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Pretreatment with gallein produced a dose - dependent potentiation of morphine - mediated antinociception , producing up to a 10 - fold leftward shift in the morphine dose - response curve and extending the duration of antinociception induced by a single dose of morphine .
 Chemical: gallein; Chemical: morphine; Chemical: morphine; 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: gallein; Chemical: morphine; Chemical: morphine; Chemical: morphine