Glutamate-Based Antidepressants: Preclinical Psychopharmacology (original) (raw)
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The involvement of glutamate in the pathophysiology of depression
Drug News & Perspectives, 2005
A ccording to the projections, depression is expected to rank second (after ischemic heart diseases) in major disease burdens by 2020. The prevalence of depression is constantly on the rise, in spite of accessibility of several types of antidepressant drugs. 2 A variety of antidepressant drugs, acting via distinct mechanisms, including serotonergic, noradrenergic and/or dopaminergic systems, have been used for more than 40 years. Nonetheless, conventional antidepressant drugs have many limitations that hinder effective treatment, produce several adverse effects and require several weeks of treatment to evoke therapeutic effects. Such a profile has encouraged ongoing research to develop new compounds that may yield more efficacious and faster-acting therapeutic agents. In recent years, attention has focused on glutamate and the glutamatergic system, which is considered to be a promising target for a novel antidepressant therapy .
On the role of metabotropic glutamate receptors in the mechanisms of action of antidepressants
Polish journal of pharmacology
Most conventional antidepressant drugs influence serotoninergic, adrenergic, and/or dopaminergic systems, increasing serotonin, norepinephrine and dopamine synaptic availability. More recently attention has focused on glutamatergic system. Both preclinical and clinical studies, showing antidepressant-like actions of compounds which reduce transmission at N-methyl-D-aspartate (NMDA) receptors, indicate possible involvement of glutamatergic system in the etiology of depression. Since glutamatergic transmission is controlled not only by ionotropic but also by metabotropic glutamate receptors (mGluR), their involvement in the etiology and the therapy of depression was also postulated. Recent studies, showing that antidepressant treatment may influence mGlu receptors, together with the findings that group I mGluR antagonists, may possess antidepressant-like action, support this hypothesis.
Glutamate-based antidepressants: 20 years on
Trends in Pharmacological Sciences, 2009
Depression is a chronic, recurring illness that affects more than 120 million people worldwide. Drugs increasing the synaptic availability of serotonin and norepinephrine (biogenic amine-based agents) have been used to treat depression for more than 50 years. However, significant symptom improvement requires ≥2-4 weeks of treatment, and a first course of therapy provides symptom relief to only 60-65% of patients. Roche and Evotec recently announced plans to develop Nmethyl-D-aspartate (NMDA) receptor antagonists targeting the NR2B subtype for treatment resistant depression. This announcement closely follows a report that another NR2B antagonist, traxoprodil (CP 101,606), is antidepressant in patients unresponsive to a serotonin selective reuptake inhibitor (SSRI) as well as reports of rapid and sustained antidepressant effects following a single injection of the NMDA antagonist, ketamine. Here we describe evidence that glutamate-based therapies may represent an effective alternative to biogenic-amine based agents for depression, and provide perspectives on developing these agents.
ABSTRACTAt sub-anaesthetic doses, ketamine, a non competitive N-methyl-d-aspartate (NMDA) receptor antagonist, has demonstrated remarkable and rapid antidepressant (AD) efficacy in patients with treatment-resistant depression (TRD). However, its mechanism of action of ketamine is not fully understood. Since comorbid depression and anxiety disorders often occur, GABAergic/inhibitory and glutamatergic/excitatory drug treatments may be co-administered in these patients. Information regarding this combination is critical to establish efficacy or treatment restrictions to maximize translation from animal models to TRD patients, effectiveness and safety. To assess the specific role of excitatory/inhibitory neurotransmission in the medial prefrontal cortex-raphe nuclei (mPFC-DRN) circuit in the sustained antidepressant-like activity (AD) of ketamine (at t24h post dose), AMPA-R antagonist (intra-DRN) and GABAA-R agonist (intra-mPFC) were co-administered with ketamine (intra-mPFC). Twenty-fo...
Modulation of glutamate receptors: Strategies for the development of novel antidepressants
Amino Acids, 2002
On a biochemical level, conventional antidepressants have been shown to modulate synaptic levels of biogenic amines (i.e., serotonin, norepinephrine, and dopamine), most often by interfering with reuptake processes or inhibiting metabolism. Strategies directed at modulating glutamatergic transmission may overcome the principal limitations (i.e., delayed onset and low efficacy) that appear to be inherent to these conventional agents. In this brief overview, I summarize two glutamate-based approaches to develop novel antidepressants. These distinct and (on a cellular level) seemingly diametric strategies may converge on intracellular pathways that are also impacted upon by chronic treatment with biogenic amine based agents.
Glutamate and Depression: Clinical and Preclinical Studies
Annals of the New York Academy of Sciences, 2003
The past decade has seen a steady accumulation of evidence supporting a role for the excitatory amino acid (EAA) neurotransmitter, glutamate, and its receptors in depression and antidepressant activity. To date, evidence has emerged indicating that N-methyl-d-aspartate (NMDA) receptor antagonists, group I metabotropic glutamate receptor (mGluR1 and mGluR5) antagonists, as well as positive modulators of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors have antidepressant-like activity in a variety of preclinical models. Moreover, antidepressant-like activity can be produced not only by drugs modulating the glutamatergic synapse, but also by agents that affect subcellular signaling systems linked to EAA receptors (e.g., nitric oxide synthase). In view of the extensive colocalization of EAA and monoamine markers in nuclei such as the locus coeruleus and dorsal raphe, it is likely that an intimate relationship exists between regulation of monoaminergic and EAA neurotransmission and antidepressant effects. Further, there is also evidence implicating disturbances in glutamate metabolism, NMDA, and mGluR1,5 receptors in depression and suicidality. Finally, recent data indicate that a single intravenous dose of an NMDA receptor antagonist is sufficient to produce sustained relief from depressive symptoms. Taken together with the proposed role of neurotrophic factors in the neuroplastic responses to stressors and antidepressant treatments, these findings represent exciting and novel avenues to both understand depressive symptomatology and develop more effective antidepressants.
Glutamate-based anxiolytic ligands in clinical trials
Expert Opinion on Investigational Drugs, 2013
Over the past 20 years, converging lines of evidence have both linked glutamatergic dysfunction to the pathophysiology of depression and demonstrated that the glutamatergic synapse presents multiple targets for developing novel antidepressants. The robust antidepressant effects of the N-methyl-D-aspartate receptor antagonists ketamine and traxoprodil provide target validation for this family of ionotropic glutamate receptors. This article reviews the preclinical evidence that it may be possible to develop glutamate-based antidepressants by not only modulating ionotropic (N-methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid) and metabotropic glutamate (mGlu) receptors, including mGlu2/3, mGLu5 and mGlu7 receptors, but also by altering synaptic concentrations of glutamate via specialized transporters such as glial glutamate transporter 1 (excitatory amino-acid transporter 2).
Glutamate modulators as novel interventions for mood disorders
Revista Brasileira de Psiquiatria, 2005
Recent evidence suggests that critical molecules in neurotrophic signaling cascades are long-term targets for currently available monoaminergic antidepressants. As chronic and severe mood disorders are characterized by impairments in neuronal resilience, pharmacological strategies that subserve a neuroprotective function might alter disorder pathophysiology and modify disease progression. Several promising approaches involve modulation of the glutamate neurotransmitter system, via post-synaptic receptor blockade or potentiation and presynaptic vesicular release inhibition. A focused review of the extant scientific literature was conducted, with a discussion of 3 compounds or classes of drugs currently undergoing clinical investigation: ketamine, riluzole, and AMPA receptor potentiators. Recent investigations in mood disordered patients suggest that the NMDA receptor antagonist ketamine might demonstrate rapid antidepressant properties. Riluzole has been shown to reverse glutamate-me...