Effect of electroacupuncture on learning-memory ability and expression of IL-1β, IL-6 and TNF-α in hippocampus and spleen in mice with Alzheimer's disease

Abstract

To explore the effect of electroacupuncture (EA) on the ability of spatial learning-memory and the expression of IL-1β, IL-6 and TNF-α in the hippocampus and spleen tissues and the number of hippocampal neurons and spleen lymphocytes in Alzheimer's disease (AD) mice, so as to study its mechanisms underlying improvement of AD. Twenty-four SAMP8 mice were randomly and equally divided into AD model, EA and medication groups, and 8 SAMR1 mice were used as the control group. EA (2 Hz, 0.1 mA) was applied to "Baihui"(GV20) and "Yintang"(EX-HN3) for 20 min in the EA group, and intragastric administration of donepezil hydrochloride (0.92 mg/kg) was applied in the medication group, once daily for 15 d. The learning-memory ability was determined by Morris water maze task, and the histopathological changes of hippocampus were observed after H.E. staining, followed by determining neurons and the number of splenic lymphocytes. The expression levels of IL-1β, IL-6 and TNF-α in the hippocampus and spleen were detected by immunohistochemistry and Western blot, respectively. After mode-ling, the escape latency of place navigation test in the Morris water maze, the spleen index, immunoactivity and expression levels of IL-1β, IL-6 and TNF-α proteins in the hippocampus and spleen tissues were significantly increased (P<0.05, P<0.01). Compared with the model group, the escape latency, spleen index, immunoactivity and expression levels of IL-1β, IL-6 and TNF-α proteins in both hippocampus and spleen were significantly down-regulated in the medication (except the escape latency) and EA groups (P<0.01, P<0.05). The effect of EA was evidently superior to that of medication in shortening the escape latency, lowering the spleen index, and immunoactivity of hippocampal IL-6 and splenic TNF-α immunoactivity (P<0.01, P<0.05). Outcomes of H.E. staining showed disordered arrangement of neurons with nuclear pyknosis or apoptosis in partial neurons in the hippocampus, and thickened and swollen spleen capsule tissue with loose structure and an increased number of lymphocytes in the model group, which was relatively milder in the EA and medication groups. EA can improve the learning-memory ability of AD mice, which may be associated with its effect in relieving the inflammation reaction in the hippocampus and spleen tissues.