81 Gen. Physiol. Biophys. (2014), 33, 81–90 doi: 10.4149/gpb_2013059 Extremely low frequency magnetic fields induce oxidative stress in rat brain Pavan K. Manikonda 1,2 , Pilankatta Rajendra 3,4 , D. Devendranath 3 , B. Gunasekaran 3 , Channakeshava 3 , Shivakumara R. S. Aradhya 3 , Rao B. Sashidhar 1 and Chivukula Subramanyam 1,5 1 Department of Biochemistry, University College of Science, Osmania University, Hyderabad-500 007, AP, India 2 Division of Pre-clinical Toxicology, Sugen Life Sciences Pvt. Ltd. Tirupati-517 505, AP, India 3 Ultra High Voltage Research Laboratory, Central Power Research Institute, Hyderabad-500 039, AP, India 4 Central University of Kerala, Kasaragod-671 328, Kerala, India 5 Asian Institute of Gastroenterology, Hyderabad-500 082, AP, India Abstract. Te present investigation was conducted to understand the influence of long-term ex- posure of rats to extremely low frequency magnetic fields (ELF-MF), focusing on oxidative stress (OS) on different regions of rat’s brain. Male Wistar rats (21-day-old) were exposed to ELF-MF (50 Hz; 50 and 100 µT) for 90 days continuously; hippocampal, cerebellar and cortical regions from rats were analyzed for (i) reactive oxygen species (ROS), (ii) metabolites indicative of OS and (iii) antioxidant enzymes. In comparison to control group rats, the rats that were continuously exposed to ELF-MF caused OS and altered glutathione (GSH/GSSG) levels in dose-dependent manner in all the regions of the brain. Accumulation of ROS, lipid peroxidation end products and activity of superoxide dismutase in different regions was in the descending order of cerebellum > hippocampus > cortex. Decrement in GSH/GSSG levels and increment in glutathione peroxidase activity were in the descending order of hippocampus > cerebellum > cortex. Te continuous exposure to ELF-MF caused OS in all the examined regions of brain more significantly at 100 µT than at 50 µT. Varied influences observed in different regions of the brain, as documented in this study, may contribute to altered metabolic patterns in its related regions of the central nervous system, leading to aberrant neuronal functions. Key words: Central nervous system — Magnetic fields — Oxidative stress — Antioxidant enzymes Abbreviations: ELF-MF, extremely low frequency magnetic fields; GSH, glutathione (reduced); GSSG, glutathione (oxidized); GPx, glutathione peroxidase; SOD, superoxide dismutase; TBARS, thiobarbituric acid reactive substances. Correspondence to: Rao B. Sashidhar, Department of Biochemistry, University College of Science, Osmania University, Hyderabad- 500 007, AP, India E-mail: sashi_rao@yahoo.com Introduction A variety of central nervous system disorders, such as nervousness, anxiety, sleep disturbances and stress have been reported to occur in human population when exposed to magnetic field (Akerstedt et al. 1998; Jadidi et al. 2007; Funk et al. 2009), which has been attracting increased public interest. Previous epidemiological surveys conducted on human exposure to extremely low frequency (ELF) electro- magnetic fields (EMF) have implicated that ELF-EMF causes several health disorders in humans, such as various types of brain cancers, depression and suicide, neurodegenerative, cardiovascular and reproductive diseases (Central Power Research Institute Report 2000; Ahlbom et al. 2001; World Health Organization Report, 2007; Schuz and Ahlbom 2008;