[Acupuncture and Moxibustion Improves Learning-memory Ability of Alzheimer's Disease Rats Possibly by Up-regulating Serum Aβ Internalization Enzyme Contents]

Objective: To observe the effect of acupuncture and moxibustion (AM) on learning-memory ability and expression of amyloid beta (Aβ) in the hippocampal dentate gyrus (DG) of Alzheimer's disease (AD) rats, so as to explore its mechanism underlying improvement of AD.

Methods: Forty male Wistar rats were randomly divided into normal, sham operation, model and AM groups (n＝10 in each). The AD model was established by bilateral hippocampal injection of Aβ_1-42(5 µL). The AM was applied at "Baihui" (GV 20) and "Shenshu" (BL 23) for 15 min, once daily for 12 times. Morris water maze tests were used to assess the rats' learning-memory ability. The levels of serum Aβ_1-42 and Aβ internalizing enzymes including transthyretin (TTR), lipoprotein lipase (LPL), alpha 2 macroglobulin (α ₂M) and apolipoprotein E (ApoE) were detected by ELISA. The expression of Aβ_1-42 in the hippocampal DG was detected by immunohistochemistry.

Results: Compared with the sham operation group, the average escape latency of location navigation test was significantly prolonged in the first 5 days and the last 3 days (P<0.01), and the residence time of the target-quadrant and the platform crossing times of special probing task were significantly reduced in the model group (P<0.01). After the intervention, the average escape latency was obviously shortened in the first 5 days and the last 3 days (P<0.01), and both the residence time and the platform crossing times were significantly increased in the AM group relevant to the model group (P<0.01, P<0.05). After modeling, the contents of TTR, LPL, α ₂M and ApoE in the serum were significantly lower in the model group than in the sham operation group (P<0.01, P<0.05), while the levels of serum Aβ_1-42 and hippocampal Aβ_1-42 expression were considerably increased relevant to the sham operation group (P<0.01). Following the intervention, the TTR, LPL, α₂M and ApoE contents in the serum were significantly increased (P<0.01, P<0.05), and both serum Aβ_1-42 and hippocampal Aβ_1-42 expression were notably down-regulated in comparison with the model group (P<0.05). No significant differences were found between the normal and sham operation groups in the levels of all the above-mentioned indexes (P>0.05).

Conclusion: AM can improve the learning-memory ability of AD rats, which may be related to its effects in up-regulating the contents of serum Aβ internalizing enzymes and promoting the clearance of hippocampal Aβ. It suggests a protective role of AM on hippocampal neurons.