• Korean Journal of Biological Psychiatry
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• v.23 no.2
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• pp.48-56
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• 2016

Alzheimer's disease (AD) is a neurodegenerative disorder in which neuronal loss causes cognitive decline and other neuropsychiatric problems. It can be diagnosed based on history, examination, and appropriate objective assessments, using standard criteria such as the Diagnostic and Statistical Manual of Mental Disorders or the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA). Brain imaging and biomarkers are making progress in the differential diagnoses among the different disorders. The cholinesterase inhibitors, donepezil, rivastigmine and galantamine and N-methyl-D-aspartate receptors antagonist memantine are approved by the US Food and Drug Administration for AD. Recently some acetylcholinesterase inhibitors gained approval for the treatment of severe AD and became available in a higher dose formulation or a patch formulation. Optimal care in AD is multifactorial and it should include early diagnosis and multidisciplinary care with pharmacological and nonpharmacological interventions including exercise interventions, cognitive interventions and maintenance of social networks.

• Molecules and Cells
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• v.40 no.9
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• pp.613-620
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• 2017

The most common form of senile dementia is Alzheimer's disease (AD), which is characterized by the extracellular deposition of amyloid ${\beta}-peptide$ ($A{\beta}$) plaques and the intracellular formation of neurofibrillary tangles (NFTs) in the cerebral cortex. Tau abnormalities are commonly observed in many neurodegenerative diseases including AD, Parkinson's disease, and Pick's disease. Interestingly, tau-mediated formation of NFTs in AD brains shows better correlation with cognitive impairment than $A{\beta}$ plaque accumulation; pathological tau alone is sufficient to elicit frontotemporal dementia, but it does not cause AD. A growing amount of evidence suggests that soluble $A{\beta}$ oligomers in concert with hyperphosphorylated tau (pTau) serve as the major pathogenic drivers of neurodegeneration in AD. Increased $A{\beta}$ oligomers trigger neuronal dysfunction and network alternations in learning and memory circuitry prior to clinical onset of AD, leading to cognitive decline. Furthermore, accumulated damage to mitochondria in the course of aging, which is the best-known nongenetic risk factor for AD, may collaborate with soluble $A{\beta}$ and pTau to induce synapse loss and cognitive impairment in AD. In this review, I summarize and discuss the current knowledge of the molecular and cellular biology of AD and also the mechanisms that underlie $A{\beta}-mediated$ neurodegeneration.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2006.04a
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• pp.123-135
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• 2006

Alzheimer's disease (AD) is the most common form of dementia in the aging population and is clinically characterized by a progressive loss of cognitive abilities. Pathologically, it is defined by the appearance of senile plaques - extracellular insoluble, congophilic protein aggregates composed of amyloid $\beta$ (A$\beta$) and neurofibrillary tangles (NFTs) - inyracellular lesions consisting of paired helical filaments from hyperphosphorylated cytoskeletal tau protein as described by Alois Alzheimer a century ago. These hallmarks still serve as the major criteria for a definite diagnosis of the disease. Consequently, one of the key strategy for drug development in this disease area focuses on reducing the concentration of cerebral A$\beta$ plaque by using substances that inhibit A$\beta$ fibril formation. We focused on developing inhibitors by synthesizing several kinds of aromatic molecules. The synthetic compounds were initially screened to evaluate the effective compound by tioflavin T fluorescence assay. The selected effective compounds were tested cytotoxicity and protective effect from A$\beta$-induced neuronal toxicity by cell based MTT assay with HT22 hippocampal neurons. The BBB permeability on effectors was also tested in in vitro co-culture model(HUVEC/C6 cell line). The behavior test wea carried out in mutant APP/PS1 transgenic mouse model of Alzheimer's disease. And inhibition of A$\beta$ fibril formation by the effective compound was monitored with transmitted electron microscopic images.

