Effects of Capsule Yi‐Zhi on Learning and Memory Disorder and β‐Amyloid Peptide Induced Neurotoxicity in Rats

Objective: To investigate the effects of Capsule Yi-Zhi (CYZ is extracted and purified by our department mainly from Polygonum Multiflorum, Ginseng and Korean Epimedium herb, among which quantitatively effective ingredients are more than 50%.) on learning and memory disorder and â-amyloid protein induced neurotoxicity in rats. Methods: Various doses of CYZ were administered to Sprague-Dawley (SD) rats for 8 days, twice a day. Then scopolamine hydrobromide (Sco) intraperitoneal injection was performed on each rat and the Morris water maze test and step-though test were carried out respectively to explore the changes of the rats’ learning and memory capacities. Primary rat cortex neurons were cultured in vitro for 7 days and then, serum containing CYZ was added to neurons before or after the addition of â Amyloid peptide25–35 (Aâ25–35) to see the extent of CYZ’s protectiveness on neurotoxicity. MTT assay and test of level of LDH in the culture media were performed to achieve this aim. Results Compared with control group, rats in Morris water maze test required significantly decreased time in finding the platform under the water surface from 19.5 ± 11.40 to 8.5 ± 2.39, 8.8 ± 3.07, and 7.4 ± 3.87 sec, respectively, and in step-though test, the latent period rose from 22.70 ± 23.07 to 148.50 ± 124.02, 176.50 ± 143.36, and 196.60 ± 128.00 sec and the error number decreased from 14.20 ± 7.74 to 7.50 ± 8.02, 3.40 ± 4.43 and 2.50 ± 3.10 respectively, all with statistical significance. Moreover, in cultured primary neurons, the dramatic drop of LDH level in culture media from 3670.2 ± 437.65 to 864.5 ± 371.69 and 1444 ± 635.18 U L and the high A scores rising from 0.68 ± 0.193 to 0.93 ± 0.009 and 0.96 ± 0.239 in MTT test indicated that CYZ could effectively resist the neurotoxicity induced by Aâ25–35. Conclusions: CYZ presented promising effects on learning and memory dysfunction and Aâ induced neurotoxicity in vitro.