17943
OBJECTIVES : The objectives of this study were to investigate perseverative , compulsive , stereotypical , and hyperactive behaviors , as well as serotonin and its involvement with these behaviors , in DAT gene - altered mice .
 Chemical: serotonin
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: serotonin