Jeong Seon Yoon - Academia.edu (original) (raw)
Papers by Jeong Seon Yoon
Intra-arterial delivery and efficient engraftment of mesenchymal stem cells in a rat chronic stroke model
IBRO Reports
Uric Acid Enhances Longevity and Endurance, and Protects the Brain Against Ischemia
Neurobiology of Aging
Spatiotemporal Protein Atlas of Cell Death-Related Molecules in the Rat MCAO Stroke Model
Experimental neurobiology, 2018
Ischemic stroke and cerebral infarction triggered by the blockage of blood supply can cause damag... more Ischemic stroke and cerebral infarction triggered by the blockage of blood supply can cause damage to the brain via a complex series of pathological changes. Recently, diverse therapies have emerged as promising candidates for the treatment of stroke. These treatments exert therapeutic effects by acting on diverse target molecules and cells in different time windows from the acute to chronic phases. Here, using immunohistochemistry, we show pathophysiological changes in the brain microenvironment at the hyperacute (within 6 h), acute (1~3 days), subacute (7 days), and chronic (1 month) phases following ischemic injury. Ischemic injury in rats was induced by occluding the middle cerebral artery and was validated by magnetic resonance imaging. The progression of damage to the brain was evaluated by immunohistochemistry for NeuN neurons, GFAP astrocytes, and Iba1 microglia, and by the emergence of the cell death-related molecules such as AIF, FAF1, and activated caspase-3. Our data reg...
Immune network, 2016
Thymic atrophy is a complication that results from exposure to many environmental stressors, dise... more Thymic atrophy is a complication that results from exposure to many environmental stressors, disease treatments, and microbial challenges. Such acute stress-associated thymic loss can have a dramatic impact on the host's ability to replenish the necessary naïve T cell output to reconstitute the peripheral T cell numbers and repertoire to respond to new antigenic challenges. We have previously reported that treatment with the orexigenic hormone ghrelin results in an increase in the number and proliferation of thymocytes after dexamethasone challenge, suggesting a role for ghrelin in restraint stress-induced thymic involution and cell apoptosis and its potential use as a thymostimulatory agent. In an effort to understand how ghrelin suppresses thymic T cell apoptosis, we have examined the various signaling pathways induced by receptor-specific ghrelin stimulation using a restraint stress mouse model. In this model, stress-induced apoptosis in thymocytes was effectively blocked by ...
Limonoids from Dictamnus dasycarpus Protect Against Glutamate-induced Toxicity in Primary Cultured Rat Cortical Cells
Journal of Molecular Neuroscience, Feb 1, 2010
In our previous report, four limonoids, obacunone, limonin, fraxinellone, and calodendrolide, iso... more In our previous report, four limonoids, obacunone, limonin, fraxinellone, and calodendrolide, isolated from Dictamnus dasycarpus showed significant neuroprotective activity against glutamate toxicity in primary cultured rat cortical cells. This study investigated neuroprotective mechanism of these compounds using the same in vitro culture system. These four compounds showed significant neuroprotective activity at the concentration of 0.1 muM. They effectively inhibited calcium influx and overproduction of cellular nitric oxide and reactive oxygen species accompanied by glutamate-induced neurotoxicity. In addition, these compounds significantly preserved mitochondrial membrane potential and activities of antioxidative enzymes. Our results showed that obacunone, limonin, fraxinellone, and calodendrolide significantly protect primary culture cortical cells against glutamate-induced toxicity by preserving the antioxidant defense system. These compounds might offer potential drug development candidate for various neurodegenerative diseases involved with glutamate.
Iridoids fromScrophularia buergeriana attenuate glutamate-induced neurotoxicity in rat cortical cultures
J Neurosci Res, 2003
In previous work, we isolated 7 neuroprotective iridoid glycosides from the 90% MeOH fraction of ... more In previous work, we isolated 7 neuroprotective iridoid glycosides from the 90% MeOH fraction of Scrophularia buergeriana (Scrophulariaceae). We therefore investigated the mode of action of 8-O-E-p-methoxycinnamoyl-harpagide (8-MCA-Harp), the most potent neuroprotective iridoid, and its aglycone, harpagide (Harp) using primary cultures of rat cortical cells in vitro. 8-MCA-Harp only revealed its neuroprotective activity in a pretreatment paradigm; this iridoid had more selectivity in protecting neurons against N-methyl-D-aspartate (NMDA)-induced neurotoxicity as opposed to that induced by kainic acid (KA). On the other hand, Harp exerted significant neuroprotective activity when it was administered either before or after glutamate insult and protected cultured neuronal cells from neurotoxicity induced by NMDA or KA. Furthermore, Harp significantly prevented the decrease of glutathione, an antioxidative compound in the brain, in our cultures. Finally, 8-MCA-Harp and Harp could successfully reduce the overproduction of nitric oxide and the level of cellular peroxide in cultured neurons. Collectively, these results suggested that Harp and 8-MCA-Harp protected primary cultured neurons against glutamate-induced oxidative stress primarily by acting on the antioxidative defense system and on glutamatergic receptors, respectively.
