POTENTIATION OF GLUTAMATERGIC EPSPS IN RAT CA1 HIPPOCAMPAL-NEURONS AFTER SELECTIVE CHOLINERGIC DENERVATION BY 192 IGG-SAPORIN

A complete and selective destruction of the basal forebrain cholinergi c neurons projecting to the cerebral cortex and the hippocampus was in duced in the rat by the toxin 192 IgG-saporin. Using electrophysiologi c techniques, we have investigated the consequences of this cholinergi c denervation on inhibitory and excitatory synaptic responses of CA1 p yramidal cells in rat hippocampal slices ex vivo, Histochemical experi ments were performed in slices from control and 192 IgG-saporin-treate d rats to check the efficacy of the intracerebroventricular injection of the immunotoxin. Stimulation of stratum radiatum elicits a glutamat ergic excitatory postsynaptic potentials followed by a biphasic GABAer gic inhibitory postsynaptic potential (IPSP). No significant change in IPSP was observed in 192 IgG-saporin-treated rats. By contrast, the N -methyl-D-aspartate (NMDA) and to a lesser extent the non-NMDA compone nts of the glutamatergic response were potentiated in these animals. T he possible pre- and postsynaptic mechanisms of this potentiation were discussed. (C) 1997 Wiley-Liss, Inc.