• Proceedings of the PSK Conference
• /
• 2002.10a
• /
• pp.304.1-304.1
• /
• 2002

Brain injury resulting from cerebral ischemia remains a major public health problem. Aloesin. main component of aloe possesses various biological activities such as wound healing, anti-gastric ulcer, and chemopreventive activity. In this study we investigated whether treatment with aloes in could protect brain injury induced by permanent focal cerebral ischemia in rats. We also compared aloes in with other neuroprotective. drugs such as MK801 and ebselen. (omitted)

• Neonatal Medicine
• /
• v.17 no.2
• /
• pp.181-192
• /
• 2010

Purpose: Current studies have demonstrated the neuroprotective effects of dizocilpine (MK-801) in many animal models of brain injury, including hypoxic-ischemic (HI) encephlopathy, trauma and excitotoxicity, but limited data are available for those during the neonatal periods. Here we investigated whether dizocilpine can protect the developing rat brain from HI injury via anti-apoptosis. Methods: In an in vitro model, embryonic cortical neuronal cell culture of Sprague-Dawley (SD) rats at 18-day gestation was done. The cultured cells were divided into three groups: normoxia (N), hypoxia (H), and hypoxia treated with dizocilpine (HD). The N group was prepared in 5% $CO_2$ incubators and the other groups were placed in 1% $O_2$ incubators (94% N2, 5% $CO_2$) for 16 hours. In an in vivo model, left carotid artery ligation was done in 7-day-old SD rat pups. The animals were divided into six groups; hypoxia (N), hypoxia (H), hypoxia with sham-operation (HS), hypoxia with operation (HO), HO treated with vehicle (HV), and HO treated with dizocilpine (HD). Hypoxia was made by exposure to a 2 hour period of hypoxic incubator (92% N2, 8% $O_2$). Results: In the in vitvo and in vivo models, the expressions of Bcl-2 in the hypoxia groups were reduced compared to the normoxia group. whereas those in the dizocilpine-treated group were increased compared to the hypoxia group. However. the expressions of Bax and caspase-3 and the ratio of Bax/Bcl-2 were revealed reversely. Conclusion: Dizocilpine has neuroprotective property over perinatal HI brain injury via anti-apoptosis.

• Journal of Periodontal and Implant Science
• /
• v.41 no.1
• /
• pp.17-22
• /
• 2011

Purpose: Nitric oxide (NO) has been known as an important regulator of osteoblasts and periodontal ligament cell activity. This study was performed to investigate the relationship between NO-mediated cell death of human periodontal ligament fibroblasts (PDLFs) and N-methyl-D-aspartic acid (NMDA) receptor antagonist (+)-5-methyl-10, 11-dihydro-5H-dibenzo[a,d]cyclohepten-5, 10-imine hydrogen maleate (MK801). Methods: Human PDLFs were treated with various concentrations (0 to 4 mM) of sodium nitroprusside (SNP) with or without $200\;{\mu}M$ MK801 in culture media for 16 hours and the cell medium was then removed and replaced by fresh medium containing MTS reagent for cell proliferation assay. Western blot analysis was performed to investigate the effects of SNP on the expression of Bax, cytochrome c, and caspase-3 proteins. The differences for each value among the sample groups were compared using analysis of variance with 95% confidence intervals. Results: In the case of SNP treatment, as a NO donor, cell viability was significantly decreased in a concentration-dependent manner. In addition, a synergistic effect was shown when both SNP and NMDA receptor antagonist was added to the medium. SNP treated PDLFs exhibited a round shape in culture conditions and were dramatically reduced in cell number. SNP treatment also increased levels of apoptotic marker protein, such as Bax and cytochrome c, and reduced caspase-3 in PDLFs. Mitogen-activated protein kinase signaling was activated by treatment of SNP and NMDA receptor antagonist. Conclusions: These results suggest that excessive production of NO may induce apoptosis and that NMDA receptor may modulate NO-induced apoptosis in PDLFs.

