Hyperosmotic induction of aquaporin expression in rat astrocytes through a different MAPK pathway.

Water homeostasis of the nervous system is important during neural signal transduction. Astrocytes are crucial in water transport in the central nervous system under both physiological and pathological conditions. To date, five aquaporins (AQP) have been found in rat brain astrocytes. Most studies have focused on AQP4 and AQP9, however, little is known about the expression of AQP3, -5, and -8 as well as their regulating mechanism in astrocytes. The expression patterns of AQP3, -5, and -8 in astrocytes exposed to hyperosmotic solutions were examined to clarify the roles of AQP3, -5, and -8 in astrocyte water movement. The expression of AQP4 and AQP9 under the same hyperosmotic conditions was also investigated. The AQP4 and AQP9 expressions continuously increased until 12 h after hyperosmotic solution exposure, whereas the AQP3, -5, and -8 expressions continued to increase until 6 h after hyperosmotic solution exposure. The different AQPs decreased at corresponding time points (24 h for AQP4 and AQP9; 12 h for AQP3, -5, and -8 after hyperosmotic solution exposure). The ERK inhibitor can attenuate the expression of AQP3, -5, and -8 after hyperosmotic solution exposure. The p38 inhibitor can inhibit the AQP4 and AQP9 expressions in cultured astrocytes. AQP expression is directly related to the extracellular hyperosmotic stimuli. Moreover, different AQPs can be regulated by a distinct MAPK signal transduction pathway.

Neuroglobin expression and function in the temporal cortex of bilirubin encephalopathy rats.

Bilirubin encephalopathy (BE) is a neurological syndrome in newborns, mainly caused by neuronal injury due to excessive oxidative stress produced by unconjugated bilirubin (UCB). Neuroglobin (NGB) can protect the brain by removing oxidative stress species, but its expression and significance in BE are not clear. To address this question, the neonatal BE model was established by injecting UCB into the cerebellomedullary cistern of 7-day-old SD rats. Rats were divided into a sham and BE 6 hr group, BE 12 hr group, BE 24 hr group, and BE 7 d group according to UCB action times. Hematoxylin/eosin and Nissl staining, and electron microscopy were employed to observe the pathological and ultrastructural changes of nerve cells in each group. Immunofluorescence staining was used to detect NGB expression sites and cell types. Western blotting and quantitative PCR served to detect NGB expression and test the mitochondrial apoptosis signal pathway. The results confirm that UCB can lead to pathological damage and ultrastructural changes in rats' temporal cortex, increasing the expression of apoptosis-related proteins Bax, Bcl-2, Cyt c, Caspase-3, and neuronal NGB. UCB promotes NGB expression with an increase in action time and reach a peak at 12 hr. In summary, brain damage induced by UCB will cause an increase in NGB expression, the increasing NGB can inhibit neuron apoptosis in early BE phases. Therefore, promoting the expression of endogenous NGB, to act as a neuroprotective agent may be a potential treatment strategy for BE.

Silencing Akt1 enhances the resistance of prostate cancer cells to starvation and inhibits starvation-induced lung metastasis through epithelial-mesenchymal transition in prostate cancer.

Nutritional starvation (NST) is the basis of tumor anti-angiogenesis and metabolic therapy strategy. Silencing Akt1 inhibits prostate cancer (PCa) cells growing; slow-growing cells tend to consume less nutrition. It is suggested that Akt1-silenced cancer cells will have a more substantial tolerance to NST. Clarify this critical question is vital for tumor treatment strategies based on Akt1 and NST. The Akt1 gene of PC3 and DU145 cells was silenced by lent-virus. NST model was established by serum stripping. Cell viability was detected by MTT assay and cell counting method. Apoptosis was detected by TUNEL and flow cytometry, and cell invasion was determined by transwells and ECIS. The markers of epithelial-mesenchymal transition (EMT) were detected by western blotting. PCa lung metastasis model was established by tail vein injection and quantified by Indian ink and GFP fluorescence. Silencing Akt1 slowed down the decrease of cell number and increase of apoptosis caused by NST. Silencing Akt1 with NST exposure in PCa cells could down-regulate epithelial markers (E-cadherin, claudin-5, and ZO-1) and up-regulate mesenchymal markers N-cadherin and EMT regulators Snail. Although silencing Akt1 enhanced the invasion of PCa cells induced by NST in vitro, silencing Akt1 inhibited the PCa lung metastasis induced by NST in vivo. Silencing Akt1 gene enhances the resistance of PCa cells to NST. The invasion results in vitro were inconsistent with those metastases in vivo, which may be related to a combination of NST with silencing Akt1 to maintain the mesenchymal state of PCa cells through EMT.

