OBJECTIVE: Brain activity is known to be voluntarily controllable by neurofeedback, a kind of electroencephalographic (EEG) operant conditioning. Although its efficacy in clinical effects has been reported, it is yet to be uncovered whether or how a specific band activity is controllable. Here, we examined EEG spectral profiles along with conditioning training of a specific brain activity, theta band (4–8 Hz) amplitude, in rats. METHODS: During training, the experimental group received electrical stimulation to the medial forebrain bundle contingent to suppression of theta activity, while the control group received stimulation non-contingent to its own band activity. RESULTS: In the experimental group, theta activity gradually decreased within the training session, while there was an increase of theta activity in the control group. There was a significant difference in theta activity during the sessions between the two groups. The spectral theta peak, originally located at 7 Hz, shifted further towards higher frequencies in the experimental group. CONCLUSION: Our results showed that an operant conditioning technique could train rats to control their specific EEG activity indirectly, and it may be used as an animal model for studying how neuronal systems work in human neurofeedback.
Animals ; Brain ; Conditioning, Operant ; Electric Stimulation ; Electroencephalography ; Humans ; Medial Forebrain Bundle ; Models, Animal ; Neurofeedback ; Neurons ; Rats

Axon guidance molecules (AGMs), such as Netrins, Semaphorins, and Ephrins, have long been known to regulate axonal growth in the developing nervous system. Interestingly, the chemotactic properties of AGMs are also important in the postnatal period, such as in the regulation of immune and inflammatory responses. In particular, AGMs play pivotal roles in inflammation of the nervous system, by either stimulating or inhibiting inflammatory responses, depending on specific ligand-receptor combinations. Understanding such regulatory functions of AGMs in neuroinflammation may allow finding new molecular targets to treat neurodegenerative diseases, in which neuroinflammation underlies aetiology and progression.
Axons ; Ephrins ; Inflammation ; Nervous System ; Neurodegenerative Diseases ; Neuroglia ; Semaphorins

Protein tyrosine phosphatases (PTPs) are key regulatory factors in inflammatory signaling pathways. Although PTPs have been extensively studied, little is known about their role in neuroinflammation. In the present study, we examined the expression of 6 different PTPs (PTP1B, TC-PTP, SHP2, MEG2, LYP, and RPTPβ) and their role in glial activation and neuroinflammation. All PTPs were expressed in brain and glia. The expression of PTP1B, SHP2, and LYP was enhanced in the inflamed brain. The expression of PTP1B, TC-PTP, and LYP was increased after treating microglia cells with lipopolysaccharide (LPS). To examine the role of PTPs in microglial activation and neuroinflammation, we used specific pharmacological inhibitors of PTPs. Inhibition of PTP1B, TC-PTP, SHP2, LYP, and RPTPβ suppressed nitric oxide production in LPS-treated microglial cells in a dose-dependent manner. Furthermore, intracerebroventricular injection of PTP1B, TC-PTP, SHP2, and RPTPβ inhibitors downregulated microglial activation in an LPS-induced neuroinflammation model. Our results indicate that multiple PTPs are involved in regulating microglial activation and neuroinflammation, with different expression patterns and specific functions. Thus, PTP inhibitors can be exploited for therapeutic modulation of microglial activation in neuroinflammatory diseases.
Brain ; Microglia ; Neuroglia ; Nitric Oxide ; Protein Tyrosine Phosphatase, Non-Receptor Type 2 ; Protein Tyrosine Phosphatases*

BACKGROUND: Lipocalin-2 (LCN2), a small glycoprotein, has a pivotal role in diverse biological processes such as cellular proliferation and differentiation. We previously reported that LCN2 is implicated in osteoclast formation induced by receptor activator of nuclear factor-kappa B ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). In the present study, we used a knockout mouse model to further investigate the role of LCN2 in osteoclast development. METHODS: Osteoclastogenesis was assessed using primary bone marrow-derived macrophages. RANKL and M-CSF signaling was determined by immunoblotting, cell proliferation by bromodeoxyuridine (BrdU) enzyme-linked immunosorbent assay (ELISA), and apoptosis by cell death detection ELISA. Bone morphometric parameters were determined using a micro-computed tomography system. RESULTS: Our results showed that LCN2 deficiency increases tartrate-resistant acid phosphatase (TRAP)-positive multinucleated osteoclast formation in vitro, a finding that reflects enhanced proliferation and differentiation of osteoclast lineage cells. LCN2 deficiency promotes M-CSF-induced proliferation of bone marrow macrophages (BMMs), osteoclast precursors, without altering their survival. The accelerated proliferation of LCN2-deficient precursors is associated with enhanced expression and activation of the M-CSF receptor, c-Fms. Furthermore, LCN2 deficiency stimulates the induction of c-Fos and nuclear factor of activated T cells c1 (NFATc1), key transcription factors for osteoclastogenesis, and promotes RANKL-induced inhibitor of kappa B (IkappaBalpha) phosphorylation. Interestingly, LCN2 deficiency does not affect basal osteoclast formation in vivo, suggesting that LCN2 might play a role in the enhanced osteoclast development that occurs under some pathological conditions. CONCLUSIONS: Our study establishes LCN2 as a negative modulator of osteoclast formation, results that are in accordance with our previous findings.
Acid Phosphatase ; Animals ; Apoptosis ; Biological Processes ; Bone Marrow ; Bromodeoxyuridine ; Cell Death ; Cell Proliferation ; Enzyme-Linked Immunosorbent Assay ; Glycoproteins ; Immunoblotting ; Macrophage Colony-Stimulating Factor ; Macrophages ; Mice ; Mice, Knockout ; NF-kappa B ; Osteoclasts* ; Phosphorylation ; RANK Ligand ; T-Lymphocytes ; Transcription Factors

