Effects of styrene exposure on middle latency auditory evoked potentials and glial cells in rat

Neurophysiological and neurochemical effects of treatment with styrene at 400 mg/kg and 800 mg/kg per day for two weeks were investigated. Significant delay in latencies of No, Po, Na, and Pa components of middle latency auditory-evoked potentials (MAEPs) was observed in dose- and time-dependent manner after exposure. Moreover, the peak to peak intervals of No-Po, Po-Na, and Na-Pa components were also prolonged in the 800 mg/kg styrene-treated group compared with those in both the 400 mg/kg styrene-treated group and the control. However, no significant change of amplitudes was observed. Furthermore, brain tissue damage was examined by measuring the expression of glial fibrillary acidic protein (GFAP) immunocytochemistry using confocal laser scanning microscopy. Both styrene-treated groups had a marked increase of GFAP expression in cerebral cortex and hippocampus compared to those in the control group. These results of delay in the latency and the peak to peak interval of (MAEPs) components and increased expression of GFAP in cerebral cortex and hippocampus indicate that the effects of styrene on the central nervous system were not only in electrophysiological changes but also in the structure of cerebral cortex and hippocampus.