Patchouli alcohol as a selective estrogen receptor ß agonist ameliorates AD-like pathology of APP/PS1 model mice.

ABSTRACT

Clinical evidence shows that postmenpausal women are almost twice as likely to develop Alzheimer's disease (AD) as men of the same age, and estrogen is closely related to the occurrence of AD. Estrogen receptor (ER) α is mainly expressed in the mammary gland and other reproductive organs like uterus while ERß is largely distributed in the hippocampus and cardiovascular system, suggesting that ERß selective agonist is a valuable drug against neurodegenerative diseases with low tendency in inducing cancers of breast and other reproductive organs. In this study we identified a natural product patchouli alcohol (PTA) as a selective ERß agonist which improved the cognitive defects in female APP/PS1 mice, and explore the underlying mechanisms. Six-month-old female APP/PS1 mice were administered PTA (20, 40 mg · kg-1 · d-1, i.g.) for 90 days. We first demonstrated that PTA bound to ERß with a dissociation constant (KD) of 288.9 ± 35.14 nM in microscale thermophoresis. Then we showed that PTA administration dose-dependently ameliorated cognitive defects evaluated in Morris water maze and Y-maze testes. Furthermore, PTA administration reduced amyloid plaque deposition in the hippocampus by promoting microglial phagocytosis; PTA administration improved synaptic integrity through enhancing BDNF/TrkB/CREB signaling, ameliorated oxidative stress by Catalase level, and regulated Bcl-2 family proteins in the hippocampus. The therapeutic effects of PTA were also observed in vitro PTA (5, 10, 20 µM) dose-dependently increased phagocytosis of o-FAM-Aß42 in primary microglia and BV2 cells through enhancing ERß/TLR4 signaling; PTA treatment ameliorated o-Aß25-35-induced reduction of synapse-related proteins VAMP2 and PSD95 in primary neurons through enhancing ERß/BDNF/TrkB/CREB pathways; PTA treatment alleviated o-Aß25-35-induced oxidative stress in primary neurons through targeting ERß and increasing Catalase expression. Together, this study has addressed the efficacy of selective ERß agonist in the amelioration of AD and highlighted the potential of PTA as a drug lead compound against the disease.