Glucagon like peptide-1 (GLP-1) stimulates glucose-dependent insulin secretion. Dipeptidyl peptidase-4 (DPP-4) inhibitors, which block inactivation of GLP-1, are currently in clinical use for type 2 diabetes mellitus. Recently, GLP-1 has also been reported to have neuroprotective effects in cases of cerebral ischemia. We therefore investigated the neuroprotective effects of GLP-1 receptor (GLP-1R) agonist, exendin-4 (ex-4), after cerebral ischemia-reperfusion injury. Transient middle cerebral artery occlusion (tMCAO) was induced in rats by intracerebroventricular (i.c.v.) administration of ex-4 or ex9-39. Oxygen-glucose deprivation was also induced in primary neurons, bEnd.3 cells, and BV-2. Ischemia-reperfusion injury reduced expression of GLP-1R. Additionally, higher oxidative stress in SOD2 KO mice decreased expression of GLP-1R. Downregulation of GLP-1R by ischemic injury was 70% restored by GLP-1R agonist, ex-4, which resulted in significant reduction of infarct volume. Levels of intracellular cyclic AMP, a second messenger of GLP-1R, were also increased by 2.7-fold as a result of high GLP-1R expression. Moreover, our results showed that ex-4 attenuated pro-inflammatory cyclooxygenase-2 (COX-2) and prostaglandin E₂ after MCAO. C-Jun NH₂ terminal kinase (JNK) signaling, which stimulates activation of COX-2, was 36% inhibited by i.c.v. injection of ex-4 at 24 h. Islet-brain 1 (IB1), a scaffold regulator of JNK, was 1.7-fold increased by ex-4. GLP-1R activation by ex-4 resulted in reduction of COX-2 through increasing IB1 expression, resulting in anti-inflammatory neuroprotection during stroke. Our study suggests that the anti-inflammatory action of GLP-1 could be used as a new strategy for the treatment of neuroinflammation after stroke accompanied by hyperglycemia.
Animals ; Brain Ischemia ; Cyclic AMP ; Cyclooxygenase 2 ; Diabetes Mellitus, Type 2 ; Down-Regulation ; Glucagon* ; Glucagon-Like Peptide 1 ; Glucagon-Like Peptide-1 Receptor ; Hyperglycemia ; Infarction, Middle Cerebral Artery ; Insulin ; Mice ; Neurons ; Neuroprotection ; Neuroprotective Agents ; Oxidative Stress ; Phosphotransferases ; Rats ; Reperfusion Injury ; Second Messenger Systems ; Stroke*

Postconditioning has been shown to protect the mouse brain from ischemic injury. However, the neuroprotective mechanisms of postconditioning remain elusive. We have found that toll-like receptor 5 (TLR5) plays an integral role in postconditioning-induced neuroprotection through Akt/nuclear factor kappa B (NF-κB) activation in cerebral ischemia. Compared to animals that received 30 min of transient middle cerebral artery occlusion (tMCAO) group, animals that also underwent postconditioning showed a significant reduction of up to 60.51% in infarct volume. Postconditioning increased phospho-Akt (p-Akt) levels and NF-κB translocation to the nucleus as early as 1 h after tMCAO and oxygen-glucose deprivation. Furthermore, inhibition of Akt by Akt inhibitor IV decreased NF-κB promoter activity after postconditioning. Immunoprecipitation showed that interactions between TLR5, MyD88, and p-Akt were increased from postconditioning both in vivo and in vitro. Similar to postconditioning, flagellin, an agonist of TLR5, increased NF-κB nuclear translocation and Akt phosphorylation. Our results suggest that postconditioning has neuroprotective effects by activating NF-κB and Akt survival pathways via TLR5 after cerebral ischemia. Additionally, the TLR5 agonist flagellin can simulate the neuroprotective mechanism of postconditioning in cerebral ischemia.
Animals ; Brain ; Brain Ischemia* ; Flagellin ; Immunoprecipitation ; In Vitro Techniques ; Infarction, Middle Cerebral Artery ; Mice* ; Neuroprotection ; Neuroprotective Agents ; NF-kappa B ; Phosphorylation ; Toll-Like Receptor 5

