Reduced long-term potentiation in hippocampal slices prepared using sucrose-based artificial cerebrospinal fluid

Sucrose-based artificial cerebrospinal fluid (aCSF) is sometimes used to pr epare brain slices for in vitro electrophysiological experiments. This stud y compared the effect of preparing brain slices using chilled sucrose-based aCSF versus the conventional method using chilled aCSF on hippocampal syna ptic plasticity. Brain slices from each treatment group were transferred to normal aCSF before electrophysiological recordings were made. The stimulus response relationship of field excitatory postsynaptic potentials (fEPSPs) in the CA1 region was indistinguishable between the two treatment groups. However, the amount of LTP induced by either a theta-burst (four stimuli at 100 Hz repeated ten times at 200 ms intervals) or tetanic stimulation (100 Hz for 1 s) was significantly reduced in slices that had been prepared usi ng sucrose-based aCSF. This was associated with reduced facilitation of the fEPSPs during the high frequency stimulus, reduced post-tetanic potentiati on and short-term potentiation. In sucrose-cut slices the fEPSPs: were slig htly shorter in duration (29%, P < 0.01), and during paired-pulse stimulati on the broadening of the second fEPSP was enhanced. The LTP deficit in sucr ose-cut slices was reversed by blocking GABA(A) receptor. function with pic rotoxin. These data suggest that the use of sucrose based aCSF better prese rves GABA-mediated synaptic transmission, which limits the induction of LTP in hippocampal brain slices. (C) 2000 Elsevier Science B.V. All rights res erved.