[Effect of electroacupuncture of different acupoint groups on learning-memory ability and expression of IL-1ß and TNF-α in hippocampus and prefrontal cortex in rats with Alzheimer's disease].

OBJECTIVE: To compare the effect of electroacupuncture (EA) of acupoint group for "reinforcing the kidney and regulating Governor Vessel" and acopoint group for "reinforcing the kidney and lung and regulating Governor Vessel" on lear-ning-memory ability and expression of tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) proteins in the hippocampus and prefrontal cortex (PFC) in Alzheimer's disease （AD） rats, so as to explore the efficacy of the two acupoint groups and mechanisms underlying improvement of AD. METHODS: Forty male SD rats were randomly divided into control, sham operation, model, "Baihui" + "Shenshu" (GV20+BL23, for "reinforcing the kidney and regulating Governor Vessel") EA and GV20+BL23+ "Feishu" (BL13, GV20+BL23+BL13, for "reinforcing the kidney and lung and regulating Governor Vessel") EA groups (n=8 rats in each group). The AD model was established by bilateral injection of amyloid ß peptide （Aß25-35，10 µL) into bilateral hippocampus, and rats of the sham operation group received injection of normal saline. After successful establishment of the model，EA (2 Hz, 2 mA) was applied to these acupoints for 15 min, once daily for 10 days. Then, the learning-memory ability was assessed by using Morris water maze tests, and the expression levels of TNF-α and IL-1ß proteins in the PFC and hippocampus tissues were detected by using Western blot. RESULTS: Following modeling, the average escape latency of place navigation test were significantly increased (P<0.05) and the platform crossing times of spatial probe test was significantly decreased in the model group than in the control and sham operation groups (P<0.05). The expression levels of IL-1ß and TNF-α proteins in the PFC and hippocampus were apparently up-regulated in the model group than in the control and the sham operation groups (P<0.000 1, P<0.001, P<0.01). After the intervention, the increase of the average escape latency and expression of IL-1ß and TNF-α in the PFC and hippocampus, and the decrease of space exploration test were revised in both GV20+BL23 EA and GV20+BL23+BL13 EA groups (P<0.05,P<0.01). No significant differences were found between the GV20+BL23 and GV20+BL23+BL13 EA groups in the above mentioned indexes (P>0.05). CONCLUSION: EA of both GV20+BL23 and GV20+BL23+BL13 acupoint can improve learning-memory ability of AD rats, which is associated with their effects in down-regulating the expression of IL-1ß and TNF-α in the PFC and hippocampus to reduce inflammatory reaction. There were no significant differences between the two acupoint groups in the therapeutic effects.

[Effect of electroacupuncture on the P35/P25-cyclin-dependent kinase 5-Tau pathway in hippocampus of rats with Alzheimer's disease].

OBJECTIVE: To investigate the effect of electroacupuncture on the P35/P25-cyclin-dependent kinase 5 (CDK5)-Tau pathway in rats with Alzheimer's disease (AD), as well as the mechanism of electroacupuncture in the prevention and treatment of AD. METHODS: Sprague-Dawley rats were randomly divided into control group, sham-operation group, model group, and electroacupuncture treatment group, with 12 rats in each group. A rat model of AD was established by injection of Aß25-35 into the bilateral hippocampus. The rats in the electroacupuncture treatment group were given electroacupuncture at "Baihui" (GV20) and "Shenshu" (BL23) once a day, 15 min each time, for 10 days. Morris water maze was used to evaluate learning and memory abilities, immunohistochemistry was used to measure the distribution and expression of P35/P25, CDK5, and Tau5 in the hippocampus, and Western blot was used to measure the expression of the above mentioned proteins, phosphory-lated Tau(Ser199, Ser202). RESULTS: In the visual platform test, there were no significant differences in escape latency and search path between groups (P>0.05). In the hidden platform test, there were no significant differences in escape latency and search path between the control group and the sham-operation group (P>0.05); the model group had significantly longer escape latency and search path than the control group and the sham-operation group (P<0.05). Compared with the model group, the electroacupuncture treatment group had significantly shorter escape latency and search path (P<0.05). In the spatial exploration test, there was no significant difference in the number of platform crossings between the control group and the sham-operation group (P<0.05). The model group had a significantly lower number of platform crossings than the control group and the sham-operation group (P<0.01, P<0.05). The electroacupuncture treatment group had a significantly higher number of platform crossings than the model group (P<0.05). Compared with the control group and the sham-operation group, the model group had significant increases in the protein expression of P35/P25 and CDK5 (P<0.001), and the electroacupuncture treatment group had significant reductions compared with the model group (P<0.001). There was no significant difference in the protein expression of Tau5 between groups (P>0.05). The model group had significantly higher protein expression of phosphorylated Tau(Ser199, Ser202) in the hippocampus than the control group and the sham-operation group (P<0.01, P<0.05). The electroacupuncture treatment group had significantly lower protein expression of phosphorylated Tau(Ser199，Ser202) than the model group (P<0.05, P<0.01). CONCLUSION: Electroacupuncture may delay the progression of AD by affecting the expression of proteins involved in the P35/P25-CDK5-Tau pathway in the hippocampus of rats.

