Preparation of acute hippocampal slices
For fEPSP recordings and GABA uptake studies, the hippocampus (6-12
weeks-old Sprague-Dawley rats or C57BL/6 mice as specified in results
section) were dissected within ice-cold artificial cerebrospinal fluid
(aCSF) solution composed of (mM): NaCl 124, KCl 3,
NaHCO3 25,
NaH2PO4.H2O 1.2,
MgSO4 1, CaCl2 2; and glucose
monohydrate 10, previously gassed with 95% O2 and 5%
CO2, pH 7.4. Slices (400 µm thick for fEPSP recordings
or 300 µm thick for GABA uptake studies) were cut perpendicularly to the
long axis of the hippocampus with a McIlwain tissue chopper (Campden
Instruments) and allowed to recover functionally and energetically for
at least 1 hour in a resting chamber filled with the same solution, at
room temperature (RT) and continuously gassed. For patch clamp
recordings, the slices (300 µM thick from 5-8 weeks old Wistar rats)
were cut with a vibratome (Leica VT 1000S, Leica Microsystems) in the
ice-cold dissecting solution containing (in mM): sucrose 110; KCl 2.5;
CaCl2 0.5; MgCl2 7;
NaHCO3 25; NaH2PO4 1.25;
glucose monohydrate 7, oxygenated with 95% O2 and 5%
CO2, pH 7.4; after dissection, the slices were incubated
for 20 minutes at 35°C in aCSF and then transferred to a resting chamber
at RT for at least 1 hour before use.