• The Korean Journal of Pain
• /
• v.13 no.2
• /
• pp.164-174
• /
• 2000

Background: After an injury to tissue such as the skin, hyperalgesia develops. Hyperalgesia is characterized by an increase in the magnitude of pain evoked by noxious stimuli. It has been postulated that in the mechanism of hyperalgesia (especially secondary hyperalgesia) and allodynia, a sensitization of central nervous system such as spinal dorsal horn may contribute to development of hyperalgesia. However, the precise mechanism is still unclear. In the present study, we investigated the roles of N-methyl-D-aspartate (NMDA) receptor and nitric oxide (NO) system in the mechanism of hyperalgesia, and their relations with c-fos expression Methods: Inflammation was induced by injection of complete Freund adjuvant (CFA) into unilateral hindpaw of Sprague-Dawley rat. Behavioral studies measuring paw withdrawal responses by von Frey filaments and paw withdrawal latencies by radiant heat stimuli and stainings of nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase and c-fos immunoreactivity were performed. The effects of MK-801, an NMDA receptor blocker and $N^\omega$-nitro-L-arginine (L-NNA), a nitric oxide synthase (NOS) inhibitor were evaluated. Results: 1) Injection of CFA induced mechanical allodynia, mechanical hyperalgesia and thermal hyperalgesia. And it increased the number of NADPH-diaphorase positive neurons and c-fos expression neurons. 2) MK-801 inhibited mechanical hyperalgesia and thermal hyperalgesia induced by CFA and reduced the number of NADPH-diaphorase positive neurons and c-fos expression neurons. 3) L-NNA inhibited the thermal hyperalgesia and reduced the number of NADPH-diaphorase positive neurons, but did not affect the number of c-fos expression neurons. Conclusions: These results suggest that in the mechanism of mechanical hyperalgesia, NMDA receptor but not NO-system is involved and in the case of thermal hyperalgesia both NMDA receptor and NO system are involved. NO system did not affect the expression of c-fos, but c-fos expression and NOS activity were dependent on the activity of NMDA receptor.

• The Korean Journal of Pain
• /
• v.19 no.1
• /
• pp.33-44
• /
• 2006

Background: Peripheral nerve injury leads to neuropathic pain, including mechanical hyperalgesia (MH). Nerve discharges produced by an injury to the primary afferents cause the release of glutamate from both central and peripheral terminals. While the role of centrally released glutamate in MH has been well studied, relatively little is known about its peripheral role. This study was carried out to determine if the peripherally conducting nerve impulses and peripheral glutamate receptors contribute to the generation of neuropathic pain. Methods: Rats that had previously received a left L5 dorsal rhizotomy were subjected to a spinal nerve lesion (SNL) or brief electrical stimulation (ES, 4 Hz pulses for 5 min) of the left L5 spinal nerve. The paw withdrawal threshold (PWT) to von Frey filaments was measured. The effects of an intraplantar (i.pl.) injection of a glutamate receptor (GluR) antagonist or agonist on the changes in the SNL- or ES-produced PWT was investigated. Results: SNL produced MH, as evidenced by decrease in the PWT, which lasted for more than 42 days. ES also produced MH lasting for 7 days. MK-801 (NMDAR antagonist), DL-AP3 (group-I mGluR antagonist), and APDC (group-II mGluR agonist) delayed the onset of MH when an i.pl. injection was given before SNL. The same application blocked the onset of ES-induced MH. NBQX (AMPA receptor antagonist) had no effect on either the SNL- or ES-induced onset of MH. When drugs were given after SNL or ES, MK-801 reversed the MH, whereas NBQX, DL-AP3, and APDC had no effect. Conclusions: Peripherally conducting impulses play an important role in the generation of neuropathic pain, which is mediated by the peripheral glutamate receptors.

