Molecular profile of dissociative drug ketamine in relation to its rapid antidepressant action.

Background: The NMDA receptor antagonist ketamine was found to act as a fast-acting antidepressant. The effects of single treatment were reported to persist for days to weeks, even in otherwise treatment-refractory cases. Identification of the mechanisms underlying ketamine's antidepressant action may permit development of novel drugs, with similar clinical properties but lacking psychotomimetic, sedative and other side effects.

Methods: We applied whole-genome microarray profiling to analyze detailed time-course (1, 2, 4 and 8 h) of transcriptome alterations in the striatum and hippocampus following acute administration of ketamine, memantine and phencyclidine in C57BL/6 J mice. The transcriptional effects of ketamine were further analyzed using next-generation sequencing and quantitative PCR. Gene expression alterations induced by the NMDA antagonists were compared to the molecular profiles of psychotropic drugs: antidepressants, antipsychotics, anxiolytics, psychostimulants and opioids.

Results: We identified 52 transcripts (e.g. Dusp1, Per1 and Fkbp5) with altered expression (FDR < 1 %) in response to treatment with NMDA receptor antagonists. Functional links that connect expression of the regulated genes to the MAPK, IL-6 and insulin signaling pathways were indicated. Moreover, ketamine-regulated expression of specific gene isoforms was detected (e.g. Tsc22d3, Sgk1 and Hif3a). The comparison with other psychotropic drugs revealed that the molecular effects of ketamine are most similar to memantine and phencyclidine. Clustering based on expression profiles placed the NMDA antagonists among fluoxetine, tianeptine, as well as opioids and ethanol.

Conclusions: The identified patterns of gene expression alteration in the brain provided novel molecular classification of ketamine. The transcriptional profile of ketamine reflects its multi-target pharmacological nature. The results reveal similarities between the effects of ketamine and monoaminergic antidepressants that may explain the mechanisms of its rapid antidepressant action.