18783
Serotonin ( 5 - HT ) has been long recognized to modulate the stress response , and dysfunction of 5 - HT has been implicated in numerous stress disorders .
 Serotonin, 5 - HT, 5 - HT
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Serotonin, 5 - HT, 5 - HT