Modulating effects of on‐line low frequency electromagnetic fields on hippocampal long‐term potentiation in young male Sprague‐Dawley rat

Abstract The low frequency electromagnetic fields (LF‐EMFs) are attracting more attention and studied deeply because of their effects on human health and biology. Recent reports indicate that exposure of rats to LF‐EMFs induces persistent changes in neuronal activity. The studies used the following standard methods: the rats or rat brain slices were first stimulated in an external electromagnetic exposure system, and then moved to a patch clamp perfusion chamber to record electrophysiological characteristics (off‐line magnetic exposure). However, this approach is susceptible to many disturbances, such as the effects of brain slice movements. In this paper, we describe a novel patch‐clamp setup which is modified to allow accurate on‐line LF‐EMFs stimulation. We performed the computational simulations of the stimulation coils to describe the uniformity of the distribution of the on‐line magnetic field. The 0.5, 1, 2 mT magnetic field of 15 Hz, 50 Hz, and 100 Hz was produced and applied to slices to study the effect of LF‐EMFs on synaptic plasticity. We demonstrated that the slope of field excitatory postsynaptic potentials (fEPSPs) decreased significantly under the priming on‐line uninterrupted or pulsed sinusoidal LF‐EMFs stimulation. In the present study, we investigated whether LF‐EMFs can induce long‐term potentiation (LTP) in male Sprague‐Dawley rat hippocampal slices in vitro. Interestingly, these results highlight the role of 100 Hz pulsed sinusoidal LF‐EMFs only as a modulator, rather than an LTP inducer.