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The present review is focused on the role of genes coding for serotonin receptors in MD pathogenesis , since the serotonin transporter and enzymes involved in serotonin metabolism have been reviewed elsewhere .
 Chemical: serotonin; Chemical: serotonin; Chemical: serotonin
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: serotonin; Chemical: serotonin; Chemical: serotonin