5621
The effects of social isolation on morphine - induced locomotor activity were compared in : ( i ) animals with an intact hypothalamo - pituitary - adrenal ( HPA ) axis ; ( ii ) animals in which stress - induced corticosterone secretion was blocked by adrenalectomy .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
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