About 5~12% of school-aged children suffer from the Attention-Deficit/Hyperactivity Disorder (ADHD). However, the core mechanism of ADHD remains unclear. G protein-coupled receptor kinase-interacting protein-1 (GIT1) has recently been reported to be associated with ADHD in human and the genetic deletion of GIT1 result in ADHD-like behaviors in mice. Mice lacking GIT1 shows a shift in neuronal excitation/inhibition (E/I) balance. However, the pricise mechanism for E/I imbalance and the role of neuron-glia interaction in GIT1 knockout (KO) mice have not been studied. Especially, a possible contribution of glial GABA and tonic inhibition mediated by astrocytic GABA release in the mouse model for ADHD remains unexplored. Therefore, we investigated the changes in the amount of GABA and degree of tonic inhibition in GIT1 KO mice. We observed a decreased glial GABA intensity in GIT1 KO mice compared to wild type (WT) mice and an attenuation of tonic current from cerebellar granule cells in GIT1 KO mice. Our study identifies the previously unknown mechanism of reduced astrocytic GABA and tonic inhibition in GIT1 lacking mice as a potential cause of hyperactivity disorder.
Animals ; Astrocytes ; Cerebellum* ; Child ; gamma-Aminobutyric Acid* ; Humans ; Mice* ; Neuroglia ; Neurons

NADPH-oxidase (NOX) mediated superoxide originally found on leukocytes, but now recognized in several types of cells in the brain. It has been shown to play an important role in the progression of stroke and related cerebrovascular disease. NOX is a multisubunit complex consisting of 2 membrane-associated and 4 cytosolic subunits. NOX activation occurs when cytosolic subunits translocate to the membrane, leading to transport electrons to oxygen, thus producing superoxide. Superoxide produced by NOX is thought to function in long-term potentiation and intercellular signaling, but excessive production is damaging and has been implicated to play an important role in the progression of ischemic brain. Thus, inhibition of NOX activity may prove to be a promising treatment for ischemic brain as well as an adjunctive agent to prevent its secondary complications. There is mounting evidence that NOX inhibition in the ischemic brain is neuroprotective, and targeting NOX in circulating immune cells will also improve outcome. This review will focus on therapeutic effects of NOX assembly inhibitors in brain ischemia and stroke. However, the lack of specificity and toxicities of existing inhibitors are clear hurdles that will need to be overcome before this class of compounds could be translated clinically.
Brain ; Brain Ischemia ; Cerebrovascular Disorders ; Cytosol ; Leukocytes ; Long-Term Potentiation ; Membranes ; NADPH Oxidase ; Oxygen ; Sensitivity and Specificity ; Stroke* ; Superoxides ; Therapeutic Uses

Despite paramount clinical significance of white matter stroke, there is a paucity of researches on the pathomechanism of ischemic white matter damage and accompanying oligodendrocyte (OL) death. Therefore, a large gap exists between clinical needs and laboratory researches in this disease entity. Recent works have started to elucidate cellular and molecular basis of white matter injury under ischemic stress. In this paper, we briefly introduce white matter stroke from a clinical point of view and review pathophysiology of ischemic white matter injury characterized by OL death and demyelination. We present a series of evidence that Toll-like receptor 2 (TLR2), one of the membranous pattern recognition receptors, plays a cell-autonomous protective role in ischemic OL death and ensuing demyelination. Moreover, we also discuss our recent findings that its endogenous ligand, high-mobility group box 1 (HMGB1), is released from dying OLs and exerts autocrine trophic effects on OLs and myelin sheath under ischemic condition. We propose that modulation of TLR2 and its endogenous ligand HMGB1 can be a novel therapeutic target for ischemic white matter disease.
Demyelinating Diseases ; HMGB1 Protein ; Ischemia ; Leukoencephalopathies ; Myelin Sheath ; Oligodendroglia* ; Receptors, Pattern Recognition ; Stroke ; Toll-Like Receptor 2* ; Toll-Like Receptors* ; White Matter*

