title: The selective mGlu5 receptor antagonist MTEP, similar to NMDA receptor antagonists, induces social isolation in rats.
abstract: It has repeatedly been shown that uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonists can mimic certain aspects of positive and negative symptoms of schizophrenia in human volunteers and laboratory animals. The purpose of the present study was to expand these findings and to determine whether the selective metabotropic glutamate receptor subtype 5 (mGluR5) antagonist, MTEP (3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine), could induce similar effects in Wistar rats. First, MTEP (1.0-10.0 mg/kg; intraperitoneally) after acute and subchronic (daily for 5 days) administration as well as the uncompetitive antagonists of the NMDA receptor of either high affinity, phencyclidine (0.5-4.0 mg/kg; subcutaneously (s.c.)) and (+)-MK-801 (0.03-0.25 mg/kg; s.c.), or low-moderate affinity, ketamine (2.0-16.0 mg/kg; s.c.) and memantine (0.15-20.0 mg/kg; s.c.), following daily administration for 3 days were tested in the social interaction test to determine their ability to reproduce the negative and positive symptoms measured by social isolation and stereotyped behavior, respectively. Second, the compounds were tested in the motility test following acute administration to determine their ability to induce locomotor hyperactivity reflecting the positive symptoms. In line with previous findings, all examined NMDA receptor antagonists produced social interaction deficits, locomotor hyperactivity, and stereotypy except memantine. Notably, this study found that MTEP following both acute and subchronic administration dose-dependently induced social isolation, but did not cause either locomotor hyperactivity or stereotypy. These data demonstrate that social behavior deficits in rats can be caused by both the blockade of the NMDA receptor and the inhibition of mGluR5, whereas mGluR5 antagonists may not independently be able to mimic the positive symptoms.
authors.affiliation: Department of CNS Research, Boehringer-Ingelheim Pharma GmbH & Co. KG, Biberach, Germany. Eliza.Koros@bc.boehringer-ingelheim.com
authors.forename: Eliza
authors.initials: E
authors.lastname: Koros
authors.forename: Holger
authors.initials: H
authors.lastname: Rosenbrock
authors.forename: Gerald
authors.initials: G
authors.lastname: Birk
authors.forename: Carmen
authors.initials: C
authors.lastname: Weiss
authors.forename: Frank
authors.initials: F
authors.lastname: Sams-Dodd
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage*; D007398:Interpersonal Relations; D008297:Male; D009068:Movement / Q000187:drug effects; D011725:Pyridines / Q000008:administration & dosage*; D051381:Rats; D017208:Rats, Wistar; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D012934:Social Isolation; D013239:Stereotyped Behavior / Q000187:drug effects; D013844:Thiazoles / Q000008:administration & dosage*
chemical_list: C472365:3-((2-methyl-1,3-thiazol-4-yl)ethynyl)pyridine; D018691:Excitatory Amino Acid Antagonists; C578935:GRM5 protein, human; C578937:Grm5 protein, rat; D011725:Pyridines; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D013844:Thiazoles