24272
Some of these compounds displayed significant activity in vitro as positive allosteric modulators of the GABAB receptor by potentiating GTP gamma S stimulation induced by GABA at 2 . 5 and 25 mu M while failing to exhibit intrinsic agonist activity .
 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