REGIONAL BRAIN-DERIVED NEUROTROPHIC FACTOR MESSENGER-RNA AND PROTEIN-LEVELS FOLLOWING TRANSIENT FOREBRAIN ISCHEMIA IN THE RAT

Levels of BDNF mRNA and protein were measured in the rat brain using i n situ hybridization and a two-site enzyme immunoassay. Under basal co nditions, the highest BDNF concentration was found in the dentate gyru s (88 ng/g), while the levels in CA3 (50 ng/g), CA1 (18 ng/g) and pari etal cortex (8 ng/g) were markedly lower. Following 10 min of forebrai n ischemia, BDNF protein increased transiently in the dentate gyrus (t o 124% of control at 6 h after the insult) and CA3 region (to 131% of control, at 1 week after the insult). In CA1 and parietal cortex, BDNF protein decreased to 73-75% of control at 24 h. In contrast, BDNF mRN A expression in dentate granule cells and CA3 pyramidal layer was tran siently elevated to 287 and 293% of control, respectively, at 2 h, whe reas no change was detected in CA1 or neocortex. The regional BDNF pro tein levels shown here correlate at least partly with regional differe nces in cellular resistance to ischemic damage, which is consistent wi th the hypothesis of a neuroprotective role of BDNF.