Astrocytes as targets for CNS effects of organic solvents in vitro

The aim of the study was to evaluate astrocytes in vitro as a model for studies of solvent neurotoxicity. Primary astrocyte cultures were established from newborn rat cerebella. The cells were cultured in the modified Minimum Essential Medium (MEM), and the neural membranes isolated from cultures were exposed to solvents in incubation mixtures containing different solvent concentrations (3, 6, and 9 mM) for one hour. The activity of membrane-bound total ATPase was determined after exposure to aromatic hydrocarbons (benzene, toluene, xylene, styrene and ethylbenzene), and to n-hexane and cyclohexane. The enzyme activities were decreased by aromatic hydrocarbons linearly according to the log dose and in order to the log lipid/water partition coefficients, benzene having the smallest and ethylbenzene the greatest effect in all concentrations studied. Cyclohexane caused much smaller enzyme inhibition (18% of control activity in 9 mM concentration) than ethylbenzene (67% in 9 mM), in spite of very similar partition coefficients. N-hexane had clearly slighter enzyme inhibiting effect than aromatic hydrocarbons, in spite of its markedly greater lipophilicity. In addition to lipophilicity, the structure of solvent molecule seems to be important when considering the CNS toxicity. These results suggest that organic solvents exert their toxic effects on CNS, at least in part, by disturbing ATPase-dependent astrocytic regulatory functions.