Neuronal firing patterns and frequencies determine the nature of encoded information of the neurons. Here we discuss the molecular identity and cellular mechanisms of spike-frequency adaptation in central nervous system (CNS) neurons. Calcium-activated potassium (K(Ca)) channels such as BK(Ca) and SK(Ca) channels have long been known to be important mediators of spike adaptation via generation of a large afterhyperpolarization when neurons are hyper-activated. However, it has been shown that a strong hyperpolarization via these KCa channels would cease action potential generation rather than reducing the frequency of spike generation. In some types of neurons, the strong hyperpolarization is followed by oscillatory activity in these neurons. Recently, spike-frequency adaptation in thalamocortical (TC) and CA1 hippocampal neurons is shown to be mediated by the Ca²⁺-activated Cl- channel (CACC), anoctamin-2 (ANO2). Knockdown of ANO2 in these neurons results in significantly reduced spike-frequency adaptation accompanied by increased number of spikes without shifting the firing mode, which suggests that ANO2 mediates a genuine form of spike adaptation, finely tuning the frequency of spikes in these neurons. Based on the finding of a broad expression of this new class of CACC in the brain, it can be proposed that the ANO2-mediated spike-frequency adaptation may be a general mechanism to control information transmission in the CNS neurons.
Action Potentials ; Brain ; Central Nervous System* ; Fires ; Neurons* ; Potassium ; Potassium Channels, Calcium-Activated

Individuals with autism spectrum disorder (ASD) have altered gut microbiota, which appears to regulate ASD symptoms via gut microbiota-brain interactions. Rapid assessment of gut microbiota profiles in ASD individuals in varying physiological contexts is important to understanding the role of the microbiota in regulating ASD symptoms. Microbiomes secrete extracellular membrane vesicles (EVs) to communicate with host cells and secreted EVs are widely distributed throughout the body including the blood and urine. In the present study, we investigated whether bacteria-derived EVs in urine are useful for the metagenome analysis of microbiota in ASD individuals. To address this, bacterial DNA was isolated from bacteria-derived EVs in the urine of ASD individuals. Subsequent metagenome analysis indicated markedly altered microbiota profiles at the levels of the phylum, class, order, family, and genus in ASD individuals relative to control subjects. Microbiota identified from urine EVs included gut microbiota reported in previous studies and their up- and down-regulation in ASD individuals were partially consistent with microbiota profiles previously assessed from ASD fecal samples. However, overall microbiota profiles identified in the present study represented a distinctive microbiota landscape for ASD. Particularly, the occupancy of g_Pseudomonas, g_Sphingomonas, g_Agrobacterium, g_Achromobacter, and g_Roseateles decreased in ASD, whereas g_Streptococcus, g_Akkermansia, g_Rhodococcus, and g_Halomonas increased. These results demonstrate distinctively altered gut microbiota profiles in ASD, and validate the utilization of urine EVs for the rapid assessment of microbiota in ASD.
Autism Spectrum Disorder* ; Autistic Disorder* ; DNA, Bacterial ; Down-Regulation ; Gastrointestinal Microbiome ; Humans ; Membranes* ; Metagenome ; Microbiota*

Glioblastoma multiforme (GBM) is the most common and aggressive form of brain tumors. GBMs, like other tumors, rely relatively less on mitochondrial oxidative phosphorylation (OXPHOS) and utilize more aerobic glycolysis, and this metabolic shift becomes augmented under hypoxia. In the present study, we investigated the physiological significance of altered glucose metabolism and hypoxic adaptation in the GBM cell line U251 and two newly established primary GBMs (GBM28 and GBM37). We found that these three GBMs exhibited differential growth rates under hypoxia compared to those under normoxia. Under normoxia, the basal expressions of HIF1α and the glycolysis-associated genes, PDK1, PDK3, and GLUT1, were relatively low in U251 and GBM28, while their basal expressions were high in GBM37. Under hypoxia, the expressions of these genes were enhanced further in all three GBMs. Treatment with dichloroacetate (DCA), an inhibitor of pyruvate dehydrogenase kinase (PDK), induced cell death in GBM28 and GBM37 maintained under normoxia, whereas DCA effects disappeared under hypoxia, suggesting that hypoxic adaptation dominated DCA effects in these GBMs. In contrast, the inhibition of HIF1α with chrysin suppressed the expression of PDK1, PDK3, and GLUT1 and markedly promoted cell death of all GBMs under both normoxia and hypoxia. Interestingly, however, GBMs treated with chrysin under hypoxia still sustained higher viability than those under normoxia, and chrysin and DCA co-treatment was unable to eliminate this hypoxia-dependent resistance. Together, these results suggest that hypoxic adaptation is critical for maintaining viability of GBMs, and targeting hypoxic adaptation can be an important treatment option for GBMs.
Anoxia ; Brain Neoplasms ; Cell Death* ; Cell Line ; Dichloroacetic Acid ; Glioblastoma* ; Glucose ; Glycolysis ; Metabolism ; Oxidative Phosphorylation ; Oxidoreductases ; Phosphotransferases ; Pyruvic Acid

