title: Effect of exposure to extremely low frequency magnetic fields on melatonin levels in calves is seasonally dependent.
abstract: The question of health effects of extremely low frequency (50/60 Hz) magnetic fields (ELFMF) has been widely discussed, but the mechanisms of interaction of these fields with biological systems for intensities relevant to human and animal exposure are still under question. The melatonin (MLT) hypothesis suggests that exposure to ELFMF might decrease MLT production thereby promoting cancerogenesis. So far, most studies of MLT secretion under exposure to ELFMF reported negative or inconsistent results. Here, we measured salivary MLT in 1-2 months old cattle calves exposed to 50 Hz-MF in the hundreds of nT-range. We found an inhibitory effect of the ELFMF upon MLT secretion in winter (in accordance with the MLT hypothesis). In contrast, in summer, MLT concentration was increased by ELFMF exposure (contrary to the MLT hypothesis). The inhibitory effect in winter was much stronger than the positive effect in summer. We hypothesize that this season-dependent effect upon MLT synthesis might by mediated by an effect of ELFMF upon the serotonin metabolism and conclude that future tests of ELFMF effects should also measure serotonin levels and consider association with the seasonal effects (photoperiod or temperature) during the exposure.
authors.affiliation: Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6, Czech Republic.
authors.forename: Tereza
authors.initials: T
authors.lastname: Kolbabová
authors.affiliation: Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6, Czech Republic.|Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Universitätsstr. 2, 45117 Essen, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Pascal Malkemper
authors.affiliation: Department of Ethology, Institute of Animal Science, Přátelství 815, 104 00 Prague-Uhříněves, Czech Republic.
authors.forename: Luděk
authors.initials: L
authors.lastname: Bartoš
authors.affiliation: Research Center on Environmental Health and Work Health, School of Public Health, Université Libre de Bruxelles, CP 593, Route de Lennik 808, 1070 Brussels, Belgium.
authors.forename: Jacques
authors.initials: J
authors.lastname: Vanderstraeten
authors.affiliation: Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6, Czech Republic.
authors.forename: Marek
authors.initials: M
authors.lastname: Turčáni
authors.affiliation: Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6, Czech Republic.|Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Universitätsstr. 2, 45117 Essen, Germany.
authors.forename: Hynek
authors.initials: H
authors.lastname: Burda
mesh_terms: D000818:Animals; D002417:Cattle; D005260:Female; D060526:Magnetic Fields / Q000009:adverse effects; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D008954:Models, Biological; D012463:Saliva / Q000378:metabolism; D012621:Seasons
chemical_list: D008550:Melatonin