23853
IDO is also the gatekeeper enzyme for kynurenine metabolism , a pathway involved in serotonin and melatonin biosynthesis and the regulation of glutamate and dopamine levels in the brain .
 Chemical: kynurenine; Chemical: serotonin; Chemical: glutamate; Chemical: dopamine
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: kynurenine; Chemical: serotonin; Chemical: glutamate; Chemical: dopamine