• 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.

• Journal of Ginseng Research
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• v.23 no.1 s.53
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• pp.38-43
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• 1999

Ginseng total saponins (ginsenosides) are biologically active main ingredients of Panax ginseng. In present study, we have investigated whether pretreatment of ginsenosides inhibited capsaicin-induced pain at the spinal level, in the view that capsaicin causes substance P (SP) release from primary afferents. Ginsenosides relieved capsaicin-induced pain in a dose-dependent manner. The $ED_{50}$ of the effect was 43 (20-93, $95\%$ C.I.) ${\mu}g/mouse$. We investigated excitatory amino acids-induced nociceptive responses in mice, because these agents are also involved in nociceptive transmission in the spinal cord. Coadministration of ginsenosides with N-methyl-D-aspartate (NMDA) or kainate via i.t. inhibited NMDA- but not kainate-induced pain behaviors. The $ED_{50}$ for the inhibition of NMDA-induced pain by ginsenosides was 37 (21-66, $95\%$ C.I.) ${\mu}g/mouse$. These results suggest that the ginsenosides-induced antinociception results from blocking of pain transmitter-induced nociceptive information at the spinal level.

• BMB Reports
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• v.39 no.3
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• pp.284-291
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• 2006

In this study, the cDNA of a new peptide from the venom of the scorpion, Buthotus saulcyi, was cloned and sequenced. It codes for a 64 residues peptide (Bsaul1) which shares high sequence similarity with depressant insect toxins of scorpions. The differences between them mainly appear in the loop1 which connects the $\beta$-strand1 to the $\alpha$-helix and seems to be functionally important in long chain scorpion neurotoxins. This loop is three amino acids longer in Bsaul1 compared to other depressant toxins. A comparative amino acid sequence analysis done on Bsaul1 and some of $\alpha$-, $\beta$-, excitatory and depressant toxins of scorpions showed that Bsaul1 contains all the residues which are highly conserved among long chain scorpion neurotoxins. Structural model of Bsaul1 was generated using Ts1 (a $\beta$-toxin that competes with the depressant insect toxins for binding to $Na^+$ channels) as template. According to the molecular model of Bsaul1, the folding of the polypeptide chain is being composed of an anti-parallel three-stranded $\beta$-sheet and a stretch of $\alpha$-helix, tightly bound by a set of four disulfide bridges. A striking similarity in the spatial arrangement of some critical residues was shown by superposition of the backbone conformation of Bsaul1 and Ts1.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.1
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• pp.23-26
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• 2009

During operations, neurosurgeons usually perform multiple temporary occlusions of parental artery, possibly resulting in the neuronal damage. It is generally thought that neuronal damage by cerebral ischemia is associated with extracellular concentrations of the excitatory amino acids. In this study, we measured the dynamics of extracellular glutamate release in 11 vessel occlusion(VO) model to compare between single occlusion and repeated transient occlusions within short interval. Changes in cerebral blood flow were monitored by laser-Doppler flowmetry simultaneously with cortical glutamate level measured by amperometric biosensor. From real time monitoring of glutamate release in 11 VO model, the change of extracellular glutamate level in repeated transient occlusion group was smaller than that of single occlusion group, and the onset time of glutamate release in the second ischemic episode of repeated occlusion group was delayed compared to the first ischemic episode which was similar to that of single 10 min ischemic episode. These results suggested that repeated transient occlusion induces less glutamate release from neuronal cell than single occlusion, and the delayed onset time of glutamate release is attributed to endogeneous protective mechanism of ischemic tolerance.

• International Journal of Oral Biology
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• v.32 no.2
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• pp.59-65
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• 2007

It has been well known that excitatory amino acids, primarily glutamate, are involved in the transmission of nociception in pathological and physiological conditions in the spinal and brainstem level. Recently, peripheral glutamate also play a critical role in the peripheral nociceptive transmissions. The present study investigated the role of N-methyl-D-aspartic acid (NMDA) or non-NMDA ionotropic glutamate receptors in formalin-induced TMJ pain. Experiments were carried out on male Sprague-Dawley rats weighing 220-280 g. Intra-articular injection was performed under halothane anesthesia. Under anesthesia, AP-7 (10, $100\;{\mu}M$, $1\;mM/20\;{\mu}L$), a NMDA receptor antagonist, or CNQX disodium salt (0.5, 5, 50, $500\;{\mu}M/20\;{\mu}L$), a non-NMDA receptor antagonist, were administered intra-articularly 10 min prior to the application of 5% formalin. For each animal, the number of behavioral responses, such as rubbing and/or scratching the TMJ region, was recorded for nine successive 5-min intervals. Intra-articular pretreatment with 1 mM of AP-7 or $50\;{\mu}M$ CNQX significantly decreased the formalin-induced scratching behavioral responses during the second phase. Intra-articular pretreatment with $500\;{\mu}M$ of CNQX significantly decreased the formalin-induced scratching behavior during both the first and the second phase. These results indicate that the intra-articular administration of NMDA or non-NMDA receptor antagonists inhibit formalin-induced TMJ nociception, and peripheral ionotropic glutamate receptors may play an important role in the TMJ nociception.

