In the present study, rabbits were treated with hyperbaric oxygen for 1 hour after detonator-blastinduced craniocerebral injury. Immunohistochemistry showed significantly reduced aquaporin 4 expression and adrenocorti...In the present study, rabbits were treated with hyperbaric oxygen for 1 hour after detonator-blastinduced craniocerebral injury. Immunohistochemistry showed significantly reduced aquaporin 4 expression and adrenocorticotropic hormone expression in the pituitary gland of rabbits with craniocerebral injury. Aquaporin 4 expression was positively correlated with adrenocorticotropic hormone expression. These findings indicate that early hyperbaric oxygen therapy may suppress adrenocorticotropic hormone secretion by inhibiting aquaporin 4 expression.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
Objective To investigate the role of extracellular signal-regulated kinase1/2（ERK1/2） pathway in the regulation of aquaporin 4（AQP4） expression in cultured astrocytes after scratch-injury. Methods The scratch-inju...Objective To investigate the role of extracellular signal-regulated kinase1/2（ERK1/2） pathway in the regulation of aquaporin 4（AQP4） expression in cultured astrocytes after scratch-injury. Methods The scratch-injury model was produced in cultured astrocytes of rat by a 10-μL plastic pipette tip. The morphological changes of astrocytes and lactate dehydrogenase（LDH） leakages were observed to assess the degree of scratch-injury. AQP4 expression was detected by immunofluorescence staining and Western blot, and phosphorylated-ERK1/2（p-ERK1/2） expression was determined by Western blot. To explore the effect of ERK1/2 pathway on AQP4 expression in scratch-injured astrocytes, 10 μmol/L U0126（ERK1/2 inhibitor） was incubated in the medium at 30 min before the scratch-injury in some groups. Results Increases in LDH leakage were observed at 1, 12, and 24 h after scratch-injury, and AQP4 expression was reduced simultaneously. Decrease in AQP4 expression was associated with a significant increase in ERK1/2 activation. Furthermore, pretreatment with U0126 blocked both ERK1/2 activation and decrease in AQP4 expression induced by scratch-injury. Conclusion These results indicate that ERK1/2 pathway down-regulates AQP4 expression in scratch-injured astrocytes, and ERK1/2 pathway might be a novel therapeutic target in reversing the effects of astrocytes that contribute to traumatic brain edema.展开更多
OBJECTIVE To examine the effects of aquaporin 4(AQP4) on opioid addiction and underlie the mechanism behind it. METHODS(1) In the heroin-induced self-administration(SA) experiment,we explored the role of AQP4 on heroi...OBJECTIVE To examine the effects of aquaporin 4(AQP4) on opioid addiction and underlie the mechanism behind it. METHODS(1) In the heroin-induced self-administration(SA) experiment,we explored the role of AQP4 on heroin-induced psychological addiction. After the mice were trained to learn heroin-induced SA under a fixedratio1(FR1) reinforcement program for 7 d,we randomly switched the heroin doses to 0.00625,0.0125,0.025,0.05 or 0.1 mg·kg^(-1)per infusion to counterbalance assignment design. In the end,all mice underwent extinction training and reinstatement testing.(2) In oral sucrose self-administration,5% sucrose solution was used for the mice and the procedures were similar to heroin SA.(3) In morphine-induced hyperactivity test,mice were habituated in the test apparatus for 30 min and then were given saline(10 mL·kg^(-1),sc) or morphine(10 or 20 mg·kg^(-1),sc) to record the locomotion for 1.5 h.(4) For the in vivo microdialysis experiment,mice were surgically implanted with intracranial guide cannula into nucleus accumbens(AP +1.4 mm,ML ±0.9 mm,DV-3.8 mm from bregma). After 5 d of recovery from surgery,the mice were challenged by saline(10 mL·kg^(-1),sc)or morphine(10 mg·kg^(-1),sc),and then samples were collected every 20 min. RESULTS We found that AQP4 deletion had no effects on sucrose-seeking and sucrose-taking,but it significantly attenuated heroin-taking and heroin-seeking behaviors in heroin self-administration. Besides these,AQP4 deletion had no effects on basal level of locomotion,but dramatically decreased morphine-induced hyperactivity.Furthermore,the in vivo microdialysis studies showed that AQP4 deficiency inhibited morphine(10mg · kg^(-1),sc)-induced elevation of extracellular dopamine levels in nucleus accumbens in mice.CONCLUSION Our present findings demonstrate that AQP4 was potentially involved in the properties of opioid rewarding by inhibiting dopamine release in nucleus accumbens(NAc).展开更多
