Brain-derived neurotrophic factor (BDNF) is the most prevalent neurotrophin in brain;via actions on its high affinity trkB receptor it enhances the survival of many types of central neurons and is implicated in several forms of neural plasticity in the brain. Recent work suggests that endogenous BDNF in the hippocampus may be involved in mediating antidepressant responses, in depression models in mice. A rather surprising finding in the field of depression has been the demonstration that ketamine, an ionotropic glutamatergic n-methyl-daspartate (NMDA) receptor antagonist, has rapid and long-lasting antidepressant effects in depressed individuals. We have started to investigate the mechanisms of the antidepressant activity of ketamine, specifically the potential involvement of endogenous BDNF in the hippocampus. In preliminary experiments, we find that the NMDA receptor antagonists, ketamine, MK801 or CPP, produce fast-acting antidepressant behavioral effects in depression models in mice. The fast acting antidepressant effects of ketamine occurs via a BDNF dependent manner because these effects are lost in forebrain specific BDNF knockout mice. Our findings also suggest that the antidepressant effects of ketamine require protein translation, but not transcription, resulting in increases in BDNF protein levels that are important for the behavioral effect. Recent work has suggested a strong causal link between blockade of resting NMDA receptor activation and rapid increases in local dendritic protein translation. In agreement with recent in vitro work, we find that ketamine causes a decrease in phosphorylation of eukaryotic elongation factor 2 (eEF2), which normally impedes translation in its phosphorylated state, suggesting translational de-repression of BDNF mRNA. Importantly, we provide preliminary evidence that inhibitors of the eEF2 kinase (also called CaMKIII) that normally phosphorylates eEF2 trigger a fast-acting antidepressant-like effect in depression models in mice. These findings suggest a behavioral and clinically relevant correlate of dendritic translational de-repression by NMDA receptors. The objective of this grant is to link the regulation of translational repression to the effects of antidepressants. Collectively, these studies promise to provide fundamentally novel information concerning how endogenous BDNF in the hippocampus is involved in the fast acting antidepressant response of ketamine and offer new leads toward the development of faster acting antidepressants.
The objective of this grant is to study the role of BDNF in the hippocampus in mediating antidepressant responses in mice. Based on our preliminary data presented in this application, we will examine the role of the eEF2 signaling pathway in mediating fast acting antidepressant responses upstream of BDNF. These studies will use molecular, cellular and behavioral approaches to investigate the the signaling pathways involved in mediating fast acting antidepressant responses, in the hopes of developing faster acting antidepressants.
|Monteggia, Lisa M (2016) Toward Better Animal Models for Molecular Psychiatry. Biol Psychiatry 79:2-3|
|BjÃ¶rkholm, Carl; Monteggia, Lisa M (2016) BDNF - a key transducer of antidepressant effects. Neuropharmacology 102:72-9|
|Monteggia, Lisa M; Zarate Jr, Carlos (2015) Antidepressant actions of ketamine: from molecular mechanisms to clinical practice. Curr Opin Neurobiol 30:139-43|
|Kavalali, Ege T; Monteggia, Lisa M (2015) How does ketamine elicit a rapid antidepressant response? Curr Opin Pharmacol 20:35-9|
|Gideons, Erinn S; Kavalali, Ege T; Monteggia, Lisa M (2014) Mechanisms underlying differential effectiveness of memantine and ketamine in rapid antidepressant responses. Proc Natl Acad Sci U S A 111:8649-54|
|Nosyreva, Elena; Autry, Anita E; Kavalali, Ege T et al. (2014) Age dependence of the rapid antidepressant and synaptic effects of acute NMDA receptor blockade. Front Mol Neurosci 7:94|
|Burke, Teresa F; Advani, Tushar; Adachi, Megumi et al. (2013) Sensitivity of hippocampal 5-HT1A receptors to mild stress in BDNF-deficient mice. Int J Neuropsychopharmacol 16:631-45|
|Mahgoub, Melissa; Monteggia, Lisa M (2013) Epigenetics and psychiatry. Neurotherapeutics 10:734-41|
|Costa-Mattioli, Mauro; Monteggia, Lisa M (2013) mTOR complexes in neurodevelopmental and neuropsychiatric disorders. Nat Neurosci 16:1537-43|
|Bal, Manjot; Leitz, Jeremy; Reese, Austin L et al. (2013) Reelin mobilizes a VAMP7-dependent synaptic vesicle pool and selectively augments spontaneous neurotransmission. Neuron 80:934-46|
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