• Journal of Yeungnam Medical Science
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• v.30 no.1
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• pp.4-9
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• 2013

Leptin, a 16-kDa cytokine, is secreted by adipose tissue in response to the surplus of fat store. Thereby, the brain is informed about the body's energy status. In the hypothalamus, leptin triggers specific neuronal subpopulations (e.g., POMC and NPY neurons) and activates several intracellular signaling events, including the JAK/STAT, MAPK, PI3K, and mTOR pathway, which eventually translates into decreased food intake and increased energy expenditure. Leptin signal is inhibited by a feedback inhibitory pathway mediated by SOCS3. PTP1B involves another inhibitory pathway of leptin. Leptin potently promotes fat mass loss and body weight reduction in lean subjects. However, it is not widely used in the clinical field because of leptin resistance, which is a common feature of obesity characterized by hyperleptinemia and the failure of exogenous leptin administration to provide therapeutic benefit in rodents and humans. The potential mechanisms of leptin resistance include the following: 1) increases in circulating leptin-binding proteins, 2) reduced transport of leptin across the blood-brain barrier, 3) decreased leptin receptor-B (LRB), and/or 4) the provocation of processes that diminish cellular leptin signaling (inflammation, endoplasmic reticulum stress, feedback inhibition, etc.). Thus, interference of the cellular mechanisms that attenuate leptin signaling improves leptin action in cells and animal models, suggesting the potential utility of these processes as points of therapeutic intervention. Various experimental trials and compounds that improve leptin resistance are introduced in this paper.

• BMB Reports
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• v.50 no.1
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• pp.37-42
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• 2017

The tubby protein (Tub), a putative transcription factor, plays important roles in the maintenance and function of neuronal cells. A splicing defect-causing mutation in the 3'-end of the tubby gene, which is predicted to disrupt the carboxy-terminal region of the Tub protein, causes maturity-onset obesity, blindness, and deafness in mice. Although this pathological Tub mutation leads to a loss of function, the precise mechanism has not yet been investigated. Here, we found that the mutant Tub proteins were mostly localized to puncta found in the perinuclear region and that the C-terminus was important for its solubility. Immunocytochemical analysis revealed that puncta of mutant Tub co-localized with the aggresome. Moreover, whereas wild-type Tub was translocated to the nucleus by extracellular signaling, the mutant forms failed to undergo such translocation. Taken together, our results suggest that the malfunctions of the Tub mutant are caused by its misfolding and subsequent localization to aggresomes.

• Korean Journal of Clinical Laboratory Science
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• v.38 no.3
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• pp.179-183
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• 2006

Alzheimer's disease (AD) is characterised neuropathologically by the accumulation of neuritic plaques and neurofibrillary tangles as well as by cerebrovascular amyloid deposition and neuronal cell loss. Current advances have shown the apolipoproteinE-epsilon 4 (ApoE4) allele to be highly associated with late-onset familial and sporadic Alzheimer's disease (AD) in Western populations. The association of ApoE allele frequencies and dementia remains unknown in populations from many countries. We recently initiated a project to examine ApoE frequencies in non-demented healthy Koreans. Genomic DNA in hair root from a thousand persons was collected and ApoE gene type was investigated with the methods of polymerase chain reaction (PCR) and restriction fragment length polymorphism. A group of a thousand non-demented Koreans over the age of 40 years were found to be positive in 15.7% of the cases for ApoE4. AD and ApoE4 were closely related. ApoE epsilon 4 was a dangerous factor of AD and ApoE 4 allele made a contribution to the heterogenicity of AD.

• Natural Product Sciences
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• v.16 no.2
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• pp.99-106
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• 2010

This experiment was undertaken to investigate whether methanol extract of fruit peel of Dimocarpus longan Lour. (MEFL) protects against kainic acid (KA)-induced seizure. Oral administration of MEFL (1, 2 and 4 mg/kg) increased KA (50 mg/kg)-induced survival rate and latency of convulsion onset, and deceased seizure scores and weight loss induced by intraperitoneal (i.p) injection of KA in mice. In addition, MEFL protected against cell death in the hippocampus of rat brain after KA-administration as analyzed by using TUNEL assay in rats. MEFL also significantly blocked seizure-form of electroencephalogram (EEG) power spectra induced by KA in rats. MEFL also inhibited elevation of [$Ca^{2+}$]i and increased [$Cl^-$]i induced by KA in cultured neuronal cells. Therefore, it is suggested that MEFL protects against seizure induced by KA, decreasing [$Ca^{2+}$]i.

