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 activity, postsynaptic field potential (population spike, PS) of granule cells as well as antidromic potential (AP) and presynaptic fiber potential (FP) (perforant path) were recorded in the guinea pig hippocampal slices. Toluene at the concentration of 0.2 ng/ml to 20 micrograms/ml in the perfusion medium increased the amplitude of PS to 109-150%. Toluene also increased the amplitude of FP and AP, although the most remarkable enhancement was observed in the PS. However, toluene at the concentrations over 1000 micrograms/ml completely depressed the PS, whereas it increased the amplitude of AP to 130% of the original level. These results indicate that toluene has excitatory and inhibitory biphasic effects on neurotransmission in the hippocampal slices according to concentration applied.