Modifications of excitatory and inhibitory transmission in rat hippocampal pyramidal neurons by acute lithium treatment

Abstract The acute effects of high-dose Li + treatment on glutamatergic and GABAergic transmissions were studied in the “synaptic bouton” preparation of isolated rat hippocampal pyramidal neurons by using focal electrical stimulation. Both action potential-dependent glutamatergic excitatory and GABAergic inhibitory postsynaptic currents (eEPSC and eIPSC, respectively) were dose-dependently inhibited in the external media containing 30–150 mM Li + , but the sensitivity for Li + was greater tendency for eEPSCs than for eIPSCs. When the effects of Li + on glutamate or GABA A receptor-mediated whole-cell responses ( I Glu and I GABA ) elicited by an exogenous application of glutamate or GABA were examined in the postsynaptic soma membrane of CA3 neurons, Li + slightly inhibited both I Glu and I GABA at the 150 mM Li + concentration. Present results suggest that acute treatment with high concentrations of Li + acts preferentially on presynaptic terminals, and that the Li + -induced inhibition may be greater for excitatory than for inhibitory transmission.