EFFECT OF GLOBAL SYSTEM FOR MOBILE COMMUNICATION MICROWAVE EXPOSURE ON THE GENOMIC RESPONSE OF THE RAT-BRAIN

The acute effect of global system for mobile communication (GSM) micro wave exposure on the genomic response of the central nervous system wa s studied in rats by measuring changes in the messenger RNAs of hsp70, the transcription factor genes c-fos and c-jun and the glial structur al gene GFAP using in situ hybridization histochemistry. Protein produ cts of transcription factors, stress proteins and marker proteins of a stroglial and microglial activation were assessed by immunocytochemist ry. Cell proliferation was evaluated by bromodeoxyuridine incorporatio n. A special GSM radiofrequency test set, connected to a commercial ce llular phone operating in the discontinuous transmission mode, was use d to simulate GSM exposure. The study was conducted at time averaged a nd brain averaged specific absorption rates of 0.3 W/kg (GSM exposure) , 1.5 W/kg (GSM exposure) and 7.5 W/kg (continuous wave exposure), res pectively. Immediately after exposure, in situ hybridization revealed slight induction of hsp70 messenger RNA in the cerebellum and hippocam pus after 7.5 W/kg exposure, but not at lower intensities. A slightly increased expression of c-fos messenger RNA was observed in the cerebe llum, neocortex and piriform cortex of all groups subjected to immobil ization, but no differences were found amongst different exposure cond itions. C-jun and GFAP messenger RNAs did not increase in any of the e xperimental groups. 24 h after exposure, immunocytochemical analysis o f FOS and JUN proteins (c-FOS, FOS B, c-JUN, JUN B, JUN D), of HSP70 o r of KROX-20 and -24 did not reveal any alterations. Seven days after exposure, neither increased cell proliferation nor altered expression of astroglial and microglial marker proteins were observed. In conclus ion, acute high intensity microwave exposure of immobilized rats may i nduce some minor stress response but does not result in lasting adapti ve or reactive changes of the brain. (C) 1997 IBRO. Published by Elsev ier Science Ltd.