the important structural basis for water regulation and transportation between glial cells and cerebrospinal fluid or vessels. Phosphorylation is involved in the regulation of AQP4. AQP4 participates in the formation of brain edema caused by various factors. Studies on the structure and pathological changes of AQP4 are still in the initial stage, and the role and mechanism of AQP4 in the formation of brain edema is very unclear. CONCLUSION： AQP4 plays a critical regulating role in the formation of ischemic brain edema, but whether it is regulated by drugs lacks reliable evidence.
基金the National Natural Science Foundation of China,No.30825039,30973236,30872346,30770748Chinese Postdoctoral Training Grant,No. 20070420575+1 种基金Application Basic Research Foundation of Sichuan Province,No. 2008JY0131Youth Science and Technology Foundation of Sichuan Province,No. 07zq026-135
文摘BACKGROUND：Previous studies have demonstrated that aquaporin-4 （AQP4） plays a key role in the formation and resolution of brain edema.However,the molecular mechanisms and role of AQP4 in hypoxia-ischemia-induced brain edema remain poorly understood.OBJECTIVE：To establish a newborn animal model of astrocytic oxygen-glucose deprivation and reintroduction,to observe the correlation between AQP4 and cellular volume,and to investigate the role of AQP4 in the development of brain edema following oxygen deprivation and reintroduction.DESIGN,TIME AND SETTING：A comparative experiment was performed at the Experimental Center of West China Second University Hospital between October 2007 and April 2009.MATERIALS：Astrocytes were derived from the neocortex of Sprague Dawley rats aged 3 days.METHODS：Astrocytes were incubated in glucose/serum-free Dulbecco＇s modified Eagle＇s medium,followed by 1% oxygen for 6 hours.Finally,oxygen-glucose deprivation and reintroduction models were successfully established.MAIN OUTCOME MEASURES：Real-time polymerase chain reaction and Western blot analysis were used to measure expression of AQP4 mRNA and protein in cultured rat astrocytes following oxygen-glucose deprivation and reintroduction.Astrocytic cellular volume,as determined by [3H]-3-O-methyl-D-glucose,was used to represent the extent of astrocytic swelling.RESULTS：During oxygen-glucose deprivation,AQP4 mRNA and protein expression gradually decreased in astrocytes,whereas cellular volume increased in a time-dependent manner （P〈 0.01）.Following oxygen-glucose reintroduction,AQP4 mRNAand protein expression was upregulated,peaked at day 7,and then gradually decreased,but still higher than normal levels （P 〈 0.05）.However,cellular volume gradually decreased （P 〈 0.01）,and then reached normal levels at day 7.CONCLUSION：AQP4 expression highly correlated with cellular volume changes,suggesting that AQP4 played an important role in modulating brain water transport in an astrocytic oxygen-glucose deprivation and reintroduction model.
基金the Scientific Research Foundation of Health Department of Jiangsu Province of China, No. H9908the International Communication Program of Education Department of Jiangsu Province of China in 2007
文摘BACKGROUND： Ischemic cerebrovascular disease causes injury to the blood-brain barrier. The occurrence of brain edema is associated with aquaporin expression following cerebral ischemia/reperfusion. OBJECTIVE： To analyze the correlation of aquaporin-4 expression to brain edema and blood-brain barrier permeability in brain tissues of rat models of ischemia/reperfusion. DESIGN, TIME AND SETTING： The randomized control experiment was performed at the Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical College, China from December 2006 to October 2007. MATERIALS： A total of 112 adult, male, Sprague-Dawley rats, weighing 220-250 g, were used to establish rat models of middle cerebral artery occlusion and reperfusion by the suture method. Rabbit anti-aquaporin-4 （Santa Cruz, USA） and Evans blue （Sigma, USA） were used to analyze the tissue. METHODS： The rats were randomized into sham-operated （n = 16） and ischemia/reperfusion （n = 96） groups. There were 6 time points in the ischemia/reperfusion group, comprising 4, 6, 12, 24, 48, and 72 hours after reperfusion, with 16 rats for each time point. Rat models in the sham-operated group at 4 hours after surgery and rat models in the ischemia/reperfusion group at different time points