| Objective To investigate the changes of endoplasmic reticulum stress-related protein of aging rats and the modulation of saponins from Panax japonicus(SPJ).Methods(1)Male SD rats were randomly divided into four groups: 6-month old group(6M),12-month old group(12M),18-month old group(18M)and 24-month old group(24M),ten rats in each group: Western blot was used to detect the expression of endoplasmic reticulum stress-related proteins in cortex and hippocampus of SD rats.Including Glucose-regulated protein 78(GRP78)and its three main endoplasmic reticulum pathways: phosphorylated Protein Kinase R-like ER kinase(p-PERK),phosphorylated eukaryotic translation initiation factor 2α(p-EIF2α),activating transcription factor 4(ATF4),activating transcription factor 6(ATF6),phosphorylated inositol-requiring enzyme1(p-IRE1)and X-box binding protein-1(XBP1),(2)Detect the colocalization of endoplasmic reticulum stress-related proteins(GRP78,p-PERK,p-EIF2α,ATF4,XBP1)with neuronal marker protein(Neu N),microglial marker protein(Iba-1)and astrocyte marker protein(GFAP)in cerebral cortex and hippocampus of 12-month-old SD rats by immunofluorescence.(2)Male SD rats were randomly divided into four groups: 6-month old group,ten rats per group,24-month old group and SPJ-treated groups with the doses of 10mg/kg and30mg/kg.The control group was given saline from 18-month-old,and the SPJ-treated groups were given SPJ for 6 days per week for 6 months from 18-month old.Western blot was used to detect the expression of endoplasmic reticulum stress-related proteins(GRP78,p-PERK,p-EIF2α,ATF4,ATF6,XBP1)and apoptosis-related proteins(p-JNK,CHOP,Bcl-2,Bax)in cerebral cortex and hippocampus of SD rats.Results(1)Western blot results showed that the expression levels of endoplasmic reticulum stress-related proteins(GRP78,p-PERK,p-EIF2α,ATF4,ATF6,p-IRE1,XBP1)were gradually decreased with aging in cerebral cortex and hippocampus;(2)Immunofluorescence results showed that endoplasmic reticulum stress-related proteins including GRP78,p-PERK,p-EIF2α,ATF4 and XBP1 were mainly colocalized with neurons;(3)Western blot results showed that compared with the 6-month-old group,expression levels of endoplasmic reticulum stress-related proteins of 24-month-old rats were significantly decreased.But these changes were reversed after SPJ treatment for six months as demonstrated by increasement of the expression of endoplasmic reticulum stress-related proteins and down-regulation of the expression of apoptosis-related proteins including p-JNK,CHOP and Bax.Conclusion The expression levels of endoplasmic reticulum stress-related proteins were decreased in cortex and hippocampus with aging and endoplasmic reticulum stress-related proteins mainly expressed in neurons.SPJ treatment can up-regulate endoplasmic reticulum stress-related proteins and anti-apoptosis-related proteins,down-regulate pro-apoptosis-related proteins. |
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