Extremely Low Frequency Electromagnetic Fields Facilitate Vesicle Endocytosis by Increasing Presynaptic Calcium Channel Expression at a Central Synapse

Abstract

Accumulating evidence suggests significant biological effects caused by extremely low frequency electromagnetic fields (ELF-EMF). Although exo-endocytosis plays crucial physical and biological roles in neuronal communication, studies on how ELF-EMF regulates this process are scarce. By directly measuring calcium currents and membrane capacitance at a large mammalian central nervous synapse, the calyx of Held, we report for the first time that ELF-EMF critically affects synaptic transmission and plasticity. Exposure to ELF-EMF for 8 to 10 days dramatically increases the calcium influx upon stimulation and facilitates all forms of vesicle endocytosis, including slow and rapid endocytosis, endocytosis overshoot and bulk endocytosis, but does not affect the RRP size and exocytosis. Exposure to ELF-EMF also potentiates PTP, a form of short-term plasticity, increasing its peak amplitude without impacting its time course. We further investigated the underlying mechanisms and found that calcium channel expression, including the P/Q, N, and R subtypes, at the presynaptic nerve terminal was enhanced, accounting for the increased calcium influx upon stimulation. Thus, we conclude that exposure to ELF-EMF facilitates vesicle endocytosis and synaptic plasticity in a calcium-dependent manner by increasing calcium channel expression at the nerve terminal.

Effects of Fifty-Hertz Electromagnetic Fields on Granulocytic Differentiation of ATRA-Treated Acute Promyelocytic Leukemia NB4 Cells

“…In recent decades, the scientific community has extensively investigated the possible effects of ELF-EMFs on biological systems both in vitro and in vivo [2-6]. Some epidemiological studies offered evidence of a correlation between exposure to ELF-EMFs and increased incidence of brain, breast and haematological malignancies, but these results have not been confirmed by other studies [7-9].…”

Exposure to extremely low frequency electromagnetic fields alters the behaviour, physiology and stress protein levels of desert locusts

“…In response to electrical stimulation of tail afferents the spikes and synaptic potentials in LG increased in amplitude during exposure leading the authors to suggest that these changes could lead to an increase in the sensitivity of LG. They also suggest that these effects were caused by the action of the magnetic fields on Ca 2+ channels as they are in mice where EMF exposure leads to an increase in Ca 2+ channels15.…”

“…More recent studies on ELF-EMF over 1mT have been restricted to in vitro cell systems but have shown marked effects, including an increase in HSP70 transcription that leads to protection of chronic hypoxia20, and Ca 2+ channel expression in neuronal synapses15 leading to effects on neuronal activity. In insects such as the locust stress or heat shock leads to a marked increase in Hsp levels2122 that play a key role in thermoprotection.…”

Disruption of Gpr45 causes reduced hypothalamic POMC expression and obesity

“…Whole-cell patch clamp recordings of neurons from P14 male mice were performed as previously described (78,79). Briefly, pups were decapitated and blocks of tissue containing the arcuate nucleus were placed in artificial cerebrospinal fluid solution (125 mM NaCl, 25 mM NaHCO 3 , 3 mM myo-inositol, 2 mM Napyruvate, 2.5 mM KCl, 1.25 mM NaH 2 PO 4 , 0.4 mM ascorbic acid, 25 mM glucose, 3 mM MgCl 2 , and 0.05 mM CaCl 2 ).…”