• Biomolecules & Therapeutics
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• v.27 no.2
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• pp.152-159
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• 2019

Multiple sclerosis (MS) is an autoimmune disease characterized by progressive neuronal loss, neuroinflammation, axonal degeneration, and demyelination. Previous studies have reported that 6-shogaol, a major constituent of ginger (Zingiber officinale rhizome), and its biological metabolite, 6-paradol, have anti-inflammatory and anti-oxidative properties in the central nervous system (CNS). In the present study, we investigated whether 6-shogaol and 6-paradol could ameliorate against experimental autoimmune encephalomyelitis (EAE), a mouse model of MS elicited by myelin oligodendrocyte glycoprotein ($MOG_{35-55}$) peptide immunization with injection of pertussis toxin. Once-daily administration of 6-shogaol and 6-paradol (5 mg/kg/day, p.o.) to symptomatic EAE mice significantly alleviated clinical signs of the disease along with remyelination and reduced cell accumulation in the white matter of spinal cord. Administration of 6-shogaol and 6-paradol into EAE mice markedly reduced astrogliosis and microglial activation as key features of immune responses inside the CNS. Furthermore, administration of these two molecules significantly suppressed expression level of tumor necrosis $factor-{\alpha}$, a major proinflammatory cytokine, in EAE spinal cord. Collectively, these results demonstrate therapeutic efficacy of 6-shogaol or 6-paradol for EAE by reducing neuroinflammatory responses, further indicating the therapeutic potential of these two active ingredients of ginger for MS.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.1
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• pp.79-85
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• 2021

α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors are differentially regulated in the nucleus accumbens (NAcc) of the brain after cocaine exposure. However, these results are supported only by biochemical and electrophysiological methods, but have not been validated with immunohistochemistry. To overcome the restriction of antigen loss on the postsynaptic target molecules that occurs during perfusion-fixation, we adopted an immersion-fixation method that enabled us to immunohistochemically quantify the expression levels of the AMPA receptor GluA1 subunit in the NAcc. Interestingly, compared to saline exposure, cocaine significantly increased the immunofluorescence intensity of GluA1 in two sub-regions, the core and the shell, of the NAcc on withdrawal day 21 following cocaine exposure, which led to locomotor sensitization. Increases in GluA1 intensity were observed in both the extra-post synaptic density (PSD) and PSD areas in the two sub-regions of the NAcc. These results clearly indicate that AMPA receptor plasticity, as exemplified by GluA1, in the NAcc can be visually detected by immunohistochemistry and confocal imaging. These results expand our understanding of the molecular changes occurring in neuronal synapses by adding a new form of analysis to conventional biochemical and electrophysiological methods.

• Biomolecules & Therapeutics
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• v.30 no.1
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• pp.55-63
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• 2022

Oleanolic acid (OA), a natural pentacyclic triterpenoid, has been reported to exert protective effects against several neurological diseases through its anti-oxidative and anti-inflammatory activities. The goal of the present study was to evaluate the therapeutic potential of OA against acute and chronic brain injuries after ischemic stroke using a mouse model of transient middle cerebral artery occlusion (tMCAO, MCAO/reperfusion). OA administration immediately after reperfusion significantly attenuated acute brain injuries including brain infarction, functional neurological deficits, and neuronal apoptosis. Moreover, delayed administration of OA (at 3 h after reperfusion) attenuated brain infarction and improved functional neurological deficits during the acute phase. Such neuroprotective effects were associated with attenuation of microglial activation and lipid peroxidation in the injured brain after the tMCAO challenge. OA also attenuated NLRP3 inflammasome activation in activated microglia during the acute phase. In addition, daily administration of OA for 7 days starting from either immediately after reperfusion or 1 day after reperfusion significantly improved functional neurological deficits and attenuated brain tissue loss up to 21 days after the tMCAO challenge; these findings supported therapeutic effects of OA against ischemic stroke-induced chronic brain injury. Together, these findings showed that OA exerted neuroprotective effects against both acute and chronic brain injuries after tMCAO challenge, suggesting that OA is a potential therapeutic agent to treat ischemic stroke.