21551
Using female Siberian hamsters ( Phodopus sungorus ) , we investigated the effects of chronic nightly exposure to dim light on daily rhythms in locomotor activity , serum cortisol concentrations , and brain expression of circadian clock proteins ( i . e . , PER1 , PER2 , BMAL1 ) .
 Chemical: cortisol
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: cortisol 
Answer:
 Chemical: cortisol