| Extremely low frequency electromagnetic fields(ELF-EMFs)devices are widely used in modern society.Long-term exposure to ELF-EMFs may pose potential risks to human memory and cognitive function.ELF-EMFs stimulation is also an effective treatment for neurodegenerative diseases such as Alzheimer's disease,but its mechanism is still unclear.Synaptic plasticity is a cellular and molecular mechanism of learning and memory.Therefore,it is of great significance to study the effects of ELF-EMFs stimulation on synaptic plasticity.Synaptic plasticity of Schaffer-CA1 pathway in the hippocampus is a classical model for evaluating learning and memory mechanisms.In this study,nine groups of ELF-EMFs stimulation parameters with different frequencies and intensities were selected from the hippocampal slices of SD rats.Long-term potentiation(LTP)was recorded by field excitatory postsynaptic potential(fEPSP)recording system.The ELF-EMFs parameters of 15Hz/2mT were determined for subsequent experiments.On this basis,three different ELF-EMFs stimulation modes were adopted from the point of view of the time point of ELF-EMFs stimulation,including the synchronization of ELF-EMFs stimulation before and after plasticity induction,LTP and Long-term Depression(LTD)experiments were carried out respectively.The results show that the three ELF-EMFs stimulation modes can be suppressed to some extent.The synaptic plasticity of Schaffer-CA1 pathway in the hippocampus was most obvious when ELF-EMFs stimulation and plasticity induction were synchronized.Finally,we completed the effect of ELF-EMFs stimulation on synaptic plasticity under very weak plasticity induction and in the presence ot NMDA receptor antagonist MK-801 in ACSF.The experimental results showed that ELF-EMFs and NMDA receptor-type synapses were dependent,and were regulators of NMDA receptor-type synaptic plasticity,not inducers.In conclusion,synaptic plasticity is the cellular mechanism of learning and memory.This study provides experimental basis for revealing the effects of EMF-ELFs stimulation on synaptic plasticity on memory and cognition,and has guiding significance for the parameter design of clinical ELF-EMFs therapeutic instrument. |
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