EARLY ULTRASTRUCTURAL-CHANGES AFTER BRIEF HISTOTOXIC HYPOXIA IN CULTURED CORTICAL AND HIPPOCAMPAL CA1 NEURONS

Primary cortical and hippocampal neuronal cultures submitted to brief histotoxic hypoxia suffer delayed neuronal death after 24 h [Uto et al . (1995) J Neurochem 64: 2185-2192], In this study the ultrastructural changes were monitored during the first 6 h following 5-min histotoxi c hypoxia induced by exposure to 100 mu M iodoacetate. In both cortica l and hippocampal CA1 neurons, disaggregation of ribosomes was the ear liest sign of histotoxic pathology. Vacuolizations of mitochondria, en doplasmic reticulum and Golgi apparatus, as well as fragmentation and disintegration of neurofilaments followed later, Signs of apoptotic nu clear degeneration were absent. Our observations demonstrate that, sim ilar to that seen in ischemia, disaggregation of ribosomes after brief histotoxic hypoxia is one of the first pathological alterations heral ding delayed neuronal death.