were equally and randomly assigned into 4 different subgroups. MAIN OUTCOME MEASURES： Brain water content on the ischemic side and the control side was measured using the dry-wet weight method. Blood-brain barrier function was determined by Evans Blue. Aquaporin-4 expression surrounding the ischemic focus, as well as the correlation of aquaporin-4 expression with brain water content and Evans blue staining, were measured using immunohistochemistry and Western blot analysis. RESULTS： Brain water content on the ischemic side significantly increased at 12 hours after reperfusion, reached a peak at 48 hours, and was still high at 72 hours. Brain water content was greater on the ischemic hemispheres, compared with the control hemispheres at 6, 12, 24, 48, and 72 hours after reperfusion, as well as both hemispheres in the sham-operated group （P 〈 0.05）. Evans blue content significantly increased on the ischemic side at 4 hours after ischemia/reperfusion, and reached a peak at 48 hours. Evans blue content was greater on the ischemic hemispheres, compared with the control hemispheres at various time points, as well as both hemispheres in the sham-operated group （P 〈 0.05）. Aquaporin-4-positive cells were detected in the cortex and hippocampus, surrounding the ischemic penumbra focus, at 4-6 hours after ischemia/reperfusion. The number of positive cells significantly increased at 12 hours and reached a peak at 48-72 hours. Aquaporin-4 was, however, weakly expressed in the control hemispheres and the sham-operated group. The absorbance ratio of aquaporin-4 to β-actin was greater at 12, 24, 48, and 72 hours following cerebral ischemia/reperfusion, compared with the sham-operated group （P 〈 0.05）. Aquaporin-4 expression positively correlated to brain water content and Evans blue staining following cerebral ischemia/reperfusion （r1 = 0.68, r2 = 0.81, P 〈 0.05）. CONCLUSION： Aquaporin-4 is highly expressed in brain tissues, participates in the occurrence of ischemic brain edema, and is positively correlated to blood-brain barrier permeability following cerebral ischemia/reperfusion.
基金the Shandong Provincial Science and Technology Program,No. 2006GG202004
文摘Cromakalim,an adenosine triphosphate-sensitive potassium channel opener,exhibits protective effects on cerebral ischemia/reperfusion injury.However,there is controversy as to whether this effect is associated with aquaporin-4 and blood-brain barrier permeability.Immunohistochemistry results show that preventive administration of cromakalim decreased aquaporin-4 and IgG protein expression in rats with ischemia/reperfusion injury;it also reduced blood-brain barrier permeability,and alleviated brain edema,ultimately providing neuroprotection.
基金a Research Subject of General Hospital of Shenyang Military Area Command of Chinese PLA
文摘The present results demonstrated that in an adult rat model of permanent middle cerebral artery occlusion （pMCAO）, pretreatment with bilobalide reduced brain water content and infarct area, down-regulated aquaporin 1, 4 mRNA expression in brain edema tissue, then inhibited their synthesis in the striatum, in particular at the early stage of ischemia （at 8 hours after pMCAO）, inhibited glial fibrillary acidic protein expression, and lightened reactive gliosis. These data sug-gest that bilobalide attenuates brain edema formation due to reduced expression of aquaporins.
文摘Objective:To characterize the expression of aquaporin-4(AQP4),one of the aquaporins(AQPs),in human brainspecimens from patients with traumatic brain injury or brain tumors.Methods:Nineteen hnman brain specimens were obtahledfrom the patients with traumatic brain injury,brain tumors,benign meningioma or early stage hemorrhagic stroke.MRI or CTimaging was used to assess brain edema.Hematoxylin and eosm staining were used to evaluate cell damage,Immunohistochem-istry was used to detect the AQP4 expression.Results:AQP4 expression was increased from 15 h to at least 8 d after injury.AQP4immunoreactivity was strong around astrocytomas,ganglioglioma and metastatic adenocarcinoma.However,AQP4 immunore-activity was only found in the centers of astrocytomas and ganglioglioma,but not in metastatic adenocarcinoma derived from lung.Conclusion:AQP4 expression increases in human brains alter traumatic brain injury,within brain-derived tumors,and aroundbrain tumors.
