This study aims to explore the pharmacodynamic effect of baicalin on rat brain edema induced by cerebral ischemia reperfusion injury and discuss the mechanism from the perspective of inhibiting astrocyte swelling, which is expected to serve as a refe-rence for the treatment of cerebral ischemia with Chinese medicine. To be specific, middle cerebral artery occlusion(suture method) was used to induce cerebral ischemia in rats. Rats were randomized into normal group, model group, high-dose baicalin(20 mg·kg~(-1)) group, and low-dose baicalin(10 mg·kg~(-1)) group. The neurobehavior, brain index, brain water content, and cerebral infarction area of rats were measured 6 h and 24 h after cerebral ischemia. Brain slices were stained with hematoxylin and eosin(HE) for the observation of pathological morphology of cerebral cortex after baicalin treatment. Enzyme-linked immunosorbent assay(ELISA) was employed to determine the content of total L-glutathione(GSH) and glutamic acid(Glu) in brain tissue, Western blot to measure the content of glial fibrillary acidic protein(GFAP), aquaporin-4(AQP4), and transient receptor potential vanilloid type 4(TRPV4), and immunohistochemical staining to observe the expression of GFAP. The low-dose baicalin was used for exploring the mechanism. The experimental results showed that the neurobehavioral scores(6 h and 24 h of cerebral ischemia), brain water content, and cerebral infarction area of the model group were increased, and both high-dose and low-dose baicalin can lower the above three indexes. The content of GSH dropped but the content of Glu raised in brain tissue of rats in the model group. Low-dose baicalin can elevate the content of GSH and lower the content of Glu. According to the immunohistochemical staining result, the model group demonstrated the increase in GFAP expression, and swelling and proliferation of astrocytes, and the low-dose baicalin can significantly improve this situation. The results of Western blot showed that the expression of GFAP, TRPV4, and AQP4 in the cerebral cortex of the model group increased, and the low-dose baicalin reduce their expression. The cerebral cortex of rats in the model group was severely damaged, and the low-dose baicalin can significantly alleviate the damage. The above results indicate that baicalin can effectively relieve the brain edema caused by cerebral ischemia reperfusion injury in rats, possibly by suppressing astrocyte swelling and TRPV4 and AQP4.
Animals ; Aquaporin 4/genetics* ; Astrocytes ; Brain Edema/drug therapy* ; Brain Ischemia/metabolism* ; Flavonoids ; Infarction, Middle Cerebral Artery/drug therapy* ; Rats ; Rats, Sprague-Dawley ; Reperfusion ; TRPV Cation Channels/therapeutic use*

OBJECTIVES: To observe the changes of expression of aquaporin-1（AQP-1） and AQP-4 in drowned and postmortem immersed rats' lungs. METHODS: Thirty healthy male Wistar rats were randomly divided into drowning group, postmortem immersion group and cervical dislocation group. The morphological changes of rats' lungs were observed using HE staining. The mRNA and protein expressions of AQP-1 and AQP-4 in rats' lungs were detected by real-time PCR, immunohistochemistry and Western blotting, respectively. RESULTS: The results of immunohistochemistry and the Western blotting showed that the protein expression of AQP-1 of the drowning group was higher than the postmortem immersion group and the cervical dislocation group （P<0.05）. The result of immunohistochemistry showed that the protein expression of AQP-4 of the drowning group was higher than the postmortem immersion group and the cervical dislocation group （P<0.05） while no difference were detected among the three of them by Western blotting （P>0.05）. The mRNA expressions of AQP-1 and AQP-4 in rats' lungs of the drowning group was significantly higher than the postmortem immersion group （P<0.05）. CONCLUSIONS The increase of mRNA and protein expressions of AQP-1 and AQP-4 in lungs of rats with cute lung injury of the drowning group would be useful for differentiating vital drowning from postmortem immersion.
Animals ; Aquaporin 1/metabolism* ; Aquaporin 4/metabolism* ; Autopsy ; Blotting, Western ; Drowning ; Immunohistochemistry ; Lung/metabolism* ; Male ; RNA, Messenger ; Rats ; Rats, Sprague-Dawley ; Rats, Wistar ; Real-Time Polymerase Chain Reaction

