7796
The density of serotonin and norepinephrine transporters in the hippocampus was significantly higher in MRL / MpJ mice .
 Chemical: serotonin; Chemical: norepinephrine
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: serotonin, norepinephrine 
Answer:
 Chemical: serotonin; Chemical: norepinephrine