• Title/Summary/Keyword: excitatory-inhibitory amino acids

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Isolation and electrical characterization of the rat spinal dorsal horn neurons

  • Han, Seong-Kyu;Lee, Mun-Han;Ryu, Pan-Dong
    • Proceedings of the Korean Society of Applied Pharmacology
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    • 1996.04a
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    • pp.175-175
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    • 1996
  • The spinal dorsal horn is the area where primary afferent fibers terminate and cutaneous sensory information is Processed. A number of putative neurotransmitter substances, including excitatory and inhibitory amino acids and peptides, are present in this region and sites and cellular mechanisms of their actions have been a target of numerous studies. In this study, single neurons were acutely isolated and the properties of whole cell current and responses to excitatory and inhibitory neurotransmitters were studied by the patch clamp method. Young rats (7-14 days) were anesthetized with diethyl-ether, and the lumbar spinal cord was excised and cut transversely at a thickness of 30$\mu\textrm{m}$ by Vibroslicer. The treatment of spinal slices with low concentration of proteases (pronase and thermolysin 0.75 mg/$m\ell$) and mechanical dissociation yielded isolated neurons with near intact morphology. Multipolar, ellipsoidal and bipolar, and pyramidal cells were shown. By applying step voltage pulses to neurons held at -70 mV, two types of inward currents and one outward currents observed. The fast activating and inactivating inward current was the Na$\^$+/ current because of its fast kinetics and blocking by 0.5${\mu}$M TTX, a specific blocker of Na$\^$+/ channel. The second type of inward currents were sustained. Based on their kinetics and current-voltage relations, it was likely that the second type of inward current was the voltage-dependent Ca$\^$2+/ current. In the presence of TTX, the steady-state currents mainly represented outward K$\^$+/ current which looked like the delayed rectifier K$\^$+/ current. In addition, the membrane currents produced by agonist of excitatory amino acid (EAA) receptor and the endogenous transmitter candidate L-glutamate were recorded in isolated whole-cell voltage clamped neurons as well as responses to inhibitory amino acids (${\gamma}$-amino butyric acid, glycine). Drugs were applied by a method that allows complete exchange of the solution within 1 sec; an infinite number of solutions can be applied to a single cell.

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Inhibitory Effect of Fangchinoline on Excitatory Amino Acids. Induced Neurotoxicity in Cultured Rat Cerebellar Granule Cells

  • Kim, Su-Don;Oh, Sei-Kwan;Kim, Hack-Seang;Seong, Yeon-Hee
    • Archives of Pharmacal Research
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    • v.24 no.2
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    • pp.164-170
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    • 2001
  • Glutamate receptors-mediated excitoxicity is believed to play a role in the pathophysiology of neurodegenerative diseases. The present study was performed to evaluate the inhibitory effect of fanschinoline, a bis-benzylisoquinoline alkaloid, which has a characteristic as a $Ca^{2+}$channel blockers on excitatory amino acids (EAAS)-induced neurotoxicity in cultured rat cerebellar granule neuron. Fangchinoline (1 and 5$\mu\textrm{m}$) inhibited glutamate (1 ${m}M$), N-methyl-D-aspartate (NMDA; 1 ${m}M$) and kainate (100$\mu\textrm{m}$)-induced neuronal cell death which was measured by trypan blue exclusion test. Fangchinoline (1 and 5$\mu\textrm{m}$) inhibited glutamate release into medium induced by NMDA (1 ${m}M$) and kainate (100$\mu\textrm{m}$), which was measured by HPLC. And fangchinoline (5$\mu\textrm{m}$) inhibited glutamate (1 ${m}M$)-induced elevation of intracellular calcium concentration. These results suggest that inhibition of $Ca^{2+}$influx by fangchinoline may contribute to the beneficial effects on neurodegenerative effect of glutamate in pathophysiological conditions.

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Isolation and Electrical Characterization of the Rat Spinal Dorsal Horn Neurons (랫드 척수후각 단일세포 분리 및 특성에 관한 연구)

