All experimental procedures were approved by the Ethics Committees at Xinxiang Medical University for the Care and Use of Laboratory Animals, and all efforts were made to minimize animal suffering and reduce the number of animals used. Electrophysiological studies were performed on hippocampal slices prepared from Sprague Dawley rats (male, 4–5 week-old). Animals were anesthetized by intraperitoneal injection of Sagital (sodium pentobarbitone, 100 mgkg−1, Rhône Mérieux Ltd, Harlow, UK). When all pedal reflexes were abolished, the animals were perfused intracardially with chilled (5°C), oxygenated cutting solution containing (in mM): 225 sucrose, 3 KCl, 1.25 NaH2PO4, 24 NaHCO3, 6 MgSO4, 0.5 CaCl2 and 10 glucose (305 mosmol l−1). Horizontal brain slices (400 μm) containing the ventral hippocampus were cut at 4–5°C in cutting solution, using a Leica VT1000S vibratome (Leica Microsystems UK, Milton Keynes, UK).
