title: The protective effect and underlying mechanism of Hainan papaya water extract against neuronal apoptosis induced by Aβ40.
abstract: OBJECTIVE
  To investigate whether Hainan papayas has protective effects in an Aβ40-induced primary neuron injury model and elucidate the underlying molecular mechanism.
  
  
  METHODS
  Cultured primary neurons from the dorsal root ganglia (DRG) of Sprague-Dawley (SD) rats were treated with 20 μM Aβ40 peptide, 100 μg/L Hainan papaya water extract, peptide plus extract, or culture medium for 24 h. Cell viability was measured by MTT assay, and neuronal apoptosis was evaluated by DAPI staining. ERK signaling pathway-associated molecule activation and changes in Bax expression were analyzed by Western blotting and immunofluorescence.
  
  
  RESULTS
  A cell viability rate of (44.11 ± 6.59)% in the Aβ40 group was rescued to (79.13 ± 6.64)% by adding different concentrations of the extract. DAPI showed pyknotic nuclei in 39.5% of Aβ40-treated cells; the fraction dropped to 17.4% in the 100 μg/L extract group. ERK phosphorylation was observed in the Aβ40 group but was ameliorated by pretreatment with 100 μg/L extract. Hainan papaya water extract also prevented Aβ40-induced phosphorylation of MEK, RSK1 and CREB associated with ERK signaling and downregulated Bax expression in the neurons.
  
  
  CONCLUSIONS
  The results suggest that Hainan papaya water extract has protective effects on neurons; the mechanism may be related to suppression of ERK signaling activation.
authors.affiliation: Department of Anatomy, Hainan Medical College, Haikou 571199, China.
authors.forename: Jiu-Hong
authors.initials: JH
authors.lastname: Zhao
authors.affiliation: Department of Anatomy, Hainan Medical College, Haikou 571199, China.
authors.forename: Hai-Ying
authors.initials: HY
authors.lastname: Zhang
authors.affiliation: Department of Anatomy, Hainan Medical College, Haikou 571199, China.
authors.forename: Xian-Fang
authors.initials: XF
authors.lastname: Zhang
authors.affiliation: Neuroscience Research Institute, Hainan Medical College, Haikou 571199, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Dong
authors.affiliation: School of Pharmacy, Hainan Medical College, Haikou 571101, China.
authors.forename: Qi-Bing
authors.initials: QB
authors.lastname: Liu
authors.affiliation: School of Pharmacy, Hainan Medical College, Haikou 571101, China.
authors.forename: Yue-Li
authors.initials: YL
authors.lastname: Liu
authors.affiliation: Department of Anatomy, Hainan Medical College, Haikou 571199, China.
authors.forename: Yi-Di
authors.initials: YD
authors.lastname: Huang
authors.affiliation: Department of Anatomy, Hainan Medical College, Haikou 571199, China.
authors.forename: Quan-Peng
authors.initials: QP
authors.lastname: Zhang
authors.affiliation: Department of Anatomy, Hainan Medical College, Haikou 571199, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Luo
authors.affiliation: Department of Anatomy, Hainan Medical College, Haikou 571199, China; Neuroscience Research Institute, Hainan Medical College, Haikou 571199, China.
authors.forename: Zhi-Jian
authors.initials: ZJ
authors.lastname: Ma
authors.affiliation: Department of Anatomy, Hainan Medical College, Haikou 571199, China; Neuroscience Research Institute, Hainan Medical College, Haikou 571199, China. Electronic address: 1272791897@qq.com.
authors.forename: Xi-Nan
authors.initials: XN
authors.lastname: Yi
keywords: Aβ peptide; ERK signaling pathway; Neuron protection