  • Han, Seong-Kyu;Ryu, Pan-Dong
    • The Korean Journal of Pharmacology
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    • v.32 no.2
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    • pp.283-292
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    • 1996
  • The spinal dorsal horn is the area where primary afferent fibers terminate and cutaneous sensory information is processed. A number of putative neurotransmitter substances, including excitatory and inhibitory amino acids and peptides, are present in this region. In this study, single neurons of the spinal dorsal horn were acutely isolated and the properties of whole cell current and responses to excitatory and inhibitory neurotransmitters were studied by patch clamp technique. Transverse slice ($(300{\mu}m$) of lumbar spinal cords from young rats$(7{\sim}14\;days)$ were sequentially treated with two pretenses(pronase 0.75 mg/ml and thermolysin 0.75 mg/ml), then single neurons were mechanically dissociated. These neurons showed near-intact morphology such as multipolar, ellipsoidal and bipolar, and pyramidal cells and we recorded the typical whole cell currents of $K^+$, $Ca^{2+}$ and ligand-operated channels from these neurons. Glutamate $(30{\mu}M)$ and N-methyl-D-aspartate(NMDA, $30{\mu}M)$ induced inward currents of $117{\pm}12.4$ pA(n=5) and $49{\pm}6.9$ pA(n=3), respectively. Glycine $(1{\mu}M)$ potentiated glutamate-induced currents $4{\sim}5$ times and NMDA-induced currents $8{\sim}10$ times. In addition, glycine $(30{\mu}M)$ induced Inward current ($31{\pm}6.1$ nA, n=2), which was rapidly desensitized after the peak to a new steady-state level. However, the inward currents induced by ${\gamma}-amino$ butyric acid(GABA, $1{\mu}M$) decreased continuously after the peak($226{\pm}41.6$ pA, n=3) under the similar experimental condition. The ionic currents and pharmacological responses of isolated neurons in this work were similar to those observed in vivo or in vitro spinal cord slice, indicating that acutely isolated neurons could be effectively used for further pharmacological studies.

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Distribution Pattern of Inhibitory and Excitatory Nerve Terminals in the Rat Genioglossus Motoneurons (흰쥐의 턱끝혀근 지배 운동신경원에 대한 억제성 및 흥분성 신경종말의 분포 양식)

  • Moon, Yong-Suk
    • Journal of Life Science
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    • v.21 no.1
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    • pp.102-109
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    • 2011
  • The genioglossus muscle plays an important role in maintaining upper airway patency during inspiration; if this muscle does not contract normally, breathing disorders occur due to closing of the upper airway. These occur because of disorders of synaptic input to the genioglossus motoneurons, however, little is known about it. In this study, the distribution of GABA-, glycine-, and glutamate-like immunoreactivity in axon terminals on dendrites of the rat genioglossus motoneurons, stained intracellularly with horseradish peroxidase (HRP), was examined by using postembedding immunogold histochemistry in serial ultrathin sections. The motoneurons were divided into four compartments: the soma, and primary (Pd), intermediate (Id), and distal dendrites (Dd). Quantitative analysis of 157, 188, 181, and 96 boutons synapsing on 3 soma, 14 Pd, 35 Id, and 28 Dd, respectively, was performed. 71.9% of the total number of studied boutons had immunoreactivity for at least one of the three amino acids. 32.8% of the total number of studied boutons were immunopositive for GABA and/or glycine and 39.1% for glutamate. Among the former, 14.2% showed glycine immunoreactivity only and 13.3% were immunoreactive to both glycine and GABA. The remainder (5.3%) showed immunoreactivity for GABA only. Most boutons immunoreactive to inhibitory amino acids contained a mixture of flattened, oval, and round synaptic vesicles. Most boutons immunoreactive to excitatory amino acids contained clear and spherical synaptic vesicles with a few dense-cored vesicles. When comparisons of the inhibitory and excitatory boutons were made between the soma and three dendritic segments, the proportion of the inhibitory to the excitatory boutons was high in the Dd (23.9% vs. 43.8%) but somewhat low in the soma (35.7% vs. 38.2%), Pd (34.6% vs. 37.8%) and Id (33.1% vs. 38.7%). The percentage of synaptic covering of the inhibitory synaptic boutons decreased in the order of soma, Pd, Id, and Dd, but this trend was not applicable to the excitatory boutons. The present study provides possible evidence that the spatial distribution patterns of inhibitory and excitatory synapses are different in the soma and dendritic tree of the rat genioglussus motoneurons.

