Extremely low frequency electromagnetic field exposure promotes differentiation of pituitary corticotrope-derived AtT20 D16V cells.
The pituitary corticotrope-derived AtT20 D16V cell line responds to nerve growth factor (NGF) by extending neurite-like processes and differentiating into neurosecretory-like cells. The aim of this work is the study of the effect of extremely low frequency electromagnetic fields (ELF-EMF) at a frequency of 50 Hz on these differentiation activities. To establish whether exposure to the field could influence the molecular biology of the cells, they were exposed to a magnetic flux density of 2 milli-Tesla (mT). Intracellular calcium ([Ca2+]i) and intracellular pH (pHi) were monitored in single exposed AtT20 D16V cells using fluorophores Indo-1 and SNARF for [Ca2+]i and pHi, respectively. Single-cell fluorescence microscopy showed a statistically significant increase in [Ca2+]i followed by a drop in pHi in exposed cells. Both scanning electron microscopy (SEM) and transmission microscopy of exposed AtT20 D16V cells show morphological changes in plasma membrane compared to non-exposed cells; this modification was accompanied by a rearrangement in actin filament distribution and the emergence of properties typical of peptidergic neuronal cells-the appearance of secretory-like granules in the cytosol and the increase of synaptophysin in synaptic vesicles, changes typical of neurosecretory-like cells. Using a monoclonal antibody toward the neurofilament protein NF-200 gave additional evidence that exposed cells were in an early stage of differentiation compared to control. Pre-treatment with 0.3 microM nifedipine, which specifically blocks L-type Ca2+ channels, prevented NF-200 expression in AtT20 D16V exposed cells. The above findings demonstrate that exposure to 50 Hz ELF-EMF is responsible for the premature differentiation in AtT20 D 16 V cells.
Lisi
Antonella
A
Consiglio Nazionale delle Ricerche Istituto di Neurobiologia e Medicina Molecolare, Rome, Italy.
Ledda
Mario
M
Rosola
Emanuela
E
Pozzi
Deleana
D
D'Emilia
Enrico
E
Giuliani
Livio
L
Foletti
Alberto
A
Modesti
Andrea
A
Morris
Stephen J
SJ
Grimaldi
Settimio
S
D008841:Actin Cytoskeleton / Q000378:metabolism / Q000528:radiation effects; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000528:radiation effects*; D002454:Cell Differentiation / Q000528:radiation effects*; D002478:Cells, Cultured; D004574:Electromagnetic Fields / Q000009:adverse effects*; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D016900:Neurofilament Proteins / Q000378:metabolism / Q000528:radiation effects*; D009543:Nifedipine / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000000981:diagnostic imaging* / Q000378:metabolism; D011859:Radiography; D051381:Rats
D020746:Calcium Channels, L-Type; D016900:Neurofilament Proteins; D009543:Nifedipine; D002118:Calcium