The effect of acupuncture on hippocampal synaptic plasticity in Alzheimer Disease Mouse Model: Possible mechanisms of energy transportation in neurons

Abstract

Objective: To study the mechanism of acupuncture-promoted synaptic plasticity in hippocampal neurons of senescence-accelerated mouse-prone 8 mice with respect to neuronal energy substrate transport. Methods: Forty-three senescence-accelerated mouse-prone 8 mice were randomly divided into Alzheimer’s disease model and acupuncture groups, and twenty senescence-accelerated mouse resistant 1 mice were used as the normal group. Acupuncture group received acupuncture at the “Baihui” and “Yongquan” acupoints for 40 days. The Morris water maze was used to detect the learning and memory capabilities of the mice, and in vivo electrophysiology and transmission electron microscopy were used to evaluate the synaptic functional and structural plasticity of hippocampal neurons. Glucose, lactate, and pyruvate in the hippocampal intercellular fluid, as well as the expression of glucose transporter 3 and monocarboxylate transporters 2 and 4, were analyzed using microdialysis, immunohistochemistry, and western blotting. Results: The Morris water maze data showed that compared with Alzheimer’s disease model mice, mice of acupuncture group exhibited a shorter escape latency, increased number of effective zone crossings, and increased percentage of swimming distance in the target quadrant. Acupuncture increased the postsynaptic density thickness of Alzheimer’s disease model mice and decreased the latency amplitude after tetanic stimulation and width of the synaptic cleft. Glucose, lactate, and pyruvate contents in the hippocampal intercellular fluid were significantly reduced in Alzheimer’s disease model mice, but the reductions were more pronounced after acupuncture treatment. Furthermore, acupuncture prominently elevated glucose transporter 3 and monocarboxylate transporters 2 expression in the CA1 and dentate gyrus regions of the hippocampus of Alzheimer’s disease model mice. The elevation of monocarboxylate transporters 4 expression mostly appeared in the CA1 region. Conclusion: Acupuncture improved the learning and memory capabilities as well as the hippocampal synaptic structural plasticity of senescence-accelerated mouse-prone 8 mice. Its effects were likely related to the regulation of glucose transporter 3, monocarboxylate transporters 2, and monocarboxylate transporters 4 expression in the hippocampal tissue to increase the energy substrate reserve of neurons and improve the substrate-matching ability of the cellular response.