EXCITATORY AND INHIBITORY EFFECTS OF TOLUENE ON NEURAL ACTIVITY IN GUINEA-PIG HIPPOCAMPAL SLICES

To investigate the effect of toluene and its derivatives on neural act ivity, postsynaptic field potential (population spike, PS) of granule cells as well as antidromic potential (AP) and presynaptic fiber poten tial (FP) (perforant path) were recorded in the guinea pig hippocampal slices. Toluene at the concentration of 0.2 ng/ml to 20 mug/ml in the perfusion medium increased the amplitude of PS to 109-150%. Toluene a lso increased the amplitude of FP and AP, although the most remarkable enhancement was observed in the PS. However, toluene at the concentra tions over 1000 mug/ml completely depressed the PS, whereas it increas ed the amplitude of AP to 130% of the original level. These results in dicate that toluene has excitatory and inhibitory biphasic effects on neurotransmission in the hippocampal slices according to concentration applied.