PloS one, 2016
Necroptosis as a molecular program, rather than simply incidental cell death, was established by ... more Necroptosis as a molecular program, rather than simply incidental cell death, was established by elucidating the roles of receptor interacting protein (RIP) kinases 1 and 3, along with their downstream partner, mixed lineage kinase-like domain protein (MLKL). Previous studies suggested that phosphoglycerate mutase family member 5 (PGAM5), a mitochondrial protein that associates with RIP1/RIP3/MLKL complex, promotes necroptosis. We have generated mice deficient in the pgam5 gene and surprisingly found PGAM5-deficiency exacerbated rather than reduced necroptosis in response to multiple in vitro and in vivo necroptotic stimuli, including ischemic reperfusion injury (I/R) in the heart and brain. Electron microscopy, biochemical, and confocal analysis revealed that PGAM5 is indispensable for the process of PINK1 dependent mitophagy which antagonizes necroptosis. The loss of PGAM5/PINK1 mediated mitophagy causes the accumulation of abnormal mitochondria, leading to the overproduction of r...
Cancer Medicine, 2014
Vismodegib, a highly selective inhibitor of hedgehog (Hh) pathway, is an approved treatment for b... more Vismodegib, a highly selective inhibitor of hedgehog (Hh) pathway, is an approved treatment for basal-cell carcinoma. Patients on treatment with vismodegib often report profound alterations in taste sensation. The cellular mechanisms underlying the alterations have not been studied. Sonic Hh (Shh) signaling is required for cell growth and differentiation. In taste buds, Shh is exclusively expressed in type IV taste cells, which are undifferentiated basal cells and the precursors of the three types of taste sensing cells. Thus, we investigated if vismodegib has an inhibitory effect on taste cell turnover because of its known effects on Hh signaling. We gavaged C57BL/6J male mice daily with either vehicle or 30 mg/kg vismodegib for 15 weeks. The gustatory behavior and immunohistochemical profile of taste cells were examined. Vismodegibtreated mice showed decreased growth rate and behavioral responsivity to sweet and bitter stimuli, compared to vehicle-treated mice. We found that vismodegib-treated mice had significant reductions in taste bud size and numbers of taste cells per taste bud. Additionally, vismodegib treatment resulted in decreased numbers of Ki67-and Shh-expressing cells in taste buds. The numbers of phospholipase Cb2-and a-gustducin-expressing cells, which contain biochemical machinery for sweet and bitter sensing, were reduced in vismodegib-treated mice. Furthermore, vismodegib treatment resulted in reduction in numbers of T1R3, glucagon-like peptide-1, and glucagon-expressing cells, which are known to modulate sweet taste sensitivity. These results suggest that inhibition of Shh signaling by vismodegib treatment directly results in alteration of taste due to local effects in taste buds.
Proceedings of the National Academy of Sciences, 2012
Recent findings suggest that neurons can efficiently repair oxidatively damaged DNA, and that bot... more Recent findings suggest that neurons can efficiently repair oxidatively damaged DNA, and that both DNA damage and repair are enhanced by activation of excitatory glutamate receptors. However, in pathological conditions such as ischemic stroke, excessive DNA damage can trigger the death of neurons. Oxidative DNA damage is mainly repaired by base excision repair (BER), a process initiated by DNA glycosylases that recognize and remove damaged DNA bases. Endonuclease VIII-like 1 (NEIL1) is a DNA glycosylase that recognizes a broad range of oxidative lesions. Here, we show that mice lacking NEIL1 exhibit impaired memory retention in a water maze test, but no abnormalities in tests of motor performance, anxiety, or fear conditioning. NEIL1 deficiency results in increased brain damage and a defective functional outcome in a focal ischemia/reperfusion model of stroke. The incision capacity on a 5-hydroxyuracil-containing bubble substrate was lower in the ipsilateral side of ischemic brains and in the mitochondrial lysates of unstressed old NEIL1deficient mice. These results indicate that NEIL1 plays an important role in learning and memory and in protection of neurons against ischemic injury. I ncreased oxidative stress and decreased DNA repair occur during normal brain aging and in disorders in which neurons degenerate, including stroke (1) and Alzheimer's disease (2, 3). Neuronal cells encounter relatively more oxidative DNA damage due to their high metabolic rate, which is necessary for maintaining their electrochemical signaling functions. Reactive oxygen species generated as a byproduct of metabolic activities can create oxidative DNA lesions in addition to damage to other cellular constituents. Unrepaired oxidative DNA lesions can cause detrimental effects to the cell, including dysregulation of gene expression and cell death. The integrity of DNA repair systems is therefore presumed to be an important prerequisite for proper brain function and oxidative stress resistance.
Anti-Acetylcholinesterase and Anti-Amnesic Activities of a Pregnane Glycoside, Cynatroside B, from Cynanchum atratum
Planta Medica, 2005
We previously reported that seven pregnane glycosides including cynatroside B isolated from the r... more We previously reported that seven pregnane glycosides including cynatroside B isolated from the roots of Cynanchum atratum significantly inhibited acetylcholinesterase (AChE) activity. In the present study, we have characterized the mode of AChE inhibition of cynatroside B, the most potent of these isolated pregnane glycoside inhibitors. We have also examined the anti-amnesic activity of cynatroside B. Cynatroside B inhibited AChE activity in a dose-dependent manner and its IC50 value was 3.6 microM. The mode of AChE inhibition by cynatroside B was reversible and non-competitive in nature. Moreover, cynatroside B (1.0 mg/kg body weight i.p.) significantly ameliorated memory impairments induced in mice by scopolamine (1.0 mg/kg body weight s.c.) as measured in the passive avoidance and the Morris water maze tests. We suggest, therefore, that cynatroside B has both anti-AChE and anti-amnesic activities that may ultimately hold significant therapeutic value in alleviating certain memory impairments observed in Alzheimer's disease.
