• The Korean Journal of Physiology and Pharmacology
• /
• v.5 no.3
• /
• pp.205-212
• /
• 2001

It has been proposed that nitirc oxide is involved in the pathogenesis of cerebral ischemia-reperfusion. Because superoxide production is also enhanced during reperfusion, the cytotoxic oxidant peroxynitrite could be formed, but it is not known if this occurs following global forebrain ischemia-reperfusion. We examined whether peroxynitrite generation is increased in the vulnerable regions after forebrain ischemia-reperfusion. Transient forebrain ischemia was produced in the conscious rat by four-vessel occlusion. Rats were subjected to 10 or 15 min of forebrain ischemia. Immunohistochemical method was used to detect 3-nitrotyrosine, a marker of peroxynitrite production. 3-Nitrotyrosine immunoreactivity was enhanced in the hippocampal CA1 area 3 days after reperfusion. Furthermore, in rats subjected to ischemia for 15 min, this change was also observed in the lateral striatal region and the lateral septal nucleus $2{\sim}3$ days after reperfusion. The cresyl violet staining of adjacent sections showed that neuronal cell death was induced in parallel with the nitrotyrosine immunoreactivity in the hippocampal CA1 area and the lateral striatal region. Our findings suggest that oxygen free radical accumulation and consequent peroxynitrite production play a role in neuronal death caused by cerebral ischemia-reperfusion.

• BMB Reports
• /
• v.49 no.7
• /
• pp.382-387
• /
• 2016

Reactive oxygen species generated under oxidative stress are involved in neuronal diseases, including ischemia. Glutathione S-transferase pi (GSTpi) is a member of the GST family and is known to play important roles in cell survival. We investigated the effect of GSTpi against oxidative stress-induced hippocampal HT-22 cell death, and its effects in an animal model of ischemic injury, using a cell-permeable PEP-1-GSTpi protein. PEP-1-GSTpi was transduced into HT-22 cells and significantly protected against H2O2-treated cell death by reducing the intracellular toxicity and regulating the signal pathways, including MAPK, Akt, Bax, and Bcl-2. PEP-1-GSTpi transduced into the hippocampus in animal brains, and markedly protected against neuronal cell death in an ischemic injury animal model. These results indicate that PEP-1-GSTpi acts as a regulator or an antioxidant to protect against oxidative stress-induced cell death. Our study suggests that PEP-1-GSTpi may have potential as a therapeutic agent for the treatment of ischemia and a variety of oxidative stress-related neuronal diseases.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.23 no.5
• /
• pp.1019-1024
• /
• 2009

Diabetic neuropathy is characterized by the decrease of cell viability in neuron, which is induced by the hyperglycemia. HT22 cell is the neuron cell line originated from hippocampus. Ginsenosides have been reported to retain anti-diabetic effect. However, the preventive effect of ginsenosides in the condition of diabetic neuropathy was not elucidated. Thus, this study was conducted to examine the protective effect of ginsenoside total saponin (GTS), panoxadiol (PD), and panoxatriol (PT) in the high glucose-induced cell death of HT22 cells, an in vitro cellular model for diabetic neuropathy. In present study, high glucose increased lactate dehydrogenase(LDH) activity, the lipid peroxide(LPO) formation and induced the decrease of cell viability. These effects were completely prevented by the treatment of GTS, but partially prevented by the treatment of PD and PT. High glucose also increased the expression of Bax and cleaved form of caspase-3 but decreased that of Bcl-2. These effects of high glucose on Bax, Bcl-2 and cleaved form of caspase-3 were completely prevented by the treatment of GTS, but partially prevented by the treatment of PD and PT in HT22 cells. In conclusion, ginsenosides prevented high glucose-induced cell death of hippocampal neuron through the inhibition of oxidative stress and apoptosis in HT 22 cells.

• BMB Reports
• /
• v.46 no.8
• /
• pp.383-390
• /
• 2013

Mammalian neural stem cells (NSCs) are of particular interest because of their role in brain development and function. Recent findings suggest the intimate involvement of programmed cell death (PCD) in the turnover of NSCs. However, the underlying mechanisms of PCD are largely unknown. Although apoptosis is the best-defined form of PCD, accumulating evidence has revealed a wide spectrum of PCD encompassing apoptosis, autophagic cell death (ACD) and necrosis. This mini-review aims to illustrate a unique regulation of PCD in NSCs. The results of our recent studies on autophagic death of adult hippocampal neural stem (HCN) cells are also discussed. HCN cell death following insulin withdrawal clearly provides a reliable model that can be used to analyze the molecular mechanisms of ACD in the larger context of PCD. More research efforts are needed to increase our understanding of the molecular basis of NSC turnover under degenerating conditions, such as aging, stress and neurological diseases. Efforts aimed at protecting and harnessing endogenous NSCs will offer novel opportunities for the development of new therapeutic strategies for neuropathologies.

