TIME-COURSE OF NEUROFILAMENT PROTEIN LOSS FOLLOWING DEPOLARIZATION-INDUCED INJURY IN CNS CULTURE

In septo-hippocampal cell cultures, brief potassium depolarization pro duces calcium-dependent decreases in neurofilament proteins and loss o f fine neuritic processes within 24 h. It is not known whether neurons later exhibit delayed degeneration and die, live with enduring neurof ilament loss, or restore neurofilament protein levels. Therefore, we e xposed septohippocampal cultures to 6 min potassium depolarization (60 mM) with 2.8-11.8 mM extracellular Ca2+ and evaluated immunoreactivit y for low, medium and heavy neurofilament proteins, neuronal number, a nd neuronal morphology for 10 days. Neuronal number remained unchanged ; neurofilament protein levels recovered to between 31% and 99% of con trol levels, and fine neuritic processes reappeared.