Pediatric Research, 2014
Background: Neonatal asphyxia is one of the leading causes of death in newborn and permanent neur... more Background: Neonatal asphyxia is one of the leading causes of death in newborn and permanent neurological disabilities in surviving children. The underlying hypoxic-ischemic (HI) injury triggers an inflammatory response lading to neuronal damage. Here, we tested the hypothesis that high-dose intravenous immunoglobulin (IVIG) could exert immunomodulatory effect in rat pups subjected to HI injury. Methods: HI injury was induced in 7-d-old pups by ligating the common carotid artery followed by exposure to 8% oxygen for 2 h. Brain infarction was evaluated by imaging stained coronal brain sections. Neurological deficits were assessed in weeks 1 through 4 after HI. Western blotting and immunohistochemistry were used to assess complement fragment deposition in the brain tissue. results: Treatment with IVIG at 2 g/kg significantly and in a dose-responsive manner reduced brain infarction size as well as mortality and neurological deficits caused by HI. Anatomical and functional improvements in IVIG-treated pups correlated with decreased deposition of C3b complement fragments in the injured brain hemisphere. conclusion: IVIG significantly improved the outcome of HI injury in rat pups and could potentially be used for the treatment of human neonatal asphyxia to target proinflammatory complement fragments.
NeuroMolecular Medicine, 2011
Preclinical evaluation of drugs for neurological disorders is usually performed on overfed rodent... more Preclinical evaluation of drugs for neurological disorders is usually performed on overfed rodents, without consideration of how metabolic state might affect drug efficacy. Using a widely employed mouse model of focal ischemic stroke, we found that that the NMDA receptor antagonist dizocilpine (MK-801) reduces brain damage and improves functional outcome in mice on the usual ad libitum diet, but exhibits little or no therapeutic efficacy in mice maintained on an energy-restricted diet. Thus, NMDA receptor activation plays a central role in the mechanism by which a high dietary energy intake exacerbates ischemic brain injury. These findings suggest that inclusion of subjects with a wide range of energy intakes in clinical trials for stroke may mask a drug benefit in the overfed/obese subpopulation of subjects.
Neurobiology of Disease, 2011
Pregabalin, a Ca 2+ channel α 2 δ-subunit antagonist with analgesic and antiepileptic activity, r... more Pregabalin, a Ca 2+ channel α 2 δ-subunit antagonist with analgesic and antiepileptic activity, reduced neuronal loss and improved functional outcome in a mouse model of focal ischemic stroke. Pregabalin administration (5 -10 mg/kg, i.p.) 30-90 min after transient middle cerebral artery occlusion/reperfusion reduced infarct volume, neuronal death in the ischemic penumbra and neurological deficits at 24 h post-stroke. Pregabalin significantly decreased the amount of Ca 2+ / calpain-mediated α-spectrin proteolysis in the cerebral cortex measured at 6 h post-stroke. Together with the extensive clinical experience with pregabalin for other neurological indications, our findings suggest the potential for a therapeutic benefit of pregabalin in stroke patients.
Life Sciences, 2005
We assessed the effects of oral treatments of ESP-102, a standardized combined extract of Angelic... more We assessed the effects of oral treatments of ESP-102, a standardized combined extract of Angelica gigas, Saururus chinensis and Schizandra chinensis, on learning and memory deficit. The cognition-enhancing effect of ESP-102 was investigated in scopolamine-induced (1 mg/kg body weight, s.c.) amnesic mice with both passive avoidance and Morris water maze performance tests. Acute oral treatment (single administration prior to scopolamine treatment) of mice with ESP-102 (doses in the range of 10 to 100 mg/kg body weight) significantly reduced scopolamine-induced memory deficits in the passive avoidance performance test. Another noteworthy result included the fact that prolonged oral daily treatments of mice with much lower amounts of ESP-102 (1 and 10 mg/kg body weight) for ten days reversed scopolamine-induced memory deficits. In the Morris water maze performance test, both acute and prolonged oral treatments with ESP-102 (single administration of 100 mg/kg body weight or prolonged daily administration of 1 and 10 mg/kg body weight for ten days, respectively, significantly ameliorated scopolamine-induced memory deficits as indicated by the formation of long-term and/or short-term spatial memory. In addition, we investigated the effects of ESP-102 on neurotoxicity induced by amyloid-h peptide (Ah 25-35 ) or glutamate in primary cultured cortical neurons of rats. Pretreatment of cultures 0024-3205/$ -see front matter D Life Sciences 76 www.elsevier.com/locate/lifescie with ESP-102 (0.001, 0.01 and 0.1 Ag/ml) significantly protected neurons from neurotoxicity induced by either glutamate or Ah 25-35 . These results suggest that ESP-102 may have some protective characteristics against neuronal cell death and cognitive impairments often observed in Alzheimer's disease, stroke, ischemic injury and other neurodegenerative diseases. D
Iridoids fromScrophularia buergeriana attenuate glutamate-induced neurotoxicity in rat cortical cultures
Journal of Neuroscience Research, 2003
In previous work, we isolated 7 neuroprotective iridoid glycosides from the 90% MeOH fraction of ... more In previous work, we isolated 7 neuroprotective iridoid glycosides from the 90% MeOH fraction of Scrophularia buergeriana (Scrophulariaceae). We therefore investigated the mode of action of 8-O-E-p-methoxycinnamoyl-harpagide (8-MCA-Harp), the most potent neuroprotective iridoid, and its aglycone, harpagide (Harp) using primary cultures of rat cortical cells in vitro. 8-MCA-Harp only revealed its neuroprotective activity in a pretreatment paradigm; this iridoid had more selectivity in protecting neurons against N-methyl-D-aspartate (NMDA)-induced neurotoxicity as opposed to that induced by kainic acid (KA). On the other hand, Harp exerted significant neuroprotective activity when it was administered either before or after glutamate insult and protected cultured neuronal cells from neurotoxicity induced by NMDA or KA. Furthermore, Harp significantly prevented the decrease of glutathione, an antioxidative compound in the brain, in our cultures. Finally, 8-MCA-Harp and Harp could successfully reduce the overproduction of nitric oxide and the level of cellular peroxide in cultured neurons. Collectively, these results suggested that Harp and 8-MCA-Harp protected primary cultured neurons against glutamate-induced oxidative stress primarily by acting on the antioxidative defense system and on glutamatergic receptors, respectively.
