Expression of aquaporin8 in human astrocytomas: correlation with pathologic grade.

Aquaporin8 (AQP8), a member of the aquaporin (AQP) protein family, is weakly distributed in mammalian brains. Previous studies on AQP8 have focused mainly on the digestive and the reproductive systems. AQP8 has a pivotal role in keeping the fluid and electrolyte balance. In this study, we investigated the expression changes of AQP8 in 75 cases of human brain astrocytic tumors using immunohistochemistry, Western blotting, and reverse transcription polymerase chain reaction. The results demonstrated that AQP8 was mainly distributed in the cytoplasm of astrocytoma cells. The expression levels and immunoreactive score of AQP8 protein and mRNA increased in low-grade astrocytomas, and further increased in high-grade astrocytomas, especially in glioblastoma. Therefore, AQP8 may contribute to the proliferation of astrocytomas, and may be a biomarker and candidate therapy target for patients with astrocytomas.

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.

Role of rno-miR-124-3p in regulating MCT1 expression in rat brain after permanent focal cerebral ischemia.

This study aimed to assess the role of microRNAs (miRNAs) in regulating monocarboxylate transporter-1 (MCT1) expression in rat brain after permanent focal cerebral ischemia to identify a new target for early treatment of cerebral ischemia. Focal cerebral ischemia was induced by permanent middle cerebral artery occlusion (pMCAO) in rats. Morphology and protein expression levels of MCT1 were assessed by immunofluorescence and Western blotting. Using bioinformatics and double luciferase reporter assays, rno-miR-124-3p was selected as a direct target for rat MCT1. Expression of rno-miR-124-3p after pMCAO was detected. Then, rats were treated with rno-miR-124-3p agomir via lateral ventricle injection, and after 6 h or 24 h ischemia, rno-miR-124-3p expression and gene and protein expression of MCT-1 were detected by qRT-PCR and Western blotting. Brain infarction was identified by 2, 3, 5-triphenyltetrazolium chloride (TTC) staining. Results showed that pMCAO induced brain infarction and increased the expression of MCT1. The levels of rno-miR-124-3p after pMCAO were in contrast to those of MCT1 protein in ischemic region, while declined after 3, 6 and 12 h of pMCAO in ischemic penumbra. After administration of rno-miR-124-3p agomir, MCT1 mRNA and protein levels were increased after 6 h of pMCAO, while decreased after 24 h of pMCAO. Meanwhile, rno-miR-124-3p levels increased after both times. TTC staining showed treatment with rno-miR-124-3p agomir reduced brain infarction. The role of rno-miR-124-3p in regulating MCT1 was as a positive regulator after 6 h of pMCAO, while a negative regulator after 24 h of pMCAO, however, both activities had protective effects against cerebral ischemia.

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.

p53-Mediated oligodendrocyte apoptosis initiates demyelination after compressed spinal cord injury by enhancing ER-mitochondria interaction and E2F1 expression.

Oligodendrocyte apoptosis mediated demyelination is a pathological change characteristic of compressed spinal cord injury (CSCI). However, the mechanism of demyelination due to oligodendrocyte apoptosis is not known. In this study, after successfully establishing a rat CSCI model using a custom-made compressor, we investigated the pathological changes, MBP expression, as well as apoptosis-related protein (p53, active caspase-3) expression to determine whether or not apoptosis and demyelination occurred after injury. To understand the possible mechanism of oligodendrocyte apoptosis, caspase-12 and cytochrome C were analyzed to explore the relationship between oligodendrocyte apoptosis and endoplasmic reticulum(ER)-mitochondria interaction. The transcription factor, E2F1, was also detected by immunofluorescence and Western blot assays. The results showed that CSCI increased the expression levels of p53, E2F1 and active caspase-3 followed by the swelling and breakdown of myelin sheaths. The number of myelinated nerve fibers also decreased with down-regulated expression of MBP. Expression levels of caspase-12 and cytochrome C were enhanced along with a reduction in the number of oligodendrocytes. After treatment of CSCI in rats with Pifithrin-µ(PFT-µ), a specific inhibitor of p53, pathomorphological changes of myelin sheath improved significantly. Expression levels of E2F1, active caspase-3, caspase-12 and cytochrome C were down-regulated, consistent with reduced the number of apoptotic oligodendrocytes. These results demonstrated that over-expression of p53 could mediate oligodendrocyte apoptosis thus resulting in demyelination in two ways; by enhancing ER-mitochondria interaction and by triggering the E2F1 mediated apoptosis pathway.

An applied anatomical study on the external laryngeal nerve loop and the superior thyroid artery in the neck surgical region.

This study was conducted to investigate the topographic relationship between the external laryngeal nerve (ELN) loop and the superior thyroid artery (STA), in order to provide the anatomical foundations for protecting the ELN during surgery. In the present study, 48 adult human cadavers were dissected and analyzed. For the 21 (21.9%) low-position ELN loops observed, the neurovascular relationship between the STA and the nerve was classified into four types: (1) the artery overlapped the nerve; (2) the artery passed through the ELN loop; (3) the muscular branch of the ELN loop and the laryngeal branch of the STA coursed together; and (4) the branches of the STA and the ELN loop were interlaced. Our study suggested that the patterns of ELN loops are so complicated that they have not been statistically defined in any previous study, which should be kept in mind when attempting to protect the nerve from injury. Also, because of the variable morphology of the ELN loop and its complicated topographic relationship to the STA, the vessels should be individually isolated and then ligated during thyroidectomy. When ligating the laryngeal branch of the STA during larynx surgery, special attention should be paid to avoiding damage to the muscular branch of the ELN/ELN loop.

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.

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.

Lysosomal degradation of retinal glial AQP4 following its internalization induced by acute ocular hypertension.

The membrane-bound water channel aquaporin-4 plays a significant role in the regulation of water movement within the retina. In retinal ischemia-reperfusion injury, changes in the expression and localization of aquaporin-4 have been reported. Previous studies also suggest that the internalization of several membrane-bound proteins, including aquaporin-4, may occur with or without lysosomal degradation. In this study, the internalization of aquaporin-4 was detected in the ischemic rat retina via double immunofluorescence labeling. Specifically, both aquaporin-4 and the mannose-6-phosphate receptor co-localized post-ischemic injury (10, 30 and 60 min). The same results were found during a 12-h reperfusion window (2, 4 and 8 h, respectively) following 60 min of ischemia. Moreover, the co-expression of aquaporin-4 and lysosomal-associated membrane protein-1 was observed at 1-12 h of reperfusion, with co-expression increasing followed by a gradual decrease. These combined findings suggest that AQP4 is internalized in the ischemic-reperfused retina, and the lysosome is involved in degrading the internalized aquaporin-4 during the reperfusion phase. Both the internalization of aquaporin-4 and its lysosomal degradation may serve as valuable therapeutic targets for managing ischemic-reperfused retinal injury.