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Taken together , this work demonstrates the critical role of NPY signaling in the regulation of bone and energy homeostasis , and more importantly , suggests that reduced leptin levels or leptin resistance , which occurs in obesity , could potentially inhibit cortical bone formation via increased central NPY signaling .
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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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