scholarly journals Effects of inflammation on the ultrastructural localization of spinal cord dorsal horn group I metabotropic glutamate receptors

2007 ◽  
Vol 506 (2) ◽  
pp. 371-372
Keyword(s):  
Spinal Cord ◽  
Glutamate Receptors ◽  
Dorsal Horn ◽  
Metabotropic Glutamate Receptors ◽  
Ultrastructural Localization ◽  
Spinal Cord Dorsal Horn ◽  
Metabotropic Glutamate ◽  
Group I ◽  
Spinal Cord Dorsal

scholarly journals Peripheral Glutamate Receptors Are Required for Hyperalgesia Induced by Capsaicin

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
You-Hong Jin ◽  
Motohide Takemura ◽  
Akira Furuyama ◽  
Norifumi Yonehara
Keyword(s):  
Spinal Cord ◽  
Glutamate Receptors ◽  
Dorsal Horn ◽  
Transient Receptor Potential ◽  
Small Diameter ◽  
Spinal Cord Dorsal Horn ◽  
Group I ◽  
Nociceptive Responses ◽  
Spinal Cord Dorsal ◽  
Fos Expression

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.

Groups II and III Metabotropic Glutamate Receptors Differentially Modulate Brief and Prolonged Nociception in Primate STT Cells

2000 ◽  
Vol 84 (6) ◽  
pp. 2998-3009 ◽  
Author(s):  
Volker Neugebauer ◽  
Ping-Sun Chen ◽  
William D. Willis
Keyword(s):  
Glutamate Receptors ◽  
Dorsal Horn ◽  
Central Sensitization ◽  
Metabotropic Glutamate Receptors ◽  
Background Activity ◽  
Mechanical Stimuli ◽  
Group Iii ◽  
Metabotropic Glutamate ◽  
Group I ◽  
Group Ii

The heterogeneous family of G-protein-coupled metabotropic glutamate receptors (mGluRs) provides excitatory and inhibitory controls of synaptic transmission and neuronal excitability in the nervous system. Eight mGluR subtypes have been cloned and are classified in three subgroups. Group I mGluRs can stimulate phosphoinositide hydrolysis and activate protein kinase C whereas group II (mGluR2 and 3) and group III (mGluR4, 6, 7, and 8) mGluRs share the ability to inhibit cAMP formation. The present study examined the roles of groups II and III mGluRs in the processing of brief nociceptive information and capsaicin-induced central sensitization of primate spinothalamic tract (STT) cells in vivo. In 11 anesthetized male monkeys ( Macaca fascicularis), extracellular recordings were made from 21 STT cells in the lumbar dorsal horn. Responses to brief (15 s) cutaneous stimuli of innocuous (brush), marginally and distinctly noxious (press and pinch, respectively) intensity were recorded before, during, and after the infusion of group II and group III mGluR agonists into the dorsal horn by microdialysis. Different concentrations were applied for at least 20 min each (at 5 μl/min) to obtain cumulative concentration-response relationships. Values in this paper refer to the drug concentrations in the microdialysis fibers; actual concentrations in the tissue are about three orders of magnitude lower. The agonists were also applied at 10–25 min after intradermal capsaicin injection. The group II agonists (2S,1′S,2′S)-2-(carboxycyclopropyl)glycine (LCCG1, 1 μM-10 mM, n = 6) and (−)-2-oxa-4-aminobicyclo[3.1.0]hexane-4,6-dicarboxylate (LY379268; 1 μM-10 mM, n = 6) had no significant effects on the responses to brief cutaneous mechanical stimuli (brush, press, pinch) or on ongoing background activity. In contrast, the group III agonist L(+)-2-amino-4-phosphonobutyric acid (LAP4, 0.1 μM-10 mM, n = 6) inhibited the responses to cutaneous mechanical stimuli in a concentration-dependent manner, having a stronger effect on brush responses than on responses to press and pinch. LAP4 did not change background discharges significantly. Intradermal injections of capsaicin increased ongoing background activity and sensitized the STT cells to cutaneous mechanical stimuli (ongoing activity > brush > press > pinch). When given as posttreatment, the group II agonists LCCG1 (100 μM, n = 5) and LY379268 (100 μM, n = 6) and the group III agonist LAP4 (100 μM, n = 6) reversed the capsaicin-induced sensitization. After washout of the agonists, the central sensitization resumed. Our data suggest that, while activation of both group II and group III mGluRs can reverse capsaicin-induced central sensitization, it is the actions of group II mGluRs in particular that undergo significant functional changes during central sensitization because they modulate responses of sensitized STT cells but have no effect under control conditions.

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