Featured Paper of the Month – June 2023
Published in Biological Psychiatry by Marjorie Levinstein and Michael Michaelides, et al. of the NIDA IRP Biobehavioral Imaging and Molecular Neuropsychopharmacology Unit.
Summary
Ketamine is a mixture of its two enantiomers, (R)-ketamine and (S)-ketamine, in equal proportion. (S)-ketamine is FDA-approved as a rapid-acting antidepressant. Previously, we found that (S)-ketamine binds to mu opioid receptors (MOR) in vitro. In this study, we show that S-ketamine not only binds to and activates MOR, but that this interaction is critical for its abuse liability. Specifically, we show that the opioid receptor antagonist naltrexone blocks brain activation by (S)-ketamine in the nucleus accumbens, a region crucial for reward, and also decreases lever pressing for (S)-ketamine in rats. We also show that repeated exposure to (S)-ketamine decreases the amount and functioning of MOR throughout the brain. Finally, we found that rats which had been previously exposed to repeated (S)-ketamine subsequently had greater self-administration of heroin. These results suggest that (S)-ketamine’s abuse liability is mediated in part by brain MORs.
Publication Information
Mu Opioid Receptor Activation Mediates (S)-ketamine Reinforcement in Rats: Implications for Abuse Liability Journal Article
In: Biol Psychiatry, vol. 93, no. 12, pp. 1118–1126, 2023, ISSN: 1873-2402.