3850
The obtained results indicate that rat brain CYP2D isoforms catalyze the formation of serotonin from 5 - methoxytryptamine , and that the deficit or genetic defect of CYP2D may affect serotonin metabolism in the brain .
 serotonin, 5 - methoxytryptamine, serotonin
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 serotonin, 5 - methoxytryptamine, serotonin