Clinical information and serum samples of 20 neuromyelitis patients and 30 patients with multiple sclerosis were collected in this study. The expression of anti-aquaporin 4 antibody in the serum of all patients was de...Clinical information and serum samples of 20 neuromyelitis patients and 30 patients with multiple sclerosis were collected in this study. The expression of anti-aquaporin 4 antibody in the serum of all patients was detected with an indirect immunofluorescence assay, using human embryonic kidney 293 cell line that stably express human-derived aquaporin 4 as a substrate. The characteristics of head and spinal magnetic resonance imaging were also observed in patients who had neuromyelitis and were positive for anti-aquaporin 4 antibody. Results showed that the expression of anti-aquaporin 4 antibody was significantly different between multiple sclerosis patients and neuromyelitis patients. There were 13 out of 20 neuromyelitis patients （including high-risk syndrome） that were positive for anti-aquaporin 4 antibody. The magnetic resonance imaging examinations of the head and spinal cord found that among the 13 positive patients, nine cases showed normal cerebral hemisphere and optic nerve, two cases had optic nerve changes, and one case had an atypical lesion in the brain. All 30 multiple sclerosis patients were negative for this antibody. The experimental findings indicate that patients with neuromyelitis optica had more than three lesioned segments in the spinal cord by magnetic resonance imaging, and the segment length of the injured spinal cord was not associated with the titer of aquaporin 4 antibody in neuromyelitis patients.展开更多
To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 pL shRNA- aquapo...To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 pL shRNA- aquaporin-4 （control group） or siRNA- aquaporin-4 solution （1：800） （RNA interference group） into the rat right basal ganglia immediately before occlusion of the middle cerebral artery. At 0.25 hours after occlusion of the middle cerebral artery, diffusion-weighted MRI displayed a high signal; within 2 hours, the relative apparent diffusion coefficient decreased markedly, aquaporin-4 expression increased rapidly, and intracellular edema was obviously aggravated; at 4 and 6 hours, the relative apparent diffusion coefficient slowly returned to control levels, aquaporin-4 expression slightly increased, and angioedema was observed. In the RNA interference group, during 0.25- 6 hours after injection of siRNA- aquaporin-4 solution, the relative apparent diffusion coefficient slightly fluctuated and aquaporin-4 expression was upregulated; during 0.5 4 hours, the relative apparent diffusion coefficient was significantly higher, while aquaporin-4 expression was significantly lower when compared with the control group, and intracellular edema was markedly reduced; at 0.25 and 6 hours, the relative apparent diffusion coefficient and aquaporin-4 expression were similar when compared with the control group; obvious angioedema remained at 6 hours. Pearson＇s correlation test results showed that aquaporin-4 expression was negatively correlated with the apparent diffusion coefficient （r = -0.806, P 〈 0.01）. These findings suggest that upregulated aquaporin-4 expression is likely to be the main molecular mechanism of intracellular edema and may be the molecular basis for decreased relative apparent diffusion coefficient. Aquaporin-4 gene interference can effectively inhibit the upregulation of aquaporin-4 expression during the stage of intracelfular edema with time-effectiveness. Moreover, diffusion-weighted MRI can accurately detect intracellular edema.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
Ammonia induces astrocyte swelling, which is strongly associated with overexpression of aquaporin-4. However, the mechanisms by which ammonia induces astrocyte swelling, and subsequently upregulating aquaporin-4 expre...Ammonia induces astrocyte swelling, which is strongly associated with overexpression of aquaporin-4. However, the mechanisms by which ammonia induces astrocyte swelling, and subsequently upregulating aquaporin-4 expression, remain unknown. In the present study, astrocytes were cultured in vitro and exposed to ammonium chloride （NH4CI）, followed by propofol protein kinase C agonist, or antagonist, respectively. Astrocyte morphology was observed by light microscopy, and aquaporin-4 expression was detected by western blot analysis. Results showed that propofol or protein kinase C agonist significantly attenuated the degree of NH4CI-induced astrocyte swelling and inhibited increased aquaporin-4 expression. Propofol treatment inhibited aquaporin-4 overexpression in cultured astrocyte induced by NH4CI; protein kinase C pathway activation is potentially involved.展开更多