3,6′-DITHIOTHALIDOMIDE Improves Experimental Stroke Outcome by Suppressing Neuroinflammation
Journal of Neuroscience Research, 2013
Tumor necrosis factor-α (TNF) plays a prominent role in the brain damage and functional deficits ... more Tumor necrosis factor-α (TNF) plays a prominent role in the brain damage and functional deficits that result from ischemic stroke. It was recently reported that the thalidomide analog 3,6'-dithiothalidomide (3,6'-DT) can selectively inhibit the synthesis of TNF in cultured cells. We therefore tested the therapeutic potential of 3,6'-DT in a mouse model of focal ischemic stroke. Administration of 3,6'-DT immediately prior to a stroke or within 3 hr after the stroke reduced infarct volume, neuronal death, and neurological deficits, whereas thalidomide was effective only when administered prior to stroke. Neuroprotection was accompanied by decreased inflammation; 3,6'-DT-treated mice exhibited reduced expression of TNF, interleukin-1β, and inducible nitric oxide synthase; reduced numbers of activated microglia/macrophages, astrocytes, and neutrophils; and reduced expression of intercellular adhesion molecule-1 in the ischemic brain tissue. 3,6'-DT treatment attenuated stroke-induced disruption of the blood-brain barrier by a mechanism that appears to involve suppression of matrix metalloproteinase-9 and preservation of occludin. Treatment with 3,6'-DT did not reduce ischemic brain damage in mice lacking TNF receptors, consistent with a critical role for suppression of TNF production and TNF signaling in the therapeutic action of 3,6'-DT. These findings suggest that anti-inflammatory mechanisms underlie the therapeutic actions of 3,6-DT in an animal model of stroke.
Journal of Natural Products, 2006
Bioactivity-guided fractionation of the methanolic extract of the rhizomes of Imperata cylindrica... more Bioactivity-guided fractionation of the methanolic extract of the rhizomes of Imperata cylindrica afforded a new compound, 5-hydroxy-2-(2-phenylethyl)chromone (1), together with three known compounds, 5-hydroxy-2-[2-(2hydroxyphenyl)ethyl]chromone (2), flidersiachromone (3), and 5-hydroxy-2-styrylchromone (4). Among these four compounds, 1 and 2 showed significant neuroprotective activity against glutamate-induced neurotoxicity in primary cultures of rat cortical cells.
Journal of Natural Products, 2008
Limonoids from Dictamnus dasycarpus Protect Against Glutamate-induced Toxicity in Primary Cultured Rat Cortical Cells
Journal of Molecular Neuroscience, 2010
In our previous report, four limonoids, obacunone, limonin, fraxinellone, and calodendrolide, iso... more In our previous report, four limonoids, obacunone, limonin, fraxinellone, and calodendrolide, isolated from Dictamnus dasycarpus showed significant neuroprotective activity against glutamate toxicity in primary cultured rat cortical cells. This study investigated neuroprotective mechanism of these compounds using the same in vitro culture system. These four compounds showed significant neuroprotective activity at the concentration of 0.1 muM. They effectively inhibited calcium influx and overproduction of cellular nitric oxide and reactive oxygen species accompanied by glutamate-induced neurotoxicity. In addition, these compounds significantly preserved mitochondrial membrane potential and activities of antioxidative enzymes. Our results showed that obacunone, limonin, fraxinellone, and calodendrolide significantly protect primary culture cortical cells against glutamate-induced toxicity by preserving the antioxidant defense system. These compounds might offer potential drug development candidate for various neurodegenerative diseases involved with glutamate.
Journal of Enzyme Inhibition and Medicinal Chemistry, 2012
The methanolic extract of Dictamnus dasycarpus root barks afforded one new glycosidic quinoline a... more The methanolic extract of Dictamnus dasycarpus root barks afforded one new glycosidic quinoline alkaloid, 3-[1βhydroxy-2-(β-D-glucopyranosyloxy)-ethyl)-4-methoxy-2(1H)-quinolinone (1), together with nine known compounds, preskimmianine (2), 8-methoxy-N-methylflindersine (3), dictamine (4), γ-fagarine (5), halopine (6), skimmianine , dictangustine-A (8), iso-γ-fagarine (9), isomaculosidine (10). The isolated alkaloids significantly inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated BV2 cells. Among them, compounds 3 and 7 showed the most potent inhibitory activities on LPS-induced NO production.
