1125
In contrast , administration of the 5HT2AR antagonist MDL 11 , 939 ( 0 . 5 mg / kg , i . p . ) delayed the acquisition of extinction of fear memory .
 Chemical: MDL 11 , 939
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: MDL 11 , 939