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Ketamine's rapid and sustained antidepressant effects are driven by distinct mechanisms.

Radhika Rawat, Elif Tunc-Ozcan, Sara Dunlop, Yung-Hsu Tsai, Fangze Li, Ryan Bertossi, Chian-Yu Peng, John A Kessler

Cellular and Molecular Life Sciences February 27, 2024 DOI: 10.1007/s00018-024-05121-6 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Experimental study Peer reviewed
Population Mice
Intervention Ketamine
Dose multiple subanesthetic doses
Duration Two-week treatment period
Topics Ketamine Neuroplasticity Esketamine
Keywords Adult neurogenesis Antidepressant Bmp Hippocampus Mechanism Ketamine therapy Neuroscience research Depression treatment
Citations 17
Key findings Ketamine's sustained antidepressant effects require decreased BMP signaling and increased neurogenesis in the hippocampal dentate gyrus, whereas its rapid effects depend on increased activity of immature neurons without neurogenesis.

Abstract

Administration of multiple subanesthetic doses of ketamine increases the duration of antidepressant effects relative to a single ketamine dose, but the mechanisms mediating this sustained effect are unclear. Here, we demonstrate that ketamine's rapid and sustained effects on affective behavior are mediated by separate and temporally distinct mechanisms. The rapid effects of a single dose of ketamine result from increased activity of immature neurons in the hippocampal dentate gyrus without an increase in neurogenesis. Treatment with six doses of ketamine over two weeks doubled the duration of behavioral effects after the final ketamine injection. However, unlike ketamine's rapid effects, this more sustained behavioral effect did not correlate with increased immature neuron activity but instead correlated with increased numbers of calretinin-positive and doublecortin-positive immature neurons. This increase in neurogenesis was associated with a decrease in bone morphogenetic protein (BMP) signaling, a known inhibitor of neurogenesis. Injection of a BMP4-expressing lentivirus into the dentate gyrus maintained BMP signaling in the niche and blocked the sustained - but not the rapid - behavioral effects of ketamine, indicating that decreased BMP signaling is necessary for ketamine's sustained effects. Thus, although the rapid effects of ketamine result from increased activity of immature neurons in the dentate gyrus without requiring an increase in neurogenesis, ketamine's sustained effects require a decrease in BMP signaling and increased neurogenesis along with increased neuron activity. Understanding ketamine's dual mechanisms of action should help with the development of new rapid-acting therapies that also have safe, reliable, and sustained effects.

Comparable studies

Other preclinical and animal studies on ketamine, most cited first.

Study Year Design Participants
mTOR-Dependent Synapse Formation Underlies the Rapid Antidepressant Effects of NMDA Antagonists Rats 2010 Observational study
Activation of Glutamatergic Neurotransmission by Ketamine: A Novel Step in the Pathway from NMDA Receptor Blockade to Dopaminergic and Cognitive Disruptions Associated with the Prefrontal Cortex Conscious rats 1997 Dose-response study with microdialysis and behavioral testing
NMDAR inhibition-independent antidepressant actions of ketamine metabolites Mice 2016 Preclinical study
The dissociative anaesthetics, ketamine and phencyclidine, selectively reduce excitation of central mammalian neurones by N‐methyl‐aspartate Spinal neurons in decerebrate or pentobarbitone-anaesthetized cats and rats 1983 Experimental study
R-ketamine: a rapid-onset and sustained antidepressant without psychotomimetic side effects Mice 2015 Experimental study

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Ketamine Neuroplasticity Esketamine