Development of a direct exposure system for studying the mechanisms of central neurotoxicity caused by volatile organic compounds.

Many volatile organic compounds (VOCs) used in work places are neurotoxic. However, it has been difficult to study the cellular mechanisms induced by a direct exposure to neurons because of their high volatility. The objective of this study was to establish a stable system for exposing brain slices to VOCs. With a conventional recording system for brain slices, it is not possible to keep a constant bath concentration of relatively highly volatile solvents, e.g. 1-bromopropane (1-BP). Here we report a new exposure system for VOCs that we developed in which a high concentration of oxygen is dissolved to a perfused medium applying a gas-liquid equilibrium, and in which the tubing is made of Teflon, non adsorptive material. Using our system, the bath concentration of the perfused 1-BP remained stable for at least 2 h in the slice chamber. Both 6.4 and 2.2 mM of 1-BP did not change the paired-pulse response, but fully suppressed long-term potentiation in the dentate gyrus (DG) of hippocampal slices obtained from rats, suggesting that 1-BP decreases synaptic plasticity in the DG at the concentrations tested. Our new system can be applicable for investigating the underlying mechanisms of the neurotoxicity of VOCs at the cellular level.