12323
In this study we show that new gene expression induced in vivo by morphine withdrawal occurs with concomitant epigenetic modifications in brain regions critically involved in drug - dependent behaviors .
 Chemical: morphine
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: morphine