Coronal Brain Slice Preparation for Electrophysiology

Adult male and female rats were anesthetized with isoflurane and killed as previously described [25 (link), 26 , 28 (link), 29 (link)]. The brain was sliced (300 µm) in the coronal plane with a vibratome (Integraslice, Campden Instruments) in a sucrose-based solution at 4 °C (in mm as follows: 87 NaCl, 75 sucrose, 25 glucose, 2.5 KCl, 4 MgCl₂, 0.5 CaCl₂, 23 NaHCO₃ and 1.25 NaH₂PO₄). Immediately after cutting, slices containing the medial prefrontal cortex (PFC) were stored for 1 h at 32 °C in a low-calcium ACSF that contained (in mm) as follows: 130 NaCl, 11 glucose, 2.5 KCl, 2.4 MgCl₂, 1.2 CaCl₂, 23 NaHCO₃, 1.2 NaH₂PO₄, and were equilibrated with 95% O₂/5% CO₂ and then at room temperature until the time of recording. During the recording, slices were placed in the recording chamber and superfused at 2 ml/min with low Ca²⁺ ACSF. All experiments were done at 32 °C. The superfusion medium contained picrotoxin (100 mM) to block gamma-aminobutyric acid types A (GABA-A) receptors. All drugs were added at the final concentration to the superfusion medium.