OBJECTIVE: To observe the expression of aquaporin 4 (AQP4) in diffuse brain injury (DBI) of rats and to explore the corresponding effect of AQP4 for brain edema. METHODS: The rat model of DBI was established using Marmarou's impact-compression trauma model. Brain water content was measured by dry-wet weight method. Blood-brain barrier permeability was evaluated by Evans blue (EB) staining. Immunohistochemical method was used to observe the expression of AQP4. RESULTS: Brain water content increased after 3 h and peaked at 24 h after DBI. Brain EB content significantly increased and peaked at 12 h after DBI. The expression of AQP4 significantly increased after 3 h and peaked at 24 h after DBI, and the number of AQP4 positive astrocytes increased. CONCLUSION The increment of the permeability of blood-brain barrier and the expression of AQP4 may contribute to the development of brain edema in rat DBI. The change of AQP4 expression in astrocytes may also contribute to determine DBI.
Animals ; Aquaporin 4/metabolism* ; Astrocytes ; Blood-Brain Barrier/metabolism* ; Brain ; Brain Edema/metabolism* ; Brain Injuries/metabolism* ; Cell Membrane Permeability/genetics* ; Disease Models, Animal ; Permeability ; Rats ; Water

OBJECTIVETo 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.

METHODSThe 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.

RESULTSIncreases 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.

CONCLUSIONThese 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.

Animals ; Aquaporin 4 ; metabolism ; Astrocytes ; enzymology ; metabolism ; Butadienes ; administration & dosage ; Cells, Cultured ; Down-Regulation ; Enzyme Activation ; Extracellular Signal-Regulated MAP Kinases ; metabolism ; MAP Kinase Signaling System ; Nitriles ; administration & dosage ; Rats ; Rats, Wistar ; Skin ; injuries

Aquaporins (AQPs) are expressed in myocardium and the implication of AQPs in myocardial water balance has been suggested. We investigated the expression patterns of AQP subtypes in normal myocardium and their changes in the process of edema formation and cardiac dysfunction following myocardial infarction (MI). Immunostaining demonstrated abundant expression of AQP1, AQP4, and AQP6 in normal mouse heart; AQP1 in blood vessels and cardiac myocytes, AQP4 exclusively on the intercalated discs between cardiac myocytes and AQP6 inside the myocytes. However, neither AQP7 nor AQP9 proteins were expressed in CD1 mouse myocardium. Echocardiography revealed that cardiac function was reduced at 1 week and recovered at 4 weeks after MI, whereas myocardial water content determined by wet-to-dry weight ratio increased at 1 week and rather reduced below the normal at 4 weeks. The expression of cardiac AQPs was up-regulated in MI-induced groups compared with sham-operated control group, but their time-dependent patterns were different. The time course of AQP4 expression coincided with that of myocardial edema and cardiac dysfunction following MI. However, expression of both AQP1 and AQP6 increased persistently up to 4 weeks. Our findings suggest a different role for cardiac AQPs in the formation and reabsorption of myocardial edema after MI.
Animals ; Aquaporin 1/metabolism ; Aquaporin 4/metabolism ; Aquaporin 6/metabolism ; Aquaporins/*metabolism ; Edema/pathology ; Immunohistochemistry ; Mice ; Muscle Cells/metabolism ; Myocardial Infarction/*metabolism/pathology/ultrasonography ; Myocardium/metabolism/pathology ; Time Factors

