16674
CONCLUSIONS : The present study demonstrated that chronic treatment with ethanol enhanced the rewarding effects of morphine by up - regulating functional changes in mu - opioid receptor , mediated by GRK2 .
 Chemical: ethanol; 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: ethanol; Chemical: morphine