1483
Because 5 - HT transporters play a key element in the regulation of synaptic 5 - HT transmission it may be important to control for the potential covariance effect of a polymorphism in the 5 - HT transporter promoter gene region ( 5 - HTTLPR ) when studying the effects of MDMA as well as cognitive functioning .
 Chemical: 5 - HT; Chemical: 5 - HT; Chemical: 5 - HT; Chemical: MDMA
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Chemical: 5 - HT; Chemical: 5 - HT; Chemical: 5 - HT; Chemical: MDMA