[Effect of electroacupuncture pretreatment on hippocampal oxidative stress in aged mice with postoperative cognitive...

To observe the effect of electroacupuncture (EA) pretreatment on hippocampal oxidative stress in aged mice with postoperative cognitive dysfunction (POCD) and explore the relevant mechanism of EA pretreatment on the improvement of learning and memory in POCD aged mice.

A total of 72 healthy male aged mice were randomized into a blank group, a model group, a medication group and an EA group, 18 mice in each one. In each group, 1-day, 3-day and 7-day subgroups were divided separately, 6 mice in each subgroup. In the EA group, "Baihui" (GV 20) and "Dazhui" (GV 14) were selected and stimulated with EA, using continuous wave (15 Hz, 1 mA), continuously for 30 min, once a day, for 5 days consecutively. In the medication group, 10% minocycline was injected intraperitoneally, 40 mg/kg, once a day, consecutively for 5 days. In the blank and the control group, intraperitoneal injection of 0.9% sodium chloride solution was given with equal dosage. Except the blank group, at the end of intervention, partial hepatectomy was conducted to establish POCD model in the rest groups. Morris water maze test was adopted to evaluate the learning and memory ability of the aged mice. ELISA was used to determine the contents of reactive oxygen species (ROS) and malondialdehyde (MDA) in the hippocampal tissue. Western blot method was applied to detect the protein expressions of superoxide dismutase 1 (SOD 1) and superoxide dismutase 2 (SOD 2) in the hippocampal tissue.

Compared with the blank group, the percentage of platform quadrant residence time was obviously reduced in the mice in the model group (P<0.01), and those in the medication group and the EA group were larger than the model group (P<0.01). Compared with the model group, the contents of ROS were reduced in each subgroup of the medication group and the 3-day subgroup and the 7-day subgroup of the EA group separately (P<0.01, P<0.05), MDA contents were reduced in the medication group and the EA group (P<0.01, P<0.05), the protein expressions of SOD 1 and SOD 2 were all increased in each subgroup of the medication group and the 3-day subgroup and the 7-day subgroup of the EA group (P<0.05, P<0.01). Compared with the medication group, the contents of ROS and MDA in the 1-day subgroup of the EA group were increased (P<0.05), the hippocampal SOD 1 protein expression was increased in the 7-day group of the EA group (P<0.05) and the hippocampal SOD 2 protein expression was reduced in the 1-day subgroup of the EA group (P<0.05).

Electroacupuncture pretreatment at "Baihui" (GV 20) and "Dazhui" (GV 14) may increase the learning and memory ability of POCD aged mice, which is probably related to the decrease of oxidative stress and the strengthening of hippocampal antioxidant capacity.