Figure 2.

CREB levels in the dorsal hippocampus are specifically decreased 6 h after in vivo antisense ODN treatment. Rats received infusions of CREB antisense ODN in one hippocampus and scrambled ODN in the other before being killed and before tissue dissection. Three different treatment conditions were included: treatment 1, rats received EC-ODN infusions and were killed 6 h later; treatment 2, rats received S-ODN infusions and were killed 6 h later; treatment 3, rats received EC-ODN infusions and were killed 54 h later. In all cases, 2 nmol of ODN (in 1 μl) was infused; antisense ODN infusions were alternated between left and right hippocampi. Tissue punches were taken from dorsal and ventral hippocampi, and protein extracts were prepared. Extracts for each treatment, group, and punch location (i.e., treatment 1, group 1, CREB antisense ODN, dorsal hippocampus) were pooled for immunoblot analysis. Group pools were obtained from three to five rats; the number of groups given each treatment condition is noted. Immunoblot analysis was performed sequentially for CREB and then GluR1. Levels of CREB immunoreactivity were normalized to those of GluR1 for each sample. Additionally, treatment 1 dorsal hippocampal extracts were analyzed for ATF-2 immunoreactivity; as for CREB, ATF-2 levels were normalized to GluR1. Values were obtained from two to three independent blots. Normalized CREB levels from CREB antisense ODN samples are expressed as a percentage of normalized CREB levels from scrambled ODN samples for the same group. CREB antisense EC-ODN infused into the dorsal hippocampus 6 h before death produced a specific, significant reduction in CREB (∗∗, P < 0.02, t test) but not in ATF-2.