SB 206553 hydrochloride

5-HT2A and 5-HT2C/2B receptor subtypes modulate dopamine release induced in vivo by amphetamine and morphine in both the rat nucleus accumbens and striatum.[Pubmed:11850146]

Neuropsychopharmacology. 2002 Mar;26(3):311-24.

In vivo microdialysis and single-cell extracellular recordings were used to assess the involvement of serotonin(2A) (5-HT(2A)) and serotonin(2C/2B) (5-HT(2C/2B)) receptors in the effects induced by amphetamine and morphine on dopaminergic (DA) activity within the mesoaccumbal and nigrostriatal pathways. The increase in DA release induced by amphetamine (2 mg/kg i.p.) in the nucleus accumbens and striatum was significantly reduced by the selective 5-HT(2A) antagonist SR 46349B (0.5 mg/kg s.c.), but not affected by the 5-HT(2C/2B) antagonist SB 206553 (5 mg/kg i.p.). In contrast, the enhancement of accumbal and striatal DA output induced by morphine (2.5 mg/kg s.c.), while insensitive to SR 46349B, was significantly increased by SB 206553. Furthermore, morphine (0.1-10 mg/kg i.v.)-induced increase in DA neuron firing rate in both the ventral tegmental area and the substantia nigra pars compacta was unaffected by SR 46349B (0.1 mg/kg i.v.) but significantly potentiated by SB 206553 (0.1 mg/kg i.v.). These results show that 5-HT(2A) and 5-HT(2C) receptors regulate specifically the activation of midbrain DA neurons induced by amphetamine and morphine, respectively. This differential contribution may be related to the specific mechanism of action of the drug considered and to the neuronal circuitry involved in their effect on DA neurons. Furthermore, these results suggest that 5-HT(2C) receptors selectively modulate the impulse flow-dependent release of DA.

In vitro and in vivo profile of SB 206553, a potent 5-HT2C/5-HT2B receptor antagonist with anxiolytic-like properties.[Pubmed:8821530]

Br J Pharmacol. 1996 Feb;117(3):427-434.

1. SB 206553 (5-methyl-1-(3-pyridylcarbamoyl)-1,2,3,5-tetrahydropyrrolo[2 ,3-f]indole) displays a high affinity (pK1 7.9) for the cloned human 5-HT2C receptor expressed in HEK 293 cells and the 5-HT2B receptor (pA2 8.9) as measured in the rat stomach fundus preparation. SB 206553 has low affinity for cloned human 5-HT2A receptors expressed in HEK 293 cells (pK1 5.8) and (pK1 < 6) for a wide variety of other neurotransmitter receptors. 2. SB 206553 appears to be a surmountable antagonist of 5-HT-stimulated phosphoinositide hydrolysis in HEK 293 cells expressing the human 5-HT2C receptor (pKB 9.0). 3. The compound potently (ID50 5.5 mg kg-1, p.o., 0.27 mg kg-1, i.v.) inhibited the hypolocomotor response to m-chlorophenylpiperazine (mCPP), a putative model of 5-HT2C/5-HT2B receptor function in vivo. 4. At similar doses (2-20 mg kg-1, p.o.) SB 206553 increased total interaction scores in a rat social interaction test and increased punished responding in a rat Geller-Seifter conflict test. These effects are consistent with the possession of anxiolytic properties. 5. SB 206553 also increased suppressed responding in a marmoset conflict model of anxiety at somewhat higher doses (15 and 20 mg kg-1, p.o.) but also reduced unsuppressed responding. 6. These results suggest that SB 206553 is a potent mixed 5-HT2C/5-HT2B receptor antagonist with selectivity over the 5-HT2A and all other sites studied and possesses anxiolytic-like properties.

5-Methyl-1-(3-pyridylcarbamoyl)-1,2,3,5-tetrahydropyrrolo[2,3-f]indole: a novel 5-HT2C/5-HT2B receptor antagonist with improved affinity, selectivity, and oral activity.[Pubmed:7629791]

J Med Chem. 1995 Jul 7;38(14):2524-30.

The preparation of a series of conformationally restricted analogues of indolylurea 1, namely tetrahydropyrroloindoles and tetrahydropyrroloquinolines, is described. The binding affinities of these compounds at 5-HT2A, 5-HT2B, and 5-HT2C receptors were determined. Of these compounds, the 1,2,3,5-tetrahydropyrrolo[2,3-f]indole derivative, compound 11, was found to have high affinity for the 5-HT2C (pKI 8.0) and 5-HT2B receptors (pA2 8.5), with excellent selectivity over the 5-HT2A and various other receptors (pKI < 6). 11 is also considerably more active than 1 in both an in vitro functional model, 5-HT-stimulated phosphoinositol hydrolysis (pKB 8.8), and an in vivo functional model, mCPP-induced hypolocomotion (ID50 5.5 mg/kg po). 11 should therefore be of significant utility as a pharmacological tool to delineate the functional significance of blockade of 5-HT2B and 5-HT2C receptors.