2738
Dopamine D2 receptors were elevated in the striatum , whereas serotonin 2C , but not serotonin 1A , receptors were elevated in the orbital frontal cortex .
 Dopamine, serotonin, serotonin
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Dopamine, serotonin, serotonin