Normal glutamic decarboxylase activity in rat striatum and retina following administration of L-DOPA

Recent reports of the in vivo action of L-dihydroxyphenylalanine (L-DOPA) on glutamic acid decarboxylase (GAD) activity are contradictory. This investigation was undertaken to clarify the situation. Both acute (100 mg/kg and 1 g/kg) and chronic (1 g/kg) administration of L-DOPA to rats failed to produce any alteration in the activity of striatal or retinal GAD activity. These results are discussed in the light of a report relating L-DOPA therapy to modification of GAD activity in Parkinson's disease.