6355
Additionally , direct evidence has been provided that D ( 2 ) and 5 - HT ( 2A ) receptors form physical heterocomplexes which exert a functional cross - talk , as demonstrated by studies on hallucinogen - induced signaling .
 Chemical: 5 - HT
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: 5 - HT 
Answer:
 Chemical: 5 - HT