Proteomic Study Reveals the Involvement of Energy Metabolism in the Fast Antidepressant Effect of (2R, 6R)-Hydroxy Norketamine

Purpose: Depression is a major disabling psychiatric disorder which causes severe financial burden and social consequences worldwide. Recently, (2R, 6R)-hydroxynorketamine (HNK), a metabolite of ketamine, showed strong antidepressant effect through N-methyl-D-aspartate (NMDA) antagonizing independent mechanism. In the current study the goal is to identify the potential intracellular molecules and pathways that might be involved in different therapeutic effects underlying HNK as compared to NMDA antagonist MK-801.

Experimental design: Forced-swim behavioral test, 2D fluorescence difference gel electrophoresis, and MALDI-TOF-MS/MS proteomics are used.

Results: Compared to saline group, 14 differential proteins are identified in MK-801 treated group, with six proteins significantly up-regulated, while in HNK treated group 18 distinct proteins are identified with 11 proteins significantly up-regulated. Likewise, two proteins are significantly upregulated in HNK treated group when compared to MK-801 treated group. Among these differentially expressed proteins, phosphoglycerate mutase 1, malate dehydrogenase/ cytoplasmic, and triosephosphate isomerase are co-affected by MK-801 and HNK treatment. Representative protein expression changes are quantified by western blot, showing consistent results as determined by MALDI-TOF-MS/MS.

Conclusion and clinical relevance: The core protection mechanisms of HNK observed herein involves improving the abnormal ATP synthesis, impaired glycolysis, and the defense system therefore provides mechanistic insight and molecular targets for novel antidepressants.