ALTERATIONS IN THE GLIAL FIBRILLARY ACIDIC PROTEIN-CONTENT OF PRIMARY ASTROCYTE CULTURES FOR EVALUATION OF GLIAL-CELL TOXICITY

Astrocyte-enriched primary glial cell cultures from the rat cerebral cortex were exposed to a range of neurotoxic compounds and the effects on three proteins were examined by enzyme-linked immunosorbent assay (ELISA). The most consistent marker for astrocyte toxicity was the intermediate filament protein glial fibrillary acidic protein (GFAp). Many toxicants reported to have specificity for astrocytes (e.g. mercuric chloride, aluminium chloride, toluene or ethanol) produced a similar dose-response curve: increases in the GFAp content of the cells at sub-cytotoxic concentrations with attenuation at higher concentrations. Some of the concentrations required to increase GFAp were extremely low, indicating that this is a sensitive and consistent marker of cellular damage, as has been shown in vivo. Toxicants that have neuronal specificity (such as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridinium or acrylamide) had no effects on GFAp levels, indicating that the system measures the susceptibility of astrocytes to specific toxicants rather than neurotoxicity. The levels of S-100 protein and vimentin were measured for a smaller number of toxicants. S100 was a less sensitive and inconsistent marker in comparison with GFAp, whilst vimentin levels were not seen to increase with any tested compound. These results suggest that astrocytes have a valuable place in culture models for neurotoxicity testing.