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BACKGROUND: The main components of the traditional Chinese medicine compound Nao Yikang have been shown to possibly alleviate neural damage.OBJECTIVE: To observe the effects of Nao Yikang on expression of choline acetyltransferase (CHAT) and caspase-3 in the rat brains of an experimental Alzheimer's disease (AD) model, and to investigate the mechanisms of potential neuropretective effects.DESIGN, TIME AND SETTING: A randomized, controlled experiment was performed at the Department of Pathophysiology, Medical School of Nantong University between November 2006 and December 2007.MATERIALS: The main active components of Nao Yikangware as follows: prepared polygonum multiflorum, Rhizoma anemarrhenae, and Rhizoma acori tatarinowii. Nao Yikang granules were prepared by Nantong Hospital of Traditional Chinese Medicine. Ibotenic acid (IBO) was purchased from Sigma-Aldrich, USA, ChAT goat anti-rat antibody from Chemicon, USA, and cleaved caspase-3 rabbit anti-rat (Asp175) (5A1) antibody from Cell Signaling, USA.METHODS: A total of 60 male, Sprague Dawley rats (2 months old) were randomly assigned to 6 groups: sham-surgery, model, Nao Yikang 1.73, 3.45, 6.90 g/kg per day, and piracetam, with 10 rats in each group. Bilateral infusions of 5 μg IBO into the nucleus basalis of Meynert were performed with Hamilton syringe and stereotaxic apparatus for AD model establishment. For the sham-surgery group, rats received 1 μL saline in the identical stereotaxic position. From the second day, Nao Yikang groups were administrated 1.73, 3.45, and 6.90 g/kg per day Nao Yikang, respectively, while the piracetam group received 0.04 g/mL piracetam, the model group received 0.5% sodium carboxymethyl cellulose, and the sham-surgery group received normal saline. Rats were intragastrically administered 1 mL/100 g daily for 28 consecutive days.MAIN OUTCOME MEASURES: Following treatment of the various solutions for 28 days, Westem blot was utilized to observe ChAT expression in the frontal cortex of AD rats, and immunohistochemistry was applied to quantify caspase-3-positive cells in the frontal cortex.RESULTS: ChAT protein expression significantly decreased in the model group (P < 0.01), however,caspase-3 expression was significantly elevated (P < 0.01) compared with the sham-surgery group.Compared with the model group, ChAT protein expression increased in the Nao Yikang 1.73 g/kg per day, 3.45 g/kg per day, 6.90 g/kg per day groups, and the piracetam group (P < 0.05 or P < 0.01),and the number of caspase-3-positive cells decreased in the Nao Yikang 3.45 g/kg per day and 6.90 g/kg per day groups (P < 0.01). However, there was no change in the number of caspase-3-positive cells in the 3.45 g/kg per day group.CONCLUSION: The traditional Chinese medicine compound Nao Yikang increased ChAT protein expression and suppressed caspase-3 expression in the frontal cortex in a dose-dependent manner.