COMBINED LEAD ACETATE AND DISULFIRAM TREATMENT-INDUCED ALTERATIONS OF GLIAL FIBRILLARY ACIDIC PROTEIN (GFA) IMMUNOREACTIVE ASTROCYTES IN BRAIN SMEARS

Dithiocarbamates are known to form lipid-soluble complexes with lead and greatly increase brain lead levels. The present study was undertaken to investigate whether lead acetate, when administered together with disulfiram (Antabuse , metabolite of dithiocarbamate) during development, would induce morphological changes in brain astrocytes. Female Sprague-Dawley rats were given 0.25% lead acetate in the drinking water from day one of pregnancy and this treatment was continued after birth until the litters were 4 weeks old. In addition, some dams received disulfiram in a dose of 0.1 mmol/kg p.o. twice weekly and after parturition this dose was given s.c. directly to the offspring twice a week. Lead acetate and disulfiram treatments were discontinued at weaning and animals sacrificed 3 weeks later. Samples of parietal cortex, hippocampal formation and cerebellar cortex were dissected out and smeared onto glass-slides and astrocytes were visualized in toto using immunohistochemistry with antibodies against glial fibrillary acid protein (GFA), enabling morphometric analysis with a computerized image analyser. Animals treated with lead acetate showed a minor increase in the size of the GFA-immunoreactive astrocytes in parietal cortex smears, while animals treated with disulfiram showed no difference in size or form compared to controls. However, in combined lead acetate and disulfiram-treated animals a profound increase in astrocyte size and an increase in the number of processes of the individual GFA-immunoreactive astrocytes could be demonstrated in parietal cortex. No significant changes were noted in GFA-immunoreactive astrocytes of hippocampal smears following the different treatments, while GFA-immunoreactive astrocytes in cerebellar cortex smears were significantly smaller and had reduced number or processes following the combined lead acetate and disulfiram treatment compared to lead acetate treatment or controls. It is concluded that combined exposure to lead acetate and disulfiram during development induces regionally specific changes in GFA-immunoreactive astrocyte morphology. Furthermore, the present study demonstrates the usefulness of smear preparations combined with computerized image analysis to study the morphology of GFA-immunoreactive astrocytes as an index of toxic effects in CNS.