Gene expression in rat hippocampal CA1 during the consolidation of contextual fear memory

Adult rats (male Lister hooded) received a single unsignaled scrambled footshock (0.5 mA for 2 s) 2 min into a 3min exposure to a novel context. One half rats received bilateral microinfusions (1 microlitre/hemisphere) of 2 nmol/microlitre BDNF antisense ODN (BDNFASO, 5’-TCTTCCCCTTTTAATGGT-3’ in PBS, pH 7.4) or BDNF missense ODN (BDNFMSO, 5’ -ATACTTTCTGTTCTTGCC-3’ in PBS, pH 7.4) into the dorsal hippocampus (AP -3.50, relative to bregma), 90 min before contextual fear conditioning (CFC). Infusions were made in awake rats via previously surgically implanted indwelling stainless steel cannula. Rats were housed in the home cages at all times outside the conditioning procedure. Rats were killed by CO2 inhalation 2 hours after CFC. CA1 enriched dorsal hippocampus was immediately dissected on ice before rapid freezing and storage at -80oC. The BDNFASO-infused group represent consolidation-impaired rats. Samples from individual rats were hybridized to separate microarrays. There was no amplification of cDNA before hybridization. There were 16 separate samples. The BDNFMSO-treated rats (n = 8) represent the consolidation group; BDNFASO-treated rats (n = 8) represent the consolidation-impaired group. All tissue was taken 2 hours after contextual fear conditioning.