Effects of ginsenoside Rg1 or 17β-estradiol on a cognitively impaired, ovariectomized rat model of Alzheimer's disease.

Abstract Ginsenoside Rg1, which could improve spatial learning and memory, might be a useful agent for preventing and treating cognitive impairment in Alzheimer’s disease (AD). The present study was designed to test the neuroprotective effects of ginsenoside Rg1 on an ovariectomized (OVX) and d -galactose ( d -gal)-injected rat model of AD, which is characterized with progressive learning and memory deficits, AD-related molecules alteration and differentiation/apoptosis imbalance in hippocampal neurons. OVX Wistar rats received daily injections of d -gal (100 mg/kg) combined with different concentrations of ginsenoside Rg1 (5, 10, 20 mg/kg) or 17-β-estradiol (E2, 100 μg/kg), or normal saline (NS, 1.0 ml/kg) for 6 weeks. Ovarian steroid deprivation plus d -gal injection led to spatial learning and memory capacity impairments, as well as increased Aβ 1-42 production. Ginsenoside Rg1 and E2-treatment significantly ameliorated these deteriorations in AD rats. Seven weeks after surgery, α-secretase a disintegrin and metallopeptidase domain 10 (ADAM 10) in hippocampus of AD rats was dramatically decreased, while β-secretase β-site APP-cleaving enzyme 1 (BACE 1) increased compared with those in sham-operated ones ( P