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Eur J Pharmacol. 2000 Apr 21;395(1):23-9.

Effect of acute treatment with YM992 on extracellular serotonin levels in the rat frontal cortex.

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Neuroscience Research, Pharmacology Laboratories, Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co., Ltd., 21 Miyukigaoka, Tsukuba, Japan.


(S)-2-[[(7-fluoroindan-4-yl)oxy]methyl]morpholine monohydrochloride (YM992) is a novel putative antidepressant exhibiting both selective serotonin (5-hydroxytryptamine, 5-HT) reuptake inhibition and 5-HT(2A) receptor antagonism. In vivo microdialysis revealed that a single treatment with YM992 (3, 10, 30 mg/kg i.p.) dose-dependently increased extracellular 5-HT levels in the rat frontal cortex. Fluoxetine, citalopram and venlafaxine also produced significant increases in 5-HT levels at doses of 10-30 mg/kg. However, the increase in 5-HT levels induced by YM992 was significantly larger than increases elicited by these three compounds at 30 mg/kg. The combined administration of R-(+)-alpha-(2, 3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidine-methanol (MDL100,907) (a selective 5-HT(2A) receptor antagonist) and citalopram produced no additional increase in 5-HT levels compared with citalopram treatment alone. YM992 moderately enhanced [3H]5-HT release from rat cerebral cortex synaptosomes using different mechanisms than p-chloroamphetamine. In comparison, 10-microM fluoxetine markedly induced 5-HT release in vitro, while citalopram and venlafaxine had no noticeable effect on release. YM992 produces a more robust increase of 5-HT levels acutely than other antidepressants in vivo and the effect may be due to 5-HT releasing properties of the drug.

[Indexed for MEDLINE]

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