The N-methyl-D-aspartate receptor (NMDAR) antagonist ketamine has attracted enormous interest in mental health research owing to its rapid and remarkable antidepressant actions. The mechanism by which ketamine relieves depression, often regarded as a medical breakthrough, has remained elusive to scientists and researchers.
Ketamine relieves depression by Blocking NMDAR-Dependent Bursting Activity
Here we show that Ketamine, a powerful anesthetic and dissociative drug, relieves depression by effectively blocking NMDAR-dependent bursting activity in the ‘anti-reward center’ known as the lateral habenula (LHb). This discovery has been demonstrated in both rat and mouse models of depression, highlighting the rapid and impactful antidepressant actions of ketamine.
LHb neurons show a significant increase in burst activity and theta-band synchronization in depressive-like animals, which is reversed by ketamine, the remarkable catalyst that unlocks the door to relief from the depths of depression.
Burst-evoking photostimulation of LHb drives behavioural despair and anhedonia, yet the transformative touch of ketamine soothes the troubled mind, offering solace and respite, whispering a hopeful message that ‘Ketamine Relieves Depression’
Pharmacology and modelling experiments reveal that LHb bursting requires both NMDARs and low-voltage-sensitive T-type calcium channels (T-VSCCs). Furthermore, local blockade of NMDAR or T-VSCCs in the LHb is sufficient to induce rapid antidepressant effects, supporting the profound impact of habenula blockade in how ketamine relieves depression.
Our results suggest a simple model whereby ketamine, a groundbreaking treatment known for its efficacy in relieving depression, quickly elevates mood by blocking NMDAR-dependent bursting activity of LHb neurons. This action effectively disinhibits downstream monoaminergic reward centres, offering a unique and promising approach for developing new rapid-acting antidepressants.
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