Extremely low-freauency electromagnetic fields promote in vitro neurogenesis via upregulation of Cav1-channel activity

We previously reported that exposure to extremely low-frequency electromagnetic fields (ELFEFs) increases the expression and function of voltage-gated Ca²⁺ channels and that Ca²⁺ influx through Ca_v1 channels plays a key role in promoting the neuronal differentiation of neural stem/progenitor cells (NSCs). The present study was conducted to determine whether ELFEFs influence the neuronal differentiation of NSCs isolated from the brain cortices of newborn mice by modulating Ca _v1-channel function. In cultures of differentiating NSCs exposed to ELFEFs (1 mT, 50 Hz), the percentage of cells displaying immunoreactivity for neuronal markers (β-111-tubulin, MAP2) and for Ca_v1.2 and Ca_v1.3 channels was markedly increased. NSC-differentiated neurons in ELFEF-exposed cultures also exhibited significant increases in spontaneous firing, in the percentage of cells exhibiting Ca²⁺ transients in response to KCI stimulation, in the amplitude of these transients and of Ca ²⁺ currents generated by the activation of Ca_v1 channels. When the Ca_v1-channel blocker nifedipine (5 μM) was added to the culture medium, the neuronal yield of NSC differentiation dropped significantly, and ELFEF exposure no longer produced significant increases in β-III-tubulin- and MAP2-immunoreactivity rates. In contrast, the effects of ELFEFs were preserved when NSCs were cultured in the presence of either glutamate receptor antagonists or Ca_v2.1- and Ca_v2.2- channel blockers. ELFEF stimulation during the first 24 h of differentiation caused Ca_v1-dependent increases in the number of cells displaying CREB phosphorylation. Our data suggest that ELFEF exposure promotes neuronal differentiation of NSCs by upregulating Ca_v1-channel expression and function.