title: Neuroprotective effects of 20(S)-protopanaxadiol against glutamate-induced mitochondrial dysfunction in PC12 cells.
abstract: Ginseng (Panax ginseng C.A. Mey.) is commonly used in traditional oriental medicine for its wide spectrum of medicinal properties, including anti-inflammatory, antitumorigenic, adaptogenic and anti-aging properties. 20(S)-Protopanaxadiol (PPD), the main intestinal metabolite of ginsenosides, is one of the active ingredients in ginseng. In this study, we aimed to investigate the neuroprotective effects of PPD on PC12 cells; however, the underlying mechanisms remain elusive. We examined cell viability by MTT assay and the morphological changes of PC12 cells following glutamate‑induced cell damage and evaluated the anti‑apoptotic effects of PPD using Hoechst 33258 staining, western blot analysis and Muse™ Cell Analyzer and the antioxidant effects of PPD using FACS analysis and immunofluorescence. Furthermore, PPD exerted protective effects on PC12 cells via the inhibition of mitochondrial damage against glutamate-induced excitotoxicity using immunofluorescence, electron microscopy and FACS analysis. We demonstrate that treatment with PPD suppresses apoptosis, which contributes to the neuroprotective effects of PPD against glutamate‑induced excitotoxicity in PC12 cells. Treatment with PPD inhibited nuclear condensation and decreased the number of Annexin V-positive cells. In addition, PPD increased antioxidant activity and mitochondrial homeostasis in the glutamate-exposed cells. These antioxidant effects were responsible for the neuroprotection and enhanced mitochondrial function following treatment with PPD. Furthermore, PD inhibited the glutamate-induced morphological changes in the mitochondria and scavenged the mitochondrial and cytosolic reactive oxygen species (ROS) induced by glutamate. In addition, mitochondrial function was significantly improved in terms of mitochondrial membrane potential (MMP) and enhanced mitochondrial mass compared with the cells exposed to glutamate and not treated with PPD. Taken together, the findings of our study indicate that the antioxidant effects and the enhanced mitochondrial function triggered by PPD contribute to the inhibition of apoptosis, thus leading to a neuroprotective response, as a novel survival mechanism.
authors.affiliation: Department of Anatomy, College of Medicine, Konyang University, Daejeon 302-718, Republic of Korea.
authors.forename: Dong-Ho
authors.initials: DH
authors.lastname: Bak
authors.affiliation: Department of Herbal Crop Research, National Institute of Horticultural and Herbal Science (NIHHS), Rural Development Administration (RDA), Eumseong, Chungbuk 369-873, Republic of Korea.
authors.forename: Hyung Don
authors.initials: HD
authors.lastname: Kim
authors.affiliation: Department of Herbal Crop Research, National Institute of Horticultural and Herbal Science (NIHHS), Rural Development Administration (RDA), Eumseong, Chungbuk 369-873, Republic of Korea.
authors.forename: Young Ock
authors.initials: YO
authors.lastname: Kim
authors.affiliation: Department of Herbal Crop Research, National Institute of Horticultural and Herbal Science (NIHHS), Rural Development Administration (RDA), Eumseong, Chungbuk 369-873, Republic of Korea.
authors.forename: Chun Geun
authors.initials: CG
authors.lastname: Park
authors.affiliation: Department of Anatomy, College of Medicine, Konyang University, Daejeon 302-718, Republic of Korea.
authors.forename: Seung-Yun
authors.initials: SY
authors.lastname: Han
authors.affiliation: Department of Anatomy, College of Medicine, Konyang University, Daejeon 302-718, Republic of Korea.
authors.forename: Jwa-Jin
authors.initials: JJ
authors.lastname: Kim
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D018698:Glutamic Acid / Q000633:toxicity; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000473:pathology; D018696:Neuroprotective Agents / Q000008:administration & dosage* / Q000737:chemistry; D016716:PC12 Cells; D005894:Panax / Q000737:chemistry; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D012502:Sapogenins / Q000008:administration & dosage* / Q000737:chemistry
chemical_list: D018696:Neuroprotective Agents; D017382:Reactive Oxygen Species; D012502:Sapogenins; D018698:Glutamic Acid; C062916:protopanaxadiol