EXPRESSION OF THE UBIQUITIN GENES IN BRAIN OF NORMAL AND FE DEXTRAN INJECTED RATS/

Using in situ hybridization techniques with an RNA probe coding for ap proximately 3.5 repeats of ubiquitin, corresponding to the polyubiquit in genes, we were able to demonstrate that under normal conditions the expression of the ubiquitin genes predominates specially in regions C AI, CA2 and CA3 of the hippocampus, in the dentate gyrus and in Purkin je cells of the cerebellum, being less prominent in neuronal cell bodi es of the cerebral cortex. When the animals were submitted to an acute oxidative stress by injection of Fe/Dextran, the hybridization signal was apparently increased in the above mentioned regions of the hippoc ampus and in the cerebral cortex. On the other hand, the animals chron ically injected with Fe/Dextran showed a highly intense gene expressio n in the cerebral cortex and in the cerebellum, particularly in the gr anular cell layer of this structure. The hybridization signal of the t ranscripts was absent in the Purkinje cells. The results suggest that the expression of the ubiquitin genes by CNS neurons depends on the an atomical location of the cells and that it increases as a consequence of the oxidative stress conditions to which they are submitted.