Upregulation of cytosolic branched chain aminotransferase in substantia nigra following developmental striatal target injury

We have previously shown that apoptotic cell death can be induced in substantia nigra (SN) by developmental striatal target lesion. In this model, only a portion of nigral neurons dies, so it provides a paradigm to examine not only the molecular basis of cell death, but also the cellular responses of adjacent neurons which survive. Using a differential display approach, we have found that cytosolic branched chain aminotransferase (BCATc) mRNA is upregulated in SN in this model. This upregulation is associated with an increased number of BCATc-positive neuronal profiles, demonstrated by immunostaining. BCATc-positive neurons show normal morphology and rarely contain apoptotic chromatin. We conclude that BCATc is upregulated in neurons, which are likely to survive, and plays a role in either maintenance of viability or restoration of normal function.