Figure 6.

γ-Aminobutyric acid type A (GABA_A) receptor blockade facilitates memory retrieval. (a, b), Fifteen minutes before the retention trial, bicuculline methiodide (BMI: 0.25, 0.5, or 1 μg/μl/side, a) or flumazenil (0.5, 1, or 2 μg/μl/side, b) was administered bilaterally into the hippocampus. The latency times that were measured during retention trial were increased by BMI administration in a dose-dependent manner. (c), To test state-dependency of BMI (1 μg/μl/side), the mice were treated with BMI bilaterally 15 min before both the acquisition and the retention trial. Data are presented as the means±SEM (n=8–10 per group). ^*p<0.05, compared with the vehicle-treated group. (d), The effect of BMI (1 μg/μl/side) on memory retrieval-induced ERK activation. The mice were killed immediately after the retention trial. Data are presented as means±SEM (n=4 per group). ^*p<0.05, compared with the control group; ^#p<0.05, compared with the vehicle-treated group. Control, animals exposed to the acquisition but not the retention trial. (e), The motoric effect of BMI (0.25, 0.5, or 1 μg/μl/side) in the open field test. Drugs were injected 15 min before the test and the distance each mouse moved was recorded for 5 min. Data are presented as means±SEM (n=10 per group).