Effects of radiofrequency exposure on the GABAergic system in the rat cerebellum: clues from semi-quantitative immunohistochemistry

The widespread use of cellular phones raises the problem of interaction of electromagnetic fields with the central nervous system (CNS). In order to m easure these effects on neurotransmitter content in the CNS, we developed a protocol of neurotransmitter detection based on immunohistochemistry and i mage analysis. Gamma-vinyl-GABA (GVG), an inhibitor of the GABA-transaminas e was injected in rats to increase GABA concentration in the CNS. The cellu lar GABA contents were then revealed by immunohistochemistry and semi-quant ified by image analysis thanks to three parameters: optical density (O.D.), staining area, and number of positive cells. The increase in cerebellar GA BA content induced by GVG 1200 mg/kg was reflected in these three parameter s in the molecular and the granular layers. Therefore, control of immunohis tochemistry parameters, together with appropriate image analysis, allowed b oth the location and the detection of variations in cellular neurotransmitt er content. This protocol was used to investigate the effects of exposure t o 900 MHz radiofrequencies on cerebellar GABA content. Both pulsed emission with a specific absorption rate (SAR) of 4 W/kg and continuous emission wi th high SAR (32 W/kg) were tested. We observed a selective diminution of th e stained processes area in the Purkinje cell layer after exposure to pulse d radiofrequency and, in addition, a decrease in O.D. in the three cell lay ers after exposure to continuous waves. Whether this effect is, at least pa rtly, due to a local heating of the tissues is not known. Overall, it appea rs that high energetic radiofrequency exposure induces a diminution in cell ular GABA content in the cerebellum. (C) 2001 Elsevier Science B.V. All rig hts reserved.