文摘This study aimed to investigate aquaporin 4 expression and the ultrastructure of the blood-brain barrier at 2-72 hours following cerebral contusion injury, and correlate these changes to the formation of brain edema. Results revealed that at 2 hours after cerebral contusion and laceration injury, aquaporin 4 expression significantly increased, brain water content and blood-brain barrier permeability increased, and the number of pinocytotic vesicles in cerebral microvascular endothelia cells increased. In addition, the mitochondrial accumulation was observed. As contusion and laceration injury became aggravated, aquaporin 4 expression continued to increase, brain water content and blood-brain barrier permeability gradually increased, brain capillary endothelial cells and astrocytes swelled, and capillary basement membrane injury gradually increased. The above changes were most apparent at 12 hours after injury, after which they gradually attenuated. Aquaporin 4 expression positively correlated with brain water content and the blood-brain barrier index. Our experimental findings indicate that increasing aquaporin 4 expression and blood-brain barrier permeability after cerebral contusion and laceration injury in humans is involved in the formation of brain edema.
基金supported by a grant for Scientific Research Program from the Health Bureau of Henan Province (No.200202)
文摘To investigate the role of AQP9 in brain edema, the expression of AQP9 in an infectious rat brain edema model induced by the injection of lipopolysaccharide （LPS） was examined. Immuno- histochemistry and reverse transcription-polymerase chain reaction （RT-PCR） analysis demonstrated that the expressions of AQP9 mRNA and protein at all observed intervals were significantly increased in LPS-treated animals in comparison with the control animals. Time-course analysis showed that the first signs of blood-brain barrier disruption and the increase of brain water content in LPS-treated animals were evident 6 h after LPS injection, with maximum value appearing at 12 h, which coincided with the expression profiles of AQP9 mRNA and protein in LPS-treated animals. The further correlation analysis revealed strong positive correlations among the brain water content, the disruption of the blood-brain barrier and the enhanced expressions of AQP9 mRNA and protein in LPS-treated animals. These results suggested that the regulation of AQP9 expression may play im- portant roles in water movement and in brain metabolic homeostasis associated with the pathophysi- ology of brain edema induced by LPS injection.
基金The research was supported by science research foundation in Hubei province (2004AA30C97)
文摘Objective：To determine the relationship between the expression of aquaporin-4（AQP4） after intracerebral hemorrhage and dexamethasone treated. Methods：Collagenase Ⅶ was injected in caudate nucleus in a stereotaxis frame to establish the intracerebral hemorrhage（ICH） animal models. The intracerebral hemorrhage（ICH） rats were randomly divided into four groups： the sham group （group A）, the ICH group（group B）, low dose-treated group（group C）, moderate dose group（group D） and high dose group（group E）. The groups were respectively received an intraperitoneal dexamethasone injection with 1 mg/kg, 15 mg/kg, 30 mg/kg, twice a day for three days. The brain water content（BWC）, the permeability of blood-brain barrier（BBB） and the expression of AQP4 were observed. Results：Both the BBB disruption and AQP4 expression decreased in treated groups, and the AQP4 expression had a dose-dependent manner in the dexamethasone treatment. And it seemed that low dose dexamethasone was in favor of brain swelling elimination, but the higher dosage had not similar effect. Conclusion：Dexamethesone may play a critical role on expression of AQP4 in the physiopathology of hemorrhagic edema.
基金the Natural Science Foundation of Shanghai, No. 09ZR1405500the Research Projects of Shanghai Municipal Health Bureau, No. 2008-08
文摘Recurrent epileptic seizures can lead to brain edema, indicating that water regulation may be perturbed by seizures. We hypothesized that the expression of the brain water channel aquaporin-4 （AQP-4） may be upregulated in the epileptic brain. In the present study, we established the amygdala kindling model of epilepsy, and quantified AQP-4 protein and mRNA levels, using reverse transcription-PCR, immunohistochemistry and western blotting, in epileptic and control rats. We found that AQP-4 was overexpressed in the cerebral cortex of rats with epilepsy compared with controls. These findings show that AQP-4 is highly expressed in the brain of amygdala-kindled rats, suggesting that repeated seizures affect water homeostasis in the brain.
文摘Aquaporin-4 （AQP-4）, a water-channel protein,is highly expressed in the brain, which is important ele- ments in the formation of brain edema and plays an important role in the rapid transmembrane transport. AQP-4 ex- pression up-regulates after ischemia-reperfusion injury in rats, making the astrocytic endfeet swelling, with the con- sequence of the injury of blood-brain barrier（BBB） , increasing the permeability of BBB, render too much water in the blood flow to the brain parenchyma, which results in cytotoxic edema, disordering the stability of the central nervous system. In addintion, the increased permeability of BBB is one of the important reasons for the cerebral stroke, therefore, it is essential that research the relationship between AQP-4 with BBB further and restore the blood-brain barrier injury be a new strategy for the prevention and treatment of stroke, worthy of further research.