Excessive microglial activation and subsequent neuroinflammation lead to synaptic loss and dysfunction as well as neuronal cell death, which are involved in the pathogenesis and progression of several neurodegenerative diseases. Thus, the regulation of microglial activation has been evaluated as effective therapeutic strategies. Although dieckol (DEK), one of the phlorotannins isolated from marine brown alga Ecklonia cava, has been previously reported to inhibit microglial activation, the molecular mechanism is still unclear. Therefore, we investigated here molecular mechanism of DEK via extracellular signal-regulated kinase (ERK), Akt and nicotinamide adenine dinuclelotide phosphate (NADPH) oxidase-mediated pathways. In addition, the neuroprotective mechanism of DEK was investigated in microglia-mediated neurotoxicity models such as neuron-microglia co-culture and microglial conditioned media system. Our results demonstrated that treatment of anti-oxidant DEK potently suppressed phosphorylation of ERK in lipopolysaccharide (LPS, 1 microg/ml)-stimulated BV-2 microglia. In addition, DEK markedly attenuated Akt phosphorylation and increased expression of gp91(phox), which is the catalytic component of NADPH oxidase complex responsible for microglial reactive oxygen species (ROS) generation. Finally, DEK significantly attenuated neuronal cell death that is induced by treatment of microglial conditioned media containing neurotoxic secretary molecules. These neuroprotective effects of DEK were also confirmed in a neuron-microglia co-culture system using enhanced green fluorescent protein (EGFP)-transfected B35 neuroblastoma cell line. Taken together, these results suggest that DEK suppresses excessive microglial activation and microglia-mediated neuronal cell death via downregulation of ERK, Akt and NADPH oxidase-mediated pathways.
Adenine ; Cell Death* ; Cell Line ; Coculture Techniques ; Culture Media, Conditioned ; Down-Regulation ; Microglia ; NADP* ; NADPH Oxidase ; Neuroblastoma ; Neurodegenerative Diseases ; Neurons* ; Neuroprotective Agents ; Niacinamide ; Phosphorylation ; Phosphotransferases ; Reactive Oxygen Species

Endoplasmic reticulum (ER) stress is involved in many neurological diseases and inflammatory responses. Inflammatory mediators induce neuronal damage and trigger the neuropathic or inflammatory pain. But there is very little data on the role of the ER stress response in pain mechanisms. In this study, we explored whether the ER stress response is involved in orofacial inflammatory pain by using a complete Freund's adjuvant (CFA)-injected rat model. The thermal pain hypersensitivity increased significantly after CFA injection. We found that the protein and mRNA levels of ER stress response genes, GRP78/Bip and p-eIF2alpha, increased significantly in trigeminal ganglion (TG) of CFA-injected rats compared to control animals. In immunofluorescence analysis, a significant increase of GRP78 and p-eIF2alpha immunopositive neurons was observed in CFA-injected TG compared to control TG. When we administered an ER stress modulator, salubrinal, CFA-induced thermal pain hypersensitivity was temporally reduced. Thus, our study suggests that ER stress responses in TG neurons contribute to CFA-induced inflammatory pain, and may comprise an important molecular mechanism underlying the orofacial inflammatory pain pathway.
Animals ; Endoplasmic Reticulum ; Endoplasmic Reticulum Stress* ; Facial Pain ; Fluorescent Antibody Technique ; Freund's Adjuvant ; Hypersensitivity ; Models, Animal ; Neurons ; Rats ; RNA, Messenger ; Trigeminal Ganglion

