title: Developmental profiles of growth-associated protein (Gap43), Ngfb, Bndf and Ntf4 mRNA levels in the rat forebrain after exposure to 60 Hz magnetic fields.
abstract: Fischer 344 rats were exposed to 60 Hz magnetic fields (EMFs) during gestation and lactation. Rats received continuous exposure to 2-, 200- or 1000-microT magnetic fields for 18.5 h per day, 7 days a week, or sham exposure (sham controls). During postnatal development, on postnatal days 1, 3, 6, 9, 15 and 20, forebrain tissue from male pups was examined for alterations in mRNA level for developmentally regulated central nervous system-specific proteins. Alterations in these factors during critical periods of development could result in alterations in the final neural network. Gap43 (growth-associated protein 43) mRNA was measured by Northern hybridization as a developmental indicator of axonal growth during the development of the neuron. Between postnatal days 1 and 9, detectable levels of Gap43 mRNA displayed a similar pattern across all sham control and exposure groups. In addition to Gap43, mRNA levels for the nervous system-specific growth factors ciliary neurotrophic factor (Cntf), brain-derived neurotrophic factor (Bdnf), beta nerve growth factor (Ngfb), neurotrophin-3 (Ntf3), and neurotrophin-4 (Ntf4) were examined by RNase protection assay. While there is public concern for developmental neurotoxicity associated with exposure to EMFs, these data, generated from animals exposed to 2-, 200- or 1000-microT magnetic fields during both gestational and lactational periods of development, suggest that under these conditions no significant alterations in these critical factors for brain development occur.
authors.affiliation: Neurotoxicology Group, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
authors.forename: G J
authors.initials: GJ
authors.lastname: Harry
authors.forename: M
authors.initials: M
authors.lastname: Bartenbach
authors.forename: W
authors.initials: W
authors.lastname: Haines
authors.forename: A
authors.initials: A
authors.lastname: Bruccoleri
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000833:Animals, Suckling; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D004574:Electromagnetic Fields / Q000009:adverse effects*; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D019922:GAP-43 Protein / Q000235:genetics / Q000378:metabolism*; D051100:Glial Cell Line-Derived Neurotrophic Factor; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects*; D020932:Nerve Growth Factor / Q000235:genetics / Q000378:metabolism; D009414:Nerve Growth Factors / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D020933:Neurotrophin 3 / Q000235:genetics / Q000378:metabolism; D016548:Prosencephalon / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011916:Rats, Inbred F344; D017207:Rats, Sprague-Dawley; D012260:Ribonucleases / Q000378:metabolism
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D019922:GAP-43 Protein; C495041:Gdnf protein, rat; D051100:Glial Cell Line-Derived Neurotrophic Factor; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D020933:Neurotrophin 3; D012333:RNA, Messenger; D020932:Nerve Growth Factor; D012260:Ribonucleases; C073922:neurotrophin 4