基金General program of Chongqing Natural Science Foundation(No.cstc2019jcyj-msxmx0353)Science and technology program of Banan District of Chongqing(No.018-25)
文摘The aquaporin-4(AQP4)is a highly selective membrane protein.It is important for the body to maintain the water balance between internal and external environment of cells,the studies have found that the abnormal expression of AQP4 is related to the occurrence of many diseases.The cerebral edema is the most common and serious complication of brain trauma,and its pathogenesis is closely related to AQP4.The development of multimodal magnetic resonance imaging(M-MRI)could been provided imaging basis for accurate diagnosis of traumatic brain edema.In recent years,the correlation between AQP4 and M-MRI has become a hotspot of research.This paper reviews the research progress on the correlation between AQP4 expression in traumatic cerebral edema and M-MRI.
文摘The present study evaluated the effect of dl-3-n-butylphthalide(NBP) ,a novel brain protective agent, on brain edema in rats following focal ischemia. Edema was induced by occluding the right middle cerebral artery (MCAO).producing permanent focal ischemia in the right cerebral hemisphere,which developed ip-silateral brain edema reproducibly. Edema was assessed 24 h after MCA occlusion by determining the brain water content from wet and dry weight measurements,and the sodium,potassium concentrations with ion-selective electrodes. In this model,NBP at the dose of 80,160 and 240 mg/kg po 15 min after MCAO prevented from brain edema in a dose-dependent manner. A significant reduction of sodium content and an increase in potassium level were observed in all drug-treated groups. It showed that NBP strongly attenuated brain water entry,sodium accumulation and potassium loss. Nimodipine treatment(5mg/kg sc) also reduced brain edema (P<0. 05). The results suggest that a strong anti-edema activity of NBP may play an important role to contribute to the treatment of ischemic damage.
文摘BACKGROUND： Several studies have demonstrated that propofol exhibits protective effects in the central nervous system. OBJECTIVE： To observe the effects of propofol on neuronal apoptosis and aquaporin-4 （AQP-4） expression in a rat model of traumatic brain injury and to further investigate the mechanisms of action. DESIGN, TIME AND SETTING： The present neuronal, pathomorphological experiment was performed at the Institute of Cerebrovascular Disease, Qingdao University Medical College between April 2007 and March 2008. MATERIALS： Traumatic brain injury was induced by free falling objects in 150 healthy, male, Wistar rats. Propofol was produced by AstraZeneca, China. Rabbit anti-rat AQP-4 polyclonal antibody, SABC immunohistochemistry kit, and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick-end labeling （TUNEL） kit were purchased from Wuhan Boster Bioengineering Co., Ltd., China. METHODS： All 150 rats were randomly and evenly divided into lesion-only and propofol-treated groups. One hour after traumatic brain injury, propofol-treated animals received 1% propofol （10 mg/kg） through the caudal vein, followed by a sustained perfusion of 30 mg/kg propofol per hour for 2 hours, while the lesion-only group received equal volumes of physiological saline in parallel. MAIN OUTCOME MEASURES： At 6, 12, 24, 48, and 72 hours after traumatic brain injury, morphological changes in the peritraumatic and adjacent brain areas were analyzed in all rats by hematoxylin-eosin （HE） staining. In addition, cellular apoptosis was detected by TUNEL assay and the number of AQP-4-positive cells was determined by immunohistochemistry techniques. Brain water content was calculated as the ratio of dry to wet tissue weight. RESULTS： HE staining results demonstrated that, in the lesion-only group, the peritraumatic area exhibited neuronal and glial cell necrosis and disintegration. The adjacent area displayed swollen neuronal perikarya and vascular endothelial ceils, cellular edema, and a small amount of proliferating glial ceils. In contrast, these pathological changes were noticeably alleviated in the peritraumatic and adjacent areas of propofol-treated animals. Compared with the lesion-only group, the number of apoptotic cells was significantly decreased in the propofol-treated group at each time point after traumatic brain injury, in particular at 24 and 48 hours （P 〈 0.05-0.01）. In the lesion-only group, AQP-4 expression began to increase at 6 hours after traumatic brain injury, reached a peak level at 24-48 hours, and began to decrease by 72 hours. In the propofol-treated group, the number of AQP-4 positive cells was significantly less than the lesion-only group. This was the case at all time points, in particular at 12 and 24 hours （P 〈 0.01-0.05）. CONCLUSION： Propofol can dowuregulate neuronal apoptosis and AQP-4 expression in rats following traumatic brain injury, in particular at 24-48 hours.
