• 생명과학회지
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• 제27권5호
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• pp.600-610
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• 2017

가려움증의 분류는 수용체성 가려움증(Pruritoceptive itch), 신경병증 가려움증(Neuropathic itch), 신경성 가려움증(Neurogenic itch), 심인성 가려움증(Psychogenic itch)의 신경생리학적 기전에 따른 4가지 카테고리로 분류하는 것이 일반적이었으나 최근 임상적인 기준을 통해 분류하기도 한다. 가려움증의 신경전달 경로는 히스타민-의존 경로와 히스타민-비의존 경로 2가지로 나뉘며 각 가려움증 매개체마다 서로 다른 수용체와 신경펩티드가 작용한다. 히스타민, BAM8-22, chloroquine 등의 가려움증 매개체는 히스타민-의존 경로를 통해 신호가 전달되며 cowhage spicule, 단백분해효소(protease), TSLP (Thymic stromal lymphopoietin) 등의 매개체가 히스타민-비의존 경로와 관련있다는 보고가 있다. 이러한 가려움증 매개체, 수용체, 신경펩티드는 가려움증 치료의 대상이 된다. 가려움증과 통증은 대표적인 유해자극으로서 과거에는 두 감각이 하나의 유해자극수용체를 통해 전달된다는 주장이 있었지만 최근 밝혀진 바에 따르면 가려움증과 통증은 독립적인 신경전달체계를 가지고 있으며 두 신경체계는 서로 억제작용을 한다. 가려움증 뉴런의 선택적 소집단이 존재한다는 주장을 뒷받침하는 연구들이 이 주장에 무게를 싣고 있다. 또한 가려움증과 통증의 상호 길항작용에 대해서도 다양한 기전으로 설명되고 있다. 최근에도 새롭게 연구되는 매개체와 수용체들이 많은 연구들을 통해 밝혀지고 있다. 특히 최근에는 히스타민 4 수용체에 대한 연구가 활발히 진행되고 있는데, 이는 T 세포 같은 면역세포 자체에 발현되어 있어 이 H4 수용체를 차단하는 치료제는 말초의 매개체를 차단하는 기존의 히스타민 수용체 차단제와는 달리 가려움증 만성화에 중요한 염증 반응 자체를 억제할 수 있다는 점에서 그 유용성이 크다고 할 수 있다. 가려움증의 기본적인 발생 기전에 대한 이해와 새로운 가려움증 매개체에 대한 연구는 효과적인 치료법의 개발로 이어질 것이며 이것이 가려움증 연구가 나아갈 바로 생각한다.

• Journal of Microbiology and Biotechnology
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• 제26권4호
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• pp.710-716
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• 2016

Gamma-aminobutyric acid (GABA) is a non-protein amino acid, which is an important inhibitor of neurotransmission in the human brain. GABA is also used as the precursor of biopolymer Nylon-4 production. In this study, the carbon flux from the tricarboxylic acid cycle was directed to the GABA shunt pathway for the production of GABA from glucose. The GABA shunt enzymes succinate-semialdehyde dehydrogenase (GabD) and GABA aminotransferase (GabT) were co-localized along with the GABA transporter (GadC) by using a synthetic scaffold complex. The co-localized enzyme scaffold complex produced 0.71 g/l of GABA from 10 g/l of glucose. Inactivation of competing metabolic pathways in mutant E. coli strains XBM1 and XBM6 increased GABA production 13% to reach 0.80 g/l GABA by the enzymes co-localized and expressed in the mutant strains. The recombinant E. coli system developed in this study demonstrated the possibility of the pathway of the GABA shunt as a novel GABA production pathway.

• BMB Reports
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• 제46권11호
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• pp.519-526
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• 2013

Dopamine (DA) regulates emotional and motivational behavior through the mesolimbic dopaminergic pathway. Changes in DA signaling in mesolimbic neurotransmission are widely believed to modify reward-related behaviors and are therefore closely associated with drug addiction. Recent evidence now suggests that as with drug addiction, obesity with compulsive eating behaviors involves reward circuitry of the brain, particularly the circuitry involving dopaminergic neural substrates. Increasing amounts of data from human imaging studies, together with genetic analysis, have demonstrated that obese people and drug addicts tend to show altered expression of DA D2 receptors in specific brain areas, and that similar brain areas are activated by food-related and drug-related cues. This review focuses on the functions of the DA system, with specific focus on the physiological interpretation and the role of DA D2 receptor signaling in food addiction.

