Gastrodin Alleviates Vascular Dementia in a 2-VO-Vascular Dementia Rat Model by Altering Amyloid and Tau Levels

Vascular dementia (VaD) is the second most common type of dementia and has become a major public health challenge as the global population ages. VaD is caused by cerebrovascular disease, and most patients with VaD have been reported to also have Alzheimer's pathologies, which is the formation of neurofibrillary tangles and amyloid plaques that are mainly composed of hyperphosphorylated Tau and amyloid β (Aβ) respectively. However, the mechanisms of VaD are not completely understood, and very few drugs are available to treat this condition. Gastrodin (Gas) is the main bioactive component of the traditional Chinese herbal plant named Tian Ma (Gastrodia elata), and it has been used to treat neurasthenia in the clinical practice of Chinese Medicine for many years. Here, we hypothesize that Gas alleviates VaD in a rat model of permanent bilateral common carotid artery occlusion (2-VO)-induced VaD. Based on the results of the Morris water maze test and attention set shift test, either 22.5 or 90 mg/kg/day Gas improved the executive dysfunction and memory impairment of 2-VO rats following an intragastric administration for 4 weeks. Both 22.5 and 90 mg/kg/day Gas reduced Aβ1-40 and Aβ1-42 plaques in plasma and hippocampus of 2-VO rats. Mechanistically, in 2-VO rats, treatment with Gas (90 mg/kg/day) suppressed Aβ plaque deposition by decreasing the hippocampus levels of phosphorylated Tau. Thus, Gas ameliorated the cognitive deficits of 2-VO rats by inhibiting the abnormal phosphorylation of Aβ and Tau.