Effects of streptokinase on the development of rat cerebral cortical cells in vitro.

The aim of the present work was to study the effects of streptokinase (SK) on the ultrastructure of the cellular elements of the cerebral cortex of neonatal rats in vitro. Three series of cultures were used: cultures maintained in DMEM enriched with 15% fetal calf serum (control 1), some transferred to minimal nutritive medium containing only 0.5% serum (control 2), and some supplemented with SK (2000 MU/ml) (experimental). Addition of SK to the nutritive medium prevented a decrease in the viability of cells in a mature (14 days) dissociated culture from the neocortex of rat pups aged 1-2 days induced by transfer of the cultures to medium lacking serum proteins. The action of SK on 7-day cultures enhanced the loss of cell viability. Electron microscopy studies of organotypic cultures showed that at this concentration, SK prevented the development of destructive changes of astrocytes, oligodendrocytes, and neurons induced in explants by serum protein deficiency. Neurons showed an abundance of mitochondria, some of which had few cristae. Signs of destruction affected only the nuclei of neurons. After exposure to SK for 48 h, oligodendrocytes were activated (they contained an abundance of myelin-like bodies), with degradation of most astrocytes (surviving examples showing nuclear hyperchromicity). Neurons were resistant to these effects.