Which neurotransmitter is known for its excitatory role and is affected by drugs like nicotine?

The neurotransmitter known for its excitatory role and significantly affected by drugs like nicotine is acetylcholine. Acetylcholine plays a critical role in motor control, memory, and the activation of the sympathetic nervous system. Nicotine mimics acetylcholine and binds to its receptors, which leads to increased excitatory neurotransmission and dopamine release in the brain's reward pathways. This results in the stimulating effects commonly associated with nicotine use.

Dopamine, while important in the reward pathway and influenced by many drugs, particularly stimulants, is not primarily categorized as an excitatory neurotransmitter in the same way acetylcholine is noted for its excitatory function within the neuromuscular junction and autonomic nervous system.