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Role of glutamate receptors in the dorsal reticular nucleus in formalin‐induced secondary allodynia
Author(s) -
AmbrizTututi Mónica,
PalomeroRivero Marcela,
RamirezLópez Fernanda,
MillánAldaco Diana,
DruckerColín and René
Publication year - 2013
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.12302
Subject(s) - allodynia , metabotropic glutamate receptor , cnqx , chemistry , glutamate receptor , nociception , nmda receptor , hyperalgesia , rostral ventromedial medulla , neuropathic pain , receptor antagonist , ampa receptor , metabotropic receptor , pharmacology , metabotropic glutamate receptor 1 , neuroscience , antagonist , endocrinology , receptor , medicine , psychology , biochemistry
The role of glutamate receptors present in the medullary dorsal reticular nucleus ( DR t) in the formalin test and formalin‐induced secondary nociception was studied in rats. Secondary mechanical allodynia was assessed with von Frey filaments applied to the rat's hindpaw, and secondary thermal hyperalgesia was evaluated with the tail‐immersion test. The selective glutamate receptor antagonists MK 801 ( N ‐methyl‐ d ‐aspartate receptor antagonist), 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione ( CNQX ) ( AMPA / KA receptor antagonist) and A841720 (metabotropic glutamate 1 receptor antagonist) were injected into the DR t before or 6 days after formalin injection in the rat. In the formalin test, the three antagonists significantly reduced the number of flinches in both phases of the test. DR t microinjection of MK 801 or A841720, but not of CNQX , reduced both secondary nociceptive behaviors. Moreover, pre‐treatment with the three antagonists injected into the DR t prevented the development of secondary mechanical allodynia and secondary thermal hyperalgesia. Similarly, in these rats, the number of c‐Fos‐like immunoreactive neurons were markedly reduced in both the superficial and deep lamina of the dorsal horn. Our findings support the role of DR t as a pain facilitator in acute and chronic pain states, and suggest a key role of glutamate receptors during the development and maintenance of formalin‐induced secondary allodynia.