• Archives of Pharmacal Research
• /
• v.24 no.1
• /
• pp.64-68
• /
• 2001

Endothelin-1 (ET-1 ), a novel and potent vasoconstrictor in blood vessel, is known to have some functions in the rat central nervous system (CNS), In order to investigate the central functions of ET-1 , ET-1 was administered to the periaqueductal gray area (PAC) of anesthetized rats to induce barrel rolling and increase the arterial blood pressure (ABP). ET-1 had a modulatory effect on central cardiovascular and behavioral control. The selective N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 (3${u}m/ol/kg$, i.p.) blocked the ET-1 induced responses, and both the nitric oxide synthase (NOS) inhibitor L-NAME (N-nitro-L-arginine mIThyl-ester 1 nmol/rat) and the nitric oxide (NO) scavenger hemoglobin (15 nmol/rat) had similar effects in redtAcing the IT-1 (10 pmol/rat)-induced behavioral changes and ABP elevation. However, NO donor sodium nitroprusside (SNP 10${u}g$, 1${u}g/rat$) decreased the ET-1 induced ABP elevation, and recovered the ET-1 -induced barrel rolling effect that was reduced by MK-801. These results suggest that ET-1 might have neuromodulatory functions such as ABP elevation and barrel rolling induction in the PAG of the rats via the NMDA receptor and NO.

• The Korean Journal of Pharmacology
• /
• v.29 no.1
• /
• pp.9-22
• /
• 1993

To evaluate the protective effects of calcium antagonists, oxygen radical scavengers and excitatory amino acid (EAA) antagonist on the ischemic brain damage, we induced in vitro ischemic condition (namely, lack of oxygen and glucose) to rat hippocampal slices. And the degree of ischemic damage was determined by assaying changes in biochemical parameters such as ATP content and lactate ralease, MDA production in the presence or absence of the various drugs. During experimental ischemia for up to 60 min, ATP content was decreased and the amount of lactate release was markedly increased time-dependently. By changing the reaction medium which contained oxygen and glucose those biochemical parameters were recovered. But the recovery was not complete in this experimental condition. In the same ischemic conditions verapamil and vitamine E prevented the decrease of ATP content and the increase of lactate release from the slices. And verapamil and diltiazem decreased MDA release to the reaction medium. Superoxide dismutase (SOD) and MK-801 (as EAA receptor antagonist) protected the decrease of ATP content and reduced MDA release in 20 min ischemic condition, but glutathione affected ATP content and lactate release at the same condition. When oxygen and glucose were resupplied for 20 min after ischemic condition, verapamil showed the protective effect on the changes of ATP content and lactate release, and vitamine E decreased lactate release (at 20 min ischemia) and MDA release (at 60 min ischemia). These results showed that calcium antagonist and vitamine E protect the ischemic biochemical changes from rat hippocampal slices and calcium antagonist is more potent than vitamine E to protect the ischemical brain damege.

• Journal of Ginseng Research
• /
• v.24 no.4
• /
• pp.196-201
• /
• 2000

Effects of ginsenosides on NaCN-induced neuronal cell death were studied in cultured rat cerebellar granule cells. NaCN produced a concentration-dependent (1-10 mM) reduction of cell viability (measured by frypan blue exclusion test), that was blocked by N-methyl-D-aspartate receptor antagonist (MK-801) and L-type Ca$\^$2+/ channel blocker (verapamil). Pretreatment with ginsenosides (Rb$_1$, Rc, Re, Rf and Rg$_1$) significantly decreased the neuronal cell death in a concentration range of 0.5∼5$\mu\textrm{g}$/ml. Ginsenosides Rb$_1$ and Rc (5 $\mu\textrm{g}$/ml) inhibited glutamate release into medium induced by NaCN (5 mM). NaCN (1 mM)-induced increase of [Ca$\^$2+/], was significantly inhibited by the pretreatment of Rb$_1$ and Rc (5 $\mu\textrm{g}$/ml). Other ginsenosides caused relatively little inhibition on the elevation of glutamate release and of (Ca$\^$2+/). These results suggest that the NaCN-induced neurotoxicity was related to a series of cell responses consisting of glutamate release and [Ca$\^$2+/]i elevation via glutamate (NMDA and kainate) receptors and resultant cell death, and that ginsenosides, especially Rb$_1$ and Rc, prevented the neuronal cell death by the blockade of the NaCN-induced Ca$\^$2+/influx.