• Journal of Korean Neurosurgical Society
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• v.50 no.5
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• pp.420-425
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• 2011

Objective : Excitatory amino acids play important roles in the development of secondary pathology following spinal cord injury (SCI). This study was designed to evaluate morphological changes in the dorsal horn of the spinal cord and assess profiles of pain behaviors following intraspinal injection of N-methyl-D-aspartate (NMDA) or quisqualate (QUIS) in rats. Methods : Forty male Sprague-Dawley rats were randomized into three groups : a sham, and two experimental groups receiving injections of 125 mM NMDA or QUIS into their spinal dorsal horn. Following injection, hypersensitivity to cold and mechanical stimuli, and excessive grooming behaviors were assessed serially for four weeks. At the end of survival periods, morphological changes in the spinal cord were evaluated. Results : Cold allodynia was developed in both the NMDA and QUIS groups, which was significantly higher in the QUIS group than in the NMDA group. The mechanical threshold for the ipsilateral hind paw in both QUIS and NMDA groups was significantly lower than that in the control group. The number of groomers was significantly higher in the NMDA group than in the QUIS group. The size of the neck region of the spinal dorsal horn, but not the superficial layer, was significantly smaller in the NMDA and QUIS groups than in the control group. Conclusion : Intraspinal injection of NMDA or QUIS can be used as an excitotoxic model of SCI for further research on spinal neuropathic pain.

• Development and Reproduction
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• v.10 no.4
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• pp.215-225
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• 2006

Precocious puberty is defined as the appearance of secondary sex characteristics before age 8 years in girls (or menarche before age 9 years) and before 9 years in boys. The age of onset of puberty is progressing to younger age. The pubertal activation of gonadotrophin releasing hormone(GnRH) release requires coordinated changes in excitatory or inhibitory amino acids, growth factors, and a group of transcriptional regulators. A number of factors affecting precocious puberty were explored, including the role of genetic factors, nutrition(body fat) and exposure to endocrine disrupting chemicals. In addition to the psychosocial disturbances associated with precocious puberty, the premature pubertal growth spurt and the accelerated bone maturation result in reduced adult height. Precocious puberty may be gonadotrophin-dependent premature activation of the GnRH pulse generator or gonadotrophin-independent. In rapidly progressing central precocious puberty, GnRH agonists appear to increase final height. However more data on the effect and long-term safety of GnRHa are needed.

• The Korean Journal of Physiology and Pharmacology
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• v.5 no.1
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• pp.19-25
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• 2001

We have studied the effects of excitatory amino acids on the expression of the c-fos and c-jun mRNA in rat C6 glioma cells. The glutamate, $N-methyl-_D-aspartate$ (NMDA), and kainic acid (KA) increased c-fos mRNA level in a concentration-dependent manner. However, they did not affect c-jun mRNA level. In addition, forskolin and phorbol 12-myristate 13-acetate (PMA) increased c-fos mRNA level. Furthermore, PMA increased c-jun mRNA level whereas forskolin downregulated c-jun mRNA level. The glutamate, NMDA and KA, at a concentration of 0.25 mM, did not affect the basal c-fos and c-jun mRNA levels, and also did not affect forskolin- and PMA-induced responses. Furthermore, both forskolin and PMA itself increased the phosphorylation of ERK (extracellular signal regulated kinase) and CREB (cyclicAMP responsible element binding protein) proteins. The KA, NMDA, and glutamate did not affect forskolin- induced increase of ERK and CREB phosphorylation. The KA decreased PMA-induced increase of phosphorylation of ERK and CREB proteins, whereas glutamate and NMDA did not affect the phosphorylation of ERK and CREB proteins induced by PMA. These findings suggest that, in C6 glioma cells, c-fos mRNA induction induced by EAAs is not mediated by phosphorylation of ERK and CREB proteins.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.19-29
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• 1996