BACKGROUND： Aquaporin-4 （AQP-4） over-expression following cerebral ischemia results in cerebral edema. Picroside Ⅱ has been shown to exhibit a neuroprotective effect on neuronal apoptosis. However, few reports hav...BACKGROUND： Aquaporin-4 （AQP-4） over-expression following cerebral ischemia results in cerebral edema. Picroside Ⅱ has been shown to exhibit a neuroprotective effect on neuronal apoptosis. However, few reports have addressed the neuroprotective mechanisms and therapeutic times following cerebral ischemic reperfusion injury. OBJECTIVE： To explore the neuroprotective effects and ideal treatment window for picroside Ⅱ treatment of middle cerebral artery occlusion and reperfusion injury in rats. DESIGN, TIME AND SETTING; A randomized, controlled, animal experiment was performed at Institute of Cerebrovascular Diseases, Qingdao University Medical College from September 2008 to May 2009. MATERIALS： Picroside II was purchased from Tianjin Kuiqing Medical Technology, China. METHODS： A total of 165 adult, healthy, male, Wistar rats were randomly assigned to sham-surgery （n = 15）, model （n = 75）, and treatment groups （n = 75）. Rats in the model and treatment groups underwent middle cerebral artery occlusion and reperfusion through the use of an intraluminal monofilament suture on the left external-internal carotid artery, The treatment group was injected with 1.0% picroside Ⅱ （10 mg/kg） into the tail vein, and the model and sham-surgery groups were injected with 0.1 mol/L phosphate buffered saline （250 μL）. MAIN OUTCOME MEASURES： Neurological functional scores were evaluated using the Longa＇s method; cerebral infarction volume was detected through the use of tetrazolium chlodde staining; cellular apoptosis was determined through the use of the in situ end-labeling method; aquaporin-4 expression was measured using fluorescence labeling analysis and reverse transcription polymerase chain reaction technique. RESULTS： At 0.5 hour following cerebral ischemic injury, neurological functional scores were low, and a small infarction focus was detected in the ischemic cortex of the model group. Along with prolonged ischemia and an increased number of apoptosis-positive cells, AQP-4 mRNA and protein expression was increased. At 1-2 hours after ischemia, neurological scores and infarction sizes were significantly increased in the model group. Apoptotic-positive cells were widespread in the ipsilateral cortex and stdatum. In addition, AQP-4 mRNA and protein expression levels were increased. Picroside II treatment significantly decreased neurological scores and infarction volume, and reduced AQP-4 mRNA and protein expression levels compared with the model group （P 〈 0.05 or P 〈 0.01）. At 1 hour after ischemia, the therapeutic effect of picroside Ⅱ was notable （P 〈 0.01）. CONCLUSION： Picroside Ⅱ played a protective role in cerebral ischemic reperfusion injury by inhibiting apoptosis and regulating AQP-4 expression. The best therapeutic time window was 1 hour after cerebral ischemic reperfusion.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
BACKGROUND： Aquaporin-4 （AQP4） is abundant in astrocytes, ependymal cells, and the choroid plexus, and is associated with cerebrospinal fluid formation and osmoregulation. AQP4 is speculated to be the hypothalamic ...BACKGROUND： Aquaporin-4 （AQP4） is abundant in astrocytes, ependymal cells, and the choroid plexus, and is associated with cerebrospinal fluid formation and osmoregulation. AQP4 is speculated to be the hypothalamic osmoreceptor and regulator of water balance. OBJECTIVE： To examine AQP4 expression and its role in cultured rat astrocytes after exposure to hypotonic medium. DESIGN, TIME AND SETTING： Randomized control experiment. This experiment was carried out in the Research Room of Neurobiology, Chongqing University of Medical Science, China, between April and October 2003. MATERIALS： Two-day-old newborn Wistar rats （n =20）, weighing 10- 15 g, were purchased from the Experimental Animal Center of Chongqing University of Medical Science, China. METHODS： Purified rat cerebral cortical astrocytes were isolated fiom Wistar rats for in vitro cell culture experiments. The cells were randomly divided into control and hypotonic groups. The in vitro cell edema model was established by exposing astrocytes to hypotonic medium （268, 254, or 240 mmol/L）. Cells in the control group were cultured in normal culture medium. MAIN OUTCOME MEASURES： Morphological changes in astrocytes were observed under an inverted microscope and a transmission electron microscope after cells were cultured for 3, 6, 12, or 24 hours with hypotonic medium or normal culture medium. In each group, AQP4 protein and mRNA expression were assessed by immunocytochemistry, in situ hybridization, and reverse transcription polymerase chain reaction at the different time points. RESULTS： After astrocytes were cultured for 3, 6, 12, or 24 hours with hypotonic medium （268, 254, 240 mmol/L）, they showed typical features of cell edema. In the control group, no astrocytes developed pathological changes. There