Figure 3.

Enhancing histone acetylation by treatment with TSA does not enhance memory for contextual fear in CREBαΔ mutant mice. CREBαΔ mutant mice and wild-type (WT) littermates were fitted with intrahippocampal cannulas, subjected to contextual fear conditioning, and then immediately injected with either VEH or TSA (16.5 or 33 mm TSA). Injected mice were given a retrieval test 24 h later. Similar to a previous study examining contextual fear conditioning in CREBαΔ mutant mice (Graves et al., 2002), CREBαΔ mutant mice treated with vehicle (n = 6) showed significantly lower levels of freezing than wild-type littermates treated with vehicle (n = 6). Wild-type mice treated with either 16.5 mm TSA (n = 6) or 33 mm TSA (n = 6) showed significantly higher levels of freezing than wild-type mice treated with vehicle (n = 6), recapitulating results observed in C57BL/6J mice (Fig. 1). In contrast, no differences in levels of freezing were observed between CREBαΔ mutant mice treated with 16.5 mm TSA (n = 5) or 33 mm TSA (n = 6) and CREBαΔ mutant mice treated with vehicle (n = 6). *p < 0.05.