Lack of persistent effects of ketamine in rodent models of depression
Popik P, Kos T, Sowa-Kucma M, Nowak G.
Behavioral Neuroscience and Drug Development,
Institute of Pharmacology,
Polish Academy of Sciences,
12 Smetna Street, 31-343 Kraków, Poland.
[email protected]
Psychopharmacology (Berl). 2008 Jun;198(3):421-30.


RATIONALE: We investigated the immediate and enduring effects of ketamine in behavioral and neurochemical assays predictive of antidepressant activity. MATERIALS AND METHODS: One week after a single administration of ketamine (50-160 mg/kg), otherwise experimentally naive rats and mice were tested either in the forced swim test (FST) or the tail suspension test (TST). Other mice were also tested twice in the FST: immediately and 2 weeks after a single dose (1.25-50 mg/kg) of ketamine. In the next series of experiments, rats treated for 2 weeks twice daily with ketamine (50 or 160 mg/kg) or desipramine (10 mg/kg) were challenged with apomorphine and scored for locomotor activity and assayed for the density of cortical beta-adrenoceptors. The latter test was also carried out in rats that had received a single dose of ketamine (50 mg/kg) 1 week before the assay. The antidepressant-like (FST) and locomotor effects of ketamine (50 mg/kg) and desipramine (10 mg/kg) were assessed after their chronic (2 weeks, twice daily) administration as well. RESULTS: We report the lack of enduring antidepressant-like effect of ketamine in both rats and mice. A 2-week treatment with ketamine neither changed apomorphine-evoked locomotor hyperactivity nor did it decrease the density of cortical beta-adrenoceptors. However, some tolerance to the antidepressant-like effect of ketamine was noted in the FST, but it was accompanied by sensitization to its locomotor stimulatory effects. CONCLUSIONS: These data indicate that ketamine neither produces enduring antidepressant-like effects in rodents nor does it display antidepressant-like behavioral or neurochemical effects after chronic treatment.

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