Isoflurane and sevoflurane dose-dependently impair hippocampal long-term potentiation

Isoflurane and sevoflurane are commonly used volatile anaesthetics. Although acting via similar cellular mechanisms, the effect of different volatile anaesthetics on synaptic plasticity might differ. In the present study, using acute murine brain slice preparations, we compared the effects of isoflurane and sevoflurane on synaptic transmission and synaptic plasticity (long-term potentiation, LTP) in the CA1 stratum radiatum of the hippocampus. Isoflurane and sevoflurane dose-dependently diminished excitatory postsynaptic field potentials. In the presence of isoflurane (sevoflurane) at concentrations of 0.19, 0.28 and 0.37mM (0.11, 0.21 and 0.42mM), which correspond to 0.7-, 1.0- and 1.4-fold (0.3-, 0.6- and 1.1-fold) minimum alveolar concentration (MAC), high frequency stimulation reliably induced LTP. When isoflurane (sevoflurane) was applied at concentrations of 0.56 and 0.74mM (0.63 and 0.84mM), which equal 2.1- and 2.7-fold (1.7- and 2.2-fold) MAC, LTP was blocked. Our results indicate, that both anaesthetics influence synaptic strength to a similar degree, with only high concentrations blocking hippocampal CA1 stratum radiatum long-term potentiation.