were no significant changes in the AQP4 mRNA and protein expression in the control group at any of the time points alter astrocytes were cultured with normal culture medium （P 〉 0.05）. Compared with the control group, AQP4 mRNA and protein expression in the hypotonic group were remarkably increased at all time points after astrocytes cultured with hypotonic medium （268, 254, 240 mmol/L; P 〈 0.05）. AQP4 mRNA and protein expression increased with increasing exposure time and with decreasing concentration of the hypotonic medium. CONCLUSION： Hypotonic medium induced cell edema and increased AQP4 mRNA and protein expression. Up-regulated expression of AQP4 was correlated with hypotonic medium concentration in a time dependent manner.展开更多
Aquaporin-4 regulates water molecule channels and is important in tissue regulation and water transportation in the brain. Upregulation of aquaporin-4 expression is closely related to cellular edema after early cerebr...Aquaporin-4 regulates water molecule channels and is important in tissue regulation and water transportation in the brain. Upregulation of aquaporin-4 expression is closely related to cellular edema after early cerebral infarction. Cellular edema and aquaporin-4 expression can be determined by measuring cerebral infarct area and apparent diffusion coefficient using diffusion-weighted imaging（DWI）. We examined the effects of silencing aquaporin-4 on cerebral infarction. Rat models of cerebral infarction were established by occlusion of the right middle cerebral artery and si RNA-aquaporin-4 was immediately injected via the right basal ganglia. In control animals, the area of high signal intensity and relative apparent diffusion coefficient value on T2-weighted imaging（T2WI） and DWI gradually increased within 0.5–6 hours after cerebral infarction. After aquaporin-4 gene silencing, the area of high signal intensity on T2 WI and DWI reduced, relative apparent diffusion coefficient value was increased, and cellular edema was obviously alleviated. At 6 hours after cerebral infarction, the apparent diffusion coefficient value was similar between treatment and model groups, but angioedema was still obvious in the treatment group. These results indicate that aquaporin-4 gene silencing can effectively relieve cellular edema after early cerebral infarction; and when conducted accurately and on time, the diffusion coefficient value and the area of high signal intensity on T2 WI and DWI can reflect therapeutic effects of aquaporin-4 gene silencing on cellular edema.展开更多
基金supported by the Eleventh-Five Major Subjects of Nanjing Military Area Command,No.06Z19the Military Medical Science and Technology Innovation Foundation in 2009,No.09Z009
文摘In the present study, rabbits were treated with hyperbaric oxygen for 1 hour after detonator-blastinduced craniocerebral injury. Immunohistochemistry showed significantly reduced aquaporin 4 expression and adrenocorticotropic hormone expression in the pituitary gland of rabbits with craniocerebral injury. Aquaporin 4 expression was positively correlated with adrenocorticotropic hormone expression. These findings indicate that early hyperbaric oxygen therapy may suppress adrenocorticotropic hormone secretion by inhibiting aquaporin 4 expression.
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 the National Natural Science Foundation of China,No.81271286 to YUAN Fang and No.81228009 to YANG Shao Hua
文摘Objective To investigate the role of extracellular signal-regulated kinase1/2（ERK1/2） pathway in the regulation of aquaporin 4（AQP4） expression in cultured astrocytes after scratch-injury. Methods The scratch-injury model was produced in cultured astrocytes of rat by a 10-μL plastic pipette tip. The morphological changes of astrocytes and lactate dehydrogenase（LDH） leakages were observed to assess the degree of scratch-injury. AQP4 expression was detected by immunofluorescence staining and Western blot, and phosphorylated-ERK1/2（p-ERK1/2） expression was determined by Western blot. To explore the effect of ERK1/2 pathway on AQP4 expression in scratch-injured astrocytes, 10 μmol/L U0126（ERK1/2 inhibitor） was incubated in the medium at 30 min before the scratch-injury in some groups. Results Increases in LDH leakage were observed at 1, 12, and 24 h after scratch-injury, and AQP4 expression was reduced simultaneously. Decrease in AQP4 expression was associated with a significant increase in ERK1/2 activation. Furthermore, pretreatment with U0126 blocked both ERK1/2 activation and decrease in AQP4 expression induced by scratch-injury. Conclusion These results indicate that ERK1/2 pathway down-regulates AQP4 expression in scratch-injured astrocytes, and ERK1/2 pathway might be a novel therapeutic target in reversing the effects of astrocytes that contribute to traumatic brain edema.