Intra-arterial delivery and efficient engraftment of mesenchymal stem cells in a rat chronic stroke model
IBRO Reports
Uric Acid Enhances Longevity and Endurance, and Protects the Brain Against Ischemia
Neurobiology of Aging
Spatiotemporal Protein Atlas of Cell Death-Related Molecules in the Rat MCAO Stroke Model
Experimental neurobiology, 2018
Ischemic stroke and cerebral infarction triggered by the blockage of blood supply can cause damag... more Ischemic stroke and cerebral infarction triggered by the blockage of blood supply can cause damage to the brain via a complex series of pathological changes. Recently, diverse therapies have emerged as promising candidates for the treatment of stroke. These treatments exert therapeutic effects by acting on diverse target molecules and cells in different time windows from the acute to chronic phases. Here, using immunohistochemistry, we show pathophysiological changes in the brain microenvironment at the hyperacute (within 6 h), acute (1~3 days), subacute (7 days), and chronic (1 month) phases following ischemic injury. Ischemic injury in rats was induced by occluding the middle cerebral artery and was validated by magnetic resonance imaging. The progression of damage to the brain was evaluated by immunohistochemistry for NeuN neurons, GFAP astrocytes, and Iba1 microglia, and by the emergence of the cell death-related molecules such as AIF, FAF1, and activated caspase-3. Our data reg...
Immune network, 2016
Thymic atrophy is a complication that results from exposure to many environmental stressors, dise... more Thymic atrophy is a complication that results from exposure to many environmental stressors, disease treatments, and microbial challenges. Such acute stress-associated thymic loss can have a dramatic impact on the host's ability to replenish the necessary naïve T cell output to reconstitute the peripheral T cell numbers and repertoire to respond to new antigenic challenges. We have previously reported that treatment with the orexigenic hormone ghrelin results in an increase in the number and proliferation of thymocytes after dexamethasone challenge, suggesting a role for ghrelin in restraint stress-induced thymic involution and cell apoptosis and its potential use as a thymostimulatory agent. In an effort to understand how ghrelin suppresses thymic T cell apoptosis, we have examined the various signaling pathways induced by receptor-specific ghrelin stimulation using a restraint stress mouse model. In this model, stress-induced apoptosis in thymocytes was effectively blocked by ...
Limonoids from Dictamnus dasycarpus Protect Against Glutamate-induced Toxicity in Primary Cultured Rat Cortical Cells
Journal of Molecular Neuroscience, Feb 1, 2010
In our previous report, four limonoids, obacunone, limonin, fraxinellone, and calodendrolide, iso... more In our previous report, four limonoids, obacunone, limonin, fraxinellone, and calodendrolide, isolated from Dictamnus dasycarpus showed significant neuroprotective activity against glutamate toxicity in primary cultured rat cortical cells. This study investigated neuroprotective mechanism of these compounds using the same in vitro culture system. These four compounds showed significant neuroprotective activity at the concentration of 0.1 muM. They effectively inhibited calcium influx and overproduction of cellular nitric oxide and reactive oxygen species accompanied by glutamate-induced neurotoxicity. In addition, these compounds significantly preserved mitochondrial membrane potential and activities of antioxidative enzymes. Our results showed that obacunone, limonin, fraxinellone, and calodendrolide significantly protect primary culture cortical cells against glutamate-induced toxicity by preserving the antioxidant defense system. These compounds might offer potential drug development candidate for various neurodegenerative diseases involved with glutamate.
Iridoids fromScrophularia buergeriana attenuate glutamate-induced neurotoxicity in rat cortical cultures
J Neurosci Res, 2003
In previous work, we isolated 7 neuroprotective iridoid glycosides from the 90% MeOH fraction of ... more In previous work, we isolated 7 neuroprotective iridoid glycosides from the 90% MeOH fraction of Scrophularia buergeriana (Scrophulariaceae). We therefore investigated the mode of action of 8-O-E-p-methoxycinnamoyl-harpagide (8-MCA-Harp), the most potent neuroprotective iridoid, and its aglycone, harpagide (Harp) using primary cultures of rat cortical cells in vitro. 8-MCA-Harp only revealed its neuroprotective activity in a pretreatment paradigm; this iridoid had more selectivity in protecting neurons against N-methyl-D-aspartate (NMDA)-induced neurotoxicity as opposed to that induced by kainic acid (KA). On the other hand, Harp exerted significant neuroprotective activity when it was administered either before or after glutamate insult and protected cultured neuronal cells from neurotoxicity induced by NMDA or KA. Furthermore, Harp significantly prevented the decrease of glutathione, an antioxidative compound in the brain, in our cultures. Finally, 8-MCA-Harp and Harp could successfully reduce the overproduction of nitric oxide and the level of cellular peroxide in cultured neurons. Collectively, these results suggested that Harp and 8-MCA-Harp protected primary cultured neurons against glutamate-induced oxidative stress primarily by acting on the antioxidative defense system and on glutamatergic receptors, respectively.
