Effects of Carbon Tetrachloride on Neuronal Differentiation in Rat Embryo Mid-Brain Micromass Cultures

Abstract

The effects of carbon tetrachloride on neuronal development and differentiation have been studied. Rat embryo mid-brain micromass cultures were exposed for five days to 50, 100, 250, 500 or 1000ppm CCl₄ in closed chambers. Differentiation was indicated by the formation of neuronal foci in the cultures. Effects on cell survival were estimated using a neutral red staining method. Carbon tetrachloride at 100ppm caused a drastic increase in neuronal differentiation, accompanied by a slight increase in total cell number. At 250ppm the number of differentiated foci was still elevated, but the outgrowth of neurites was markedly reduced. Neuronal differentiation and cell survival were reduced by 50% at a concentration of 430ppm. Using criteria previously defined for the identification of potentially teratogenic substances in the micromass system, CCl₄ was classified as a non-teratogen. Nevertheless, the results show that a substance can cause inhibition of differentiation (reduction in neunte formation) without altering focus formation.