1523
Pregnant Wistar rats were assigned to five groups : intact - control , saline - control , melatonin - treated , BCNU - exposed and BCNU - exposed plus melatonin .
 Chemical: melatonin; Chemical: BCNU; Chemical: BCNU; Chemical: melatonin
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Chemical: melatonin; Chemical: BCNU; Chemical: BCNU; Chemical: melatonin