Neuroprotective effects of the aerial parts of Polygala tenuifolia Willd extract on scopolamine-induced learning and memory impairments in mice

Alzheimer's disease is a common neurodegenerative disease characterized by progressive cognitive dysfunction and behavioral impairment. Aerial parts of Polygala tenuifolia Willd (APT) is a traditional Chinese medicine used for the treatment of amnesia. The present study aimed to investigate the protective effects of APT on scopolamine-induced learning and memory impairments in mice. Scopolamine-induced mice were used to determine the effects of APT on learning and memory impairment. Mice were orally administered with APT (25, 50 and 100 mg/kg) and piracetam (750 mg/kg) for 14 days, and intraperitoneally injected with scopolamine (2 mg/kg) from days 8 to 14. Morris water maze and step-down tests were performed to evaluate learning and memory. Levels of acetylcholine (ACh), choline acetyltransferase (ChAT), acetylcholinesterase (AChE), interleukin (IL)-1β, IL-10 and brain-derived neurotrophic factor (BDNF) in the hippocampus and frontal cortex were measured by ELISA. Superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione (GSH) were measured via biochemical detection. The results demonstrated that APT ameliorated learning and memory impairment in scopolamine-induced mice. Correspondingly, APT significantly increased ACh and ChAT levels in the hippocampus and prefrontal cortex of scopolamine-induced mice. Additionally, treatment with APT significantly increased BDNF and IL-10 levels, and decreased IL-1β and AChE levels in the same mice. Furthermore, APT significantly increased SOD activity and GSH content, and decreased MDA levels in brain tissue. These results indicated that APT may ameliorate learning and memory impairment by regulating cholinergic activity, promoting BDNF and inhibiting neuroinflammation and oxidative stress.

Keywords: aerial parts of Polygala tenuifolia Willd; brain-derived neurotrophic factor; cholinergic activity; neuroinflammation; oxidative stress.