Curcumin Ameliorates Memory Deficits by Enhancing Lactate Content and MCT2 Expression in APP/PS1 Transgenic Mouse Model of Alzheimer's Disease.

Curcumin is a natural product with several anti-Alzheimer's disease (AD) neuroprotective properties. This study aimed to investigate the effects of curcumin on memory deficits, lactate content, and monocarboxylate transporter 2 (MCT2) in APP/PS1 mouse model of AD. APP/PS1 transgenic mice and wild-type (WT) C57BL/6J mice were used in the present study. Spatial learning and memory of the mice was detected using Morris water-maze test. Cerebral cortex and hippocampus lactate contents were detected using lactate assay. MCT2 expression in the cerebral cortex and hippocampus was examined by immunohistochemistry and Western blotting. Results showed that spatial learning and memory deficits were improved in curcumin-treated APP/PS1 mouse group compared with those in APP/PS1 mice group. Brain lactate content and MCT2 protein level were increased in curcumin-treated APP/PS1 mice than in APP/PS1 mice. In summary, our findings indicate that curcumin could ameliorate memory impairments in APP/PS1 mouse model of AD. This phenomenon may be at least partially due to its improving effect on the lactate content and MCT2 protein expression in the brain. Anat Rec, 302:332-338, 2019. © 2018 Wiley Periodicals, Inc.

Loss of AQP4 polarized localization with loss of ß-dystroglycan immunoreactivity may induce brain edema following intracerebral hemorrhage.

The aquaporin-4 (AQP4) water channel contributes to brain water homeostasis in perivascular and subpial membrane domains of astrocytes where it is concentrated. These membranes form the interface between the neuropil and the extracellular liquid spaces. The brain-selective deletion of the dystroglycan (DG) gene causes a disorganization of AQP4 on the astroglial endfeet. First, we analyzed the expression of AQP4, ß-DG in the brain following intracerebral hemorrhage (ICH) and correlated AQP4 expression with the expression pattern of the ß-DG, which is a component of dystrophin-dystroglycan complex (DDC). Besides, the vessels ultrastructure and brain water content were investigated at different time points post-ICH (day 1, day 3, day 7). We found that AQP4 polarity was disturbed in parallel with the loss of ß-DG in the perihematomal area post-ICH. At day 1 post-ICH, brain edema was obvious and the damage of vascular ultrastructure was the most severe. These results suggest a role for ß-DG in targeting and stabilizing AQP4 channel in astrocytic cells, which may be critical for water homeostasis in brain.

Internalization of aquaporin-4 after collagenase-induced intracerebral hemorrhage.

Brain edema formation following intracerebral hemorrhage (ICH) appears to be related with aquaporin-4 (AQP4), which is critically involved in brain volume homeostasis and water balance. Despite its importance, the regulation of AQP4 expression involved in transmembrane water movements still remains rudimentary. Many studies suggest that the internalization of several membrane-bound proteins, including AQP4, may occur with or without lysosomal degradation. Previously, we investigated the internalization of AQP4 in retinal ischemic-reperfusion model. Here, we test the hypothesis that AQP4 is internalized post-ICH and then degraded in the lysosome. The results demonstrated that both AQP4 and the mannose-6-phosphate receptor (MPR) co-localized in perihematomal region at 6 hr post-ICH. In addition, AQP4 and lysosomal-associated membrane protein 1 (LAMP1) also co-localized in perihematomal region, with co-expression increasing followed by a gradual decrease at different time windows post-ICH (6, 12, 24, 48, and 72 hr). After ICH, the Evans blue leakage happened very early at 1 hr and the brain swelling occurred at 3 hr. Moreover, we also found the AQP4 mRNA and AQP4 protein were increased post-ICH. These results suggest that AQP4 is internalized and the lysosome is involved in degrading the internalized AQP4 post-ICH. Both the AQP4 internalization and lysosomal degradation may provide biophysical insights regarding the potential of new treatments for brain edema.

