14995
Although the basal nociceptive responses didn ' t require the involvement of PTPs , the mechanical allodynia evoked by intrathecal injection of NMDA was greatly attenuated by orthovanadate and Bpv ( phen ) , suggesting that PTPs activity , once stimulated by NMDA receptors , became essential for spinal sensitization .
 NMDA, orthovanadate, Bpv ( phen ), NMDA
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 NMDA, orthovanadate, Bpv ( phen ), NMDA