3050
Administration of a tryptophan supplement ( 82 . 5 mg / kg p . o . ) to na i ve rats produced parallel increases in serotonin levels 2 h later in the frontal cortex ( 39 % ) and blood ( 26 % ) .
 Chemical: tryptophan; 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: tryptophan; Chemical: serotonin