Figure 1.

Systemic administration of leptin facilitates the extinction of conditioned fear. (A) Experimental protocols of fear conditioning paradigm. (B) The percentage of freezing during conditioning (4 CS‐footshock trials), trial‐by‐trial extinction training (10 CS‐alone trials), and extinction test (4 CS‐alone trials). Vehicle (white panes), leptin (gray panes), and MK‐801 + leptin (black panes) were intraperitoneal injection 30 min before extinction training. (C) Averaged percentage of freezing across all extinction training and extinction test trials. *P < 0.05 versus vehicle in the same session, ^# P < 0.05 versus leptin (1 mg/kg) in the same session, n = 9 for each group.