Animals were retrieved from the colony and allowed to rest in sound attenuating boxes for a minimum of 1 h after which they were killed by decapitation. Stressed animals were killed by cervical dislocation and decapitated immediately following termination of the last 1 h restraint exposure. A 3 mm coronal block containing the amygdala was cut using a coronal brain matrix kept on ice; 300 µm coronal slices were made on a Leica VT1000S vibratome (Leica Microsystems, Bannockburn, IL) in a 1–4°C, oxygenated (95% O2, 5% CO2), 30% sucrose, low Na+ artificial cerebral spinal fluid containing in mM: 194 sucrose, 20 NaCl, 4.4 KCl, 2 CaCl2, 1 MgCl2, 1.2 NaH2PO4, 10 glucose, 26 NaHCO3. Once cut, sections were transferred to a holding chamber containing oxygenated ACSF in mM: 124 NaCl, 4.4 KCl, 2 CaCl2, 1.2 MgSO4, 1 NaH2PO4, 10 glucose, 26 NaHCO3 at 28°C. After a minimum of 1 h, sections were placed in the recording chamber superfused with oxygenated ACSF at a flow rate of 2 ml/min. To pharmacologically isolate inhibitory postsynaptic currents (IPSCs), ACSF was supplemented with a combination of 10 µM CNQX and 50 µM D/L AP-5. All experiments were carried out at 23–25°C.