Pilocarpine-induced rat epilepsy model is an established animal model that mimics medial temporal lobe epilepsy in humans. The purpose of this study was to investigate neuroimaging abnormalities in various stages of epileptogenesis and to correlate them with seizure severity in pilocarpine-induced rat epilepsy model. Fifty male Sprague-Dawley rats were subject to continuous video and electroencephalographic monitoring after inducing status epilepticus (SE) and seizure severity was estimated by frequency and total durations of class 3 to 5 spontaneous recurrent seizures (SRS) by modified Racine's classification. The 7.0 Tesla magnetic resonance imaging (MRI) with high resolution flurodeoxyglucose positron emission tomography (FDG-PET) was performed at 3 hours, 1, 3, 7 days and 4 weeks after the initial insult. The initial SRS was observed 9.7±1.3 days after the pilocarpine injection. MRI revealed an abnormal T2 signal change with swelling in both hippocampi and amygdala in acute (day 1 after injection) and latent phases (days 3 and 7), in association with PET hypometabolism in these areas. Interestingly, the mean frequency of class 3 to 5 SRS was positively correlated with abnormal T2 signals in hippocampal area at 3 days. SRS duration became longer with more decreased glucose metabolism in both hippocampi and amygdala at 7 days after pilocarpine injection. This study indicates that development and severity of SRS at chronic phase could be closely related with structural and functional changes in hippocampus during the latent period, a pre-epileptic stage.
Amygdala ; Animals ; Classification ; Epilepsy* ; Epilepsy, Temporal Lobe ; Glucose ; Hippocampus ; Humans ; Magnetic Resonance Imaging ; Male ; Metabolism ; Models, Animal ; Neuroimaging ; Pilocarpine ; Positron-Emission Tomography ; Rats ; Rats, Sprague-Dawley ; Seizures ; Status Epilepticus

Agmatine is a decarboxylated arginine by arginine decarboxylase. Agmatine is known to be a neuroprotective agent. It has been reported that agmatine works as a NMDA receptor blocker or a competitive nitric oxide synthase inhibitor in CNS injuries. In spinal cord injury, agmatine showed reduction of neuropathic pain, improvement of locomotor function, and neuroprotection. Macrophage is a key cellular component in neuroinflammation, a major cause of impairment after spinal cord injury. Macrophage has subtypes, M1 and M2 macrophages. M1 macrophage induces a pro-inflammatory response, but M2 inspires an anti-inflammatory response. In this study, it was clarified whether the neuroprotective effect of agmatine is related with the modulation of macrophage subdivision after spinal cord injury. Spinal cord injury was induced in rats with contusion using MASCIS. Animals received agmatine (100 mg/kg, IP) daily for 6 days beginning the day after spinal cord injury. The proportion of M1 and M2 macrophages are confirmed with immunohistochemistry and FACS. CD206+ & ED1+ cells were counted as M2 macrophages. The systemic treatment of agmatine increased M2 macrophages caudal side to epicenter 1 week after spinal cord injury in immunohistochemistry. M2 macrophage related markers, Arginase-1 and CD206 mRNA, were increased in the agmatine treatment group and M2 macrophage expressing and stimulated cytokine, IL-10 mRNA, also was significantly overexpressed by agmatine injection. Among BMPs, BMP2/4/7, agmatine significantly increased only the expression of BMP2 known to reduce M1 macrophage under inflammatory status. These results suggest that agmatine reduces impairment after spinal cord injury through modulating the macrophage phenotype.
Agmatine* ; Animals ; Arginine ; Contusions ; Immunohistochemistry ; Interleukin-10 ; Macrophages* ; N-Methylaspartate ; Neuralgia ; Neuroprotection ; Neuroprotective Agents ; Nitric Oxide Synthase ; Phenotype* ; Rats* ; RNA, Messenger ; Spinal Cord Injuries* ; Spinal Cord*