• The Korean Journal of Physiology and Pharmacology
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• 제7권6호
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• pp.357-362
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• 2003

Carbon monoxide (CO) is low molecular weight oxide gas that is endogenously produced under physiological conditions and interacts with another gas, nitric oxide (NO), to act as a gastrointestinal messenger. The aim of this study was to determine the effects of exogenous CO on L-type calcium channel currents of human jejunal circular smooth muscle cells. Cells were voltage clamped with 10 mM barium ($Ba^{2+}$) as the charge carrier, and CO was directly applied into the bath to avoid perfusion induced effects on the recorded currents. 0.2% CO was increased barium current ($I_{Ba}$) by $15{\pm}2$% ($mean{\pm}S.E.$, p<0.01, n=11) in the cells. To determine if the effects of CO on barium current were mediated through the cGMP pathway, cells were pretreated with 1-H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, $10{mu}M$), a soluble guanylyl cyclase inhibitor, and exogenous CO (0.2%) had no effect on barium currents in the presence of ODQ ($2{\pm}1$% increase, n=6, p>0.05). CO mediates inhibitory neurotransmission through the nitric oxide pathway. Therefore, to determine if the effects of CO on L-calcium channels were also mediated through NO, cells were incubated with $N^G-nitro-L-arginine$ (L-NNA, 1 mM), a nitric oxide synthase inhibitor. After L-NNA pretreatment, 0.2 % CO did not increase barium current ($4{\pm}2$% increase, n=6, p>0.05). NO donor, SNAP ($20{\mu}M$) increased barium current by $13{\pm}2$% (n=6, p<0.05) in human jejunal smooth muscle cells. These data suggest that CO activates L-type calcium channels through NO/cGMP dependant mechanism.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book I
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• pp.601-610
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• 2003

Biotin is a water-soluble vitamin used as a skin conditioning agent and promotes the formation of intercellular lipid layers through increased lipid synthesis, which improves the skin's natural barrier function. The anti-inflammatory effects of biotin have been investigated using in vitro assay models, such as MTT assay, measurements of concentrations of nitric oxide(NO), prostaglandin E2(PGE$_2$), and inhibition rate of 5-lipoxygenase(5-LOX). In comparison with biotin, other plant extracts were tested at the same time which were kudzu vine extract, sage extract, paeonia extract, and dipotassium glycyrrhetinate. Nitric oxide is a signal molecule with functions such as neurotransmission, local vascular relaxation, and anti-inflammation in many physiological and pathological processes. NO can cause apoptosis and necrosis of target cells such as keratinocytes and is generated from L-arginine by nitric oxide synthase (NOS). Prostanoids, including prostaglandins and thromboxanes, are generated by the phospholipase $A_2$/cyclooxygenase(COX) pathway, and leukotrienes are generated by the 5-lipoxygenase pathway from arachidonic acid. Prostaglandin E2 recently have been shown to be beneficial in the resolution of tissue injury and inflammation, also has been implicated as an immunosuppressive agent and plasma levels of PGE$_2$ are elevated in patients sustaining thermal injury. Lipoxygenase metabolites from arachidonic acid have been implicated in inflammation, anti-inflammatory activity of the raw materials was evaluated in vitro by the offered inhibition of lipoxygenase.

• Restorative Dentistry and Endodontics
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• 제27권5호
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• pp.543-551
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• 2002

Nitric oxide (NO) is a small molecule (mol. wt. 30 Da) and oxidative free radical. It is uncharged and can therefore diffuse freely within and between cells across membrane. Such characteristics make it a biologically important messenger in physiologic processes such as neurotransmission and the control of vascular tone. NO is also highly toxic and is known to acts as a mediator of cytotoxicity during host defense. NO is synthesized by nitric oxide synthase (NOS) through L-arginine/nitric oxide pathway which is a dioxygenation process. NO synthesis involves several participants, three co-substrates, five electrons, five co-factors and two prosthetic groups. Under normal condition, low levels of NO are synthesized by type I and III NOS for a short period of time and mediates many physiologic processes. Under condition of oxidant stress, high levels of NO are synthesized by type II NOS and inhibits a variety of metabolic processes and can also cause direct damage to DNA. Such interaction result in cytostasis, energy depletion and ultimately cell death. NO has the potential to interact with a variety of intercellular targets producing diverse array of metabolic effects. It is known that NO is involved in hemodynamic regulation, neurogenic inflammation, re-innervation, management of dentin hypersensitivity on teeth. Under basal condition of pulpal blood flow, NO provides constant vasodilator tone acting against sympathetic vasoconstriction. Substance P, a well known vasodilator, was reported to be mediated partly by NO, while calcitonin-gene related peptide has provided no evidence of its relation with NO. This review describes the roles of NO in dental pulp in addition to the known general roles of it.