Abstract
The effects of lateral fluid percussion injury (FPI) on the propagation of neuronal activity in the rat hippocampal CA1 area were investigated by using optical recording techniques(voltage-sensitive dye(RH482) and HR Deltaron 1700 system).Anesthetized male Wistar rats were subjected to lateral FPI of moderate impact (4.2atm) using the FPI device(HPD-1700) or sham treatment. After a survival period of 1 week from the FPI or sham-operation, neuronal activities induced by electrical stimulation of Schaffer collaterals were recorded from the hippocampal CA1 region in horizontal brain slice preparations. In FPI rats, the neuronal activity was markedly enhanced in both ipsilateral and contralateral hippocampal CA1 region to the impact compared to those in the sham-operated rats.In addition, we evaluated the histopathological changes following the lateral FPI in rats at 1 week postinjury. The hippocampus stained with hematoxylin and eosin demonstrated degeneration in the CA1 area and glial fibrillary acidic protein(GFAP) immunostaining revealed reactive astrocytosis in the cortex and hippocampus. These changes were predominantly in the injury side.These results suggest that the moderate impact of lateral FPI produces hyperexcitability of hippocampal CA1 neurons. [Jpn J Physiol 55 Suppl:S233 (2005)]
