7808
These data suggest adolescent defeat enhances behavioral responses to initial amphetamine exposure as a function of diminished prefrontal cortex dopamine activity , which may be sufficient to promote subsequently enhanced seeking of drug - associated cues .
 amphetamine, dopamine
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 amphetamine, dopamine