FOCAL ISCHEMIA INDUCES EXPRESSION OF THE DNA DAMAGE-INDUCIBLE GENE GADD45 IN THE RAT-BRAIN

GADD45 is a DNA damage-inducible gene that accelerates DNA excision re pair and can be induced by a variety of DNA-damaging stimuli in mammal ian cells. We investigated the expression of GADD45 mRNA and protein u sing in situ hybridization and immunocytochemistry in rat brains after 2 h of temporal focal ischemia. The expression of GADD45 mRNA was ind uced in neurons throughout ischemic cortex 4 h after the onset of isch emia but was restricted to ischemic penumbra regions at 24 h after isc hemia. The expression of GADD45 protein was increased only in subletha lly injured neurons in the penumbra regions at both 4 h and 24 h follo wing ischemia. These results suggest that GADD45 could have a protecti ve role in ischemic neurons.