文摘OBJECTIVE To examine the effects of aquaporin 4(AQP4) on opioid addiction and underlie the mechanism behind it. METHODS(1) In the heroin-induced self-administration(SA) experiment,we explored the role of AQP4 on heroin-induced psychological addiction. After the mice were trained to learn heroin-induced SA under a fixedratio1(FR1) reinforcement program for 7 d,we randomly switched the heroin doses to 0.00625,0.0125,0.025,0.05 or 0.1 mg·kg^(-1)per infusion to counterbalance assignment design. In the end,all mice underwent extinction training and reinstatement testing.(2) In oral sucrose self-administration,5% sucrose solution was used for the mice and the procedures were similar to heroin SA.(3) In morphine-induced hyperactivity test,mice were habituated in the test apparatus for 30 min and then were given saline(10 mL·kg^(-1),sc) or morphine(10 or 20 mg·kg^(-1),sc) to record the locomotion for 1.5 h.(4) For the in vivo microdialysis experiment,mice were surgically implanted with intracranial guide cannula into nucleus accumbens(AP +1.4 mm,ML ±0.9 mm,DV-3.8 mm from bregma). After 5 d of recovery from surgery,the mice were challenged by saline(10 mL·kg^(-1),sc)or morphine(10 mg·kg^(-1),sc),and then samples were collected every 20 min. RESULTS We found that AQP4 deletion had no effects on sucrose-seeking and sucrose-taking,but it significantly attenuated heroin-taking and heroin-seeking behaviors in heroin self-administration. Besides these,AQP4 deletion had no effects on basal level of locomotion,but dramatically decreased morphine-induced hyperactivity.Furthermore,the in vivo microdialysis studies showed that AQP4 deficiency inhibited morphine(10mg · kg^(-1),sc)-induced elevation of extracellular dopamine levels in nucleus accumbens in mice.CONCLUSION Our present findings demonstrate that AQP4 was potentially involved in the properties of opioid rewarding by inhibiting dopamine release in nucleus accumbens(NAc).
基金the Special Scientific Research Facilities Fund for Highlevel Talents in Guizhou Province, No.TZJF-2008-57
文摘Clinical information and serum samples of 20 neuromyelitis patients and 30 patients with multiple sclerosis were collected in this study. The expression of anti-aquaporin 4 antibody in the serum of all patients was detected with an indirect immunofluorescence assay, using human embryonic kidney 293 cell line that stably express human-derived aquaporin 4 as a substrate. The characteristics of head and spinal magnetic resonance imaging were also observed in patients who had neuromyelitis and were positive for anti-aquaporin 4 antibody. Results showed that the expression of anti-aquaporin 4 antibody was significantly different between multiple sclerosis patients and neuromyelitis patients. There were 13 out of 20 neuromyelitis patients （including high-risk syndrome） that were positive for anti-aquaporin 4 antibody. The magnetic resonance imaging examinations of the head and spinal cord found that among the 13 positive patients, nine cases showed normal cerebral hemisphere and optic nerve, two cases had optic nerve changes, and one case had an atypical lesion in the brain. All 30 multiple sclerosis patients were negative for this antibody. The experimental findings indicate that patients with neuromyelitis optica had more than three lesioned segments in the spinal cord by magnetic resonance imaging, and the segment length of the injured spinal cord was not associated with the titer of aquaporin 4 antibody in neuromyelitis patients.