• Korean Journal of Biological Psychiatry
• /
• v.7 no.2
• /
• pp.164-173
• /
• 2000

This study was carried out to investigate the direct neurotoxicity of alcohol on CNS and the effects of piracetam or vitamins on ultrastructural changes of the rat cerebellar and hippocampal neurons during long-term alcohol treatment. To evaluate the results, quantitative analysis were done for light and electronic microscopic findings. On the light microscopy, red degeneration of pyramidal cells and Purkinje cells was found more apparently in the alcohol only treated group than in the control group. On the electron microscopy, increased lipofuscin pigments were found in cerebellum and hippocampus. In quantitative analysis, vitamins significantly reduced red degeneration in both hippocampus and cerebellum. However, piracetam significantly reduced red degeneration in cerebellum but not in hippocampus. Lipofuscin pigments in Purkinje cells and pyramidal cells were significantly reduced in the alcohol with piracetam treated group than the alcohol only treated group. However, vitamins had no significant reducing effect of lipofuscin pigments in Purkinje cells and pyramidal cells. According to the results, it is concluded that vitamins deficiency might cause red degeneration of pyramidal cell after long-term alcohol treatment, but increment of lipofuscin pigments in pyramidal and Purkinje cell may be caused by alcohol itself or its metabolite rather than vitamins deficiency. Piracetam seems to improve cognitive function impairment caused by alcohol consumption.

• The Korean Journal of Physiology and Pharmacology
• /
• v.6 no.3
• /
• pp.143-147
• /
• 2002

Granule cells in dentate gyrus of hippocampus relay information from entorhinal cortex via perforant fiber to pyramidal cells in CA3 region. Their electrical activities are known to be closely associated with seizure activity as well as memory acquisition. Since action potential is a stereotypic phenomena which is based on all-or-none principle of $Na^+$ current, the neuronal firing pattern is mostly dependent on afterpotentials which follows the stereotypic $Na^+$ spike. Granule cells in dentate gyrus show afterdepolarization (ADP), while interneurons in dentate gyrus have afterhyperpolarizaton. In the present study, we investigated the ionic mechanism of afterdepolarization in hippocampal dentate granule cell. Action potential of dentate granule cells showed afterdepolarization, which was characterized by a sharp notch followed by a depolarizing hump starting at about $-49.04{\pm}1.69\;mV\;(n=43,\;mean{\pm}SD)$ and lasting $3{\sim}7$ ms. Increase of extracellular $Ca^{2+}$ from 2 mM to 10 mM significantly enhanced the ADP both in amplitude and in duration. A $K^+$ channel blocker, 4-aminopyridine (4-AP, 2 mM), enhanced the ADP and often induced burst firings. These effects of 10 mM $Ca^{2+}$ and 4-AP were additive. On the contrary, the ADP was significantly suppressed by removal of external $Ca^{2+},$ even in the presence of 4-AP (2 mM). A $Na^+$ channel blocker, TTX (100 nM), did not affect the ADP. From these results, it is concluded that the extracellular $Ca^{2+}$ influx contributes to the generation of ADP in granule cells.

• The Korean Journal of Physiology and Pharmacology
• /
• v.10 no.4
• /
• pp.167-172
• /
• 2006

In the present study, we developed a simple method to predict the neuronal cell death in the mouse hippocampus and striatum following transient global forebrain ischemia by evaluating both cerebral blood flow and the plasticity of the posterior communicating artery (PcomA). Male C57BL/6 mice were anesthetized with halothane and subjected to bilateral occlusion of the common carotid artery (BCCAO) for 30 min. The regional cerebral blood flow (rCBF) was measured by laser Doppler flowmetry. The plasticity of PcomA was visualized by intravascular perfusion of India ink solution. When animals had the residual cortical microperfusion less than 15% as well as the smaller PcomA whose diameter was less than one third compared with that of basilar artery, neuronal damage in the hippocampal subfields including CA1, CA2, and CA4, and in the striatum was consistently observed. Especially, when mice met these two criteria, marked neuronal damage was observed in CA2 subfield of the hippocampus. In contrast, after transient BCCAO, neuronal damage was consistently produced in the striatum, dependent more on the degree of rCBF reduction than on the plasticity of PcomA. The present study provided simple and highly reproducible criteria to induce the neuronal cell death in the vulnerable mice brain areas including the hippocampus and striatum after transient global forebrain ischemia.

