21381
Interestingly , these effects both reflect structural and functional plasticity of brain circuits controlling reward and motor behavior , and specifically recruitment of nicotinic acetylcholine receptors ( nAChR ) in mesencephalic dopaminergic neurons .
 Chemical: acetylcholine
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: acetylcholine