Nvslm1

Mice were decapitated, the brainstems were removed and sliced into 250–400-μm-thick sections using a tissue slicer (model NVSLM1, World Precision Instruments). Sections were prepared in an ice-cold solution containing (in mM) 122 Choline chloride, 2.5 KCl, 1.25 NaH₂PO₄, 25 NaHCO₃, 8 glucose, 0.5 CaCl₂ and 7 MgCl₂, saturated with 95% O₂ and 5% CO₂ (pH 7.3–7.4; 290–300 mOsm). Then slices were incubated for 1 h at a room temperature in a chamber filled with an oxygenated aCSF containing (in mM) 126 NaCl, 3.5 KCl, 2 CaCl₂, 1.3 MgCl₂, 1.2 NaHPO₄, 10 glucose, 23.8 NaHCO₃ (pH 7.3–7.4, 290–300 mOsm).

Mice were decapitated, and brains were quickly removed and placed in a Petri dish filled with ice-cold high-K⁺ cutting solution containing 120 mM K-gluconate, 10 mM HEPES-acid, 15 mM Na-gluconate, 0.2 mM EGTA, and 4 mM NaCl (pH 7.2, 290–300 mOsm) for 1 min. The olfactory bulbs, the brainstem with the cerebellum were cut off using a scalpel; the cerebral hemispheres were separated by cutting along the longitudinal fissure and mounted onto the vibratome specimen disc using superglue, orienting them downward with the sagittal cut surface. Sagittal 350–400 μm-thick sections of the cerebral hemispheres containing the hippocampus were prepared in the ice-cold high-K⁺ cutting solution using a tissue slicer of model NVSLM1 (World Precision Instruments, Stevenage, UK). Immediately after cutting, brain slices were incubated for 20 min at room temperature in a bubbled with carbogen gas (a mix of 95% O₂ and 5% CO₂) high magnesium artificial cerebrospinal fluid (ACSF) containing 125 mM NaCl, 2.5 mM KCl, 0.8 mM CaCl₂, 8 mM MgCl₂, 1.25 mM NaHPO₄, 14 mM glucose, 25 mM NaHCO₃ (pH 7.3–7.4, 290–300 mOsm). Before recording, slices were stored for 1–6 h at room temperature in a chamber with carbogen gas bubbled standard ACSF containing 125 mM NaCl, 2.5 mM KCl, 2.3 mM CaCl₂, 1.3 mM MgCl₂, 1.25 mM NaHPO₄, 14 mM glucose, 25 mM NaHCO₃ (pH 7.3–7.4, 290–300 mOsm).

Animal studies were approved by the Institutional Care and Use Committee of Jiangxi Science and Technology Normal University. All experiments were performed on CA1 pyramidal neurons of hippocampal brain slices prepared from 15 to 22-day-old Sprague-Dawley rats as described in our previous studies [16 (link), 22 (link)]. Animals were anesthetized with isoflurane and decapitated. The brains were quickly removed from the cranial cavity and immersed in ice-cold (4°C) oxygenated (95% O₂/5% CO₂) ACSF containing the following (in mM): NaCl 117, KCl 4.7, MgCl₂ 1.2, NaH₂PO₄ 1.2, NaHCO₃ 25, CaCl₂ 2.5, and D-glucose 10 (pH 7.4). Osmolarity of bathing solution was adjusted to 325–330 mOsm with sucrose. Hippocampus was dissected free, and transverse hippocampal slices (400 μm in thickness) were obtained using a vibrating microtome (NVSLM1, World Precision Instruments, USA). Slices were allowed to recover in continuously oxygenated ACSF for at least 1 h prior to experiments.