Demyelination initiated by oligodendrocyte apoptosis through enhancing endoplasmic reticulum-mitochondria interactions and Id2 expression after compressed spinal cord injury in rats.

BACKGROUND: Demyelination is one of the most important pathological factors of spinal cord injury. Oligodendrocyte apoptosis is involved in triggering demyelination. However, fewer reports on pathological changes and mechanism of demyelination have been presented from compressed spinal cord injury (CSCI). The relative effect of oligodendrocyte apoptosis on CSCI-induced demyelination and the mechanism of apoptosis remain unclear. AIMS: In this study, a custom-designed model of CSCI was used to determine whether or not demyelination and oligodendrocyte apoptosis occur after CSCI. The pathological changes in axonal myelinated fibers were investigated by osmic acid staining and transmission electron microscopy. Myelin basic protein (MBP), which is used in myelin formation in the central nervous system, was detected by immunofluorescence and Western blot assays. Oligodendrocyte apoptosis was revealed by in situ terminal-deoxytransferase-mediated dUTP nick-end labeling. To analyze the mechanism of oligodendrocyte apoptosis, we detected caspase-12 [a representative of endoplasmic reticulum (ER) stress], cytochrome c (an apoptotic factor and hallmark of mitochondria), and inhibitor of DNA binding 2 (Id2, an oligodendrocyte lineage gene) by immunofluorescence and Western blot assays. RESULTS: The custom-designed model of CSCI was successfully established. The rats were spastic, paralyzed, and incontinent. The Basso, Beattie, and Bresnahan (BBB) locomotor rating scale scores were decreased as time passed. The compressed spinal cord slices were ischemic. Myelin sheaths became swollen and degenerative; these sheaths were broken down as time passed after CSCI. MBP expression was downregulated after CSCI and consistent with the degree of demyelination. Oligodendrocyte apoptosis occurred at 1 day after CSCI and increased as caspase-12 expression was enhanced and cytochrome c was released. Id2 was distributed widely in the white matter. Id2 expression increased with time after CSCI. CONCLUSION: Demyelination occurred after CSCI and might be partly caused by oligodendrocyte apoptosis, which was positively correlated with ER-mitochondria interactions and enhanced Id2 expression after CSCI in rats.

Upregulation and lysosomal degradation of AQP4 in rat brains with bacterial meningitis.

Brain edema is among the major complications in children with bacterial meningitis. Aquaporins are integral membrane pore proteins that form channels to regulate cellular water content. Aquaporin-4 (AQP4), which is enriched in parts of astrocytic membranes that are apposed to pial or perivascular basal laminae, is the predominant aquaporin in the central nervous system. Dystroglycan is among the proteins that are responsible for the site-specific anchorage of AQP4. To elucidate the role of AQP4 in the development of brain edema induced by meningitis, a model of bacterial meningitis was established by injecting group B ß-hemolytic Streptococci into the cerebrospinal fluid of three-week-old rats. The brain water content increased in this model compared with that in the control group. The expression of AQP4 and dystroglycan was examined by Western blot and the degradation route of AQP4 was investigated by double immunofluorescence labeling. Western blot results showed that the expression of AQP4 and dystroglycan in rat brain increased in the meningitis model. Meanwhile, AQP4 was co-localized with the marker of lysosome in this model, indicating that the lysosome is involved in AQP4 degradation.

The internalization and lysosomal degradation of brain AQP4 after ischemic injury.

