Effects of an Armillaria mellea Polysaccharide on Learning and Memory of D-Galactose-Induced Aging Mice

Armillaria mellea has been known and used in traditional medicine in East Asia for hundreds of years. It has already been reported that A. mellea extracts have various pharmacological effects, and the polysaccharides of A. mellea exhibit antioxidant and anti-apoptotic activities. In this study, a water-soluble polysaccharide (AMP-N-a-1), with an average molecular weight of 17 kD, was isolated and purified from the water extract of A. mellea using DEAE-52, Sepharose CL-4B, and Sephadex G-100 column chromatography. AMP-N-a-1 was mainly composed of Man (1.65%), Glca (1.64%), Rha (1.82%), Gala (2.49%), Glc (90.48%), Gal (0.89%), Xyl (0.42%), and Ara (0.61%). AMP-N-a-1 was used to study the effect on the learning and memory of mice and its underlying mechanisms. The results showed that AMP-N-a-1 could significantly increase the activities of catalase (CAT) and superoxide dismutase (SOD) and reduce the content of nitric oxide (NO) in mouse brain tissue. Meanwhile, AMP-N-a-1 could reduce the contents of norepinephrine (NE) and dopamine (DA) but could increase the content of 5-hydroxytryptamine (5-HT) in mouse brain tissue. In addition, the immunofluorescence experiment showed that AMP-N-a-1 could promote the proliferation of hippocampal dentate gyrus neurons. The above results indicate that AMP-N-a-1 can significantly improve the learning and memory of mice, and the mechanism may be that AMP-N-a-1 can participate in the regulation of learning and memory through a variety of ways.