Changes in the activity of GAD in the basal ganglia of the rat after striatal dopaminergic denervation.

The aim of this experiment was to study the effect of a unilateral lesion of the dopamine-containing nigro-striatal pathway, on the activity of glutamic acid decarboxilase (GAD) in different structures at two survival times: 4 and 8 weeks. The structures studied were the striatum and its output target areas, globus pallidus, entopeduncular nucleus and substantia nigra. Four weeks after the lesion, GAD activity was increased in the ipsilateral striatum, globus pallidus and substantia nigra. This effect was reversed at 8 weeks, when a decrease in enzyme activity was observed. These time related changes in enzyme activity reveal the presence of a physiological compensatory process.