Lesions of the inferior olive increase glutamic acid decarboxylase activity in the deep cerebellar nuclei of the rat.

Inferior olive-climbing fiber lesions were made by administering 3-acetylpyridine to 16-day-old rats. This treatment produced multiple motor abnormalities which gradually improved over the subsequent 28 days. A significant increase in glutamic acid decarboxylase (GAD) activity was found in the deep cerebellar nuclei 24 h after treatment. This elevation increased with time, reaching 134% of control values 28 days after treatment. GAD activity in the cerebellar vermis also increased but did so more slowly and to a lesser degree than in the deep nuclei, reaching 114% of control values 28 days after treatment. The results suggest the operation of different mechanisms in producing the increased GAD activity in the different areas.