This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': "Neurotransmitter depleted in Parkinson's disease:September 2007 \nSelect and explain. \nA. Dopamine, B. Acetylcholine, C. Glutamate, D. GABA", 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. A: DopamineParkinson's disease has both hypokinetic and hyperkinetic features. In this condition, which was originally described by James Parkinson and is named for him, the nigrostriatal dopaminergic neurons degenerate. The fibers to the putamen are most severely affected.Dopaminergic neurons and dopamine receptors are steadily lost with age in the basal ganglia in normal individuals, and an acceleration of these losses apparently precipitates parkinsonism. Symptoms appear when 60-80% of the nigrostriatal dopaminergic neurons are lost. Parkinsonism is also seen as a complication of treatment with the phenothiazine group of tranquilizer drugs and other drugs that block D2 dopamine receptors.", 'role': 'assistant'}]