893
MPEP administered into the striatum at high concentrations ( 500 microM ) increased extracellular dopamine levels , while lower concentrations ( 50 - 100 microM ) were devoid of any effect .
 MPEP, dopamine
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 MPEP, dopamine