title: Antinociceptive effect of a group II metabotropic glutamate receptor antagonist in the thalamus of monoarthritic rats.
abstract: Adult rats were rendered monoarthritic (MA) by injection of 50 microl of complete Freund's adjuvant (CFA) into the tibiotarsal joint. The ankle-bend (AB) test of nociception was performed in those animals before and during 60 min after the stereotaxic injection of 2 microl of either saline (controls) or (2S)-alpha-ethylglutamic acid (EGLU, 80 nmol in 2 microl), a group II metabotropic glutamate receptors (mGluR) antagonist, in the reticular thalamic nucleus (Rt) contralateral to the arthritic joint. AB scores reached near maximum values before the stereotaxic injections (18.7+/-0.8), and remained constant throughout the entire experimental period in the control group, denoting marked allodynia. In the EGLU-treated group, AB scores gradually decreased after EGLU injection, with minimum values at 10 min (7.7+/-1.6), recovering to scores near maximum at 60 min (19.7+/-0.3). The data point to an activation of group II mGluR by noxious inputs in the Rt of MA rats, suggesting their participation in inhibiting local gamma-aminobutyric acid (GABA)ergic inhibitory neurones.
authors: Institute of Histology and Embryology and IBMC, Faculty of Medicine of Oporto, 4200-319, Porto, Portugal.
authors: F L
authors: FL
authors: Neto
authors: J M
authors: JM
authors: Castro-Lopes
mesh_terms: D000818:Animals; D001169:Arthritis, Experimental / Q000503:physiopathology*; D005971:Glutamates / Q000008:administration & dosage / Q000494:pharmacology*; D007249:Inflammation; D007596:Joints / Q000503:physiopathology; D008297:Male; D008845:Microinjections; D009068:Movement / Q000187:drug effects / Q000502:physiology; D010146:Pain / Q000503:physiopathology / Q000517:prevention & control*; D051381:Rats; D017208:Rats, Wistar; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors*; D013238:Stereotaxic Techniques; D013787:Thalamic Nuclei / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology*
chemical_list: D005971:Glutamates; D018094:Receptors, Metabotropic Glutamate; C017302:alpha-ethylglutamic acid