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Pain Research and Treatment
Volume 2012, Article ID 915706, 8 pages
http://dx.doi.org/10.1155/2012/915706
Research Article

Peripheral Glutamate Receptors Are Required for Hyperalgesia Induced by Capsaicin

1Department of Anatomy, Affiliated Stomatological Hospital of Nanchang University, Jiangxi Province, Nanchang 330006, China
2Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
3Department of Oral Physiology, School of Dentistry, Ohu University, Koriyama, Fukushima 963-8611, Japan
4Division of Dental Pharmacology, Department of Oral Medical Science, School of Dentistry, Ohu University, Koriyama, Fukushima 963-8611, Japan
5Division of Pharmacology, School of Pharmaceutical Science, Ohu University, Koriyama, Fukushima 963-8611, Japan

Received 3 June 2011; Accepted 6 August 2011

Academic Editor: Paul G. Green

Copyright © 2012 You-Hong Jin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Transient receptor potential vanilloid1 (TRPV1) and glutamate receptors (GluRs) are located in small diameter primary afferent neurons (nociceptors), and it was speculated that glutamate released in the peripheral tissue in response to activation of TRPV1 might activate nociceptors retrogradely. But, it was not clear which types of GluRs are functioning in the nociceptive sensory transmission. In the present study, we examined the c-Fos expression in spinal cord dorsal horn following injection of drugs associated with glutamate receptors with/without capsaicin into the hindpaw. The subcutaneous injection of capsaicin or glutamate remarkably evoked c-Fos expression in ipsilateral sides of spinal cord dorsal horn. This capsaicin evoked increase of c-Fos expression was significantly prevented by concomitant administration of MK801, CNQX, and CPCCOEt. On the other hand, there were not any significant changes in coinjection of capsaicin and MCCG or MSOP. These results reveal that the activation of iGluRs and group I mGluR in peripheral afferent nerves play an important role in mechanisms whereby capsaicin evokes/maintains nociceptive responses.