Astrocytes protect cultured neurons from degeneration induced by anoxia

Neurons grown in cultures of dissociated brain cells degenerate when exposed to anoxia and deprived of glucose. We have developed culture systems in which neurons can be grown in the presence or absence of astrocytes and have used them to study the influence of astrocytes on the neuronal degeneration induced by anoxia and glucopenia. Cultures were prepared from fetal rat forebrains. Mixed cultures contained neurons (identified by immunocytochemical staining of neuron-specific enolase, NSE) and about an equal number of non-neuronal cells (identified by glial fibrillary acid protein). Pure neuronal cultures were prepared by adding a cytostatic compound (cytosine arabinoside) to the medium. Treated cultures were exposed for 4 h to glucose-free medium and an atmosphere of 95% N2 and 5% CO2, whereas control cultures were left in the usual medium containing glucose and in an atmosphere composed of 95% air and 5% CO2. After an interval of 24 h, cultures were fixed, taken for NSE staining, and the number of surviving neurons was counted. Exposure to anoxia and glucopenia reduced the number of surviving neurons in pure neuronal cultures to 5-10% of control levels. In contrast, in mixed cultures 40-60% of the neurons survived these conditions. Anoxia without glucose deprivation reduced the number of surviving neurons in both types of cultures to the same extent as anoxia combined with glucopenia. Glucose deprivation alone was ineffective. The findings suggest a protective influence of astrocytes on neurons under anoxic conditions. gamma-D-Glutamylglycine protected neurons in both types of cultures from anoxia-induced degeneration.(ABSTRACT TRUNCATED AT 250 WORDS)