Figure 2.

The effect of intrahippocampal DHβE on the enhancement of contextual fear conditioning by systemic nicotine. A, Mice received either systemic saline or nicotine (0.09 mg/kg) and intrahippocampal saline or DHβE (6.00 or 18.00 μg per side). Mice that received intrahippocampal saline and systemic nicotine froze significantly more in response to the context than mice that received intrahippocampal saline and systemic saline and intrahippocampal DHβE (18.00 μg per side) and systemic nicotine. *p < 0.05, compared with the intrahippocampal saline–systemic saline and intrahippocampal DHβE (18.00 μg per side)–systemic nicotine groups. B, In the absence of nicotine, DHβE (18.00 μg per side) has no effect on contextual fear conditioning. Error bars represent SEM. C, Dots represent the tip of infusion tracts for mice in the DHβE and nicotine experiment from A. Numbers represent distance in millimeters posterior to bregma. Pictures were modified from Paxinos and Franklin (2001).