Paeoniflorin exerts neuroprotective effects in a transgenic mouse model of Alzheimer's disease via activation of adenosine A1 receptor

Alzheimer's disease (AD) is the most common cause of dementia, characterised by advanced cognitive and memory deterioration with no effective treatments available. Previous in vitro and in vivo studies suggest that paeoniflorin (PF), a major bioactive constituent of Radix Paeoniae, might possess anti-dementia properties; however, the underlying mechanism remains unclear. The aim of the current study was to determine the therapeutic effects of PF in a transgenic mouse model of AD and to identify its mechanism. Transgenic mice with five familial AD mutations (5XFAD) were used in this study. We showed that 28 days of PF (5 mg/kg, ip) treatment significantly decreased the escape latency and path length in the Morris water maze test and increased the alternation rate in the T-maze test, compared to the vehicle treatment group. In addition, PF treatment significantly alleviated amyloid beta plaque burden, inhibited astrocyte activation, and decreased IL-1 beta and TNF-alpha expression in the brain of 5XFAD mice. However, the anti-cognitive deficits, anti-amyloidogenic, and anti-inflammatory effects of PF were abolished by 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 0.3 mg/kg), an adenosine A(1) receptor (A(1)R) antagonist. In conclusion, our results suggest that PF might act as a potential therapeutic agent for AD via activation of adenosine A(1)R.