10700
As the nucleus accumbens ( Nac ) is particularly involved in addictive behavior , we analyzed IEI - induced long - term neuroadaptations in the Nac using c - Fos immunohistochemistry and an array of neurotransmission - related genes .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 None