TY - JOUR T1 - Pharmacological Characterization of a New, Orally Active and Potent Allosteric Metabotropic Glutamate Receptor 1 Antagonist, 4-[1-(2-Fluoropyridin-3-yl)-5-methyl-1<em>H</em>-1,2,3-triazol-4-yl]-<em>N</em>-isopropyl-<em>N</em>-methyl-3,6-dihydropyridine-1(2<em>H</em>)-carboxamide (FTIDC) JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 1144 LP - 1153 DO - 10.1124/jpet.106.116574 VL - 321 IS - 3 AU - Gentaroh Suzuki AU - Toshifumi Kimura AU - Akio Satow AU - Naoki Kaneko AU - Junko Fukuda AU - Hirohiko Hikichi AU - Naoko Sakai AU - Shunsuke Maehara AU - Hiroko Kawagoe-Takaki AU - Mikiko Hata AU - Tomoko Azuma AU - Satoru Ito AU - Hiroshi Kawamoto AU - Hisashi Ohta Y1 - 2007/06/01 UR - http://jpet.aspetjournals.org/content/321/3/1144.abstract N2 - A highly potent and selective metabotropic glutamate receptor (mGluR) 1 antagonist, 4-[1-(2-fluoropyridin-3-yl)-5-methyl-1H-1,2, 3-triazol-4-yl]-N-isopropyl-N-methyl-3,6-dihydropyridine-1(2H)-carboxamide (FTIDC), is described. FTIDC inhibits, with equal potency, l-glutamate-induced intracellular Ca2+ mobilization in Chinese hamster ovary cells expressing human, rat, or mouse mGluR1a. The IC50 value of FTIDC is 5.8 nM for human mGluR1a and 6200 nM for human mGluR5. The maximal response in agonist concentration-response curves was reduced in the presence of higher concentrations of FTIDC, suggesting the inhibition in a noncompetitive manner. FTIDC at 10 μM showed no agonistic, antagonistic, or positive allosteric modulatory activity toward mGluR2, mGluR4, mGluR6, mGluR7, or mGluR8. FTIDC did not displace [3H]l-quisqualate binding to human mGluR1a, indicating FTIDC is an allosteric antagonist. Studies using chimeric and mutant receptors of mGluR1 showed that transmembrane (TM) domains 4 to 7, especially Phe801 in TM6 and Thr815 in TM7, play pivotal roles in the antagonism of FTIDC. FTIDC inhibited the constitutive activity of mGluR1a, suggesting that FTIDC acts as an inverse agonist of mGluR1a. Intraperitoneally administered FTIDC inhibited face-washing behavior elicited by a group I mGluR agonist, (S)-3,5-dihydroxyphenylglycine in mice at doses that did not produce motor impairment. Oral administration of FTIDC also inhibited the face-washing behavior. FTIDC is a highly potent and selective allosteric mGluR1 antagonist and a compound having oral activity without species differences in its antagonistic activity on recombinant human, mouse, and rat mGluR1. FTIDC could therefore be a valuable tool for elucidating the functions of mGluR1 not only in rodents but also in humans. The American Society for Pharmacology and Experimental Therapeutics ER -