• Toxicological Research
• /
• v.18 no.4
• /
• pp.355-362
• /
• 2002

Pathophysiological elevation of intracellular calcium concentration ($[Ca^{2+}]_1$) in the neuron has been considered as an important responsible factor in the neuronal cell damages. However the mechanism of increase of $[Ca^{2+}]_1$ and the relationship between $[Ca^{2+}]_1$ level and cytotocixity have not been fully demonstrated. In the present study, real-time alteration of $[Ca^{2+}]_1$and cellular response (cell damages) in the pheochromocytoma cells (PC12) stimulated by glutamate were investigated. Glutamate dose dependently decreased cell viability determined propidium iodide fluorescence method and morphology change. Conversely related with cell damages, glutamate dose dependently increased the level of［Ca$^{2+}$］$_{i}$ . To investigate the mechanism of glutamate-induced increase of $[Ca^{2+}]_1$,$[Ca^{2+}]_1$, was first measured in the cell cultured in calcium free media and in the presence of dantrolene, an inhibitor of calcium release from ryanodine receptor located in endoplasmic reticulum (ER). Similar to the increase$[Ca^{2+}]_1$ in the calcium-containing media, glutamate dose dependently increased $[Ca^{2+}]_1$ in the cell cultured in free calcium media. However pretreatment (2 hr) with 20~50 $\mu\textrm{M}$ dantrolene substantial lowered glutamate-induced increase of $[Ca^{2+}]_1$, suggesting that release of calcium from ER may be major sourse of increase of $[Ca^{2+}]_1$ in PC12 cells. Dantrolene-induced inhibition of $[Ca^{2+}]_1$ resulted in recovery of cytotoxicity by glutamate. Relevance of N-methy-D-aspartate (NMDA) receptor, a type of glutamte receptor on glutamate-induced incense of $[Ca^{2+}]_1$,$[Ca^{2+}]_1$ was also determined in the cells pretreated (2 hr) with NMDA receptor antagonist MK-80l. Glutamate-induced increase of $[Ca^{2+}]_1$ was reduced by MK-801 dose dependently. Furthermore, glutamate-induced cytotoxicity was also prevented by MK-80l. These results demonstrate that glutamte increase $[Ca^{2+}]_1$ dose dependently and thereby cause cytotoxicity. The increase of $[Ca^{2+}]_1$ may release from ER, especially through ryanodine receptor and/or through NMDA receptor Alteration of calcium homeostasis through disturbance of ER system and/or calcium influx through NMDA receptor could contribute glutamate-induced cell damages.s.

• Archives of Pharmacal Research
• /
• v.22 no.1
• /
• pp.35-43
• /
• 1999

Overstimulation of both kainate (KA) and N-methyl-D-aspartate (NMDA) receptors has been reported to induce excitatoxicity which can be characterized by neuronal damage and formation of reactive oxygen free radicals. Neuroprotective effect of melatonin against KA-induced excitotoxicity have been documented in vitro and in vivo. It is, however, not clear whether melationin is also neuroportective against excitotoxicity mediated by NMDA receptors. In the present work, we tested the in vivo protective effects of striatally infused melatonin against the oxidative stress and neuronal damage induced by the injection of KA and NMDA receptors into the rat striatum. Melatonin implants consisting of 22-gauge stainless-steel cannule with melatonin fused inside the tip were placed bilaterally in the rat brain one week prior to intrastriatal injection of glutamate receptor subtype agonists. Melatonin showed protective effects against the elevation of lipid peroxidation induced by either KA or NMDA and recovered Cu, Zn-superoxide dismutase activities reduced by both KA and NMDA into the control level. Melatonin also clearly blocked both KA- and NMDA-receptor mediated neuronal damage assessed by the determination of choline acetyltransferase activity in striatal monogenages and by microscopic observation of rat brain section stained with cresyl violet. The protective effects of melatonin are comparable to those of DNQX and MK801 which are the KA- and NMDA-receptor antagonist, respectively. It is suggested that melatonin could protect against striatal oxidative damages mediated by glutamate receptors, both non-NMDA and NMDA receptors.