20369
None of the sigma 1 antagonists tested enhanced morphine - antinociception in sigma 1 - KO mice , confirming a sigma 1 - mediated action .
 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