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Extremely low frequency electromagnetic field exposure promotes differentiation of pituitary corticotrope‐derived AtT20 D16V cells
Author(s) -
Lisi Antonella,
Ledda Mario,
Rosola Emanuela,
Pozzi Deleana,
Emilia Enrico D′,
Giuliani Livio,
Foletti Alberto,
Modesti Andrea,
Morris Stephen J.,
Grimaldi Settimio
Publication year - 2006
Publication title -
bioelectromagnetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.435
H-Index - 81
eISSN - 1521-186X
pISSN - 0197-8462
DOI - 10.1002/bem.20255
Subject(s) - corticotropic cell , neurite , intracellular , synaptophysin , biophysics , cytosol , cell culture , microbiology and biotechnology , biology , chemistry , pituitary gland , endocrinology , immunohistochemistry , hormone , biochemistry , immunology , in vitro , enzyme , genetics
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 ([Ca 2+ ] i ) and intracellular pH (pH i ) were monitored in single exposed AtT20 D16V cells using fluorophores Indo‐1 and SNARF for [Ca 2+ ] i and pH i , respectively. Single‐cell fluorescence microscopy showed a statistically significant increase in [Ca 2+ ] i followed by a drop in pH i 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 µM nifedipine, which specifically blocks L‐type Ca 2+ 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. Bioelectromagnetics 27:641–651, 2006. © 2006 Wiley‐Liss, Inc.