Induction of Rheb mRNA following middle cerebral artery occlusion in the rat

RHEB is a recently identified member of the Ras superfamily and is an immed iate early gene that is rapidly and transiently induced in the hippocampal granule cells by NMDA-dependent synaptic activity in the long term potentia tion paradigm. The close homologies with Pas and its rapid inducibility str ongly suggest that Rheb shares many biochemical and signaling properties wi th Ras. The present study investigated the effect of middle cerebral artery (MCA) occlusion on the expression of Rheb mRNA in the rat brain. In situ h ybridization autoradiography showed that Rheb mRNA was induced in the exten sive regions of cerebral cortex and medial striatum surrounding the ischemi c region and bilateral hippocampal formation following MCA occlusion. The i nduction of Rheb mRNA in the cingulate cortex persisted prominently at 24 h of MCA occlusion. Although the Rheb mRNA induction in the medial striatum and hippocampal formation decreased after 8 h of occlusion, it still remain ed significant at 24 h of occlusion. The data suggest the possibility that Ras signaling pathways can be implicated in the cerebral ischemia-elicited events through NMDA receptor activation. NeuroReport 10:1055-1059 (C) 1999 Lippincott Williams & Wilkins.