Effects of ginsenoside Rg1 on the expression of neuronal autophagosome-related proteins in brain slices of a rat model of Alzheimer's disease / 中华老年医学杂志

ABSTRACT

Objective:To explore the effects and molecular mechanisms of ginsenoside Rg1 on the expression of neuronal autophagosome-related proteins in a rat model of Alzheimer's disease(AD).Methods:Six-week-old SD rats were decapitated to prepare hippocampal brain slices.The slices were randomly divided into the blank control group, the model group, the low-concentration, medium-concentration and high-concentration Rg1 groups, with 10 in each group.In the model group, Aβ 1-42(final concentration 5 μmol/L)was added into an artificial cerebrospinal fluid(CSF)for 2 h treatment.The low-concentration, medium-concentration and high-concentration Rg1 groups were treated with Aβ 1-42(final concentration 5 μmol/L)for 2 h, and then treated with Rg1(final concentrations 60 μmol/L, 120 μmol/L, 240 μmol/L, respectively)for 3 h. The blank control group was not given any intervention drugs.At the end of intervention, histological changes of hippocampal brain slices in each group were examined via hematoxylin-eosin(HE)staining.Autophagosomes in hippocampal brain slices of each group were detected using transmission electron microscopy.The expression levels of autophagy-related proteins(P62, LC3-Ⅱ/LC3-Ⅰ), Aβ 1-42and shank protein in hippocampal brain slices of each group were detected with Western blot. Results:The results of HE staining showed that the arrangement of hippocampal neurons were disordered in the model group, with death and depletion of neurons.The arrangement and depletion of hippocampal neurons in each Rg1 group were less severe compared with the model group, with most significant improvement seen in the high-concentration Rg1 group.The results of transmission electron microscopy showed that the number of autophagosomes in brain slices in the model group was significantly higher than that in the blank control group, while each Rg1 group had fewer autophagosomes than the model group.The results of Western blot showed that, compared with the blank control group, levels of Shank1, P62 and LC3-Ⅰ proteins in brain slices were decreased(all P<0.05), while levels of Aβ 1-42and LC3-Ⅱ protein were significantly increased(all P<0.05)in the model group.Compared with the model group, levels of Shank1, P62 and LC3-Ⅰ proteins in brain slices were increased(all P<0.05), while levels of Aβ 1-42and LC3-Ⅱ protein were decreased( P<0.05)in each Rg1 group.These changes were the most significant in the high-concentration Rg1 group. Conclusions:Ginsenoside Rg1 may inhibit autophagy by up-regulating the expression of Shank1, P62 and LC3-Ⅰ proteins in hippocampal brain slices of rats in the AD model, thus playing protective roles in brain neurons.