655
Thus , in order to examine the anatomical substrates and physiological effects of group III mGluRs activation upon striatal and pallidal neurons in monkeys , we used electron microscopy immunohistochemistry to localize mGluR4 , combined with local administration of the group III mGluR agonist L - AP4 , or the mGluR4 positive allosteric modulator VU0155041 , to assess the effects of group III mGluR activation on the firing rate and pattern of striatal and pallidal neurons in 1 - methyl - 4 - phenyl - 1 , 2 , 3 , 6 - tetrahydropyridine ( MPTP ) - treated parkinsonian monkeys .
 L - AP4, VU0155041, 1 - methyl - 4 - phenyl - 1 , 2 , 3 , 6 - tetrahydropyridine, MPTP
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 L - AP4, VU0155041, 1 - methyl - 4 - phenyl - 1 , 2 , 3 , 6 - tetrahydropyridine, MPTP