Mechanism of Tiaogeng decoction in a cognitive dysfunction mouse model.

Abstract

Objective: To explore the mechanism of action of Tiaogeng decoction (, TG) in alleviating oxidative stress damage in the hippocampus of a mouse model of cognitive impairment.

Methods: Amyloid precursor protein/presenilin-1 (APP/PS1) transgenic female mice were randomly divided into model, estradiol valerate, low-, medium-, and high-dose TG groups, female C57 mice were used as the control group (n = 12/group). After 12 weeks of treatment, the behavior of mice was tested with the Morris water maze, and brain tissue samples were collected, and changes in hippocampal neurons were observed using electron microscopy. The deposition of beta-amyloid protein (Aβ) amyloid plaques in the hippocampus was determined by light microscopy. Aβ1-42 protein levels were detected through immunofluorescence. Oxidative stress indicators in the hippocampus were detected by enzyme linked immunosorbent assay. The expressions of nuclear factor-erythroid 2-related factor 2 (Nrf2), c-Jun N-terminal kinase (JNK), phospho-JNK (p-JNK), B-cell lymphoma-2 (Bcl-2), caspase-9, and cleaved caspase-9 were detected by Western blot. Hippocampal cell apoptosis was detected using the terminal deoxynucleotidyl transferase-mediated nick end Labeling.

Results: TG improved the cognitive function of APP/PS1 mice, as judged by improvements in several indices from the Morris water maze test. TG increased Nrf2, superoxide dismutase, and heme oxygenase-1 protein expression and reduced malondialdelyde and reactive oxygen species expression. TG also inhibited the expression of JNK proteins, upregulated the expression of Bcl-2, and downregulated the expression of caspase-9, reducing cell apoptosis. TG decreased the percentage of the hippocampal cornu ammonis 1 area positive for Aβ1-42, reducing mitochondrial damage caused by oxidative stress and Aβ protein deposition.

Conclusions: TG may improve memory ability while reducing oxidative stress and apoptosis. It also reduces Aβ protein deposition in the hippocampus, protecting the central nervous system and improving memory function. TG may reduce the risk of AD.