Brain region-specific action of ketamine as a rapid antidepressant.
Science (New York, N.Y.) – August 09, 2024
Source: PubMed
Summary
Ketamine's remarkable antidepressant effects stem primarily from its action in a specific brain region called the lateral habenula, rather than affecting the entire brain equally. The drug works by blocking certain receptors more effectively in this area, which acts like a master switch for mood regulation. This targeted action triggers a cascade of positive changes, including increased serotonin and growth factors in other brain regions, ultimately lifting depression symptoms rapidly.
Abstract
Ketamine has been found to have rapid and potent antidepressant activity. However, despite the ubiquitous brain expression of its molecular target, the N-methyl-d-aspartate receptor (NMDAR), it was not clear whether there is a selective, primary site for ketamine's antidepressant action. We found that ketamine injection in depressive-like mice specifically blocks NMDARs in lateral habenular (LHb) neurons, but not in hippocampal pyramidal neurons. This regional specificity depended on the use-dependent nature of ketamine as a channel blocker, local neural activity, and the extrasynaptic reservoir pool size of NMDARs. Activating hippocampal or inactivating LHb neurons swapped their ketamine sensitivity. Conditional knockout of NMDARs in the LHb occluded ketamine's antidepressant effects and blocked the systemic ketamine-induced elevation of serotonin and brain-derived neurotrophic factor in the hippocampus. This distinction of the primary versus secondary brain target(s) of ketamine should help with the design of more precise and efficient antidepressant treatments.