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Genetic deletion of the adenosine A2A receptor prevents nicotine - induced upregulation of alpha 7 , but not alpha 4 beta 2 * nicotinic acetylcholine receptor binding in the brain .
 Chemical: adenosine; Chemical: nicotine; 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: adenosine; Chemical: nicotine; Chemical: acetylcholine