• Dong K Ahn, Kwang H Kim, Chang Y Jung, Hyo S Choi, Eun J Lim, Dong H Youn, and Yong C Bae.
• Department of Oral Physiology and Neurobiology, School of Dentistry, Kyungpook National University, 188-1 Sam Deok 2 ga, Chung-gu, Daegu 700 412, South Korea. dkahn@mail.knu.ac.kr
• Pain. 2005 Nov 1; 118 (1-2): 53-60.

AbstractThe present study investigated the role of peripheral group I and II metabotropic glutamate receptors (mGluRs) in interleukin-1beta (IL-1beta)-induced mechanical allodynia in the orofacial area. Experiments were carried out on Sprague-Dawley rats weighing between 230 and 280 g. After subcutaneous administration of 0.01, 0.1, 1, or 10 pg of IL-1beta, we examined withdrawal behavioral responses produced by 10 successive trials of a ramp of air-puffs pressure applied ipsilaterally or contralaterally to the IL-1beta injection site. The thresholds of air puffs were measured 10, 30, 60, 120, or 180 min after 25 microl of IL-1beta was administered through an implanted tube. Subcutaneous injection of IL-1beta produced bilateral mechanical allodynia. While the IL-1beta-induced mechanical allodynia was blocked by pretreatment with an IL-1 receptor antagonist, the IL-1beta-induced mirror-image mechanical allodynia was not blocked by an IL-1 receptor antagonist injected into the contralateral side. Subcutaneous administration of CPCCOEt or LY367385, an mGluR1 antagonist, or MPEP or SIB1893, an mGluR5 antagonist, 10 min prior to injection of IL-1beta abolished IL-1beta-induced mechanical allodynia. Pretreatment with APDC or DCG4, a group II mGluR agonist, blocked the IL-1beta-induced mechanical allodynia. The anti-allodynic effect induced by APDC was inhibited by pretreatment with LY341495, a group II mGluR antagonist. These results suggest that peripheral group I and II mGluRs participate in IL-1beta-induced mechanical allodynia in the orofacial area. Peripheral group I mGluR antagonists blocked the IL-1beta-induced mechanical allodynia, while peripheral group II mGluR agonists produced anti-allodynic effects on IL-1beta-induced mechanical allodynia in the orofacial area of rats.

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