The deficiency of aquaporin-4 (AQP4) has been reported to alter release of neurotransmitters in the mouse brain. However, the functional relevance of AQP4 in mediating essential components of the general anaesthetic state is unknown. The aim of the present study was to investigate the role of AQP4 in general anaesthesia in mice lacking AQP4. The hypnotic effects of propofol, ketamine, and pentobarbital in AQP4 knockout (KO) and CD1 control mice were evaluated using the behavioural endpoint of loss of righting reflex (LORR). The effects of propofol on extracellular levels of amino acids in prefrontal cortex of freely moving mice were investigated using microdialysis coupled to high performance liquid chromatography with fluorescent detection. The result showed that, after receiving ketamine or pentobarbital, LORR occurred at earlier time in KO mice than that in control animals. Intraperitoneal injection of ketamine or pentobarbital increased the duration of LORR. After the administration of propofol, the duration of LORR was significantly reduced in KO mice compared with that in controls. Propofol increased the extracellular levels of aspartate, glutamate, and GABA, but not taurine, in prefrontal cortex. There were significant differences of increase patterns of the three kinds of neurotransmitters between KO and WT mice. Notably, the duration of GABA level increase correlated with the duration of LORR in two genotypes of mice. These results provide in vivo evidence of different responses in time-dependent release of excitatory and inhibitory neurotransmitters in prefrontal cortex of the two genotypes of mice. It is suggested that changes in anaesthetic reactions in mice with AQP4 loss may be related to neurotransmitter regulation, and that normal functioning of AQP4 plays an important role in the maintenance of anaesthetic hypnosis.
Anesthetics, Intravenous ; pharmacology ; Animals ; Aquaporin 4 ; deficiency ; genetics ; Hypnotics and Sedatives ; pharmacology ; Ketamine ; pharmacology ; Mice ; Mice, Knockout ; Neurotransmitter Agents ; metabolism ; Pentobarbital ; pharmacology ; Prefrontal Cortex ; drug effects ; metabolism ; Propofol ; pharmacology

BACKGROUNDAlthough some studies have reported that aquaporin-4 (AQP4) plays an important role in the brain edema after traumatic brain injury (TBI), little is known about the AQP4 expression in the early stage of TBI, or about the correlation between the structural damage to the blood-brain barrier (BBB) and angioedema. The aim of this project was to investigate the relationship between AQP4 expression and damage to the BBB at early stages of TBI.

METHODSOne hundred and twenty healthy adult Wistar rats were randomly divided into two groups: sham operation group (SO) and TBI group. The TBI group was divided into five sub-groups according to the different time intervals: 1, 3, 6, 12, and 24 hours. The brains of the animals were taken out at different time points after TBI to measure brain water content. The cerebral edema and BBB changes in structure were examined with an optical microscopy (OM) and transmission electron microscopy (TEM), and the IgG content and AQP4 protein expression in traumatic brain tissue were determined by means of immunohistochemistry and Western blotting. The data were analyzed with SPSS 13.0 statistical software.

RESULTSIn the SO group, tissue was negative for IgG, and there were no abnormalities in brain water content or AQP4 expression. In the TBI group, brain water content significantly increased at 6 hours and peaked at 24 hours following injury. IgG expression significantly increased from 1 to 6 hours following injury, and remained at a high level at 24 hours. Pathological observation revealed BBB damage at 1 hour following injury. Angioedema appeared at 1 hour, was gradually aggravated, and became obvious at 6 hours. Intracellular edema occurred at 3 hours, with the presence of large glial cell bodies and mitochondrial swelling. These phenomena were aggravated with time and became obvious at 12 hours. In addition, microglial proliferation was visible at 24 hours. AQP4 protein expression were reduced at 1 hour, lowest at 6 hours, and began to increase at 12 hours, showing a V-shaped curve.

CONCLUSIONSThe angioedema characterized by BBB damage was the primary type of early traumatic brain edema. It was followed by mixed cerebral edema that consisted of angioedema and cellular edema and was aggravated with time. AQP4 expression was down-regulated during the angioedema attack, but AQP4 expression was upregulated during intracellular edema.

Animals ; Aquaporin 4 ; metabolism ; Blood-Brain Barrier ; metabolism ; Blotting, Western ; Brain Edema ; metabolism ; Brain Injuries ; metabolism ; Immunohistochemistry ; Rats ; Rats, Wistar

OBJECTIVETo study the expression of aquaporin-4 (AQP4) protein in preeclampsia(PE) model rats.

METHODSAdult SD rats were divided into PE model group (n=7) induced by endotoxin, normal pregnancy group (n=6) and non-pregnancy group (n=12) treated with an equal volume of saline. AQP4 protein expression in the brain of the rats was detected with immunohistochemical staining and Western blotting.