PloS one, 2016
Necroptosis as a molecular program, rather than simply incidental cell death, was established by ... more Necroptosis as a molecular program, rather than simply incidental cell death, was established by elucidating the roles of receptor interacting protein (RIP) kinases 1 and 3, along with their downstream partner, mixed lineage kinase-like domain protein (MLKL). Previous studies suggested that phosphoglycerate mutase family member 5 (PGAM5), a mitochondrial protein that associates with RIP1/RIP3/MLKL complex, promotes necroptosis. We have generated mice deficient in the pgam5 gene and surprisingly found PGAM5-deficiency exacerbated rather than reduced necroptosis in response to multiple in vitro and in vivo necroptotic stimuli, including ischemic reperfusion injury (I/R) in the heart and brain. Electron microscopy, biochemical, and confocal analysis revealed that PGAM5 is indispensable for the process of PINK1 dependent mitophagy which antagonizes necroptosis. The loss of PGAM5/PINK1 mediated mitophagy causes the accumulation of abnormal mitochondria, leading to the overproduction of r...
Cancer Medicine, 2014
Vismodegib, a highly selective inhibitor of hedgehog (Hh) pathway, is an approved treatment for b... more Vismodegib, a highly selective inhibitor of hedgehog (Hh) pathway, is an approved treatment for basal-cell carcinoma. Patients on treatment with vismodegib often report profound alterations in taste sensation. The cellular mechanisms underlying the alterations have not been studied. Sonic Hh (Shh) signaling is required for cell growth and differentiation. In taste buds, Shh is exclusively expressed in type IV taste cells, which are undifferentiated basal cells and the precursors of the three types of taste sensing cells. Thus, we investigated if vismodegib has an inhibitory effect on taste cell turnover because of its known effects on Hh signaling. We gavaged C57BL/6J male mice daily with either vehicle or 30 mg/kg vismodegib for 15 weeks. The gustatory behavior and immunohistochemical profile of taste cells were examined. Vismodegibtreated mice showed decreased growth rate and behavioral responsivity to sweet and bitter stimuli, compared to vehicle-treated mice. We found that vismodegib-treated mice had significant reductions in taste bud size and numbers of taste cells per taste bud. Additionally, vismodegib treatment resulted in decreased numbers of Ki67-and Shh-expressing cells in taste buds. The numbers of phospholipase Cb2-and a-gustducin-expressing cells, which contain biochemical machinery for sweet and bitter sensing, were reduced in vismodegib-treated mice. Furthermore, vismodegib treatment resulted in reduction in numbers of T1R3, glucagon-like peptide-1, and glucagon-expressing cells, which are known to modulate sweet taste sensitivity. These results suggest that inhibition of Shh signaling by vismodegib treatment directly results in alteration of taste due to local effects in taste buds.
Proceedings of the National Academy of Sciences, 2012
Recent findings suggest that neurons can efficiently repair oxidatively damaged DNA, and that bot... more Recent findings suggest that neurons can efficiently repair oxidatively damaged DNA, and that both DNA damage and repair are enhanced by activation of excitatory glutamate receptors. However, in pathological conditions such as ischemic stroke, excessive DNA damage can trigger the death of neurons. Oxidative DNA damage is mainly repaired by base excision repair (BER), a process initiated by DNA glycosylases that recognize and remove damaged DNA bases. Endonuclease VIII-like 1 (NEIL1) is a DNA glycosylase that recognizes a broad range of oxidative lesions. Here, we show that mice lacking NEIL1 exhibit impaired memory retention in a water maze test, but no abnormalities in tests of motor performance, anxiety, or fear conditioning. NEIL1 deficiency results in increased brain damage and a defective functional outcome in a focal ischemia/reperfusion model of stroke. The incision capacity on a 5-hydroxyuracil-containing bubble substrate was lower in the ipsilateral side of ischemic brains and in the mitochondrial lysates of unstressed old NEIL1deficient mice. These results indicate that NEIL1 plays an important role in learning and memory and in protection of neurons against ischemic injury. I ncreased oxidative stress and decreased DNA repair occur during normal brain aging and in disorders in which neurons degenerate, including stroke (1) and Alzheimer's disease (2, 3). Neuronal cells encounter relatively more oxidative DNA damage due to their high metabolic rate, which is necessary for maintaining their electrochemical signaling functions. Reactive oxygen species generated as a byproduct of metabolic activities can create oxidative DNA lesions in addition to damage to other cellular constituents. Unrepaired oxidative DNA lesions can cause detrimental effects to the cell, including dysregulation of gene expression and cell death. The integrity of DNA repair systems is therefore presumed to be an important prerequisite for proper brain function and oxidative stress resistance.
Anti-Acetylcholinesterase and Anti-Amnesic Activities of a Pregnane Glycoside, Cynatroside B, from Cynanchum atratum
Planta Medica, 2005
We previously reported that seven pregnane glycosides including cynatroside B isolated from the r... more We previously reported that seven pregnane glycosides including cynatroside B isolated from the roots of Cynanchum atratum significantly inhibited acetylcholinesterase (AChE) activity. In the present study, we have characterized the mode of AChE inhibition of cynatroside B, the most potent of these isolated pregnane glycoside inhibitors. We have also examined the anti-amnesic activity of cynatroside B. Cynatroside B inhibited AChE activity in a dose-dependent manner and its IC50 value was 3.6 microM. The mode of AChE inhibition by cynatroside B was reversible and non-competitive in nature. Moreover, cynatroside B (1.0 mg/kg body weight i.p.) significantly ameliorated memory impairments induced in mice by scopolamine (1.0 mg/kg body weight s.c.) as measured in the passive avoidance and the Morris water maze tests. We suggest, therefore, that cynatroside B has both anti-AChE and anti-amnesic activities that may ultimately hold significant therapeutic value in alleviating certain memory impairments observed in Alzheimer's disease.
