Objective: To explore the mechanism of acupuncture in improving cognitive ability by regulating hippocampal phosphatidylinositol-3 kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway in vascular dementia rats.
Methods: A total of 80 male SD rats were randomized into sham operation, model, non-acupoint and acupoint groups (n=18 per group). The VD model was established by ligation of the bilateral common carotid arteries. For rats of the acupoint group, “Baihui” (GV20) and bilateral “Zusanli “(ST36) were needled and stimulated by twirling the needles with reinforcing method, and for rats of the non-acupoint group, the bilateral subcostal spots (about 10 mm superior to the iliac cresta) were needled and stimulated by twirling the needles with uniform reinforcing and reducing method.
The treatment was conducted once daily, 6 times a week for two weeks, beginning 3 days after successful modeling. Rats of the sham operation group and model group received grasps as those in the acupoint groups. Morris water maze test was used to detect the abilities of learning and spatial memory. The contents of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) and the activities of acetylcholinesterase (AChE) and acetylcholine transferase (ChAT) in the hippocampus tissue were detected by using ELISA, changes of hippocampal mitochondrial membrane potential (MMP) detected using JC-1 fluorescence probe, and the expression levels of hippocampal phosphorylated (p)-PI3K, p-Akt and mTOR proteins measured using Western blot.
Results: Compared with the sham operation group, the escape latency, contents of ROS and MDA, and AChE activity were significantly increased (P<0.05), and the spatial memory ability, SOD activity, ChAT activity, MMP, p-PI3K, p-Akt and mTOR expression levels were significantly decreased in the model group (P<0.05). Compared with the model group, carotid artery ligature-induced increase of the escape latency, contents of ROS and MDA, and AChE activity, and decrease of the spatial memory ability, SOD activity, ChAT activity, MMP, p-PI3K, p-Akt and mTOR expression levels were significantly reversed in the acupuncture group (P< 0.05), but not in the non-acupoint group (P>0.05). The therapeutic effects of acupoint needling were obviously superior to those of non-acupoint needling in decreasing the escape latency, contents of ROS and MDA, and AChE activity (P<0.05), and in increasing the spatial memory ability, SOD activity, ChAT activity, MMP, p-PI3K, p-Akt and mTOR expre-ssion levels (P<0.05).
Conclusion: Acupuncture can improve cognitive function of vascular dementia rats, which may be related with its functions in easing oxidative stress and MMP reduction by activating PI3K/Akt/mTOR signaling pathway in the hippocampus.