基金supported by the National Natural Science Foundation of China, No. 30960399, 81160181
文摘To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 pL shRNA- aquaporin-4 （control group） or siRNA- aquaporin-4 solution （1：800） （RNA interference group） into the rat right basal ganglia immediately before occlusion of the middle cerebral artery. At 0.25 hours after occlusion of the middle cerebral artery, diffusion-weighted MRI displayed a high signal; within 2 hours, the relative apparent diffusion coefficient decreased markedly, aquaporin-4 expression increased rapidly, and intracellular edema was obviously aggravated; at 4 and 6 hours, the relative apparent diffusion coefficient slowly returned to control levels, aquaporin-4 expression slightly increased, and angioedema was observed. In the RNA interference group, during 0.25- 6 hours after injection of siRNA- aquaporin-4 solution, the relative apparent diffusion coefficient slightly fluctuated and aquaporin-4 expression was upregulated; during 0.5 4 hours, the relative apparent diffusion coefficient was significantly higher, while aquaporin-4 expression was significantly lower when compared with the control group, and intracellular edema was markedly reduced; at 0.25 and 6 hours, the relative apparent diffusion coefficient and aquaporin-4 expression were similar when compared with the control group; obvious angioedema remained at 6 hours. Pearson＇s correlation test results showed that aquaporin-4 expression was negatively correlated with the apparent diffusion coefficient （r = -0.806, P 〈 0.01）. These findings suggest that upregulated aquaporin-4 expression is likely to be the main molecular mechanism of intracellular edema and may be the molecular basis for decreased relative apparent diffusion coefficient. Aquaporin-4 gene interference can effectively inhibit the upregulation of aquaporin-4 expression during the stage of intracelfular edema with time-effectiveness. Moreover, diffusion-weighted MRI can accurately detect intracellular edema.
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.
基金Supported by a Grant from Zhejiang Provincial Health Department, No. 2007A057
文摘Ammonia induces astrocyte swelling, which is strongly associated with overexpression of aquaporin-4. However, the mechanisms by which ammonia induces astrocyte swelling, and subsequently upregulating aquaporin-4 expression, remain unknown. In the present study, astrocytes were cultured in vitro and exposed to ammonium chloride （NH4CI）, followed by propofol protein kinase C agonist, or antagonist, respectively. Astrocyte morphology was observed by light microscopy, and aquaporin-4 expression was detected by western blot analysis. Results showed that propofol or protein kinase C agonist significantly attenuated the degree of NH4CI-induced astrocyte swelling and inhibited increased aquaporin-4 expression. Propofol treatment inhibited aquaporin-4 overexpression in cultured astrocyte induced by NH4CI; protein kinase C pathway activation is potentially involved.
基金the National Natural Science Foundation of China,No. 30873391
文摘BACKGROUND： Aquaporin-4 （AQP-4） over-expression following cerebral ischemia results in cerebral edema. Picroside Ⅱ has been shown to exhibit a neuroprotective effect on neuronal apoptosis. However, few reports have addressed the neuroprotective mechanisms and therapeutic times following cerebral ischemic reperfusion injury. OBJECTIVE： To explore the neuroprotective effects and ideal treatment window for picroside Ⅱ treatment of middle cerebral artery occlusion and reperfusion injury in rats. DESIGN, TIME AND SETTING; A randomized, controlled, animal experiment was performed at Institute of Cerebrovascular Diseases, Qingdao University Medical College from September 2008 to May 2009. MATERIALS： Picroside II was purchased from Tianjin Kuiqing Medical Technology, China. METHODS： A total of 165 adult, healthy, male, Wistar rats were randomly assigned to sham-surgery （n = 15）, model （n = 75）, and treatment groups （n = 75）. Rats in the model and treatment groups underwent middle cerebral artery occlusion and reperfusion through the use of an intraluminal monofilament suture on the left external-internal carotid artery, The treatment group was injected with 1.0% picroside Ⅱ （10 mg/kg） into the tail vein, and the model and sham-surgery groups were injected with 0.1 mol/L phosphate buffered saline （250 μL）. MAIN OUTCOME MEASURES： Neurological functional scores were evaluated using the Longa＇s method; cerebral infarction volume was detected through the use of tetrazolium chlodde staining; cellular apoptosis was determined through the use of the in situ end-labeling method; aquaporin-4 expression was measured using fluorescence labeling analysis and reverse transcription polymerase chain reaction technique. RESULTS： At 0.5 hour following cerebral ischemic injury, neurological functional scores were low, and a small infarction focus was detected in the ischemic cortex of the model group. Along with prolonged ischemia and an increased number of apoptosis-positive cells, AQP-4 mRNA and protein expression was increased. At 1-2 hours after ischemia, neurological scores and infarction sizes were significantly increased in the model group. Apoptotic-positive cells were widespread in the ipsilateral cortex and stdatum. In addition, AQP-4 mRNA and protein expression levels were increased. Picroside II treatment significantly decreased neurological scores and infarction volume, and reduced AQP-4 mRNA and protein expression levels compared with the model group （P 〈 0.05 or P 〈 0.01）. At 1 hour after ischemia, the therapeutic effect of picroside Ⅱ was notable （P 〈 0.01）. CONCLUSION： Picroside Ⅱ played a protective role in cerebral ischemic reperfusion injury by inhibiting apoptosis and regulating AQP-4 expression. The best therapeutic time window was 1 hour after cerebral ischemic reperfusion.
