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However , although projections from the DMH to the paraventricular hypothalamic nucleus ( PVN ) , which is the critical site of the neuroendocrine stress axis , have been described , the impact of DMH neurones in the modulation of hypothalamic - pituitary - adrenal ( HPA ) axis activation during stress is not fully understood .
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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:
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