Metabotropic glutamate receptor 5 antagonist 2-methyl-6-(phenylethynyl)pyridine produces antidepressant effects in rats: role of brain-derived neurotrophic factor.

Recent studies highlight that the brain glutamate system is involved in the etiology of depression and glutamatergic-targeting drugs are currently being explored as novel antidepressant medications. Previous studies reveal that the selective metabotropic glutamate receptor 5 antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP) produces antidepressant-like effects in behavioral despair and olfactory bulbectomy models. The current study aimed to further explore its behavioral actions in additional animal models of depression (forced swimming test (FST) and learned helplessness (LH) test) and its underlying neurobiological mechanisms. The results demonstrated that acute treatment of MPEP at 30 but not 10mg/kg significantly reduced immobility in FST without affecting locomotor activities. Sub-chronic, five-day treatment of MPEP (30 mg/kg) decreased escape failures in animals that had developed LH symptoms. This sub-chronic treatment also increased hippocampal brain-derived neurotrophic factor (BDNF) protein levels in both non-stressed and stressed animals and restored the stress-induced down-regulation of BDNF expression. Current findings provide strong evidence for further studies of MPEP as a tool to explore novel antidepressants.