Magnesium Suppresses the Responses of Dorsal Horn Cell to Noxious Stimuli in the Rat

  • Shin, Hong-Kee;Kim, Jin-Hyuk;Kim, Kee-Soon
    • The Korean Journal of Physiology and Pharmacology
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    • v.3 no.3
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    • pp.237-244
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    • 1999
  • Magnesium ion is known to selectively block the N-methyl-D-aspartate (NMDA)-induced responses and to have anticonvulsive action, neuroprotective effect and antinociceptive action in the behavioral test. In this study, we investigated the effect of $Mg^{2+}$ on the responses of dorsal horn neurons to cutaneous thermal stimulation and graded electrical stimulation of afferent nerves as well as to excitatory amino acids and also elucidated whether the actions of $Ca^{2+}$ and $Mg^{2+}$ are additive or antagonistic. $Mg^{2+}$ suppressed the thermal and C-fiber responses of wide dynamic range (WDR) cell without any effect on the A-fiber responses. When $Mg^{2+}$ was directly applied onto the spinal cord, its inhibitory effect was dependent on the concentration of $Mg^{2+}$ and duration of application. The NMDA- and kainate-induced responses of WDR cell were suppressed by $Mg^{2+}$, the NMDA-induced responses being inhibited more strongly. $Ca^{2+}$ also inhibited the NMDA-induced responses current-dependently. Both inhibitory actions of $Mg^{2+}$ and $Ca^{2+}$ were additive, while $Mg^{2+}$ suppressed the EGTA-induced augmentation of WDR cell responses to NMDA and C-fiber stimulation. Magnesium had dual effects on the spontaneous activities of WDR cell. These experimental findings suggest that $Mg^{2+}$ is implicated in the modulation of pain in the rat spinal cord by inhibiting the responses of WDR cell to noxious stimuli more strongly than innocuous stimuli.

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[$Zn^{2+}$ Modulates the Responses of Rat Dorsal Horn Neuron to C-Fiber Stimulation and Excitatory Amino Acids

  • Ahn, Chang-Hoon;Shin, Hong-Kee;Kim, Jin-Hyuk
    • The Korean Journal of Physiology and Pharmacology
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    • v.4 no.6
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    • pp.455-461
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    • 2000
  • Zinc contained in the neurons of central nervous system is activity-dependently released and then attenuates NMDA (N-methyl-D-aspartate)-induced neurotoxicity while augmenting non-NMDA-induced neurodegeneration. Zinc also has been reported to produce antinociceptive action on the inflammation- and nerve injury-induced hyperalgesia in the behavioral test. In this study, we investigated the effects of zinc on the responses of dorsal horn cells to NMDA, kainate and graded electrical stimulation of C-fibers. In the majority of WDR cells (70.6%), zinc current-dependently inhibited WDR cell responses to NMDA and in the remaining cells, produced biphasic responses; excitation followed by inhibition. Zinc augmented the responses of WDR cells to iontophoretical application of kainate. The dominant effect of $Zn^{2+}$ on the responses of WDR cells to C-fiber stimulation was excitatory, but inhibition, excitation-inhibition and no change of the responses to C-fiber stimulation were induced. $Ca^{2+}-EDTA$ antagonized the excitatory or inhibitory effects of $Zn^{2+}$ on the WDR cell responses. These experimental findings suggest that $Zn^{2+}$ modulates the transmission of sensory information in the rat spinal cord.

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Changes of Amino Acid Neurotransmitter Contents in Rat Brain by Toluene Inhalation (톨루엔 흡입이 뇌내 아미노산 신경전달물질 함량에 미치는 영향)

  • 이선희;신대섭;김부영
    • Biomolecules & Therapeutics
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    • v.3 no.1
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    • pp.91-96
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    • 1995
  • The effects of toluene inhalation on the contents of amino acid neurotransmitters in rat brain were investigated and blood toluene concentrations inducing changes of behavior and amino acid neurotransmitter contents in rat brain were observed. Male wistar rats were exposed to toluene vapor (single dose : 1700, 5000 and 10000 ppm for 2 hrs, repeated dose : 1700 and 5000 ppm for 2 hrs/day$\times$6 days). Toluene concentrations in blood and the inhalation chamber were assayed by GC with headspace sampler. HPLC method following PITC derivatization was used to measure the amino acid contents in brain tissues such as frontal cortex, caudate, hippocampus, cerebellum and brain stem. Glutamic acid and aspartic acid levels were increased by single inhalation of toluene (5000 ppm) in all the brain areas assayed in this experiment. In caudate and cerebellum, taurine levels were decreased by single inhalation of low dose toluene (1700 ppm), but increased by repeated administration. At high blood toluene concentration, GABA levels were increased in all the brain areas assayed in this experiment and the increasing extents of inhibitory amino acid contents measured in caudate and hippocampus were greater than those of excitatory amino acids. These results suggest that the changes of amino acid neurotransmitter contents in brain by exposure to toluene may modulate toluene-induced behaviors.

