Contribution of peripheral n-methyl-d-aspartate receptors to c-fos expression in the trigeminal spinal nucleus following acute masseteric inflammation

• Published in: Neuroscience Vol. 123; no. 1; pp. 213 - 219
• Main Authors: Ro, J.Y, Capra, N.F, Masri, R
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 2004; Elsevier
• Subjects: Animals; Biological and medical sciences; Dizocilpine Maleate - pharmacology; Fundamental and applied biological sciences. Psychology; Gene Expression - drug effects; Gene Expression - physiology; Genes, fos - drug effects; Genes, fos - physiology; Inflammation - metabolism; Inflammation - pathology; Male; masseter muscle; Masseter Muscle - drug effects; Masseter Muscle - metabolism; Masseter Muscle - pathology; MK-801; mustard oil; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate - antagonists & inhibitors; Receptors, N-Methyl-D-Aspartate - metabolism; Trigeminal Nucleus, Spinal - metabolism; trigeminal spinal nucleus; Vertebrates: nervous system and sense organs; MO; AMPA; EAA; Fos-LI; trigeminal spinal nucleus; PTN; Vc; mGluR; TMJ; MK-801; mustard oil; CVc; Vsp; Vi; masseter muscle; VL; NMDA; MVc; RVc; Dizocilpine; Masseter muscle; Glutamate receptor; Inflammation; Gene expression; Antagonist; Spinal trigeminal nucleus; NMDA receptor; Protooncogene; Immediate early gene
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(03)00465-2

In this study, we examined the contribution of
N-methyl-
d-aspartate (NMDA) receptors on
c-fos expression in the trigeminal brainstem nuclei following acute muscle inflammation. Mustard oil (MO; 20%, 30 μL) injected into the masseter muscle induced extensive peripheral edema and Fos-like immunoreactivity (Fos-LI) in several trigeminal brainstem areas including the subnucleus caudalis of the trigeminal spinal nucleus (Vc), the ventral and dorsal regions of the Vc/subnucleus interpolaris transition zone, and the paratrigeminal nucleus. In order to assess the effect of antagonizing NMDA receptors on MO-induced Fos-LI, rats were pre-treated with two different doses of i.v. MK-801 (0.3 mg/kg, 3 mg/kg), a non-competitive NMDA receptor antagonist, 30 min prior to MO injection. Additional groups of rats received MK-801 (0.3 mg/kg) directly in the masseter muscle or in the biceps muscle 5 min prior to MO injection. A higher dose of i.v. MK-801 (3 mg/kg) and MK-801 given locally into the masseter muscle (0.3 mg/kg) produced a significant reduction in total number of MO-induced Fos-LI. Further analyses revealed that pre-treatment with MK-801 (3 mg/kg i.v.) significantly reduced the Fos-LI all throughout the Vc. Only at the caudal Vc, there was a dose-dependent reduction of MO induced Fos-LI. Pre-treatment with masseteric MK-801 also significantly reduced the Fos-LI in the caudal Vc, with the effect greater than that produced by the same dose of MK-801 given intravenously. These results suggest that peripheral NMDA receptors contribute to nociceptive processing from craniofacial muscles.