The membrane-bound water channel aquaporin-4 (AQP4) plays a significant role in maintaining brain water homeostasis. In ischemic brain, changes in the expression level of AQP4 have been reported. Previous studies suggest that the internalization of several membrane-bound proteins, including AQP4, may occur with or without lysosomal degradation. In this study, the internalization of AQP4 was detected in the ischemic rat brain via double immunofluorescence labeling. Specifically, AQP4 and early endosome antigen-1 (EEA1) co-localized after 1 h post-ischemic injury. Moreover, the co-expression of AQP4 and lysosomal-associated membrane protein-1 (LAMP1) was observed after 3 h post-ischemia. These findings suggest that AQP4 is internalized and the lysosome is involved in degrading the internalized AQP4 in the ischemic brain. AQP4 is known to be downregulated by the protein kinase C activator phorbol 12-myristate 13-acetate (PMA) in vivo and in vitro. The results in this study displayed that PMA infusion could decrease brain edema accompanied by AQP4 downregulation in ischemic brain. However, compared with vehicle infusion, PKC activator infusion did not increase the ratio of internalized or lysosomal degraded AQP4. That is, we have not found out evidence to prove protein kinase C activator PMA can promote the internalization or lysosomal degradation of AQP4 in the ischemic brain.

Aquaporin 9 in rat brain after severe traumatic brain injury.

OBJECTIVE: To reveal the expression and possible roles of aquaporin 9 (AQP9) in rat brain, after severe traumatic brain injury (TBI). METHODS: Brain water content (BWC), tetrazolium chloride staining, Evans blue staining, immunohistochemistry (IHC), immunofluorescence (IF), western blot, and real-time polymerase chain reaction were used. RESULTS: The BWC reached the first and second (highest) peaks at 6 and 72 hours, and the blood brain barrier (BBB) was severely destroyed at six hours after the TBI. The worst brain ischemia occurred at 72 hours after TBI. Widespread AQP9-positive astrocytes and neurons in the hypothalamus were detected by means of IHC and IF after TBI. The abundance of AQP9 and its mRNA increased after TBI and reached two peaks at 6 and 72 hours, respectively, after TBI. CONCLUSIONS: Increased AQP9 might contribute to clearance of excess water and lactate in the early stage of TBI. Widespread AQP9-positive astrocytes might help lactate move into neurons and result in cellular brain edema in the later stage of TBI. AQP9-positive neurons suggest that AQP9 plays a role in energy balance after TBI.

Aquaporin 9 in rat brain after severe traumatic brain injury / Aquaporina 9 em cérebro de rato após traumatismo cerebral grave

OBJECTIVE: To reveal the expression and possible roles of aquaporin 9 (AQP9) in rat brain, after severe traumatic brain injury (TBI). METHODS: Brain water content (BWC), tetrazolium chloride staining, Evans blue staining, immunohistochemistry (IHC), immunofluorescence (IF), western blot, and real-time polymerase chain reaction were used. RESULTS: The BWC reached the first and second (highest) peaks at 6 and 72 hours, and the blood brain barrier (BBB) was severely destroyed at six hours after the TBI. The worst brain ischemia occurred at 72 hours after TBI. Widespread AQP9-positive astrocytes and neurons in the hypothalamus were detected by means of IHC and IF after TBI. The abundance of AQP9 and its mRNA increased after TBI and reached two peaks at 6 and 72 hours, respectively, after TBI. CONCLUSIONS: Increased AQP9 might contribute to clearance of excess water and lactate in the early stage of TBI. Widespread AQP9-positive astrocytes might help lactate move into neurons and result in cellular brain edema in the later stage of TBI. AQP9-positive neurons suggest that AQP9 plays a role in energy balance after TBI.

OBJETIVO: Revelar a expressão e os possíveis papéis da aquaporina 9 (AQP9) no cérebro de ratos após lesão cerebral traumática (LCT) grave. MÉTODOS: Foram utilizados: determinação do conteúdo cerebral de água, corante cloreto de tetrazólio, corante azul de Evans, imunoistoquímica (IHQ), imunofluorescência (IF), western blot e PCR em tempo real. RESULTADOS: O conteúdo cerebral de água alcançou o primeiro e o segundo (o mais alto) picos após 6 e 72 horas. A função da barreira hematoencefálica se mostrou muito prejudicada após 6 horas da LCT. A pior isquemia cerebral ocorreu após 72 horas da LCT. Astrócitos AQP9 positivos e neurônios no hipotálamo foram detectados difusamente pela IHQ e IF após LCT. A abundância de AQP9 e de sua mRNA aumentou após LCT e alcançou dois picos após 6 e 72 horas, respectivamente, da LCT. CONCLUSÕES: AQP9 aumentada pode contribuir para a eliminação de água e lactato em excesso na fase precoce da LCT. Astrócitos difusamente localizados AQP9 positivos podem ajudar a entrada do lactato nos neurônios, promovendo edema cerebral celular na fase tardia da LCT. Neurônios AQP9 positivos sugerem que AQP9 tem um papel no equilíbrio energético após LCT.