ULTRASTRUCTURAL EVIDENCE THAT MERCURIC-CHLORIDE LOWERS THE THRESHOLD FOR GLUTAMATE NEUROTOXICITY IN AN ORGANOTYPIC CULTURE OF RAT CEREBELLUM

Separate exposure of organotypic cultures, derived from newborn rat cerebellum, to non-toxic concentration of either 100 muM glutamate (GLU) or 1 muM mercuric chloride (MC), for as long as 3 days, produced no distinct ultrastructural changes in neurons and glial cells. By contrast, simultaneous exposure to both agents resulted, as early as after 30 min, in microvacuolar degeneration of neurons and later on in postsynaptic abnormalities, typically accompanying excitotoxic lesions but not heavy metal-induced lesions. The results indicate that MC at low micromolar concentrations lowers the threshold for GLU neurotoxicity.