title: The neuritogenic and neuroprotective potential of senegenin against Aβ-induced neurotoxicity in PC 12 cells.
abstract: BACKGROUND
  Improved therapeutics aimed at ameliorating the devastating effects of neurodegenerative diseases, such as Alzheimer's disease (AD), are pertinent to help attenuate their growing prevalence worldwide. One promising avenue for such therapeutics lies in botanical medicines that have been efficaciously employed in the likes of traditional medicine doctrines for millennium. Integral to this approach is the necessity of neuritogenesis and/or neuroprotection to counterbalance the deleterious effects of amyloid-β (Aβ) proteins. Senegenin, a principle saponin of Polygala tenuifolia Willd., which has empirically shown to improve cognition and intelligence, was chosen to evaluate its cytoprotective potential and possible neuritogenic and neuroprotective effects.
  
  
  METHODS
  The purpose of the present study was then to analyze morphological changes in neurite development and altered protein expression of two proteins requisite to neuritogenesis, growth associated protein 43 (Gap-43) and microtubule-associated protein 2 (MAP2) in PC 12 cells. Neuritogenic analysis was conducted with immunofluorescence after incubation with Aβ (25-35) peptide, and to deduce information on cell viability and mitochondrial functionality MTT (3,(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide) was employed.
  
  
  RESULTS
  This study found that cells pre-incubated with senegenin for 24 h (40 μg and 20 μg/ml) before introducing Aβ attenuated Aβ-cytotoxicity, and significantly increased cell viability by 23 % and 34 % (P < 0.001), respectively. In neurite outgrowth experiments, Aβ was compared to NGF positive control and senegenin treated groups which showed a drastic decrease in the quantity, average length and maximum length of neurites (P < 0.001). At concentrations of 1 μg/ml (P < 0.01) and 5 μg/ml (P < 0.05) senegenin triggered neuritogenesis with significant increases in total neurite number, average length and maximum length. This was additionally shown through the augmented expression of MAP2 and Gap-43.
  
  
  CONCLUSIONS
  These results suggest that senegenin possesses cytoprotective properties, can moderate neurite outgrowth and augment MAP2 and Gap-43, thus suggesting a potential therapeutic value for Polygala tenuifolia in neurodegenerative disorders.
authors.affiliation: Department of General Surgery-Integrated traditional Chinese and Western medicine, 1st Affiliated Hospital of Dalian Medical University, No. 222, Zhongshan Road, Xigang District, Dalian, 116011, China.
authors.forename: Robert
authors.initials: R
authors.lastname: Jesky
authors.affiliation: Department of General Surgery-Integrated traditional Chinese and Western medicine, 1st Affiliated Hospital of Dalian Medical University, No. 222, Zhongshan Road, Xigang District, Dalian, 116011, China. hailongchen2007@hotmail.com.
authors.forename: Hailong
authors.initials: H
authors.lastname: Chen
mesh_terms: D016229:Amyloid beta-Peptides / Q000037:antagonists & inhibitors* / Q000633:toxicity; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D019610:Cytoprotection / Q000187:drug effects; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000627:therapeutic use*; D015394:Molecular Structure; D016501:Neurites / Q000187:drug effects*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009498:Neurotoxins / Q000037:antagonists & inhibitors / Q000633:toxicity; D016716:PC12 Cells; D010446:Peptide Fragments / Q000037:antagonists & inhibitors* / Q000633:toxicity; D031801:Polygala / Q000737:chemistry*; D051381:Rats
chemical_list: D016229:Amyloid beta-Peptides; D004365:Drugs, Chinese Herbal; D018696:Neuroprotective Agents; D009498:Neurotoxins; D010446:Peptide Fragments; C074636:amyloid beta-protein (25-35); C493220:tenuigenin