基金funded by the National NaturalScience Foundation of China (Youth), No. 81001556
文摘This study used electroacupuncture at Renzhong （DU26） and Baihui （DU20） in a rat model of cerebral ischemia/reperfusion injury. Neurological deficit scores, western blotting, and reverse transcription-PCR results demonstrated that electroacupuncture markedly reduced neurological deficits, decreased corpus striatum aquaporin-4 protein and mRNA expression, and relieved damage to the blood-brain barrier in a rat model of cerebral ischemia/reperfusion injury. These results suggest that electroacupuncture most likely protects the blood-brain barrier by regulating aquaporin-4 expression following cerebral ischemia/reperfusion injury.
基金supported by the Chinese Traditional Medical Science Foundation of Zhejiang Province in China,No.2010ZA072the Health Bureau Foundation of Zhejiang Province in China,No.2012ZDA023the Qianjiang Project of Zhejiang Science and Technology Bureau in China,No.2010 R10073
文摘Puerarin, a traditional Chinese medicine, exerts a powerful neuroprotective effect in cerebral ischemia/reperfusion injury, but its mechanism is unknown. Here, we established rat models of middle cerebral artery ischemia/reperfusion injury using the suture method. Puerarin （100 mg/kg） was administered intraperitoneally 30 minutes before middle cerebral artery occlusion and 8 hours after reperfusion. Twenty-four hours after reperfusion, we found that puerarin significantly improved neurological deficit, reduced infarct size and brain water content, and notably diminished the expression of Toll-like receptor-4, myeloid differentiation factor 88, nuclear factor kappa B and tumor necrosis factor-α in the ischemic region. These data indicate that puerarin exerts an anti-inflammatory protective effect on brain tissue with ischemia/reperfusion damage by downregulating the expression of multiple inflammatory factors.
基金supported by the National Natural Science Foundation of China,No.81471488,81271378,81502157,and 81501291the Key Medical Subjects of Jiangsu Province of China,No.XK201120+3 种基金the Jiangsu Province Key Research and Development of Special Funds in China,No.BE2015644the Science and Technology Project of Suzhou City of China,No.SYSD2013105,SYS201446,SYS201441the Public Health Technology Project of Suzhou City of China,No.SS201536the Department of Pediatrics Clinical Center of Suzhou City of China,No.Szzx201504
文摘Autophagy has been suggested to participate in the pathology of hypoxic-ischemic brain damage（HIBD）.However,its regulatory role in HIBD remains unclear and was thus examined here using a rat model.To induce HIBD,the left common carotid artery was ligated in neonatal rats,and the rats were subjected to hypoxia for 2 hours.Some of these rats were intraperitoneally pretreated with the autophagy inhibitor 3-methyladenine（10 m M in 10 μL） or the autophagy stimulator rapamycin（1 g/kg） 1 hour before artery ligation.Our findings demonstrated that hypoxia-ischemia-induced hippocampal injury in neonatal rats was accompanied by increased expression levels of the autophagy-related proteins light chain 3 and Beclin-1 as well as of the AMPA receptor subunit GluR 1,but by reduced expression of GluR 2.Pretreatment with the autophagy inhibitor 3-methyladenine blocked hypoxia-ischemia-induced hippocampal injury,whereas pretreatment with the autophagy stimulator rapamycin significantly augmented hippocampal injury.Additionally,3-methyladenine pretreatment blocked the hypoxia-ischemia-induced upregulation of Glu R1 and downregulation of GluR2 in the hippocampus.By contrast,rapamycin further elevated hippocampal Glu R1 levels and exacerbated decreased GluR2 expression levels in neonates with HIBD.Our results indicate that autophagy inhibition favors the prevention of HIBD in neonatal rats,at least in part,through normalizing Glu R1 and GluR2 expression.