Pediatric Research, 2014
Background: Neonatal asphyxia is one of the leading causes of death in newborn and permanent neur... more Background: Neonatal asphyxia is one of the leading causes of death in newborn and permanent neurological disabilities in surviving children. The underlying hypoxic-ischemic (HI) injury triggers an inflammatory response lading to neuronal damage. Here, we tested the hypothesis that high-dose intravenous immunoglobulin (IVIG) could exert immunomodulatory effect in rat pups subjected to HI injury. Methods: HI injury was induced in 7-d-old pups by ligating the common carotid artery followed by exposure to 8% oxygen for 2 h. Brain infarction was evaluated by imaging stained coronal brain sections. Neurological deficits were assessed in weeks 1 through 4 after HI. Western blotting and immunohistochemistry were used to assess complement fragment deposition in the brain tissue. results: Treatment with IVIG at 2 g/kg significantly and in a dose-responsive manner reduced brain infarction size as well as mortality and neurological deficits caused by HI. Anatomical and functional improvements in IVIG-treated pups correlated with decreased deposition of C3b complement fragments in the injured brain hemisphere. conclusion: IVIG significantly improved the outcome of HI injury in rat pups and could potentially be used for the treatment of human neonatal asphyxia to target proinflammatory complement fragments.
NeuroMolecular Medicine, 2011
Preclinical evaluation of drugs for neurological disorders is usually performed on overfed rodent... more Preclinical evaluation of drugs for neurological disorders is usually performed on overfed rodents, without consideration of how metabolic state might affect drug efficacy. Using a widely employed mouse model of focal ischemic stroke, we found that that the NMDA receptor antagonist dizocilpine (MK-801) reduces brain damage and improves functional outcome in mice on the usual ad libitum diet, but exhibits little or no therapeutic efficacy in mice maintained on an energy-restricted diet. Thus, NMDA receptor activation plays a central role in the mechanism by which a high dietary energy intake exacerbates ischemic brain injury. These findings suggest that inclusion of subjects with a wide range of energy intakes in clinical trials for stroke may mask a drug benefit in the overfed/obese subpopulation of subjects.
Neurobiology of Disease, 2011
Pregabalin, a Ca 2+ channel α 2 δ-subunit antagonist with analgesic and antiepileptic activity, r... more Pregabalin, a Ca 2+ channel α 2 δ-subunit antagonist with analgesic and antiepileptic activity, reduced neuronal loss and improved functional outcome in a mouse model of focal ischemic stroke. Pregabalin administration (5 -10 mg/kg, i.p.) 30-90 min after transient middle cerebral artery occlusion/reperfusion reduced infarct volume, neuronal death in the ischemic penumbra and neurological deficits at 24 h post-stroke. Pregabalin significantly decreased the amount of Ca 2+ / calpain-mediated α-spectrin proteolysis in the cerebral cortex measured at 6 h post-stroke. Together with the extensive clinical experience with pregabalin for other neurological indications, our findings suggest the potential for a therapeutic benefit of pregabalin in stroke patients.
Life Sciences, 2005
We assessed the effects of oral treatments of ESP-102, a standardized combined extract of Angelic... more We assessed the effects of oral treatments of ESP-102, a standardized combined extract of Angelica gigas, Saururus chinensis and Schizandra chinensis, on learning and memory deficit. The cognition-enhancing effect of ESP-102 was investigated in scopolamine-induced (1 mg/kg body weight, s.c.) amnesic mice with both passive avoidance and Morris water maze performance tests. Acute oral treatment (single administration prior to scopolamine treatment) of mice with ESP-102 (doses in the range of 10 to 100 mg/kg body weight) significantly reduced scopolamine-induced memory deficits in the passive avoidance performance test. Another noteworthy result included the fact that prolonged oral daily treatments of mice with much lower amounts of ESP-102 (1 and 10 mg/kg body weight) for ten days reversed scopolamine-induced memory deficits. In the Morris water maze performance test, both acute and prolonged oral treatments with ESP-102 (single administration of 100 mg/kg body weight or prolonged daily administration of 1 and 10 mg/kg body weight for ten days, respectively, significantly ameliorated scopolamine-induced memory deficits as indicated by the formation of long-term and/or short-term spatial memory. In addition, we investigated the effects of ESP-102 on neurotoxicity induced by amyloid-h peptide (Ah 25-35 ) or glutamate in primary cultured cortical neurons of rats. Pretreatment of cultures 0024-3205/$ -see front matter D Life Sciences 76 www.elsevier.com/locate/lifescie with ESP-102 (0.001, 0.01 and 0.1 Ag/ml) significantly protected neurons from neurotoxicity induced by either glutamate or Ah 25-35 . These results suggest that ESP-102 may have some protective characteristics against neuronal cell death and cognitive impairments often observed in Alzheimer's disease, stroke, ischemic injury and other neurodegenerative diseases. D
Iridoids fromScrophularia buergeriana attenuate glutamate-induced neurotoxicity in rat cortical cultures
Journal of Neuroscience Research, 2003
In previous work, we isolated 7 neuroprotective iridoid glycosides from the 90% MeOH fraction of ... more In previous work, we isolated 7 neuroprotective iridoid glycosides from the 90% MeOH fraction of Scrophularia buergeriana (Scrophulariaceae). We therefore investigated the mode of action of 8-O-E-p-methoxycinnamoyl-harpagide (8-MCA-Harp), the most potent neuroprotective iridoid, and its aglycone, harpagide (Harp) using primary cultures of rat cortical cells in vitro. 8-MCA-Harp only revealed its neuroprotective activity in a pretreatment paradigm; this iridoid had more selectivity in protecting neurons against N-methyl-D-aspartate (NMDA)-induced neurotoxicity as opposed to that induced by kainic acid (KA). On the other hand, Harp exerted significant neuroprotective activity when it was administered either before or after glutamate insult and protected cultured neuronal cells from neurotoxicity induced by NMDA or KA. Furthermore, Harp significantly prevented the decrease of glutathione, an antioxidative compound in the brain, in our cultures. Finally, 8-MCA-Harp and Harp could successfully reduce the overproduction of nitric oxide and the level of cellular peroxide in cultured neurons. Collectively, these results suggested that Harp and 8-MCA-Harp protected primary cultured neurons against glutamate-induced oxidative stress primarily by acting on the antioxidative defense system and on glutamatergic receptors, respectively.
