Differential sensitivity of rat hippocampal and cortical astrocytes to oxygen-glucose deprivation injury.

Selective vulnerability of hippocampal neurons to ischemia is felt to relate to intense glutamatergic input and glutamate receptor expression. Since astrocytes are thought to have a neuroprotective role we speculated that hippocampal astrocyte sensitivity to insult could also contribute to this regional vulnerability. The purpose of the study was to determine if there is a differential sensitivity of cultured hippocampal and cortical astrocytes to oxygen-glucose deprivation (OGD). Hippocampal and cortical astrocytes were grown to confluence at matching cell density. Cultures were exposed to OGD for 2, 4, 6, 8 and 10 h. Progressive reduction in viability occurred in hippocampal astrocytes beginning at 2 h OGD. Reduction in cortical astrocyte viability was not observed until 4 h OGD. Death of hippocampal astrocytes was significantly greater than that of cortical astrocytes at each period of OGD. Based on acid phosphatase activity data the LD(50) for OGD duration in hippocampal astrocytes was 2 h compared to 8 h in cortical astrocytes. Regional differences in sensitivity of astrocytes to OGD implies that this may contribute to regional differences in neuronal vulnerability to ischemia.