EARLY REGIONAL CHANGES OF GFAP MESSENGER-RNA IN RAT HIPPOCAMPUS AND DENTATE GYRUS DURING SOMAN-INDUCED SEIZURES

WE investigated the time course of GFAP levels in the hippocampal form ation during the first 24 h following soman intoxication in rats. GFAP mRNA expression was detected by in situ hybridization. Intense GFAP m RNA expression was present in the molecular layer of the dentate gyrus as early as 6 h after intoxication. This expression was comparatively lower in other dentate gyrus layers and hippocampal CA1, CA3 and CA4 areas and seemed to be related to excessive neuronal activity. Histopa thological examination demonstrated that GFAP expression in dentate gy rus is not correlated with lesions. The high astrocytic reactivity in the molecular layer of the dentate gyrus is discussed in relation to t he maintenance of the homeostasis of glutamate and of synaptic plastic ity in this area during soman intoxication.