The neurological manifestations of AIDS include dementia, encountered even in the absence of opportunistic superinfection or malignancy. The AIDS Dementia Complex appears to be associated with several neuropathological abnormalities, including astrogliosis and neuronal injury or loss. How can HIV-1 result in neuronal damage if neurons themselves are only rarely, if ever, infected by the vitus\ulcorner In vitro experiments from several different laboratiories have lent support to the existence of HIV- and immune-related toxins. In one recently defined pathway to neuronal injury, HIV-infected macrophages/microglia as well as macrophages activated by HIV-1 envelope protein gp120 appear to secrete excitants/neurotoxins. These substances may include arachidonic acid, platelet-activating factor, free radicals (NO - and O$_2$), glutamate, quinolinate, cysteine, cytokines (TNF-${\alpha}$, IL1-B, IL-6), and as yet unidentified factors emanating from stimulated macrophages and possibly reactive astrocytes. A final common pathway for newonal suscepubility appears to be operative, similar to that observed in stroke, trauma, epilepsy, and several neurodegenerative diseases, including Huntington's disease, Parkinson's disease, and amyotrophic lateral sclerosis. This mechanism involves excessive activation of N-methyl-D-aspartate (NMDA) receptor-operated channels, with resultant excessive influx of Ca$\^$2+/ leading to neuronal damage, and thus offers hope for future pharmacological intervention. This chapter reviews two clinically-tolerated NMDA antagonists, memantine and nitroglycerin; (ⅰ) Memantine is an open-channel blocker of the NMDA-associated ion channel and a close congener of the anti-viral and anti-parkinsonian drug amantadine. Memantine blocks the effects of escalating levels of excitotoxins to a greater degree than lower (piysiological) levels of these excitatory amino acids, thus sparing to some extent normal neuronal function. (ⅱ) Niuoglycerin acts at a redox modulatory site of the NMDA receptor/complex to downregulate its activity. The neuroprotective action of nitroglycerin at this site is mediated by n chemical species related to nitric oxide, but in a higher oxidation state, resulting in transfer of an NO group to a critical cysteine on the NMDA receptor. Because of the clinical safety of these drugs, they have the potential for trials in humans. As the structural basis for redox modulation is further elucidated, it may become possible to design even better redox reactive reagents of chinical value. To this end, redox modulatory sites of NMDA receptors have begun to be characterized at a molecular level using site-directed mutagenesis of recombinant subunits (NMDAR1, NMDAR2A-D). Two types of redox modulation can be distinguished. The first type gives rise to a persistent change in the functional activity of the receptor, and we have identified two cysteine residues on the NMDARI subunit (#744 and #798) that are responsible for this action. A second site, presumably also a cysteine(s) because <1 mM N-ethylmaleimide can block its effect in native neurons, underlies the other, more transient redox action. It appears to be at this, as yet unidentified, site on the NMDA receptor that the NO group acts, at least in recombinant receptors.

• Journal of Veterinary Clinics
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• v.23 no.4
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• pp.393-399
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• 2006

Ketamine, one of general anesthetics for human and veterinary use, is a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist which interferes with the action of excitatory amino acids. It has been reported to impair various leukocyte functions. In this study, the effect of ketamine on the oxidative burst activity (OBA) of canine peripheral blood leukocytes was examined. The OBA of canine peripheral blood phagocytes was analyzed by flow cytometry system. Ketamine at higher concentration such as $1,000{\mu}M$ exhibited a low viability of leukocytes. Thus, ketamine was used at concentration of 10 to $500{\mu}M$ showing no cytotoxic effect and high cell viability. The OBA of leukocytes in the presence or absence of latex beads was analyzed by addition of dihydrorhodamine 123. The direct treatment of ketamine revealed the inhibitory effect on the OBA of peripheral blood polymorphonuclear cells (PMN) and monocyte-rich cells but not peripheral blood mononuclear cells (PBMC) in the presence of latex beads. However, when latex beads were not added to PMN, its OBA was not inhibited by ketamine. The OBA of PMN and monocyte-rich cells but not PBMC in the presence of latex beads was also inhibited by culture supernatant from ketamine-treated- PBMC but not -PMN. But the OBA of PMN in the absence of latex beads was not inhibited by culture supernatant from PBMC treated with ketamine. Therefore, these results suggested that ketamine has the inhibitory effect on the OBA of canine peripheral blood phagocytes such as neutrophils and monocytes during phagocytic response.