3,6′-DITHIOTHALIDOMIDE Improves Experimental Stroke Outcome by Suppressing Neuroinflammation
Journal of Neuroscience Research, 2013
Tumor necrosis factor-α (TNF) plays a prominent role in the brain damage and functional deficits ... more Tumor necrosis factor-α (TNF) plays a prominent role in the brain damage and functional deficits that result from ischemic stroke. It was recently reported that the thalidomide analog 3,6'-dithiothalidomide (3,6'-DT) can selectively inhibit the synthesis of TNF in cultured cells. We therefore tested the therapeutic potential of 3,6'-DT in a mouse model of focal ischemic stroke. Administration of 3,6'-DT immediately prior to a stroke or within 3 hr after the stroke reduced infarct volume, neuronal death, and neurological deficits, whereas thalidomide was effective only when administered prior to stroke. Neuroprotection was accompanied by decreased inflammation; 3,6'-DT-treated mice exhibited reduced expression of TNF, interleukin-1β, and inducible nitric oxide synthase; reduced numbers of activated microglia/macrophages, astrocytes, and neutrophils; and reduced expression of intercellular adhesion molecule-1 in the ischemic brain tissue. 3,6'-DT treatment attenuated stroke-induced disruption of the blood-brain barrier by a mechanism that appears to involve suppression of matrix metalloproteinase-9 and preservation of occludin. Treatment with 3,6'-DT did not reduce ischemic brain damage in mice lacking TNF receptors, consistent with a critical role for suppression of TNF production and TNF signaling in the therapeutic action of 3,6'-DT. These findings suggest that anti-inflammatory mechanisms underlie the therapeutic actions of 3,6-DT in an animal model of stroke.
Journal of Natural Products, 2006
Bioactivity-guided fractionation of the methanolic extract of the rhizomes of Imperata cylindrica... more Bioactivity-guided fractionation of the methanolic extract of the rhizomes of Imperata cylindrica afforded a new compound, 5-hydroxy-2-(2-phenylethyl)chromone (1), together with three known compounds, 5-hydroxy-2-[2-(2hydroxyphenyl)ethyl]chromone (2), flidersiachromone (3), and 5-hydroxy-2-styrylchromone (4). Among these four compounds, 1 and 2 showed significant neuroprotective activity against glutamate-induced neurotoxicity in primary cultures of rat cortical cells.
Journal of Natural Products, 2008
Limonoids from Dictamnus dasycarpus Protect Against Glutamate-induced Toxicity in Primary Cultured Rat Cortical Cells
Journal of Molecular Neuroscience, 2010
In our previous report, four limonoids, obacunone, limonin, fraxinellone, and calodendrolide, iso... more In our previous report, four limonoids, obacunone, limonin, fraxinellone, and calodendrolide, isolated from Dictamnus dasycarpus showed significant neuroprotective activity against glutamate toxicity in primary cultured rat cortical cells. This study investigated neuroprotective mechanism of these compounds using the same in vitro culture system. These four compounds showed significant neuroprotective activity at the concentration of 0.1 muM. They effectively inhibited calcium influx and overproduction of cellular nitric oxide and reactive oxygen species accompanied by glutamate-induced neurotoxicity. In addition, these compounds significantly preserved mitochondrial membrane potential and activities of antioxidative enzymes. Our results showed that obacunone, limonin, fraxinellone, and calodendrolide significantly protect primary culture cortical cells against glutamate-induced toxicity by preserving the antioxidant defense system. These compounds might offer potential drug development candidate for various neurodegenerative diseases involved with glutamate.
Journal of Enzyme Inhibition and Medicinal Chemistry, 2012
The methanolic extract of Dictamnus dasycarpus root barks afforded one new glycosidic quinoline a... more The methanolic extract of Dictamnus dasycarpus root barks afforded one new glycosidic quinoline alkaloid, 3-[1βhydroxy-2-(β-D-glucopyranosyloxy)-ethyl)-4-methoxy-2(1H)-quinolinone (1), together with nine known compounds, preskimmianine (2), 8-methoxy-N-methylflindersine (3), dictamine (4), γ-fagarine (5), halopine (6), skimmianine , dictangustine-A (8), iso-γ-fagarine (9), isomaculosidine (10). The isolated alkaloids significantly inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated BV2 cells. Among them, compounds 3 and 7 showed the most potent inhibitory activities on LPS-induced NO production.