Ketamine induces plasticity in a norepinephrine-astroglial circuit to promote behavioral perseverance.

Summary

Ketamine's remarkable ability to alter brain circuits offers new insights into perseverance. By studying zebrafish, researchers discovered that brief ketamine exposure changes how norepinephrine interacts with brain cells called astrocytes, creating lasting improvements in motivation. This mood-altering compound prevents animals from "giving up" during challenges, suggesting similar mechanisms might explain its antidepressant effects in humans.

Abstract

Transient exposure to ketamine can trigger lasting changes in behavior and mood. We found that brief ketamine exposure causes long-term suppression of futility-induced passivity in larval zebrafish, reversing the "giving-up" response that normally occurs when swimming fails to cause forward movement. Whole-brain imaging revealed that ketamine hyperactivates the norepinephrine-astroglia circuit responsible for passivity. After ketamine washout, this circuit exhibits hyposensitivity to futility, leading to long-term increased perseverance. Pharmacological, chemogenetic, and optogenetic manipulations show that norepinephrine and astrocytes are necessary and sufficient for ketamine's long-term perseverance-enhancing aftereffects. In vivo calcium imaging revealed that astrocytes in adult mouse cortex are similarly activated during futility in the tail suspension test and that acute ketamine exposure also induces astrocyte hyperactivation. The cross-species conservation of ketamine's modulation of noradrenergic-astroglial circuits and evidence that plasticity in this pathway can alter the behavioral response to futility hold promise for identifying new strategies to treat affective disorders.

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