Université Paris-Saclay, Faculté de Médecine, Inserm UMR 1018, CESP, MOODS Team, 94270 Bicêtre Hospital, 94270 Le Kremin-Bicêtre, France; Service Hospitalo-Universitaire de Psychiatrie de Bicêtre, Assistance Publique-Hôpitaux de Paris, Hôpitaux Universitaires Paris-Saclay, Hôpital de Bicêtre, 94270 Le Kremlin Bicêtre, France.
3 papers in the library · 4 citations · publishing 2024-2025
Ketamine produces rapid and lasting antidepressant effects in depressed patients. A metabolite called (2R,6R)-hydroxynorketamine (HNK) may contribute to these effects. In anxious male mice, blocking the liver enzyme cytochrome P450 with fluconazole before ketamine or HNK altered drug metabolism: it raised ketamine and norketamine levels in blood and brain but sharply reduced HNK levels. Fluconazole also prevented ketamine's sustained antidepressant-like actions in behavioral tests and its enhancement of cortical GABA levels 24 hours after injection. Giving (2R,6R)-HNK alone reversed fluconazole's blockade of ketamine's antidepressant-like activity. The findings suggest that HNK is essential for ketamine's sustained antidepressant effects and that drug interactions with cytochrome P450 inhibitors may affect ketamine treatment in patients.
In a mouse model of anxiety/depression, a single dose of ketamine produced rapid antidepressant effects in behavior tests, but no change in synaptic density was detected by PET imaging 24 hours later. After three weekly doses, ketamine restored synaptic density to healthy control levels, an effect that coincided with delayed antidepressant effects. The PET tracer 11C-UCB-J reliably tracked these changes, and its binding correlated with levels of synaptic proteins. The findings support using SV2A PET imaging to monitor drug-induced rebuilding of brain connections as a marker of antidepressant efficacy.
Ketamine's rapid antidepressant effects in depressed patients may depend on a specific metabolite, (2R,6R)-hydroxynorketamine ((6)-HNK). In male BALB/cJ mice with high anxiety, blocking liver enzymes that break down ketamine (using fluconazole) raised ketamine and norketamine levels in blood and brain but sharply reduced (6)-HNK levels. This blockade prevented ketamine's sustained antidepressant-like effects 24 hours later in behavioral tests and stopped the increase in cortical GABA levels. Giving a single dose of (2R,6R)-HNK alone restored the antidepressant-like activity. The findings indicate that (6)-HNK is essential for ketamine's lasting antidepressant effects and suggest that drug interactions affecting ketamine metabolism could matter in patients.