BACKGROUND: There are no effective methods to cure Alzheimer disease (AD). Now, researches have shown that panax notoginseng saponins (PNS) play an important role in improving AD, but its mechanism is unclear.OBJECTIVE: To observe the protective effect of PNS characterized by removing blood stasis to stop bleeding and promoting blood circulation to relieve pain on pathological lesion of cholinergic neuron in rat with AD.DESIGN: Completely randomized grouping design and controlled study.SETTING: Neuroscience Institute of Guangxi Traditional Chinese Medical University.MATERIALS: This experiment was completed in the Chinese Herb Pharmacodynamic Laboratory of Guangxi Traditional Chinese Medical University between June 2003 and April 2005. A total of 90 health Wistar rats of clean grade and half gender were selected in this study. Among them, there were 75 old rats with 15 months old and 15 young rats with 3 months old. METHODS: This experiment was completed in the Chinese herb Pharmacodynamic Laboratory (Key Laboratory) of Guangxi Traditional Chinese Medical University between June 2003 and April 2005. ① A total of 90 healthy Wistar rats of clean grade and half gender were selected in this study. Among them, there were 75 old rats with 15 months old and 15 young rats with 3 months old. Fifteen young rats with 3 months old were regarded as young control group, and other 15 selected from 75 rats with 15 months old were regarded as old control group. The rest 60 rats were modeled on the basis of subacute injury induced by intravenous injection of D-galactose and bilateral cerebral Meynert basal nuclei injured by ibotenic acid. Parallel control was performed with saline on rats in young control group and old control group under the same condition. ② Two weeks later,survival modeling rats were divided randomly into 4 groups: model group,high-dosage PNS group, low-dosage PNS group and huperzine A group with 12 in each group. Rats in high-and low-dosage PNS groups were perfused with 200 and 100 mg/kg PNS (provided by Yunnan Yuxi Weihe Pharmaceutical Factory), respectively, once a day; rats in huperzine A group were perfused with 0.3 mg/kg huperzine A once a day for 4 weeks; rats in model group, young control group and old control group were perfused with the same volume of saline for 4 weeks. ③ After administration, pathological sections of brain tissue were cut, and immunologic-reaction activity of choline acetyltransferase (ChAT), morphological changes and numbers of positive neuron in cerebral sections were determined by immunohistochemistry analysis. ChAT immuno-positive neurons were analyzed with IBAS imaging analysis system to assay average area of section and average absorbance (A), and amount of ChAT immuno-positive neurons was calculated with microscope micrometer. ④ Measurement data were compared with single-factor analysis of variance.MAIN OUTCOME MEASURES: Effect of PNS on distribution of cholinergic neuron and ChAT content in cerebral tissue of AD rat models.RESULTS: A total of 75 old rats and 15 young rats entered the final analysis. ① Amount of ChAT immuno-positive neurons was the most, and the color was the deepest in young control group; amount of ChAT immuno-positive neurons was higher in high-dosage PNS group than that in huperzine A group and model group; ChAT immuno-positive neurons were smaller in model group than those in other goups, and the amount was decreased obviously. Axis-cylinder and dendrite of soma were shortened remarkably. ② Amounts of ChAT immuno-positive neurons in basal forebrain were less in model group than those in other groups (P ＜ 0.05), less in lowdosage PNS group, huperzine A group and model group than those in old control group (P ＜ 0.05), less in huperzine A group and model group than those in high- and low-dosage PNS group (P ＜ 0.05), and less in young control group than those in other groups (P ＜ 0.05). The mean A value of ChAT immuno-positive neurons in basal forebrain was similar to amounts in each group. Average area of section of ChAT immuno-positive neurons in basal forebrain was smaller in low-dosage PNS group and model group than that in young control group (P ＜ 0.05), and differences in other groups were not significant (P ＞ 0.05).CONCLUSION: PNS plays a protective role in pathological lesion of cholinergic neuron in AD rat models. PNS can also increase survival amount and quality of cell and increase content and activity of ChAT so as to protect and improve central cholinergic system, and inhibit aging and dementia through improving and repairing injured cholinergic neurons.