27229
Subsequent experiments using tetrodotoxin to block activity - dependent neurotransmission suggest that KORs regulate GABA release at presynaptic sites .
 Chemical: GABA
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: GABA