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Background: Alzheimer's disease (AD) is one of the most common neurodegenerative syndromes characterized by a progressive decline in the spatial memory. There are convincing evidences on the neuroprotective effects of flavonoids against AD. Aims and Objective: To determine the effect of quercetin on the acquisition and retention of spatial memory in a rat model of AD. Materials and Methods: Twenty-four male Wistar rats were divided into four groups (six in each): group I: control rats receiving intracerebroventricular (ICV) injection of normal saline, group II: rats induced AD by ICV injection of streptozotocin (STZ; 3 mg/kg bilaterally; twice, on days 1 and 3), and groups III and IV: ICV-STZ AD rats treated intraperitoneally (IP) with 40 and 80 mg/kg/day quercetin, respectively, over a period of 12 days. Then, the rats were trained with four trials per day for five consecutive days in the Morris water maze (MWM). On the sixth day, the memory retention was evaluated. Result: The ICV-STZ AD groups showed a significant impairment in the acquisition and retrieval of spatial memory when compared with the control group (P o 0.001). In the AD groups, the escape latency during the training trials showed a significant decrease (P o 0.001). Meanwhile, during the MWM task, these rats spent more time in the target quadrant in probe trials when compared with the controls. Conclusion: Quercetin acted as a spatial memory enhancer in ICV-STZ-induced AD rats. Hence, this flavonoid can be considered potentially as a promising agent for developing prophylactic and therapeutic neuroprotection. This neuroprotective effect of quercetin may be attributed to its antioxidant and scavenging properties.

Objective and background: One of the most significant side effects of radiotherapy for head and neck cancers is xerostomia as a result of salivary gland damage. Considering pharmacological effects of propolis, we evaluated its protective effect on salivary glands subjected to radiotherapy of head and neck cancer patients. Materials and methods:Twenty-one male albino rats (8-11 W, 190 ± 5 gm) were divided into three groups of seven animals. Scintigraphy was performed in all the groups. Then groups 1 (S) and 2 (SR) received normal saline injections and group 3 (PR) received propolis injection over 3 days. After that groups 2 and 3 were exposed to gamma radiation and all the rats underwent scintigraphic assessment on third day and 70th day after irradiation. The lips and tongues of rats in groups 2 and 3 were examined for mucositis daily in first 10 days. At the end, the parotid glands of all rats were examined histologically.Results: Scintigraphy results of third and 70th day after irradiation showed statistically significant differences between PR and SR as well as SR and S. However, there was no significant difference between the PR and S groups. Histopathologic assessment demonstrated significant difference between SR, PR and S. Original research Conclusion:These results suggest that propolis has protective effects on salivary gland function in animal models whilst it did not prevent radiation-induced histologic changes in tissues. Further investigations are needed to elucidate mechanisms of propolis actions.Clinical significance: Regarding to the results of this study, propolis may be useful in reduction xerostomia due to radiation to salivary glands and may be helpful for head and neck cancer patients.