4824
In this complex scenario , two outsiders are now taking the center stage : glial cells in sensory ganglia and in the central nervous system , thanks to their ability to communicate with neurons and to modulate their firing , and the purinergic system .
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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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