16668
The direct involvement of mu - opioid receptor functions in the activation of G - proteins and changes in protein levels in the lower midbrain of mice after chronic treatment with ethanol were investigated by a [ ( 35 ) S ] GTP gamma S binding assay and Western blotting , respectively .
 Chemical: ethanol; Chemical: [ ( 35 ) S ] GTP gamma S
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: [ ( 35 ) S ] GTP gamma S