Objective
To investigate the effect and underlying mechanisms of Tiaoxin Recipe (a Chinese herbal formula) treatment on Alzheimer’s disease (AD).

Methods
Twelve-week-old APPswe/PS1ΔE9 (APP/PS1) double transgenic mice were used as a model of AD-afflicted mice. One group of mice was treated with Tiaoxin Recipe by gastrogavage for 12 weeks, while two other groups were given intraperitoneal injections of nicotinamide adenine dinucleotide or FK866 for 4 weeks. Morris water maze and thioflavin S staining tests were performed to evaluate cognitive impairment and amyloid plaque deposition, respectively. Serum amyloid-β1-42 (Aβ1-42) content was detected using an enzyme-linked immunosorbent assay, and quantitative reverse transcription-polymerase chain reaction was performed to examine the expression levels of microRNA-34a (miR-34a) in cortex and hippocampus samples of the study mice.

Results
Compared with the normal control group, the memory and learning abilities of the APP/PS1 model group were found to be impaired (P < 0.01), as shown by the increased levels of senile plaque deposition in cortex and hippocampus (P < 0.01), miR-34a expression (P < 0.01) and serum Aβ1-42 content (P < 0.01). Treatment with Tiaoxin Recipe significantly reduced memory impairment (P < 0.01) by reducing amyloid plaque accumulation in cortex and hippocampus (P < 0.01), miR-34a expression (P < 0.01) and serum Aβ1-42 content (P < 0.01) in APP/PS1 mice.

Conclusion
Tiaoxin Recipe is a viable complementary or alternative therapeutic treatment that is capable of delaying the development of early-stage AD by inhibiting the expression of miR-34a.

Key words: Alzheimer's disease,  Tiaoxin Recipe,  MicroRNA-34a,  Transgenic mice,  Amyloid-β,  Herb