6704
Congruent with previous findings , low E2 nulliparous rats showed predominant use of response memory and faster response learning , whereas high E2 nulliparous rats showed a trend towards predominant place memory use .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None