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: Psychiatry
The clinical effects of the antidepressant drugs is mainly based on ? 
Select and explain. 
A. Change in neurotransmitter receptor sensitivity, B. Decreased level of neurotransmitters, C. Change in efficacy of neurotransmitters, D. None of the above
A: Change in neurotransmitter receptor sensitivity
Answer: A: Change in neurotransmitter receptor sensitivity 
Explanation: Ans. A. Change in neurotransmitter receptor sensitivityTemporal correlation of clinical effects with changes in receptor sensitivity has given rise to hypothesis that changes in neurotransmitter receptor sensitivity may actually mediate the clinical effects of antidepressant drugs.These clinical effects include not only antidepressant and anxiolytic actions but also the development of tolerance to the acute side effects of antidepressant drugs.