Postsynaptic 5-hydroxytryptamine(1A) receptor activation increases in vivo dopamine release in rat prefrontal cortex
by
Sakaue M, Somboonthum P, Nishihara B,
Koyama Y, Hashimoto H, Baba A, Matsuda T
Laboratory of Molecular Neuropharmacology,
Graduate School of Pharmaceutical Sciences,
Osaka University,
1-6 Yamado-oka, Suita, Osaka 565-0871 Japan.
Laboratory of Medicinal Pharmacology,
Graduate School of Pharmaceutical Sciences,
Osaka University,
1-6 Yamado-oka, Suita,
Osaka 565-0871 Japan.
Br J Pharmacol 2000 Mar 5; 129(5):1028-1034

ABSTRACT

5-Hydroxytryptamine (5-HT) plays a role in the regulation of 3,4-dihydroxyphenylethylamine (dopamine) neurons in the brain, but the precise mechanism of regulation by 5-HT(1A) receptors of dopamine release has not been defined. The present study describes the effect of 5-{3-[[(2S)-1,4-benzodioxan-2ylmethyl]amino]propoxy}-1,3-benzodioxole HCl (MKC-242), a highly potent and selective 5-HT(1A) receptor agonist, on dopamine release in the prefrontal cortex using microdialysis in the freely moving rat. Subcutaneous injection of MKC-242 (0.3 - 1.0 mg kg(-1)) increased extracellular levels of dopamine in the prefrontal cortex. The effect of MKC-242 in the prefrontal cortex was antagonized by pretreatment with the selective 5-HT(1A) receptor antagonist, N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl)cyclohexanecarboxamide (WAY100635; 1 mg kg(-1), i.p.). Local application of WAY100635 (10 muM) via a microdialysis probe antagonized the effect of systemic MKC-242 in an increasing dopamine release, and locally infused 8-hydroxy-2-(di-n-propylamino)tetralin (10 muM) increased dopamine release in the prefrontal cortex. MKC-242 increased cortical dopamine release in the rats pretreated with 5,7-dihydroxytryptamine (150 mug, i.c.v.) that caused an almost complete reduction in cortical 5-HT content. The effect of MKC-242 to increase dopamine release was also observed in the hippocampus, but not in the striatum or nucleus accumbens. Fluoxetine, a selective serotonin reuptake inhibitor, increased dopamine release in the prefrontal cortex, but not in the nucleus accumbens, while buspirone, a 5-HT(1A) receptor agonist, increased dopamine release in both brain regions. The present results indicate that activation of postsynaptic 5-HT(1A) receptors increases dopamine release in a brain region-specific manner.

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