Figure 1.

Propranolol administered systemically impairs IA retrieval but has no effect on reconsolidation. Experimental timelines are shown above each experiment. Values of latencies are expressed in seconds (s) and shown as means ± SEM. (A) Animals were trained in IA with 0.9 mA footshock intensity, 48 h later they were tested (Test 1), and immediately after, they were injected i.p. with propranolol or saline. Rats were tested again 48 h later (Test 2). No significant effect of treatment was found among groups. (B) Animals underwent the same experimental protocol as in A, except that 0.6 mA footshock intensity was used during training. No significant effect of treatment was found among groups. (C) Animals underwent the same experimental protocol as in A, except that 0.25 mA footshock intensity was used during training. No significant effect of treatment was found among groups. (D) Animals underwent the same experimental protocol as in B, except that they received an i.p. injection of propranolol 30 min before reactivation (Test 1). Compared with saline, propranolol significantly disrupted IA retention at Test 1 (**, P < 0.01), but not at Test 2.