• The Korean Journal of Physiology and Pharmacology
• /
• v.1 no.5
• /
• pp.467-475
• /
• 1997

Although one of the major physiological functions of taurine(2-aminoethanesulfonic acid) is the inhibitory action on the central nervous system(CNS), the mechanism of taurine in controlling the neuronal excitation in the CNS has been in controversy. Electrically evoked pEPSP and spontaneous activity induced by the perfusion of low $Mg^{++}-ACSF$ were recorded in the CA1 pyramidal cell layer of the hippocampal slice. To test the inhibitory effect of taurine on spontaneous responses, taurine was treated for 2 min at various concentrations(1 mM-10 mM). Taurine reduced the spontaneous activity by 22.2% at 1 mM, and 100% at 2 mM in low $Mg^{++}-ACSF$. Evoked response was induced by electrical stimulation of Schaffer collateral-commissural fibers. Taurine reduced the evoked response by 11.68% at 3 mM, and 24.25% at 5 mM. Even 20 mM of taurine reduced the evoked response only by 24 % after 5 min treatment. That is, the inhibitory efficacy was much higher in spontaneous activity than in evoked response. The $GABA_A$ receptor antagonist, 100 uM bicuculline, blocked the inhibitory action of taurine, while $GABA_B$ receptor antagonist, 700 uM phaclofen, did not. Taurine blocked the spontaneous activity in the presence of CNQX, and did not block the electrically evoked responce in the presence of APV. The results suggest that taurine causes hyperpolarization in the cell by binding to $GABA_A$ receptor and preferentially attenuates NMDA receptor-mediated hyperexcitation, leaving synaptic transmission unmodified.

• Korean Journal of Pharmacognosy
• /
• v.39 no.3
• /
• pp.213-217
• /
• 2008

Oxidative stress is considered to play an important role in a variety of neurodegenerative disorders of central nervous system. The immortalized mouse hippocampal cell line, HT22, phenotypically resembles neuronal precursor cells but lacks functional ionotropic glutamate receptors, thus excluding excitotoxicity as a cause for glutamate triggered cell death. Therefore, HT22 cells are a useful model for studying oxidative glutamate toxicity. In this study, we examined whether the methanol extracts of some native plants at Mt. Baekdu could protect HT22-immortalized hippocampal cells against glutamate-induced oxidative stress. Seventy-eight plants sources were collected at Mt. Baekdu, and extracted with methanol. These extracts had been screened the protective effects against glutamate-induced oxidative damage in HT22 cells at the 100 and 300 ${\mu}g/ml$. Of these, thirteen methanolic extracts, Acer mono (leaf), Artemisia stolonifera (aerial part), Carduus crispus (aerial part), Carex mongolica (whole plant), Clematis hexapetala (whole plant), Galeopsis bifida (aerial part), Galium verum (whole plant), Ganoderma lucidum (whole plant), Ixeris chinensis (whole plant), Malva verticillata (aerial part), Polygonum senticosum (whole plant), Rebes mandshricum (branch), and Taraxacum mongolicum (aerial part), showed significant protective effects against glutamate-induced oxidative damage in HT22 cells.

• Journal of The Korean Society of Clinical Toxicology
• /
• v.17 no.2
• /
• pp.66-78
• /
• 2019

Purpose: Thallium (TI+) autometallography is often used for the imaging of neuronal metabolic activity in the rodent brain under various pathophysiologic conditions. The purpose of this study was to apply a thallium autometallographic technique to observe changes in neuronal activity in the forebrain of rats following acute carbon monoxide (CO) intoxication. Methods: In order to induce acute CO intoxication, adult Sprague-Dawley rats were exposed to 1100 ppm of CO for 40 minutes, followed by 3000 ppm of CO for 20 minutes. Animals were sacrificed at 30 minutes and 5 days after induction of acute CO intoxication for thallium autometallography. Immunohistochemical staining and toluidine blue staining were performed to observe cellular damage in the forebrain following intoxication. Results: Acute CO intoxication resulted in significant reduction of TI+ uptake in major forebrain structures, including the cortex, hippocampus, thalamus, and striatum. In the cortex and hippocampal CA1 area, marked reduction of TI+ uptake was observed in the cell bodies and dendrites of pyramidal neurons at 30 minutes following acute CO intoxication. There was also strong uptake of TI+ in astrocytes in the hippocampal CA3 area following acute CO intoxication. However, there were no significant histological findings of cell death and no reduction of NeuN (+) neuronal populations in the cortex and hippocampus at 5 days after acute CO intoxication. Conclusion: The results of this study suggest that thallium autometallography can be a new and useful technique for imaging functional changes in neural activity of the forebrain structure following mild to moderate CO intoxication.