3337
Behavioral and cardiorespiratory responses to a lethal dose of morphine were evaluated in rats pretreated with saline or naloxazone , an antagonist of high - affinity mu 1 opioid receptors .
 Chemical: morphine; Chemical: naloxazone
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Chemical: morphine; Chemical: naloxazone