Possible cause for altered spatial cognition of prepubescent rats exposed to chronic radiofrequency electromagnetic radiation.
Narayanan SN, Kumar RS, Karun KM, Nayak SB, Bhat PG.Possible cause for altered spatial cognition of prepubescent rats exposed to chronic radiofrequency electromagnetic radiation. Metab Brain Dis. 2015 Jun 3. [Epub ahead of print]
The effects of chronic and repeated radiofrequency electromagnetic radiation (RFEMR) exposure on spatial cognition and hippocampal architecture were investigated in prepubescent rats. Four weeks old male Wistar rats were exposed to RF-EMR (900 MHz; SAR-1.15 W/kg with peak power density of 146.60 μW/cm2) for 1 h/day, for 28 days. Followed by this, spatial cognition was evaluated by Morris water maze test. To evaluate the hippocampal morphology; H&E staining, cresyl violet staining, and Golgi-Cox staining were performed on hippocampal sections. CA3 pyramidal neuron morphology and surviving neuron count (in CA3 region) were studied using H&E and cresyl violet stained sections. Dendritic arborization pattern of CA3 pyramidal neuron was investigated by concentric circle method. Progressive learning abilities were found to be decreased in RF-EMR exposed rats. Memory retention test performed 24 h after the last training revealed minor spatial memory deficit in RF-EMR exposed group. However, RF-EMR exposed rats exhibited poor spatial memory retention when tested 48 h after the final trial. Hirano bodies and Granulovacuolar bodies were absent in the CA3 pyramidal neurons of different groups studied. Nevertheless, RF-EMR exposure affected the viable cell count in dorsal hippocampal CA3 region. RF-EMR exposure influenced dendritic arborization pattern of both apical and basal dendritic trees in RF-EMR exposed rats. Structural changes found in the hippocampus of RF-EMR exposed rats could be one of the possible reasons for altered cognition.
The exposure mode and dose were replicated in this study with respect to earlier published reports (Narayanan et al. 2010, 2013) with minor modifications. Briefly, animals of RF-EMR group (3 in each home cage) were exposed to RF-EMR from an activated mobile phone (GSM; 900 MHz) with a permitted power level of 2 W and SAR specification 1.15 W/kg. While exposing mobile phone to rats it was inserted in a wire mesh cage (12 × 7 × 7 cm) and placed at the center of the animal home cage. The purpose of doing this was to prevent the effect of heat emitting from the phone on rats. The phone was continuously activated by giving unattended calls (50 calls/h) during the exposure period. Duration of exposure was 1 h/day (7 days in a week) for 28 days. This was done using a mobile phone auto dialer unit (indigenously made for the current study), which can dials four phones at a time. The contact between dialing phones and call receiving phones can be changed from one to four with respect to the need.
Our observations from the current study provide certain indications for biological effects of mobile phone radiation on prepubescent rats. Growing body of research indicates that, RF-EMR exposure perturb oxidant, antioxidant defence system in the brain (Kesari et al. 2013; Megha et al. 2012). This therefore does not favor appropriate functioning of nerve cells. Whenever the physiological limit is attained, either the cell functions abnormally or dies. We term it as structural change or morphological change. Often what is happening in cellular level is expressed in the behaviour of an organism. However, it is highly difficult to categorically join up biochemical change, morphological change and then behaviour. In the current study we have looked into one of the possibilities, such as ‘hippocampal fragility’ and altered spatial cognition. There might be several other reasons or mechanisms involved in the altered spatial cognition found with rats and these have to be further evaluated. Another crucial question which has to be answered is that, whether RF-EMR induced effects are different in different individuals? This is because there are mechanisms in the body to prevent or resist the insult from external stressors. Currently we do not know this as there are no concrete experimental evidences that pin point or demonstrate this innate preventive/restrain mechanisms present in neurons under RF-EMR exposure. Further study in this regard will reveal much clearer picture of body’s (especially brain) innate mechanisms which would withstand the potential threat caused by RF-EMR.
Chronic and repeated RF-EMR exposure from a mobile phone altered spatial cognition to an extent in rats as demonstrated by their deficits in progressive learning, consolidation and retrieval of spatial information in a spatial cognition testing paradigm. It also induced dendritic remodeling and decreased viable cell number in CA3 region of the hippocampus. Structural changes found in the hippocampus of RF-EMR exposed rats could be one of the possible reasons for altered cognition.
Joel M. Moskowitz, Ph.D., Director
Center for Family and Community Health
School of Public Health
University of California, Berkeley
Electromagnetic Radiation Safety
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