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.
基金the National Natural Science Foundation of China, No.30070247
文摘BACKGROUND： Aquaporin-4 （AQP4） is abundant in astrocytes, ependymal cells, and the choroid plexus, and is associated with cerebrospinal fluid formation and osmoregulation. AQP4 is speculated to be the hypothalamic osmoreceptor and regulator of water balance. OBJECTIVE： To examine AQP4 expression and its role in cultured rat astrocytes after exposure to hypotonic medium. DESIGN, TIME AND SETTING： Randomized control experiment. This experiment was carried out in the Research Room of Neurobiology, Chongqing University of Medical Science, China, between April and October 2003. MATERIALS： Two-day-old newborn Wistar rats （n =20）, weighing 10- 15 g, were purchased from the Experimental Animal Center of Chongqing University of Medical Science, China. METHODS： Purified rat cerebral cortical astrocytes were isolated fiom Wistar rats for in vitro cell culture experiments. The cells were randomly divided into control and hypotonic groups. The in vitro cell edema model was established by exposing astrocytes to hypotonic medium （268, 254, or 240 mmol/L）. Cells in the control group were cultured in normal culture medium. MAIN OUTCOME MEASURES： Morphological changes in astrocytes were observed under an inverted microscope and a transmission electron microscope after cells were cultured for 3, 6, 12, or 24 hours with hypotonic medium or normal culture medium. In each group, AQP4 protein and mRNA expression were assessed by immunocytochemistry, in situ hybridization, and reverse transcription polymerase chain reaction at the different time points. RESULTS： After astrocytes were cultured for 3, 6, 12, or 24 hours with hypotonic medium （268, 254, 240 mmol/L）, they showed typical features of cell edema. In the control group, no astrocytes developed pathological changes. There were no significant changes in the AQP4 mRNA and protein expression in the control group at any of the time points alter astrocytes were cultured with normal culture medium （P 〉 0.05）. Compared with the control group, AQP4 mRNA and protein expression in the hypotonic group were remarkably increased at all time points after astrocytes cultured with hypotonic medium （268, 254, 240 mmol/L; P 〈 0.05）. AQP4 mRNA and protein expression increased with increasing exposure time and with decreasing concentration of the hypotonic medium. CONCLUSION： Hypotonic medium induced cell edema and increased AQP4 mRNA and protein expression. Up-regulated expression of AQP4 was correlated with hypotonic medium concentration in a time dependent manner.
基金supported by the National Natural Science Foundation of China,No.30960399a grant from Hainan Provincial International Cooperation Project of China,No.Qiongke(2012)65a grant from Hainan Provincial Health Department Project of China,No.2011-SWK-10-136/Qiongwei2011-65
文摘Aquaporin-4 regulates water molecule channels and is important in tissue regulation and water transportation in the brain. Upregulation of aquaporin-4 expression is closely related to cellular edema after early cerebral infarction. Cellular edema and aquaporin-4 expression can be determined by measuring cerebral infarct area and apparent diffusion coefficient using diffusion-weighted imaging（DWI）. We examined the effects of silencing aquaporin-4 on cerebral infarction. Rat models of cerebral infarction were established by occlusion of the right middle cerebral artery and si RNA-aquaporin-4 was immediately injected via the right basal ganglia. In control animals, the area of high signal intensity and relative apparent diffusion coefficient value on T2-weighted imaging（T2WI） and DWI gradually increased within 0.5–6 hours after cerebral infarction. After aquaporin-4 gene silencing, the area of high signal intensity on T2 WI and DWI reduced, relative apparent diffusion coefficient value was increased, and cellular edema was obviously alleviated. At 6 hours after cerebral infarction, the apparent diffusion coefficient value was similar between treatment and model groups, but angioedema was still obvious in the treatment group. These results indicate that aquaporin-4 gene silencing can effectively relieve cellular edema after early cerebral infarction; and when conducted accurately and on time, the diffusion coefficient value and the area of high signal intensity on T2 WI and DWI can reflect therapeutic effects of aquaporin-4 gene silencing on cellular edema.
