Neurotoxicity of Seven MEIC Chemicals Evaluated in Organotypic Cultures of Chick Embryonic Dorsal Root Ganglia

Abstract

The neurotoxic effects of seven selected Multicenter Evaluation of In Vitro Cytotoxicity programme chemicals (methanol, ethanol, isopropanol, sodium chloride, potassium chloride, iron [II] sulphate and chloroform) were evaluated in organotypic cultures of chick embryonic dorsal root ganglia (DRG), maintained in a soft agar culture medium. Two growth parameters of neurite outgrowth from the ganglia — the mean radial length of neurites and the area of neurite outgrowth — were used to evaluate the toxicities of the chemicals. Dose-dependent decreases of both parameters were observed in all experiments. IC50 values (the concentration causing 50% inhibition of growth) were calculated from the dose-response curves established at three time-points during culture, i.e. 24, 48 and 72 hours. The lowest toxic effect was observed in cultures exposed to methanol (the IC50 ranging from 580mM to 1020mM). The highest toxic effect was observed in cultures exposed to iron (II) sulphate (the IC50 ranging from 1.2mM to 1.7mM). The results of other recent experiments suggest that organotypic cultures of DRG can be used during in vitro studies on target organ toxicity within the peripheral nervous system. Moreover, these cultures preserve the internal organisation of the tissue, maintain intercellular contacts, and thus reflect the in vitro situation, more precisely than other cell cultures.