Rhodiola rosea L extract shows protective activity against Alzheimer's disease in 3xTg-AD mice

Purpose: To investigate the protective effect of Rhodiola rosea L. extract (RRLE) against Alzheimer's disease in 3xTg-AD mice. Methods: The cognitive function of 3xTg-AD mice was assessed using Morris water maze test. The levels of amyloid beta deposits and NeuN in the hippocampus were evaluated by immunohistochemistry. Brain neurotrophic-derived factor (BDNF) and tyrosine kinase B (TrkB) expressions were examined by western blot analysis. Results: RRLE treatment significantly ameliorated learning and memory deficits in AD mice, as shown by increased time spent in the target zone during probe tests. The escape latency in animals treated with 400 mg/kg RRLE (20.5 +/- 1.3 s) was significantly increased compared to the untreated mice (12.4 +/- 1.3 s, p < 0.01). In addition, RRLE significantly decreased A beta deposits, increased NeuN-positive cells, and upregulated the expression of BDNF (1.4 +/- 0.2, p < 0.05) and TrkB (1.1 +/- 0.2, p < 0.05) in the mice. Conclusion: The findings suggest that RRLE treatment may be a useful strategy for treating memory impairment induced by several neurodegenerative diseases.