RESULTSThe blood pressure in PE model rats (135∓9 mmHg) was significantly higher than that in normal pregnancy rats (116∓8 mmHg) and non-pregnancy rats (112∓6 mmHg) (P<0.02). The rats in PE model group showed obvious proteinuria compared with the other two groups (3.8∓0.5 vs 2.6∓0.6 and 2.3∓0.4, P<0.05). Immunohistochemistry showed that AQP4 protein was localized primarily around the brain parenchymal blood vessels. Western analysis revealed a significantly elevated AQP4 protein expression in PE model group (39.6∓4.9) compared with that in normal pregnancy group (26.5∓4.3) and non-pregnancy group (9.7∓2.1) (P<0.01).

CONCLUSIONThe up-regulation of AQP4 protein around the intraparenchymal blood vessels of the brain may play a role in the development of eclampsia.

Animals ; Aquaporin 4 ; genetics ; metabolism ; Blood Pressure ; Disease Models, Animal ; Female ; Hippocampus ; metabolism ; Pre-Eclampsia ; metabolism ; Pregnancy ; Rats ; Rats, Sprague-Dawley

Water balance is one of the basic regulation mechanisms of homeostasis. There are 13 subtypes of aquaporins in mammals (AQP0-AQP12). In neural system, the AQP4 is mainly distributed in astrocytes. Phosphorylation and expression regulation of AQP4 is involved in the formation of brain edema, particularly in the clearance of vasogenic edema and the formation of cytotoxic edema. This article reviews regulations and functions of AQP4 in vasogenic edema and cytotoxic edema.
Animals ; Aquaporin 4 ; metabolism ; physiology ; Brain ; metabolism ; physiopathology ; Brain Edema ; metabolism ; physiopathology ; Homeostasis ; Humans ; Water-Electrolyte Balance ; physiology

The aim of this study was to investigate the effects of Avastin on aquaporin4 (AQP4) expression in human retinal Müller cells in vitro under hypoxia, so as to explore the mechanism of Avastin treating retinal edema. The human Müller cells were cultured using the enzymatic digestion method. Müller cells were identified under the transmission electron microscopy and by using immunofluorescence staining. By using semi-quantitative reverse transcription polymerase chain reaction (RT-PCR), the expression of AQP4 mRNA and VEGF mRNA in Müller cells cultured with 500 μmol/L CoCl(2) for 0, 3, 6, 12 and 24 h, and with 0, 100, 300, 500 and 700 μmol/L CoCl(2) for 24 h was detected. The expression of AQP4 mRNA in Müller cells cultured with 50 ng/mL exogenous vascular endothelial growth factor (VEGF) for 0, 0.5, 1, 2 and 4 h, and with 0, 25, 50 and 75 ng/mL VEGF for 24 h was detected. Amplified cDNA products of AQP4 mRNA in Müller cells cultured with 500 μmol/L CoCl(2) and 200 μg/mL Avastin for 24 h were detected. The results showed that more than 95% cells displayed positive immunofluorescence reaction. Characteristic 8-10 nm intracellular filaments could be seen in the cytoplasm under the transmission electron microscopy. In the CoCl(2) experimental groups, the expression of AQP4 mRNA and VEGF mRNA in Müller cells was increased as compared with the control group. Alteration of AQP4 mRNA and VEGF mRNA levels showed a significantly positive correlation (r (2)=0.822, P<0.05). The expression of AQP4 mRNA in Müller cells was increased by VEGF. The expression of AQP4 mRNA was significantly decreased by Avastin as compared with the control group. It is suggested that Avastin can decrease the expression of AQP4 mRNA in human Müller cells under chemical hypoxic conditions partially via VEGF path, which may be one of the mechanisms of Avastin treating retinal edema.
Antibodies, Monoclonal, Humanized ; pharmacology ; Aquaporin 4 ; genetics ; metabolism ; Bevacizumab ; Cells, Cultured ; Ependymoglial Cells ; metabolism ; Gene Expression ; drug effects ; genetics ; Humans ; Hypoxia ; genetics ; metabolism