Intracerebroventricular microinjection of kaempferol on memory retention of passive avoidance learning in rats: involvement of cholinergic mechanism(s).

Purpose of the study: Kaempferol (KM) is a flavonoid found in plant-derived foods and medicinal plants. Recently, it is well established that KM plays a protective role to develop Alzheimer's disease. The current study aimed at evaluating the effect of intracerebroventricular micro-injection of KM on memory retention of passive avoidance learning (MRPAM) and identifying the potentially related cholinergic mechanisms (ChMs) in rats. Materials and methods: In the current study, male Wistar rats randomly divided into control, vehicle and KM (10, 20 and 40 μg/rat) groups. Moreover, MRPAM was evaluated by shuttle box test. The role of ChM was studied using non-selective and selective acetylcholine antagonists (scopolamine [SCN], 4-DAMP and methoctramine [MN], respectively) as well as pirenzepine (PZ) in combination with KM. Results: The employment of KM (40 μg/rat) improved the SCN-induced memory impairment in MRPAM. Co-treatment with KM (40 μg/rat) plus 4-DAMP significantly increased the step-through latency (STL, P  < 0.05; 167 ± 28 s) and decreased the total dark chamber (TDC, P  < 0.05; 121 ± 31 s) compared with those of the 4-DAMP group (STL: 75 ± 13 s; TDC: 178 ± 46 s). Co-treatment with KM (40 μg/rat) plus PZ attenuated STL, and also increased TDC ( P  < 0.01; 220 ± 28 s) compared with those of the PZ group. Co-treatment with KM (10 and 20 μg/rat) and MN increased STL ( P  < 0.05), and deceased TDC compared with those of the MN group ( P  < 0.01). Conclusions: Totally, the results of the present study showed that cholinergic system may be involved in improving effect of KM on SCN-induced memory impairment.