Investigation of Possible Behavioural and Molecular Effects of Mobile Phone Exposure on Rats

Authors: Ç. Gökçek-Saraç, Ş. Özen, N. Derin

Abstract:

The N-methyl-D-aspartate (NMDA)-dependent pathway is the major intracellular signaling pathway implemented in both short- and long-term memory formation in the hippocampus which is the most studied brain structure because of its well documented role in learning and memory. However, little is known about the effects of RF-EMR exposure on NMDA receptor signaling pathway including activation of protein kinases, notably Ca²⁺/calmodulin-dependent protein kinase II alpha (CaMKIIα). The aim of the present study was to investigate the effects of acute and chronic 900 MHz RF-EMR exposure on both passive avoidance behaviour and hippocampal levels of CaMKIIα and its phosphorylated form (pCaMKIIα). Rats were divided into the following groups: Sham rats, and rats exposed to 900 MHz RF-EMR for 2 h/day for 1 week (acute group) or 10 weeks (chronic group), respectively. Passive avoidance task was used as a behavioural method. The hippocampal levels of selected kinases were measured using Western Blotting technique. The results of passive avoidance task showed that both acute and chronic exposure to 900 MHz RF-EMR can impair passive avoidance behaviour with minor effects on chronic group of rats. The analysis of western blot data of selected protein kinases demonstrated that hippocampal levels of CaMKIIα and pCaMKIIα were significantly higher in chronic group of rats as compared to acute groups. Taken together, these findings demonstrated that different duration times (1 week vs 10 weeks) of 900 MHz RF-EMR exposure have different effects on both passive avoidance behaviour of rats and hippocampal levels of selected protein kinases.

Keywords: Hippocampus, protein kinase, rat, RF-EMR.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1131067

References:

[1] L. R. Squire, “Memory systems of the brain: A brief history and current perspective”, Neurobiology of learning and memory., vol. 82, pp. 171-177, 2004.
[2] B. Leuner, E. Gould, “Structural Plasticity and Hippocampal Function,” Annu Rev Psychol., vol 61, pp. 111-C3, 2010.
[3] N. Rebola, B. N. Srikumar, C. Mulle, “Activity dependent synaptic plasticity of NMDA receptors,” J. Physiol., vol. 588, pp. 93–99, 2010.
[4] M. T. Swulius, M. N. Waxham, “Ca2+/Calmodulin-dependent Protein Kinases,” Cell Mol Life Sci. vol. 65, no. 17, pp. 2637-2657, 2008.
[5] R. J. Colbran, A. M. Brown, “Calcium/calmodulin-dependent protein kinase II and synaptic plasticity,” Curr Opin Neurobiol., vol. 14, no. 3, pp.318-327, 2004.
[6] J. E. Lisman, C. C. McInytre, “Synaptic plasticity: a molecular memory switch”, Current Biology., vol. 11, pp. 788-791, 2001.
[7] S. Bhargava, M. B. Motwani, V. M. Patni, “Effect of handled mobile phone use on parptid gland salivary flow rate and volume”, Oral Surg Oral Med Oral Pathol Oral Radiol., vol. 114, no. 2, pp. 200-206, 2012.
[8] S. N. Narayanan, R. S. Kumar, B. K. Potu, S. Nayak, P.G. Bhat, M. Mailankot, “Effect of radio-frequency electromagnetic radiations (RF-EMR) on passive avoidance behavior and hippocampal morphology in Wistar rats,” Ups. J. Med. Sci. vol. 115, pp. 91–96. 2010.
[9] S. Singh, N. Kapoor, “Health Implications of Electromagnetic Fields, Mechanisms of Action, and Research Needs”, Advances in Biology., Article ID 198609, 2014.
[10] M. Jadidi, S. M. Firoozabadi, A. Rashidy-Pour, A. A. Sajadi, H. Sadeghi, A. A. Taherian, “Acute exposure to a 50 Hz magnetic field impairs consolidation of spatial memory in rats,” Neurobiol. Learn. Mem., vol. 88, pp. 387–392, 2007.
[11] E. Foroozandeh, H. Ahadi, P. Askari, M. S. Naeini, “Effects of single, brief exposure to an 8 mT electromagnetic field on avoidance learning in male and female mice,” Psychol. Neurosci. vol. 4, pp. 143–148, 2011.
[12] S. N. Narayanan, R. S. Kumar, B. K. Potu, S. Nayak, M. Mailankot, “Spatial memory perfomance of wistar rats exposed to mobile phone”, Clinics., vol. 64, no. 3, pp. 231-234, 2009.
[13] D. LeBlanc, D. Hatcher, R. Post, “Finite-difference time-domain front-end utility”, Brooks Airforce Base, Texas, USA. 2000.
[14] A. Peyman, A. A. Rezazadeh, C. Gabriel, “Changes in the dielectric properties of rat tissue as a fuction of age at microwave frequencies”, Phys. Med. Biol., vol. 46, pp. 1617-1629, 2001.
[15] P. K. Manikonda, P. Rajendra, D. Devendranath, B. Gunasekaran, Channakeshava, R. S. S. Aradhya, R. B. Sashidhar, C. Subramanyam, “Influence of extremely low frequency magnetic fields on Ca2+ signaling and NMDA receptor functions in rat hippocampus,” Neurosci. Lett. vol. 413, pp. 145–149, 2007.
[16] L. Xiong, C. F. Sun, J. Zhang, Y. B. Gao, L. F. Wang, H. Y. Zuo, S. M. Wang, H. M. Zhou, X. P. Xu, J. Dong, B. W. Yao, L. Zhao, R. Y. Peng, “Microwave Exposure Impairs Synaptic Plasticity in the Rat Hippocampus and PC12 Cells through Over-activation of the NMDA Receptor Signaling Pathway,” Biomed. Environ. Sci., vol. 28, pp. 13–24, 2015.