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Despite the potential therapeutic relevance of group II metabotropic glutamate ( mGlu ) receptors , there has been a lack of pharmacological tools for separating the roles of mGlu2 and mGlu3 receptor subtypes .
 glutamate
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 glutamate