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Ameliorating treatment-refractory depression with intranasal ketamine: potential NMDA receptor actions in the pain circuitry representing mental anguish
Published online by Cambridge University Press: 26 January 2015
Abstract
This article reviews the antidepressant actions of ketamine, an N-methyl-D-aspartame glutamate receptor (NMDAR) antagonist, and offers a potential neural mechanism for intranasal ketamine’s ultra-rapid actions based on the key role of NMDAR in the nonhuman primate prefrontal cortex (PFC). Although intravenous ketamine infusions can lift mood within hours, the current review describes how intranasal ketamine administration can have ultra-rapid antidepressant effects, beginning within minutes (5–40 minutes) and lasting hours, but with repeated treatments needed for sustained antidepressant actions. Research in rodents suggests that increased synaptogenesis in PFC may contribute to the prolonged benefit of ketamine administration, beginning hours after administration. However, these data cannot explain the relief that occurs within minutes of intranasal ketamine delivery. We hypothesize that the ultra-rapid effects of intranasal administration in humans may be due to ketamine blocking the NMDAR circuits that generate the emotional representations of pain (eg, Brodmann Areas 24 and 25, insular cortex), cortical areas that can be overactive in depression and which sit above the nasal epithelium. In contrast, NMDAR blockade in the dorsolateral PFC following systemic administration of ketamine may contribute to cognitive deficits. This novel view may help to explain how intravenous ketamine can treat the symptoms of depression yet worsen the symptoms of schizophrenia.
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- Review Article
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- © Cambridge University Press 2015
Footnotes
This work is dedicated to the memory of Daniel Friedland, with the hope that we may discover more effective treatments to alleviate suffering. This work was funded in part by NIH Pioneer Award DP1AG047744 to AFTA. The authors would like to thank Drs. G. Aghajanian, R. Duman, J. Krystal, H. Mayberg, J. Murrough, G. Sanacora, and J. Singh for informative and inspiring discussions.
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