Lipocalin-2 (LCN2) is a key mediator of various cellular processes. Recent studies have indicated that LCN2 also plays an important role in central nervous system (CNS) injuries and neurological diseases, such as spinal cord injury, stroke, experimental autoimmune encephalomyelitis, and neurodegenerative diseases. Here, we investigated the role of LCN2 in a rodent model of lipopolysaccharide (LPS)-induced neuroinflammation. At 24 hours after intraperitoneal injection of LPS, LCN2 expression was strongly induced in the brain; LCN2 was mainly expressed in endothelial cells, astrocytes, and microglia. Next, we used LCN2-deficient mice to further investigate the role of LCN2 in neuroinflammation. LCN2 deficiency attenuated LPS-induced glial activation in the brain. In a mechanistic study employing glia/neuron co-cultures, LCN2 deficiency reduced glial neurotoxicity. Our results indicate that LCN2 plays a central role in the neuroinflammatory responses following LPS administration, and that LCN2 might contribute to the uncontrolled neurotoxic glial activation under excessive and chronic inflammatory conditions.
Animals ; Astrocytes ; Brain ; Central Nervous System ; Coculture Techniques ; Encephalomyelitis, Autoimmune, Experimental ; Endothelial Cells ; Injections, Intraperitoneal ; Mice* ; Microglia ; Neurodegenerative Diseases ; Neurons ; Rodentia ; Spinal Cord Injuries ; Stroke

Hypothermia is considered a useful intervention for limiting pathophysiological changes after brain injury. Local hypothermia is a relatively safe and convenient intervention that circumvents many of the complications associated with systemic hypothermia. However, successful hypothermia treatment requires careful consideration of several factors including its practicality, feasibility, and associated risks. Here, we review the protective effects-and the cellular mechanisms that underlie them-of delayed and prolonged local hypothermia in rodent and canine brain injury models. The data show that the protective effects of therapeutic hypothermia, which mainly result from the modulation of inflammatory glial dynamics, are limited. We argue that decompressive craniectomy can be used to overcome the limitations of local brain hypothermia without causing histological abnormalities or other detrimental effects to the cooled area. Therefore, delayed and prolonged local brain hypothermia at the site of craniectomy is a promising intervention that may prove effective in the clinical setting.
Astrocytes ; Brain Injuries ; Brain* ; Decompressive Craniectomy* ; Hypothermia* ; Microglia ; Rodentia ; Stroke

Lipocalin-2 (LCN2) is an acute-phase protein induced by injury, infection, or other inflammatory stimuli. LCN2 binds small hydrophobic ligands and interacts with cell surface receptor to regulate diverse cellular processes. The role of LCN2 as a chemokine inducer in the central nervous system (CNS) has been previously reported. Based on the previous participation of LCN2 in neuroinflammation, we investigated the role of LCN2 in formalin-induced nociception and pathological pain. Formalin-induced nociceptive behaviors (licking/biting) and spinal microglial activation were significantly reduced in the second or late phase of the formalin test in Lcn2 knockout mice. Likewise, antibody-mediated neutralization of spinal LCN2 attenuated the mechanical hypersensitivity induced by peripheral nerve injury in mice. Taken together, our results suggest that LCN2 can be therapeutically targeted, presumably for both prevention and reversal of acute inflammatory pain as well as pathological pain.
Acute-Phase Proteins* ; Animals ; Central Nervous System ; Hypersensitivity ; Ligands ; Mice ; Mice, Knockout ; Microglia ; Nociception* ; Pain Measurement ; Peripheral Nerve Injuries ; Spinal Cord

Metabolic aberrations in the form of altered flux through key metabolic pathways are the major hallmarks of several life-threatening malignancies including malignant gliomas. These adaptations play an important role in the enhancement of the survival and proliferation of gliomas at the expense of the surrounding normal/healthy tissues. Recent studies in the field of neurooncology have directly targeted the altered metabolic pathways of malignant tumor cells for the development of anti-cancer drugs. Aerobic glycolysis due to elevated production of lactate from pyruvate regardless of oxygen availability is a common metabolic alteration in most malignancies. Aerobic glycolysis offers survival advantages in addition to generating substrates such as fatty acids, amino acids and nucleotides required for the rapid proliferation of cells. This review outlines the role of pyruvate dehydrogenase kinase (PDK) in gliomas as an inhibitor of pyruvate dehydrogenase that catalyzes the oxidative decarboxylation of pyruvate. An in-depth investigation on the key metabolic enzyme PDK may provide a novel therapeutic approach for the treatment of malignant gliomas.
Amino Acids ; Decarboxylation ; Dichloroacetic Acid ; Fatty Acids ; Glioma* ; Glycolysis ; Lactic Acid ; Metabolic Networks and Pathways ; Nucleotides ; Oxidoreductases* ; Oxygen ; Phosphotransferases* ; Pyruvic Acid*