• 약학회지
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• 제42권1호
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• pp.95-100
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• 1998

Male Sprague-Dawley rats were exposed to the toluene at 3,000${\pm}$200ppm via inhalation for two hours (single inhalation group), three weeks by two hours per day, six days per wee k (repeated inhalation group). We examined the level of excitatory amino acids of the extracellular neurotransmitter within the corpus striatum of rats by using in vivo microdialysis. Aspartate (Asp) and glutamate (Glu) of excitatory amino acid neurotransmitters were generally decreased in the inhalation groups compared with the control group, and more significantly decreased in the repeated inhalation group than in the single inhalation group except that Asp was increased from 60 min after the beginning of the inhalation to 30 min after the termination.

• 대한한의학회지
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• 제21권1호
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• pp.11-19
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• 2000

The present study was carried out to investigate the effects of Woowhangcheongshim-won(WCW) on the extracellular concentrations of amino acid neurotransmitters(glutamate, aspartate, GABA, glycine, taurine, alanine, and tyrosine) and organic acid (lactate and pyruvate) in striatum and cerebral infarction volume in rats subjected to permanent focal cerebral ischemia induced by 2 hours of middle cerebral artery occlusion(MCAO), using intracerebral microdialysis as the sampling technique, Microdialysis probes were inserted into the lateral part of the caudate-putamen 2 hours before the experiment and microdialyzates were collected at 20min intervals and analyzed by high performance liquid chromatography, WCW significantly decreased the infarction volume with reducing focal cerebral ischemia-induced increase of extracellular glutamate, asparate, and tyrosine. On the other hand, the increase of GABA and taurine was enhanced after treatment of WCW in the ischemia-induced rats, These results suggest that WCW can produce a neuroprotective effect against cerebral ischemia by regulating extracellular excitatory and inhibitory amino acid levels in relation to the concept of excitotoxicity in brain ischemia.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1996년도 춘계학술대회
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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.

• Biomolecules & Therapeutics
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• 제3권1호
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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.

• 대한한방내과학회지
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• 제21권1호
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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.

• Restorative Dentistry and Endodontics
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• 제20권2호
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• pp.423-431
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• 1995

Trigeminal spinal sensory nucleus is a main relay site in transmission of orofacial pain. Glutamate and aspartate playa role in transmission of primary afferents. This experiment was performed to study the role of capsaicin, KR-25018 and shogaol on the release of glutamate and aspartate from trigeminal spinal sensory nucleus. Release of excitatory amino acids(EAAs) was induced by electrical stimulation of oral mucosa with innocuous or noxious stimuli. Capsaicin($10{\mu}M$), KR-25018($10{\mu}M$), shogaol($10{\mu}M$), ruthenium red and capsazapine were added to perfusion solution to observe the changes in EAA release, and glutamate and aspartate were determined by HPLC. Release of glutamate and aspartate from trigeminal sensory nucleus was increased by noxious stimulation of oral mucosa, but innocuous stimulation did not affect on the release of EAA Capsaicin and KR-25018 increased the release of glutamate and aspartate, and effect of KR-25018 on release of EAA was more potent than capsaicin. But shogaol had a weak effect on release of EAA. Effect of capsaicin and KR-25018 was partially blocked by capsaicin antagonists, ruthenium red and capsazepine.

• 대한약리학회지
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• 제32권2호
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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.

• 수면정신생리
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• 제7권1호
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• pp.10-17
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• 2000

To investigate the neurobiological bases of learning and memory is one of the ambitious goals of modern neuroscience. The progress in this field of recent years has not only brought us closer to understanding the molecular mechanism underlying long-lasting changes in synaptic strength, but it has also provided further evidence that these mechanisms are required for memory formation. Since twenty years ago, several studies for the tests of the hypothesis that NMDA-dependent hippocampal long-term potentiation(LTP) underlies learning have been reported. Also, in the recent year, data from mutant mice showed that a potential role for NMDA-dependent LTP in hippocampal CA1 and spatial learning. Although the current evidence for the role of NMDA receptor in learning and memory is not still obvious, NMDA receptor seems to act as a critical switch for activation of a cascade of events that underlie synaptic plasticity.

• 대한한방내과학회지
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• 제22권3호
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• pp.341-351
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• 2001

Object: Acori graminei rhizoma(AGR) extract is clinically used to treat the cerebral ischemia in Korea. The present study was undertaken to study the neuroprotective effect of AGR extract in middle cerebral artery occlusion(MCAO) rats. Methods: Changes of extracellular levels of glutamate, aspartate, GABA, glycine, taurine, tyrosine, alanine in striatum were collected at 20 minutes interval by in vivo microdialysis and then analyzed by HPLC(high performance liquid chromatography) in rats subjected to permanent focal cerebral ischemia induced by 2 hours of MCAO. AGR extract was orally administrated before MCAO. Different animals were used for measurement of cerebral infarction volume induced by 24 hours of MCAO with TTC staining and image analysis. Result : The infarction volume was decreased and focal cerebral ischemia - induced increase of extracellular glutamate, aspartate, and tyrosine were inhibited after the treatment of AGR extract. On the other hand, the increase of glycine and alanine not but GABA and taurine were enhenced after the treatment of AGR extract. Conclusion: These results suggest that AGR extract can playa role in protecting against cerebral ischemia by regulating extracellular levels of excitatory and inhibitory amino acid neurotransmitters.