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Objective: The metabotropic glutamate receptor subtype 2 (mGlu ) possesses both orthosteric and allosteric modulatory sites, are expressed in the frontal cortex and limbic structures, and can affect excitatory synaptic transmission. Therefore, mGlu is a potential therapeutic target in the treatment of epilepsy. The present study seeks to evaluate the anticonvulsant potential of mGlu -acting compounds.
Methods: The anticonvulsant efficacy of two selective mGlu -positive allosteric modulators (PAMs) (JNJ-42153605 and JNJ-40411813/ADX71149) and one mGlu receptor agonist (LY404039) were evaluated alone and in combination with the antiseizure drug levetiracetam (LEV) in the mouse 6 Hz model.
Results: In the 6 Hz (32 mA stimulus intensity) model, median effective dose (ED ) values were determined for JNJ-42153605 (3.8 mg/kg), JNJ-40411813 (12.2 mg/kg), and LY404039 (10.9 mg/kg). At the 44 mA stimulus intensity, ED values were determined for JNJ-42153605 (5.9 mg/kg), JNJ-40411813 (21.0 mg/kg), LY404039 (14.1 mg/kg), and LEV (345 mg/kg). In addition, subprotective doses of each mGlu -acting compound, administered in combination with various doses of LEV, were able to shift the 6 Hz 44 mA ED for LEV by >25-fold. When JNJ-42153605 was administered at varying doses in combination with a single dose of LEV (10 mg/kg), the potency of JNJ-42153605 was increased 3.7-fold. Similarly, when a moderately effective dose of LEV (350 mg/kg) was administered in combination with varying doses of JNJ-40411813, the potency of JNJ-40411813 was increased approximately 14-fold. Plasma levels of JNJ-40411813 and LEV were not different when administered alone or in combination, suggesting that increases in potency are not due to pharmacokinetic effects.
Significance: These studies suggest a potential positive pharmacodynamic effect of mGlu -acting compounds in combination with LEV. If this effect is translated in a clinical setting, it can support a rational polypharmacy concept in treatment of epilepsy patients.
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http://dx.doi.org/10.1111/epi.13659 | DOI Listing |
Mol Pharmacol
July 2025
Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York. Electronic address:
Metabotropic glutamate receptors (mGlus) are obligate dimer G protein-coupled receptors that can all homodimerize and heterodimerize in select combinations. Responses of mGlu heterodimers to selective ligands, including orthosteric agonists and allosteric modulators, are largely unknown. The pharmacological properties of each group II and III mGlu homodimer (except the exclusively retinally expressed mGlu6) and several heterodimers were examined when stochastically assembled in HEK293T cells, or specifically measured using an improved G protein-mediated bioluminescence resonance energy transfer assay employing complemented fragments of Nanoluciferase.
View Article and Find Full Text PDFCell Rep
August 2025
Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, 34094 Montpellier, France. Electronic address:
Cell surface G protein-coupled receptors (GPCRs) are tightly regulated through constitutive and agonist-induced internalization. While the mechanisms of constitutive internalization remain elusive, agonist-induced internalization very often involves receptor phosphorylation by GPCR kinases (GRKs) and β-arrestin recruitment. Dimeric class C metabotropic glutamate (mGlu1-mGlu8) receptors regulate synaptic transmission, but their internalization process remains ambiguous.
View Article and Find Full Text PDFEur J Pharmacol
September 2025
Department of Scienza e Tecnologia del Farmaco, University of Turin, Italy.
To keep brain homeostasis, the highly specialized endothelial cells that constitute the blood-brain barrier (BBB) are also supported by astrocytes and microglia. Glial influence on barrier properties may be controversial in inflammatory conditions as they can either stabilize or compromise BBB functions. The role played by metabotropic glutamate (mGlu) receptors 2 and 3 on BBB properties in inflammatory conditions has not been investigated, and we analyzed whether these receptors represent potential pharmacological targets.
View Article and Find Full Text PDFBiomed Pharmacother
March 2025
Department of Neurosciences, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, Florence, Italy.
The objective of this study was to determine the anti-neuropathic activity of a variety of ibogalogs, including tabernanthalog (TBG), ibogaminalog (DM506), ibogainalog (IBG), nor-IBG, catharanthalog (CAG), and PNU-22394 using the oxaliplatin (OXA) neuropathic pain model in mice, and to investigate whether there is crosstalk between the 5-HT and mGlu receptors. All tested ibogalogs induce pain-relieving activity using both cold plate and paw pressure tests, without toxic effects. The most potent ibogalogs were IBG and CAG, whereas nor-IBG and DM506 were the longest-acting compounds.
View Article and Find Full Text PDFPsychopharmacology (Berl)
June 2025
Department of Medicinal Chemistry, Maj Institute of Pharmacology, Polish Academy of Sciences, 12 Smętna Street, Kraków, 31-343, Poland.
Rationale: Due to the numerous limitations of ketamine as a rapid-acting antidepressant drug (RAAD), research is still being conducted to find an effective and safe alternative to this drug. Recent studies indicate that the partial mGlu receptor negative allosteric modulator (NAM), 2-(2-(3-methoxyphenyl)ethynyl)-5-methylpyridine (M-5MPEP), has therapeutic potential as an antidepressant.
Objectives: The study aimed to investigate the potential rapid antidepressant-like effect of M-5MPEP in a mouse model of depression and to determine the mechanism of this action.