基金supported by a Grant-in-Aid for Scientific Research from Mie Medical Research Foundation to Dr.Suzuki
文摘Neuroinflammation is a well-recognized consequence of subarachnoid hemorrhage（SAH）, and Toll-like receptor（TLR） 4 may be an important therapeutic target for post-SAH neuroinflammation. Of the TLR family members, TLR4 is expressed in various cell types in the central nervous system, and is unique in that it can signal through both the myeloid differentiation primary-response protein 88-dependent and the toll receptor associated activator of interferon-dependent cascades to coordinate the maximal inflammatory response. TLR4 can be activated by many endogenous ligands having damage-associated molecular patterns including heme and fibrinogen at the rupture of an intracranial aneurysm, and the resultant inflammatory reaction and thereby tissue damages may furthermore activate TLR4. It is widely accepted that the excreted products of TLR4 signaling alter neuronal functions. Previous studies have focused on the pathway through nuclear factor（NF）-κΒ signaling among TLR4 signaling pathways as to the development of early brain injury（EBI） such as neuronal apoptosis and blood-brain barrier disruption, and cerebral vasospasm. However, many findings suggest that both pathways via NF-κΒ and mitogen-activated protein kinases may be involved in EBI and cerebral vasospasm development. To overcome EBI and cerebral vasospasm is important to improve outcomes after SAH, because both EBI and vasopasm are responsible for delayed brain injuries or delayed cerebral ischemia, the most important preventable cause of poor outcomes after SAH. Increasing evidence has shown that TLR4 signaling plays an important role in SAH-induced brain injuries. Better understanding of the roles of TLR4 signaling in SAH will facilitate development of new treatments.
基金the National Natural Science Foundation of China, No. 30470608, 30500171
文摘BACKGROUND： Aquaporin-4 （AQP-4）, which is able to rapidly transport water within the brain, is highly expressed in brain tissue. It also plays an important role in the formation of cerebral edema following brain injury. However, the role of AQP-4 in the formation of cerebral edema following severe bums remains unknown. OBJECTIVE： To study changes in AQP-4 protein and mRNA expression during formation of cerebral edema following severe burns, and to explore the correlation between AQP-4 protein and mRNA expression with plasma levels of arginine vasopressin （AVP）. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the Research Center of Neuroscience, Chongqing Medical University from 2007 to 2008. MATERIALS： Biotin-labeled goat anti-rabbit antibody was provided by Beijing Zhongshan Biotechnology, China; in situ hybridization kit was provided by Wuhan Boster Biotechnology, China; rabbit anti-AQP-4 polyclonal antibody and horseradish peroxidase-labeled goat anti-rabbit IgG were provided by Chemicon, USA; AVP radioimmunoassay kit was provided by the Research Department of Neurobiology, the Second Military Medical University of Shanghai, China. METHODS： A total of 180 adult, healthy, Wistar rats were randomly assigned to control and burn groups with 30 rats in each group. The burn group was observed at five different time points： 2, 6, 12, 24, and 48 hours after burn. Hair on the mouse back was removed to expose skin on the back. After 1 day, skin with the hair removed was dipped into 100℃ water for 15 seconds to induce grade III bum injury that measures 30% of total bum surface area. MAIN OUTCOME MEASURES： Brain water content was measured using the dry-wet weight method. AQP-4 protein and mRNA expressions were detected using immunohistochemistry, in situ hybridization, Western blot, and reverse transcription-polymerase chain reaction; dynamic changes in plasma AVP were detected using radioimmunoassay. RESULTS： Brain water content gradually increased following severe burn injury. AQP-4 protein and mRNA expressions were upregulated in the supraoptic nucleus, suprachiasmatic nucleus, paraventricular nucleus, hippocampus, choroid plexus, and cerebral cortex. Plasma AVP levels increased following burn injury. AQP-4 protein and mRNA expressions positively correlated with brain water content and AVP levels during formation of cerebral edema （r= 0.870, 0.848, P 〈 0.01）. CONCLUSION： AQP-4 participated in the formation of cerebral edema following burn injury. Plasma AVP upregulated AQP-4 expression in brain tissue, thereby promoting formation of cerebral edema.
