Effects of 60 Hz electromagnetic field exposure on APP695 transcription levels in differentiating human neuroblastoma cells Raj R. Rao a , Jaroslava Halper b , William S. Kisaalita a,b, * a Cellular Bioengineering Laboratory, Biological and Agricultural Engineering Department, University of Georgia, Athens, GA 30602, USA b Soft Tissue Center, Department of Pathology, University of Georgia, Athens, GA 30602, USA Accepted 29 October 2001 Abstract Epidemiological studies have suggested that workers with primary occupation that are likely to have resulted in the medium-to-high extremely low frequency (ELF) electromagnetic field (EMF) exposure are at increased risk of Alzheimer’s disease (AD) pathogenesis. As a first step in investigating the possibility of an association between the ELF-EMF exposure and AD at the cellular level, we have used the differentiating IMR-32 neuroblastoma cells. In double-blind experiments, IMR-32 cells were exposed to the magnetic field intensities of 50, 100, and 200 AT at a frequency of 60 Hz for a period of 4 h at the three ages of differentiation (2, 10, and 16 days after incubation in differentiation medium). We used a custom-made Helmholtz coil setup driven by a 60-Hz sinusoidal signal from a function generator and an in-house built power amplifier. Total RNA extracted from the exposed cells was separated by the agarose gel electrophoresis and transferred to a nylon membrane for the northern hybridization. Digoxygenin-labeled APP695 RNA probes were used to detect changes in the APP695 mRNA levels in response to the ELF-EMF exposure. The results reported herein provided no support for any relationship between the APP695 gene transcription and IMR-32 differentiation age, as well as the magnetic field exposure. This study constitutes the first step towards investigating the possibility of an association between the ELF-EMF exposure and AD manifestations at the cellular level. D 2002 Elsevier Science B.V. All rights reserved. Keywords: ELF-EMF; Alzheimer’s disease; Helmholtz coil; IMR-32 1. Introduction There is a significant interest in the biological effects of the power frequency (60 Hz) electromagnetic fields (EMF). Health professionals, government administrators and regu- lators, scientists and engineers, and the general public are interested in this health issue. The focus of research in this area at the cellular level is to identify cellular responses to EMFs, to develop a dose threshold for such interactions and use such information to formulate and test the appropriate interaction mechanisms. Numerous studies have been undertaken during the past two decades to examine the biological effects in the cells exposed to the extremely low frequency (ELF)-EMFs, and the major interest has been to decipher the biological mechanism and site of interaction [1,2]. Several studies have demonstrated the possibility that a mechanism of interaction of the magnetic fields is through a direct reaction with DNA rather than through the generally accepted signal transduction cascade [3]. In these condi- tions, the cell is responding to magnetic field exposure in a manner analogous to that observed under the conditions of cellular stress, such as an increase in the transcripts for some heat shock genes [4,5]. Early studies in which different cells were exposed to EMFs pointed towards the general changes in the gene transcription [6–10] but did not address the more important issue of which specific genes were affected [11]. Specific mRNA level measurements in response to the ELF-EMF exposure showed an increase in the levels of histone H3 and p53 mRNA [12], IGF-II [13], histone H2B, v-myc [14], c-fos [15], and c-myc [16]. However, it is important to note that these experiments have been difficult to replicate [17 – 20]. In the epidemiological studies, it has been shown that the workers with primary occupations that are likely to have resulted in the medium-to-high ELF-EMF exposure are at an increased risk of Alzheimer’s disease (AD) [21,22]. Alzheimer’s disease is one of the most serious 1567-5394/02/$ - see front matter D 2002 Elsevier Science B.V. All rights reserved. PII:S1567-5394(02)00004-X * Corresponding author. Cellular Bioengineering Laboratory, Bio- logical and Agricultural Engineering Department, University of Georgia, Athens, GA 30602, USA. Tel.: +1-706-542-0835; fax: +1-706-542-8806. E-mail address: williamk@engr.uga.edu (W.S. Kisaalita). www.elsevier.com/locate/bioelechem Bioelectrochemistry 57 (2002) 9 – 15