Possible protection by notoginsenoside R1 against glutamate neurotoxicity mediated by N-methyl-D-aspartate receptors composed of an NR1/NR2B subunit assembly.
Notoginsenoside R1 (NTR1) is the main active ingredient in Panax notoginseng, a herbal medicine widely used in Asia for years. The purpose of this study was to investigate pharmacological properties of NTR1 on neurotoxicity of glutamate (Glu) in primary cultured mouse cortical neurons along with its possible mechanism of action. We found that NTR1 significantly protected neurons from the loss of cellular viability caused by brief exposure to 10 microM Glu for 1 hr in a dose-dependent manner at concentrations from 0.1 to 10 microM, without affecting the viability alone. NTR1 significantly inhibited the increased number of cells positive to propidium iodide (PI) staining, increase of intracellular free Ca(2+) ions, overproduction of intracellular reactive oxygen species, and depolarization of mitochondrial membrane potential in cultured neurons exposed to Glu, in addition to blocking decreased Bcl-2 and increased Bax expression levels. We further evaluated the target site at which NTR1 protects neurons from Glu toxicity by using the acquired expression strategy of N-methyl-D-aspartate (NMDA) receptor subunits in human embryonic kidney 293 cells. We found that 10 microM NTR1 protected NR1/NR2B subunit expressing cells from cell death by 100 microM NMDA, but not cells expressing NR1/NR2A subunits, when determined by PI staining. These results suggest that NTR1 may preferentially protect neurons from Glu excitotoxicity mediated by NMDA receptor composed of an NR1/NR2B subunit assembly in the brain.
Gu
Bin
B
Division of Pharmaceutical Sciences, Kanazawa University Graduate School of Natural Science and Technology, Kanazawa, Japan.
Nakamichi
Noritaka
N
Zhang
Wen-Sheng
WS
Nakamura
Yukary
Y
Kambe
Yuki
Y
Fukumori
Ryo
R
Takuma
Kazuhiro
K
Yamada
Kiyofumi
K
Takarada
Takeshi
T
Taniura
Hideo
H
Yoneda
Yukio
Y
D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000187:drug effects / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D036145:Ginsenosides / Q000494:pharmacology*; D018698:Glutamic Acid / Q000633:toxicity*; D006801:Humans; D007202:Indicators and Reagents; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000502:physiology; D051379:Mice; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009498:Neurotoxins / Q000037:antagonists & inhibitors* / Q000633:toxicity; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D011419:Propidium; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects* / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; D018690:Excitatory Amino Acid Agonists; D036145:Ginsenosides; D007202:Indicators and Reagents; C409466:NR1 NMDA receptor; C121001:NR2B NMDA receptor; D018696:Neuroprotective Agents; D009498:Neurotoxins; D016194:Receptors, N-Methyl-D-Aspartate; D011419:Propidium; D018698:Glutamic Acid; C072936:notoginsenoside R1