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The Protective Effects of Sunghyangjeongki-San on Middle Cerebral Artery Occlusion (성향정기산(星香正氣散)이 뇌허혈(腦虛血)을 유발(誘發)시킨 백서(白鼠)의 신경전달물질(神經傳達物質)에 미치는 영향(影響))

  • Yea, Gyeong-Uk;Park, Chi-Sang;Lee, Eun-Ju;Song, Jee-Hea;Kim, Mi-Ryeo;Cho, Jung-Sook;Kim, Young-Ho;Park, Chang-Gook;Yang, Chae-Ha
    • The Journal of Internal Korean Medicine
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    • v.21 no.1
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    • pp.116-125
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    • 2000
  • Objectives : The aim of this study is to investigate that Sunghyangjeongki-San which has been frequently medicated in the early stage of stroke can protect against ischemic damage in rat brain Methods : Extracellular levels of amino acids(glutamate, aspartate, GABA, glycine, taurine, tyrosine, alanine), organic acids(pyruvate, lactate), and cerebral infarction volume were measured at the striatum of rats subjected to permanant focal cerebral ischemia induced by 2 hours of middle cerebral artery occiusion(MCAO). Rats were orally administered with Sunghyangjeongki-San at 30mins before MCAO and the microdialysate was collected by intracerebral microdialysis three times before MCAO and six times after MCAO at 20mins interval and analyzed by HPLC. After a microdialysis study, the brain was sliced and stained with cresyl violet buffer for the measurement of cerebral infarcted area and volume by image analyzer system Results : The concentrations of glutamate, aspartate, and tyrosine known as excitatory neurotransmitters were significantly decreased in Sunghyangjeongki-San group compared with control group, The concentrations of GABA, glycine, taurine and alanine known as inhibitory neurotransmitters were significantly increased in Sunghyangjeongki-San group compared with control group. The concentrations of pyruvate and lactate showed little significant change in Sunghyangjeongki-San group compared with control group. The measurement of cerebral infarcted area and volume by image analyzer system were significantly decreased in Sunghyangjeongki-San group compared with control group. Conclusions : Sunghyangjeongki-San can affect on protecting against cerebral ischemia by regulating extracellular levels of excitatory and inhibitory amino acid neurotransmitters and improve the conditions of the patients in the early stage of stroke.

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Update in the etiology and treatment of sexual precocity (사춘기 조숙증의 원인 및 치료의 최신지견)

  • Park, Mi Jung
    • Clinical and Experimental Pediatrics
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    • v.49 no.7
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    • pp.718-725
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    • 2006
  • The pubertal activation of gonadotrophin releasing hormone(GnRH) requires coordinated changes in excitatory or inhibitory amino acids, growth factors, and a group of transcriptional regulators. The age of onset of puberty is progressing to younger age. Factors affecting early puberty include genetic traits, nutrition(body fat) and exposure to endocrine disrupting chemicals. In rapidly progressing central precocious puberty, gonadotrophin releasing hormone(GnRH) agonists(GnRHa) appear to increase final height if treated early stage. Further large scaled long-term follow-up study of the effects of GnRHa on final height is needed.

Enhanced GABA content from sodium alginate-induced Sparassis latifolia influences dendrite development in primary cortical neurons (해조류 기반 엘리시터 처리에 의한 꽃송이버섯의 GABA 함량 증가 및 흥분성 신경세포의 수상돌기 발달 억제)

  • Choi, Moon-Hee;Ki, SungHwan;Lee, Seong-Eun;Lee, GumHwa;Shin, Hyun-Jae
    • Journal of Mushroom
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    • v.17 no.4
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    • pp.275-283
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    • 2019
  • Sparassis latifolia is a fungus abundant in β-glucan and amino acids and is highly valued as a medicinal mushroom. Among amino acids, γ-aminobutyric acid (GABA) is a free amino acid and has biological effects, such as increase/decrease of hypertension, improvement of cerebral blood flow, and prevention of dementia. In this study, biological elicitors were used to increase bioactive substances as a biofortification method. Sodium alginate extracted from seaweed (Sargassum horneri, Sargassum fulvellum, Sargassum fusiforme) were used as the elicitor. The levels of β-glucan and GABA in the mycelium and fruiting body grown by adding the elicitor to the medium were investigated. Addition of sodium alginate positively affected GABA production and negatively affected the β-glucan production in these fungi. Sodium alginates extracted from S. fulvellum induced the highest increase in GABA in the mycelium and fruiting bodies. Moreover, we investigated the effects of the extracts from mycelium and fruiting bodies on dendrite development in primary cortical neurons. We found that the extract from the fruiting bodies of sodium alginate treated fungi with increased levels of GABA inhibited the dendrite outgrowth of excitatory neurons, but not inhibitory neurons.